RUS  ENG JOURNALS   PEOPLE   ORGANISATIONS   CONFERENCES   SEMINARS   VIDEO LIBRARY   PACKAGE AMSBIB
General information
Latest issue
Archive

Search papers
Search references

RSS
Latest issue
Current issues
Archive issues
What is RSS



Dokl. Akad. Nauk:
Year:
Volume:
Issue:
Page:
Find






Personal entry:
Login:
Password:
Save password
Enter
Forgotten password?
Register

Archive

| table | by volume |

 Author Index

 Dokl. Akad. Nauk SSSR, Volume 112 (1957)

 Dokl. Akad. Nauk SSSR, Volume 113 (1957)

 Dokl. Akad. Nauk SSSR, Volume 114 (1957)

 Dokl. Akad. Nauk SSSR, Volume 115 (1957)

 Dokl. Akad. Nauk SSSR, Volume 116 (1957)

 Dokl. Akad. Nauk SSSR, Volume 117 (1957)

 Dokl. Akad. Nauk SSSR, Volume 118 (1958)

 Dokl. Akad. Nauk SSSR, Volume 119 (1958)

 Dokl. Akad. Nauk SSSR, Volume 120 (1958)

 Dokl. Akad. Nauk SSSR, Volume 121 (1958)

 Dokl. Akad. Nauk SSSR, Volume 122 (1958)

 Dokl. Akad. Nauk SSSR, Volume 123 (1958)

 Dokl. Akad. Nauk SSSR, Volume 130 (1960)

 Dokl. Akad. Nauk SSSR, Volume 131 (1960)

 Dokl. Akad. Nauk SSSR, Volume 132 (1960)

 Dokl. Akad. Nauk SSSR, Volume 133 (1960)

 Dokl. Akad. Nauk SSSR, Volume 134 (1960)

 Dokl. Akad. Nauk SSSR, Volume 135 (1960)

 Dokl. Akad. Nauk SSSR, Volume 136 (1961)

 Dokl. Akad. Nauk SSSR, Volume 137 (1961)

 Dokl. Akad. Nauk SSSR, Volume 138 (1961)

 Dokl. Akad. Nauk SSSR, Volume 139 (1961)

 Dokl. Akad. Nauk SSSR, Volume 140 (1961)

 Dokl. Akad. Nauk SSSR, Volume 141 (1961)

 Dokl. Akad. Nauk SSSR, Volume 142 (1962)

 Dokl. Akad. Nauk SSSR, Volume 143 (1962)

 Dokl. Akad. Nauk SSSR, Volume 144 (1962)

 Dokl. Akad. Nauk SSSR, Volume 145 (1962)

 Dokl. Akad. Nauk SSSR, Volume 146 (1962)

 Dokl. Akad. Nauk SSSR, Volume 147 (1962)

 Dokl. Akad. Nauk SSSR, Volume 148 (1963)

Dokl. Akad. Nauk SSSR, Volume 149 (1963)

Number 1
MATHEMATICS
Applications of the dispersion method in binary additive problems
B. M. Bredikhin
9
Functor operations on the class of all groups
O. N. Golovin
12
Unified methods of information transmission. The general case
R. L. Dobrushin
16
Distributions of polynomial statistics in samples from a normal population
A. A. Zinger
20
Absolutes of Hausdorff spaces
S. Iliadis
22
On the absolute of a topological space
V. Ponomarev
26
On the statistics of related trials
M. Rosenblatt-Roth
30
Scales of Orlicz spaces and interpolation theorems
Ya. B. Rutitskii
32
Nomograms and webs
S. V. Smirnov
36
The density of compactly supported functions in the space $L_p^{(m)}(E_n)$
S. L. Sobolev
40
Functors in categories of Banach spaces
A. S. Schwarz
44
Estimates in $L_p$ of solutions of elliptic equations with discontinuous coefficients and satisfying general boundary conditions and conjugacy conditions
Z. G. Sheftel
48

CYBERNETICS AND THE REGULATION THEORY
Remark on a finite-automaton game with an opponent using a mixed strategy
M. L. Tsetlin
52

MECHANICS
An investigation of three dimensional work of compound constructions
B. P. Vol'fson
54
Optimal conditions for the motion of a point of variable mass in a homogeneous central field
G. E. Kuzmak, V. K. Isaev, B. Kh. Davidson
58

THEORY OF ELASTICITY
Small deformations, stability md oscillations of unsymmetrical plates composed of three layers with a rigid filler
È. I. Grigolyuk, P. P. Chulkov
62

ASTRONOMY
Radioastronomic observation of Venus with high resolution
D. V. Korol'kov, Yu. N. Pariiskii, G. M. Timofeeva, S. E. Khaikin
65

PHYSICS
Concerning the entropy expression of the uncertainty principle
D. A. Bochvar, I. V. Stankevich, A. L. Chistyakov
68
Excitation of the hypersound by slow electromagnetic waves
E. M. Ganapol'skii, A. N. Chernets
72
The method of group integrals in scattering problems
O. A. Germogenova
76
A study of the analytic properties of ladder diagrams by the method of complex orbital angular momenta
R. M. Muradyan
80
Calculation of the stationary value of a reversible photodichroism of viscous solutions
O. V. Stolbova
84

CHEMISTRY
The “cosymmetrization” reaction of organomercuric salts
I. P. Beletskaya, G. A. Artamkina, O. A. Reutov
90
The mechanism of enamines condensation with aldehydes
N. V. Volkova, A. A. Yasnikov
94
The photoreaction of hexafluoroazomethane with unsaturated compounds
V. A. Ginsburg, E. S. Vlasova, M. N. Vasil'eva, N. S. Mirzabekova, S. P. Makarov, A. I. Shchekotikhin, A. Ya. Yakubovich
97
Translocation of the methyl group in a toluene molecule under the influence of aluminium bromide and hydrogen bromide
V. A. Koptyug, I. S. Isaev, N. N. Vorozhtsov (jr.)
100
An investigation of the reaction by which polybenzimidazoles are formed
V. V. Korshak, T. M. Frunze, V. V. Kurashev, A. A. Izyneev
104
The structural characters of the breakdown of lower oxides in slags
L. N. Rusakov, A. S. Dubrovin
107
Absorption spectrum of some ferrocene derivatives
B. M. Yavorskii, N. S. Kochetkova, G. B. Zaslavskaya, A. N. Nesmeyanov
111

PHYSICAL CHEMISTRY
Evaporation coefficients of liquid $\mathrm{C}_2\mathrm{H}_5\mathrm{OH}$, $\mathrm{BCl}_3$, $\mathrm{BF}_3$, $\mathrm{CH}_4$
I. B. Amirkhanova, A. V. Borisov, I. G. Gverdtsiteli, A. T. Karamyan, R. Ya. Kucherov
114
Equilibrium diagram of the $\mathrm{Tl}_2\mathrm{Te}_3$$\mathrm{Bi}_2\mathrm{Te}_3$ system and the properties of the alloys obtained
L. A. Borisova, M. V. Efremova, V. V. Vlasov
117
Theory of irreversible processes on a spherical electrode
E. Budevskii, G. Desimirov
120
Chemiluminescence activated by anthracene derivatives
R. F. Vasil'ev, A. A. Vichutinsky, A. S. Cherkasov
124
Heat effects produced by the solution of polymers, as dependent on the nature of the solvent
M. P. Zverev, S. P. Ruchinskii, P. I. Zubov
128
Adsorption of polydimethylsiloxane from solution by aerosil (highly dispersed non-porous silicon)
A. V. Kiselev, V. N. Novikova, Yu. A. El'tekov
131
Spectral characteristics and scintillation properties of certain 2-arylderivatives of benzoxazole and benzimidazole
L. N. Pushkina, V. V. Tkachev, I. Ya. Postovskii
135
An investigation of hydrogen overvoltage on solid and liquid hallium in a sulphuric acid solution
K. Sabo, I. A. Bagotskaya
139
The sensibilization of the photoreaction of alcohol dehydrogenation at $77^\circ$ K investigated by means of electron spin resonance
V. E. Kholmogorov, È. V. Baranov, A. N. Terenin
142

Number 2

MATHEMATICS
Elliptic boundary-value problems depending on a parameter
M. S. Agranovich, M. I. Vishik
223
Optimal quadrature formulae
Ivo Babushka
227
Semigroups which are prescribed by identities
A. P. Biryukov
230
Complex structures of a class of Kaehler–Rasevskii spaces
V. V. Vishnevskii
233
Laplace sequences of generalized conjugate Rozet nets of projective $N$-space
V. V. Goldberg
237
The classes $\mathbf{L}_{(p_1,p_2,…,p_k)}(\Omega_m)$ and an imbedding theorem for abstract set functions
A. H. Gudiev
241
A mean-value theorem
A. A. Karatsuba, N. M. Korobov
245
Lie algebras with regular automorphisms
V. A. Kreknin, A. I. Kostrikin
249
Application of complex variables to the study of the Behrens–Fisher problem
Yu. V. Linnik
252
The eigenfunction expansion of a non-selfadjoint differential operator with spectral singularities
V. È. Lyantse
256
Spectral criteria for the stability of solutions of linear differential equations with periodic coefficients
Z. I. Rekhlitskii
260
On a theorem of Vietoris and Begle
E. G. Sklyarenko
264
Variational problems for the optimization of control processes with functionals depending on intermediate values of the coordinates
V. A. Troitskii
268
Determination of a convergence class for an interpolation series for the Abel–Goncarov and Gelĺfond problems
M. I. Shabunin
272
Some problems in the oscillation of solutions of nonlinear, non-autonomous second-order equations
V. N. Chevelo, V. G. Shtelik
276
On the concept of a stochastic normalized space
A. N. Sherstnev
280

CYBERNETICS AND THE REGULATION THEORY
Examples of games with automata
M. L. Tsetlin, V. Yu. Krylov
284
Frequency conditions for absolute stability of control systems with hysteresis-like non-linearities
V. A. Yakubovich
288

MECHANICS
Some integrability cases for the equations of gyrostat motion
L. N. Sretenskii
292

THE MECHANICS OF CONTINUOUS MEDIUM
A system of defining parameters characterizing the geometrical properties of an anisotropic medium
V. V. Lokhin
295

MATHEMATICAL PHYSICS
The relationship between classical mechanics and wave mechanics
Yu. P. Pyt'ev
298

PHYSICS
An investigation of electric charges arising on the deformation of polymers
V. E. Gul', G. A. Lushcheikin, B. A. Dogadkin
302
Calculation of frequencies and shapes of normal molecular vibrations by the perturbation method
B. L. Livshits
305
Einstein's tensor of the fourth rank
I. G. Fikhtengol'ts
308

CHEMISTRY
Stepped formation of compounds with a stanno-oxane bond and reactive end groups
N. N. Zemlyansky, E. M. Panov, N. A. Slovokhotova, O. P. Shamagina, K. A. Kocheshkov
312
Addition of trialkylphosphites to acetylcarboxylic acids
K. M. Kirillova, V. A. Kukhtin, T. M. Sudakova
316
The synthesis of new mixed organogermanium compounds of types $(\mathrm{C}_6\mathrm{H}_5)_3\mathrm{GeR}$ and $(\mathrm{C}_6\mathrm{H}_5)_3\mathrm{Ge}$$\mathrm{C}_6\mathrm{H}_4\mathrm{X}$
Z. M. Manulkin, A. B. Kuchkarov, S. A. Sarankina
318
Radicals – products of thermal decomposition of substituted cyclohexadienone peroxide
V. D. Pokhodenko, L. N. Ganyuk, A. I. Brodskii
321
The thermochemistry of tetraethylgermanium and hexaethyldigermanium
I. B. Rabinovich, V. I. Tel'noy, N. V. Karyakin, G. A. Razuvaev
324
Polymers and copolymers of ferrocene derivatives obtained by polyrecombination
S. L. Sosin, V. V. Korshak, V. P. Alekseeva
327
The ion mechanism behind the nitration of unsaturated compounds. Nitrofluorination of defines and their halogen substitutes
A. I. Titov
330
The synthesis of high molecular amides and hydrazides of penicillins
S. N. Ushakov, E. F. Panarin
334
Fluoroolefine polymerization initiated by irradiation
V. A. Khramchenkov
338
The formation energy of an $\mathrm{H}$-bound quasiaromatic cycle as determined from molecular infra-red spectrum data
D. N. Shigorin, A. P. Skoldinov, T. S. Ryabchikova
341
Thiol-disulphide exchange in polysulfide polymers
R. A. Schlachter, N. P. Apukhtina, T. P. Nasonova
345
The stability of the complete compounds of transition metals
E. A. Shugam
348

PHYSICAL CHEMISTRY
The possible reason for the divergence of isotope vapour pressure ratios at equilibrium as measured by the differential method and by Rayleigh's method
I. B. Amirkhanova, A. V. Borisov, I. G. Gverdtsiteli, R. Ya. Kucherov
351
The discrete nature of the impurity-induced spectral sensitivity of the photographic emulsions
J. L. Brown, Y. A. Kirillov, K. V. Chibisov
353
The influence of iodine on the electric properties of the products formed by a radiation-thermal modification of polyethylene
A. V. Vannikov, N. A. Bakh
357
Crystallization from gaseous phase by chemical means
E. I. Givargizov
360
Electron spin resonance spectrum of a hydrated electron in irradiated frozen alkaline solutions
B. G. Ershov, A. K. Pikaev, P. Ya. Glazunov, Vikt. I. Spitsyn
363
A stationary solution to a system of equations in the theory of burning
Ya. I. Kanel'
367
Transition of plane structures of isotactic polystyrene in spherulite
V. A. Kargin, T. A. Koretskaya, T. A. Bogaevskaya
370
The influence of paramagnetic ions on the magnetic relaxation of fluorine nuclei in solution
A. A. Popel, E. D. Grazhdannikov
371
On the nature of substances with intermolecular hydrogen bond
M. I. Shakhparonov
374

Number 3

MATHEMATICS
Solution of an infinite system of linear algebraic equations in a class of increasing sequences
F. D. Berkovich
495
Irreducible unitary representations of the group of second-order unimodular matrices with elements in a locally compact field
I. M. Gel'fand, M. I. Graev
499
On a generalization of the notion of periodic continuation
V. D. Golovin
502
Singularities of fundamental solutions of partial differential equations with constant coefficients
V. A. Golubeva
505
A problem of S. L. Sobolev and S. M. Nikolʹskiĭ for the limiting exponent
A. H. Gudiev
509
The number of divisors in an angle
Laĭ Dyk Thin'
513
Application of the method of nets to a hyperbolic system of quasi-linear equations on the plane
A. Ya. Lepin
516
On the asymptotics of the distribution of a maximum likelihood statistic
Yu. V. Linnik, N. M. Mitrofanova
518
A boundary-value problem on the axis for an $n$th-order non-linear equation
G. Ya. Lyubarskii
521
Measures in a function space and difference schemes
E. V. Maikov, S. V. Fomin
525
On the stability of difference schemes
A. N. Tikhonov, A. A. Samarskii
529
Series with respect to the Haar system
P. L. Ul'yanov
532
The first boundary-value problem for non-linear parabolic equations
S. I. Khudyaev
535
Best-approximation problems in random normed spaces
A. N. Sherstnev
539
The semigroup of group varieties
A. L. Shmel'kin
543

CYBERNETICS AND THE REGULATION THEORY
Charge distribution at the vertices of a unit $n$-dimensional cube
B. S. Zil'berman
546

FLUID MECHANICS
Symmetric magnetohydrodynamic flow
L. S. Solov'ev, A. I. Morozov
550

MATHEMATICAL PHYSICS
Diffusion from an instantaneous source in a gravitational field
A. S. Kompaneets
554

PHYSICS
Kinetic equation of a nonideal Fermi system
I. B. Aleksandrov, Yu. A. Kukharenko, A. W. Niukkanen
557
Use of optical quantum generator for the excitation of recombination luminescence in semicondustors
N. G. Basov, L. M. Lisitsyn, B. D. Osipov
561
Spectral distribution of chlorophyll-$\mathrm{a}$ photoconductivity as dependent on the thickness of the chlorophyll layer
A. T. Vartanyan
563
Determination of the spectral distribution of the Gudden–Pohl flash in zinc sulfide phosphors
A. G. Gol'dman, A. I. Proskura
567
Investigation of optical oscillator on ruby at liquid-nitrogen temperature
V. K. Konyukhov, L. A. Kulevskii, A. M. Prokhorov
571
Low-temperature expansions in the ferromagnetism theory
S. V. Tyablikov
573

GEOPHYSICS
An investigation of elastic waves speeds in rock samples under joint action of allround and uniaxial compression
M. P. Volarovich, D. B. Balashov, I. S. Tomashevskaya, V. A. Pavlogradskii
583

ELECTRICAL ENGINEERING
Complex steady motions in nonlinear sampled-data systems
M. M. Simkin
586

CHEMISTRY
The solubility of three-calcium silicate in calcium chloride solutions
E. P. Andreeva, E. E. Segalova
589
Products of the thermal decomposition of anhydrous perchloric acid
V. P. Babaeva, A. A. Zinov'ev
592
An investigation of the copolymerization of butadiene with isoprene in the presence of various iontype catalysts
L. S. Bresler, B. A. Dolgoplosk, E. N. Kropacheva
595
Thermal stability of $\mathrm{ScF}_3$ and its interaction with $\mathrm{MgF}_2$
L. N. Komissarova, B. I. Pokrovskii
599
The synthesis of polypyrazoles
V. V. Korshak, E. S. Krongauz, A. N. Berlin, P. N. Gribkova
602
The influence of molecular oxygen on the breakdown of the main chain in polymethylsiloxane rubber
A. S. Kuzminskii, E. A. Goldovskii
606
Solubility of sodium borohydride in pyridine
V. I. Mikheeva, L. V. Titov
609
Some regularities in the complexing of pentavalent actinide elements
A. I. Moskwin, I. Geletseanu, A. V. Lapitskii
611
Exchange of ligands in ferrocene
A. N. Nesmeyanov, N. A. Vol'kenay, I. N. Bolesova
615
Nitrozochlorination of olefines and their derivatives by ionic mechanism. Anomalous addition to chlorethylenes
A. I. Titov
619

PHYSICAL CHEMISTRY
On spin detonation
A. A. Borisov, S. M. Kogarko
623
The structure of radioactive precipitates
V. V. Gromov
626
Homogeneous and heterogeneous crystallization of carbon
V. I. Kasatochkin, G. B. Finkelstein
629
Formation of micells in solutions of surface-active substances and kinetic wetting
L. M. Levitsky, S. A. Nikitina, A. B. Taubman
633
Proton relaxation time as influenced by the symmetry of the paramagnetic complex
A. A. Popel, R. A. Dautov, A. V. Zakharov
637
Dissociation constant values of carbonic acid at elevated temperatures
B. N. Ryzenko
639
Light emission by low rate detonation front in nitroglycerin
G. S. Sosnova, I. M. Voskoboinikov, A. V. Dubovik
642
The kinetics of the cumene cracking on zeolite $10\mathrm{X}$
K. V. Topchieva, B. V. Romanovskii, Thoang Ho-chi
644

Number 4

MATHEMATICS
Extremum problems with certain constraints
A. Ya. Dubovitskii, A. A. Milyutin
759
Stratification of two-parameter families of straight lines in a higher-dimensional projective space
K. I. Dunichev
763
Conjugate functions of two variables and double Fourier series
L. V. Zhizhiashvili
765
On the spectrum of Toeplitz matrices
R. S. Ismagilov
769
Invariants and canonical representations of quadrics in quasi-elliptic spaces
S. L. Pevzner
773
A Wiener–Hopf type equation for higher-dimensional random processes with a rational spectral density
V. F. Pisarenko
776
The isolated singular point on a surface with regular metric and negative curvature
È. R. Rozendorn
780
Comparison of bases for the realization by formulas of functions of an algebra of logic
B. A. Subbotovskaya
784
On the method of tangent hyperbolas
R. A. Shafiev
788
On the theory of general boundary-value problems for parabolic systems
S. D. Èidel'man
792

MECHANICS
Description of point groups of symmetry with the help of tensors
L. I. Sedov, V. V. Lokhin
796

FLUID MECHANICS
Stability of Chapmen–Juge detonation
V. V. Pukhnachov
798

THEORY OF ELASTICITY
Stability of a compressed plate with allowance for the rotation angles
I. D. Legenya
802
Transcritical deformations of bondedly elastic shells
A. V. Pogorelov
806

MATHEMATICAL PHYSICS
Analytic properties of contributions from Feynman diagrams
D. Ya. Petrina
808

PHYSICS
Activation energy of dark conductivity and photoconductivity of chlorophyll $\mathrm{a}$
A. T. Vartanyan
812
The effect of indium irradiation by thermal neutrons upon the molecular composition of indium vapour
E. G. Shvidkovskii, G. M. Martynkevich, G. V. Malyarova
816

GEOPHYSICS
On the determination of the initial pressure and wind fields from distributions of temperature and vertical motions of air
E. N. Blinova
824
Internal waves in an ocean inhomogeneous with respect to density
B. A. Tareev
827

ELECTRICAL ENGINEERING
Two-pole diode grids
V. V. Obraztsov
831

CHEMISTRY
Nuclear magnetic resonance spectra and the ebullioscopy of lithium alcoholates
I. B. Golovanov, A. P. Simonov, A. K. Piskunov, T. V. Talalaeva, G. V. Tsareva, K. A. Kocheshkov
835
Generality of regroupings with the rupture of $\mathrm{N}$$\mathrm{N}$ or $\mathrm{N}$$\mathrm{O}$ bonds and with the formation of the nitryl group
I. I. Grandberg, A. N. Kost, Yu. A. Naumov
838
A proof of the configuration of cis-trans-isomeric compounds $[\mathrm{Pt}\mathrm{Cl}_2(\mathrm{NH}_3)_2]\mathrm{Cl}_2$
A. A. Grinberg, O. N. Andryanova, Yuan Kang
842
Addition of triphenyl radicals to 1,3-enynic tin-hydrocarbons
V. S. Zavgorodnii, A. A. Petrov
846
Refraction of certain bonds of organoarsenic compounds
Kamai Gilm, B. D. Chernokal'skii
850
Dissociation constants of some substituted cyclopropane- and cyclopropene-carboxylic acids
R. R. Kostikov, I. A. D'yakonov
853
Ferrocene-based synthesis of polymeres and some of their electrophysical properties
Ya. M. Paushkin, T. P. Vishnyakova, I. I. Patalakh, T. A. Sokolinskaya, F. F. Machus
856
Free-radical isomerization of acetone diphenylmercuptol
R. Kh. Freidlina, A. B. Terent'ev, R. G. Petrova
860
Infrared spectra of complexes formed by vinyl esters of phenol, o-aminophenol and aniline with stannic chloride
M. F. Shostakovskii, G. G. Skvortsova, K. V. Zapunnaya, N. I. Shergina, N. N. Chipanina
862
Long-wave infrared spectra (400–20 cm$^{-1}$) of diphenyliodonium salts
L. M. Epshtein, N. G. Yaroslavskii
865

PHYSICAL CHEMISTRY
Inflammation of methane mixtures in shock waves
A. A. Borisov, S. M. Kogarko, A. V. Lyubimov
869
Infrared spectra of olefine complexes with aluminium halides
D. S. Bystrov
872
Electron spin resonance in liquid and supercooled solutions of some free radicals
N. S. Garif'yanov, A. V. Il'yasov, Yu. V. Yablokov
876
The stability of stationary states of electrolytic systems
A. Ya. Gokhshtein
880
A new method of determining the energy and solvation heat of individual ions
N. A. Izmailov
884
The influence of solubilization on the denaturation of egg albumin
V. N. Izmailova, V. A. Pchelin, L. V. Mityukhina
888
The specific surface of tobermorite as calculated from its crystal lattice constants and adsorption data
K. G. Krasil'nikov
891
Electric conductivity and electron spin resonance signal in polymeric materials built up of molecules with conjugate double bonds
V. G. Levich, V. S. Markin, Yu. G. Chirkov
894
Photoconductivity of acetylene polymers
V. S. Myl'nikov, E. K. Putseiko, A. N. Terenin
897
The formation of ion-radicals under the action of $\gamma$-rays on the tetrahydrofuran-styrene system at – $196^\circ$ C
A. I. Nepomnyashchii, V. I. Muromtsev, Kh. S. Bagdasar'yan
901
Structure formation in interphasic adsorption layers of dissolved surface-active substances and the stability of emulsions and aqueous dispersions of polymers (latexes)
S. A. Nikitina, A. B. Taubman, N. V. Kuligina, V. A. Spiridonova
905
The capacitance of a double electric layer in solid electrolytes
A. T. Filyaev, S. V. Karpachev, S. F. Pal'guev
909

Number 5

MATHEMATICS
Classification of bundles of quadratic forms in three variables
D. V. Beklemishev
1007
Dyadic bicompacta
B. Efimov
1011
Characterization of spaces by means of $H$-closed extensions
S. Iliadis
1015
Transference theorems
Yu. V. Kashirskii
1019
On the relationship of the concepts of solvability and countability for finite automata
G. M. Korpelevich
1023
Complex variables in problems with nuisance parameters and finite-rank sufficient statistics
Yu. V. Linnik
1026
On the index and normal solvability of a class of functional equations
G. S. Litvinchuk
1029
Semi-simple decompositions of semi-simple Lie algebras
A. L. Onishchik
1033
$\Omega$-semigroups, $\Omega$-rings and representations
B. I. Plotkin
1037
A constructive duality principle in the class of continuous functions convex and decreasing monotonely to zero on a semi-axis
A. Timan
1041

THEORY OF ELASTICITY
Elasto-rigid-plastic torsion of a cylindrical rod of oval cross section
B. D. Annin
1043
Lower critical load for cylindrical shells
A. V. Pogorelov
1047

PHYSICS
Radiation close to the cyclotron resonance from a charge moving in a plasma
A. E. Bazhanova, V. D. Shafranov
1049
Hydrodynamic oscillations of an inhomogeneous plasma of low pressure in a magnetic field
L. M. Kovrizhnykh, E. E. Lovetskii, A. A. Rukhadze, V. P. Silin
1052
The lines of force of a magnetic field produced by helical currents coiling about a tore
V. K. Mel'nikov
1056

CRYSTALLOGRAPHY
A contribution to the theory of quasitransverse elastic waves in crystals
F. I. Fedorov
1060

CHEMISTRY
The synthesis of sym-triazine derivatives containing $\mathrm{╬}$-alkyl- and $\mathrm{╬}$, $\mathrm{N}$-dialkylhydroxylamine groupings
Yu. A. Baskakov, N. N. Mel'nikov, I. A. Mel'nikova, N. V. Konstantinova
1064
Butadiene polymerization in the presence of alkali metals and their compounds in various media
R. V. Basova, A. A. Arest-Yakubovich, D. A. Solovykh, N. V. Desyatova, A. R. Gantmakher, S. S. Medvedev
1067
The production of oxalate-sulphite and sulphite complex compounds of thorium and uranium (IV)
A. D. Gel'man, L. N. Essen, F. A. Zakharova, D. P. Alekseeva, M. M. Orlova
1071
On the relation between the stability and reactivity of complex compounds
A. A. Grinberg
1074
A spectrophotometric investigation of the rate of oxidation of substituted derivatives of 1,5-diphenylthiocarbohydrazide
R. G. Dubenko, P. S. Pel'kis
1078
Behaviour of some polynitroalkanes on mercury dropping electrode
Yu. P. Kitaev, I. M. Skrebkova
1080
The effects of gamma-and ultraviolet rays on aqueous solutions of the triethylenediamine complex of cobalt (III)
L. N. Neokladnova, G. A. Shagisultanova
1084
The spectral line intensity of trace elements in a silicate system as dependent on the system's equilibrium diagram
M. M. Pavlyuchenko, K. V. Dubovik
1088
The synthesis of styrene and its homologues by means of phosphate pyrolysis
A. N. Pudovik, I. V. Konovalova
1091

PHYSICAL CHEMISTRY
Determination of reaction rate constants when atomic hydrogen or atomic oxygen interact with ethylene
V. V. Azatyan, A. B. Nalbandyan, Cui Meng-yuan
1095
Radiolysis of sulphuric acid
L. T. Bugaenko, Huang Guan-lin, N. A. Bakh
1099
Solvation energy of ions in formic acid, hydrazine, acetonitryl, in $n$-butyl and isoamyl alcohols and in acetone
N. A. Izmailov
1103
The use of a rotating disc electrode with a ring in studying the cathode reduction of oxygen on platinum in alkaline solutions
L. N. Nekrasov, L. Müller
1107
The activation energy of the chain reactions by which alcohols are formed and consumed in the oxidation of $n$-decane
I. P. Skibida, Z. K. Maizus, N. M. Emanuel'
1111
The joint action of mercury and radioactive emissions on the mechanical properties of single zinc crystals
O. A. Troitskii, V. I. Likhtman
1115
Impurities as they occur in strongly alloyed single $n$-type crystals of germanium and silicon
V. I. Fistul, M. G. Mil'vidskii, È. M. Omel'yanovskii, S. P. Grishina
1119
Chemisorption of oxygen and adsorption of electrolytes on activated charcoal
A. N. Frumkin, E. A. Ponomarenko, R. Kh. Burshtein
1123

Number 6

MATHEMATICS
On the structure of higher-dimensional surfaces carrying a net of lines of curvature
M. A. Akivis
1247
On Chebyshev and almost-Chebyshev subspaces
A. L. Garkavi
1250
On certain boundary-value problems for the equation $u_{xx}+\operatorname{sign}y u_{yy}=0$
G. Karatoprakliev
1253
The first boundary-value problem for certain semi-bounded hypo-elliptic differential operators
V. P. Mikhailov
1257
Unitary permutation operators in the space $\Pi_\kappa$
M. A. Naimark
1261
Estimates for the rate of convergence of solutions of difference equations to solutions of elliptic equations with discontinuous coefficients and a numerical method of solving the Dirichlet problem
V. Ya. Rivkind
1264
On the continuation of a mapping of a Boolean ring into a topological Abelian group
L. Ya. Savel'ev
1268
On the minimal radical class over a class of Abelian groups
Ch'ang Wang Hao
1270
Continuation of the solution of the Cauchy problem for parabolic systems
S. D. Èidel'man, S. D. Ivasishen
1274

AERODYNAMICS
The flow of a nonequilibrium gas
V. N. Zhigulev
1278

THE MECHANICS OF CONTINUOUS MEDIUM
General forms of the relations between tensor fields in an anisotropic continuous medium, the properties of which are described by vectors, tensors of the second rank, and antisymmetric tensors of the third rank
V. V. Lokhin
1282

PHYSICS
Wave functions and calculation of matrix elements for longitudinally polarized vector particles
A. A. Bogush
1286
Self-diffusion at the surface of polycrystalline silver
Ya. E. Geguzin, G. N. Kovalev
1290
Separation of silicon isotopes in monosilane by thermodiffusion
G. G. Devyatykh, G. K. Borisov
1293
Inductive resonance energy transfer from aromatic molecules in the triplet state
V. L. Ermolaev, E. B. Sveshnikova
1295
The maximum amount of information transmissible by an electromagnetic field
D. S. Lebedev, L. B. Levitin
1299
Melting on compression by shock wave
V. D. Urlin, A. A. Ivanov
1303

GEOPHYSICS
The structure of the $F$ layer and the reasons for convection in the earth core
S. I. Braginskii
1311

CHEMISTRY
Interaction of 2,3-diaryl-and 2-aryl-3-alkylindones with nitrogen oxides
B. V. Aleksiev, Ch. P. Ivanov, I. N. Iukhnovski
1315
Descending thin-layer chromatography of polyhydroxy compounds
L. D. Bergelson, È. V. Dyatlovitskaya, V. V. Voronkova
1319
Radiation polymerization of tetrafluoroethylene in the solid state
M. A. Bruk, A. D. Abkin, P. M. Khomikovskii
1322
Extraction of niobium pyrrolidinedithiocarbaminate
I. M. Gibalo, I. P. Alimarin, P. Davaadorzh
1326
On the stability of complex platinous compounds of diacidodiamine type
A. A. Grinberg, M. I. Gel'fman
1328
Thin-layer chromatography of carbohydrates on gypsum
Yu. A. Zhdanov, G. N. Dorofeenko, S. V. Zelenskaya
1332
Steric hindrances in the dienesynthesis of cyclopentadiene with dienophiles of the isopropenyl type
A. I. Konovalov
1334
An investigation of the $\mathrm{BeF}_2$$\mathrm{ZrF}_4$ system
Yu. M. Korenev, A. V. Novoselova
1337
The equilibrium diagram of $\mathrm{TiCr}_2$$\mathrm{NbCr}_2$
I. I. Kornilov, K. I. Shakhova, P. B. Budberg, N. A. Nedumov
1340
The mechanism of peroxomonosulphuric acid decomposition reactions investigated by means of isotopes
V. A. Lunenok-Burmakina, A. P. Potemskaya
1343
Acoplanar arrangement of molecules in benzalaniline and its derivatives
V. I. Minkin, E. A. Medyantseva, A. M. Simonov
1347
Ethylene polymerization on a chlorinated mixture of titanium and aluminium
K. S. Minsker, G. T. Fedoseeva, N. A. Vorob'eva, G. A. Razuvaev
1351
The photolysis of $\alpha$-pyridylferrocene salts
A. N. Nesmeyanov, V. A. Sazonova, A. V. Gerasimenko, N. S. Sazonova
1354

PHYSICAL CHEMISTRY
The mechanism underlying the radiation-induced oxidation or reduction of inorganic acceptors in acetone solutions
N. A. Bakh, M. Roder, L. T. Bugaenko
1356
X-ray spectroscopic study of certain polyferrocenes
È. E. Vainstein, Yu. F. Kopelev
1360
Energy of solvation and persolvation ($\lg\gamma_0$) of individual ions in non-aqueous solutions
N. A. Izmailov
1364
Spontaneous and forced decay of two-charge ions
S. E. Kupriyanov, A. A. Perov
1368
Heat conductivity of the hexaborides of alkali metals and rare-earth metals
S. N. L`vov, V. F. Nemchenko, Yu. B. Paderno
1371
Three-dimensional kinetic waves in the polarography of salts of weak acids in non-buffer solutions
S. G. Mairanovskii
1373
The structure-mechanical properties of palygorskite paste as influenced by the orientation of the particles
S. P. Nichiporenko, V. V. Khil'ko
1377
Ionization of bases and proton transfer in nucleic acids and their components
B. I. Sukhorukov, V. I. Poltev, L. A. Blumenfeld
1380
The thermomechanical characteristic of the molecular weight if linear polymers as exemplified by natural rubber
B. Ya. Teitel'baum, È. F. Gubanov
1384
A new semiconducting phase in zinc-antimony system
Ya. A. Ugai, E. M. Averbakh, Yu. Ya. Gukova, V. V. Lavrov
1387
Acceleration of polyethyleneterephthalate crystallization by mechanical forces
A. A. Frolova, P. V. Kozlov
1390

 Dokl. Akad. Nauk SSSR, Volume 150 (1963)

 Dokl. Akad. Nauk SSSR, Volume 151 (1963)

 Dokl. Akad. Nauk SSSR, Volume 152 (1963)

 Dokl. Akad. Nauk SSSR, Volume 153 (1963)

 Dokl. Akad. Nauk SSSR, Volume 154 (1964)

 Dokl. Akad. Nauk SSSR, Volume 155 (1964)

 Dokl. Akad. Nauk SSSR, Volume 156 (1964)

 Dokl. Akad. Nauk SSSR, Volume 157 (1964)

 Dokl. Akad. Nauk SSSR, Volume 158 (1964)

 Dokl. Akad. Nauk SSSR, Volume 159 (1964)

 Dokl. Akad. Nauk SSSR, Volume 160 (1965)

 Dokl. Akad. Nauk SSSR, Volume 161 (1965)

 Dokl. Akad. Nauk SSSR, Volume 162 (1965)

 Dokl. Akad. Nauk SSSR, Volume 163 (1965)

 Dokl. Akad. Nauk SSSR, Volume 164 (1965)

 Dokl. Akad. Nauk SSSR, Volume 165 (1965)

 Dokl. Akad. Nauk SSSR, Volume 166 (1966)

 Dokl. Akad. Nauk SSSR, Volume 167 (1966)

 Dokl. Akad. Nauk SSSR, Volume 168 (1966)

 Dokl. Akad. Nauk SSSR, Volume 169 (1966)

 Dokl. Akad. Nauk SSSR, Volume 170 (1966)

 Dokl. Akad. Nauk SSSR, Volume 171 (1966)

 Dokl. Akad. Nauk SSSR, Volume 172 (1967)

 Dokl. Akad. Nauk SSSR, Volume 173 (1967)

 Dokl. Akad. Nauk SSSR, Volume 174 (1967)

 Dokl. Akad. Nauk SSSR, Volume 175 (1967)

 Dokl. Akad. Nauk SSSR, Volume 176 (1967)

 Dokl. Akad. Nauk SSSR, Volume 177 (1967)

 Dokl. Akad. Nauk SSSR, Volume 178 (1968)

 Dokl. Akad. Nauk SSSR, Volume 179 (1968)

 Dokl. Akad. Nauk SSSR, Volume 180 (1968)

 Dokl. Akad. Nauk SSSR, Volume 181 (1968)

 Dokl. Akad. Nauk SSSR, Volume 182 (1968)

 Dokl. Akad. Nauk SSSR, Volume 183 (1968)

 Dokl. Akad. Nauk SSSR, Volume 184 (1969)

 Dokl. Akad. Nauk SSSR, Volume 185 (1969)

 Dokl. Akad. Nauk SSSR, Volume 186 (1969)

 Dokl. Akad. Nauk SSSR, Volume 187 (1969)

 Dokl. Akad. Nauk SSSR, Volume 188 (1969)

 Dokl. Akad. Nauk SSSR, Volume 189 (1969)

 Dokl. Akad. Nauk SSSR, Volume 190 (1970)

 Dokl. Akad. Nauk SSSR, Volume 191 (1970)

 Dokl. Akad. Nauk SSSR, Volume 192 (1970)

 Dokl. Akad. Nauk SSSR, Volume 193 (1970)

 Dokl. Akad. Nauk SSSR, Volume 194 (1970)

 Dokl. Akad. Nauk SSSR, Volume 195 (1970)

 Dokl. Akad. Nauk SSSR, Volume 196 (1971)

 Dokl. Akad. Nauk SSSR, Volume 197 (1971)

 Dokl. Akad. Nauk SSSR, Volume 198 (1971)

 Dokl. Akad. Nauk SSSR, Volume 199 (1971)

 Dokl. Akad. Nauk SSSR, Volume 200 (1971)

 Dokl. Akad. Nauk SSSR, Volume 201 (1971)

 Dokl. Akad. Nauk SSSR, Volume 202 (1972)

 Dokl. Akad. Nauk SSSR, Volume 203 (1972)

 Dokl. Akad. Nauk SSSR, Volume 204 (1972)

 Dokl. Akad. Nauk SSSR, Volume 205 (1972)

 Dokl. Akad. Nauk SSSR, Volume 206 (1972)

 Dokl. Akad. Nauk SSSR, Volume 207 (1972)

 Dokl. Akad. Nauk SSSR, Volume 208 (1973)

 Dokl. Akad. Nauk SSSR, Volume 209 (1973)

 Dokl. Akad. Nauk SSSR, Volume 210 (1973)

 Dokl. Akad. Nauk SSSR, Volume 211 (1973)

 Dokl. Akad. Nauk SSSR, Volume 212 (1973)

 Dokl. Akad. Nauk SSSR, Volume 213 (1973)

 Dokl. Akad. Nauk SSSR, Volume 214 (1974)

 Dokl. Akad. Nauk SSSR, Volume 215 (1974)

 Dokl. Akad. Nauk SSSR, Volume 216 (1974)

 Dokl. Akad. Nauk SSSR, Volume 217 (1974)

 Dokl. Akad. Nauk SSSR, Volume 218 (1974)

 Dokl. Akad. Nauk SSSR, Volume 219 (1974)

 Dokl. Akad. Nauk SSSR, Volume 220 (1975)

 Dokl. Akad. Nauk SSSR, Volume 221 (1975)

 Dokl. Akad. Nauk SSSR, Volume 222 (1975)

 Dokl. Akad. Nauk SSSR, Volume 223 (1975)

 Dokl. Akad. Nauk SSSR, Volume 224 (1975)

 Dokl. Akad. Nauk SSSR, Volume 225 (1975)

 Dokl. Akad. Nauk SSSR, Volume 226 (1976)

 Dokl. Akad. Nauk SSSR, Volume 227 (1976)

 Dokl. Akad. Nauk SSSR, Volume 228 (1976)

 Dokl. Akad. Nauk SSSR, Volume 229 (1976)

 Dokl. Akad. Nauk SSSR, Volume 230 (1976)

 Dokl. Akad. Nauk SSSR, Volume 231 (1976)

 Dokl. Akad. Nauk SSSR, Volume 232 (1977)

 Dokl. Akad. Nauk SSSR, Volume 233 (1977)

 Dokl. Akad. Nauk SSSR, Volume 234 (1977)

 Dokl. Akad. Nauk SSSR, Volume 235 (1977)

 Dokl. Akad. Nauk SSSR, Volume 236 (1977)

 Dokl. Akad. Nauk SSSR, Volume 237 (1977)

 Dokl. Akad. Nauk SSSR, Volume 238 (1978)

 Dokl. Akad. Nauk SSSR, Volume 239 (1978)

 Dokl. Akad. Nauk SSSR, Volume 240 (1978)

 Dokl. Akad. Nauk SSSR, Volume 241 (1978)

 Dokl. Akad. Nauk SSSR, Volume 242 (1978)

 Dokl. Akad. Nauk SSSR, Volume 243 (1978)

 Dokl. Akad. Nauk SSSR, Volume 244 (1979)

 Dokl. Akad. Nauk SSSR, Volume 245 (1979)

 Dokl. Akad. Nauk SSSR, Volume 246 (1979)

 Dokl. Akad. Nauk SSSR, Volume 247 (1979)

 Dokl. Akad. Nauk SSSR, Volume 248 (1979)

 Dokl. Akad. Nauk SSSR, Volume 249 (1979)

 Dokl. Akad. Nauk SSSR, Volume 250 (1980)

 Dokl. Akad. Nauk SSSR, Volume 251 (1980)

 Dokl. Akad. Nauk SSSR, Volume 252 (1980)

 Dokl. Akad. Nauk SSSR, Volume 253 (1980)

 Dokl. Akad. Nauk SSSR, Volume 254 (1980)

 Dokl. Akad. Nauk SSSR, Volume 255 (1980)

 Dokl. Akad. Nauk SSSR, Volume 256 (1981)

 Dokl. Akad. Nauk SSSR, Volume 257 (1981)

 Dokl. Akad. Nauk SSSR, Volume 258 (1981)

 Dokl. Akad. Nauk SSSR, Volume 259 (1981)

 Dokl. Akad. Nauk SSSR, Volume 260 (1981)

 Dokl. Akad. Nauk SSSR, Volume 261 (1981)

 Dokl. Akad. Nauk SSSR, Volume 262 (1982)

 Dokl. Akad. Nauk SSSR, Volume 263 (1982)

 Dokl. Akad. Nauk SSSR, Volume 264 (1982)

 Dokl. Akad. Nauk SSSR, Volume 265 (1982)

 Dokl. Akad. Nauk SSSR, Volume 266 (1982)

 Dokl. Akad. Nauk SSSR, Volume 267 (1982)

 Dokl. Akad. Nauk SSSR, Volume 268 (1983)

 Dokl. Akad. Nauk SSSR, Volume 269 (1983)

 Dokl. Akad. Nauk SSSR, Volume 270 (1983)

 Dokl. Akad. Nauk SSSR, Volume 271 (1983)

 Dokl. Akad. Nauk SSSR, Volume 272 (1983)

 Dokl. Akad. Nauk SSSR, Volume 273 (1983)

 Dokl. Akad. Nauk SSSR, Volume 274 (1984)

 Dokl. Akad. Nauk SSSR, Volume 275 (1984)

 Dokl. Akad. Nauk SSSR, Volume 276 (1984)

 Dokl. Akad. Nauk SSSR, Volume 277 (1984)

 Dokl. Akad. Nauk SSSR, Volume 278 (1984)

 Dokl. Akad. Nauk SSSR, Volume 279 (1984)

 Dokl. Akad. Nauk SSSR, Volume 280 (1985)

 Dokl. Akad. Nauk SSSR, Volume 281 (1985)

 Dokl. Akad. Nauk SSSR, Volume 282 (1985)

 Dokl. Akad. Nauk SSSR, Volume 283 (1985)

 Dokl. Akad. Nauk SSSR, Volume 284 (1985)

 Dokl. Akad. Nauk SSSR, Volume 285 (1985)

 Dokl. Akad. Nauk SSSR, Volume 286 (1986)

 Dokl. Akad. Nauk SSSR, Volume 287 (1986)

 Dokl. Akad. Nauk SSSR, Volume 288 (1986)

 Dokl. Akad. Nauk SSSR, Volume 289 (1986)

 Dokl. Akad. Nauk SSSR, Volume 290 (1986)

 Dokl. Akad. Nauk SSSR, Volume 291 (1986)

 Dokl. Akad. Nauk SSSR, Volume 292 (1987)

 Dokl. Akad. Nauk SSSR, Volume 293 (1987)

 Dokl. Akad. Nauk SSSR, Volume 294 (1987)

 Dokl. Akad. Nauk SSSR, Volume 295 (1987)

 Dokl. Akad. Nauk SSSR, Volume 296 (1987)

 Dokl. Akad. Nauk SSSR, Volume 297 (1987)

 Dokl. Akad. Nauk SSSR, Volume 298 (1988)

 Dokl. Akad. Nauk SSSR, Volume 299 (1988)

 Dokl. Akad. Nauk SSSR, Volume 300 (1988)

 Dokl. Akad. Nauk SSSR, Volume 301 (1988)

 Dokl. Akad. Nauk SSSR, Volume 302 (1988)

 Dokl. Akad. Nauk SSSR, Volume 303 (1988)

 Dokl. Akad. Nauk SSSR, Volume 304 (1989)

 Dokl. Akad. Nauk SSSR, Volume 305 (1989)

 Dokl. Akad. Nauk SSSR, Volume 306 (1989)

 Dokl. Akad. Nauk SSSR, Volume 307 (1989)

 Dokl. Akad. Nauk SSSR, Volume 308 (1989)

 Dokl. Akad. Nauk SSSR, Volume 309 (1989)

 Dokl. Akad. Nauk SSSR, Volume 310 (1990)

 Dokl. Akad. Nauk SSSR, Volume 311 (1990)

 Dokl. Akad. Nauk SSSR, Volume 312 (1990)

 Dokl. Akad. Nauk SSSR, Volume 313 (1990)

 Dokl. Akad. Nauk SSSR, Volume 314 (1990)

 Dokl. Akad. Nauk SSSR, Volume 315 (1990)

 Dokl. Akad. Nauk SSSR, Volume 316 (1991)

 Dokl. Akad. Nauk SSSR, Volume 317 (1991)

 Dokl. Akad. Nauk SSSR, Volume 318 (1991)

 Dokl. Akad. Nauk SSSR, Volume 319 (1991)

 Dokl. Akad. Nauk SSSR, Volume 320 (1991)

 Dokl. Akad. Nauk SSSR, Volume 321 (1991)

 Dokl. Akad. Nauk, Volume 322 (1992)

 Dokl. Akad. Nauk, Volume 323 (1992)

 Dokl. Akad. Nauk, Volume 324 (1992)

 Dokl. Akad. Nauk, Volume 325 (1992)

 Dokl. Akad. Nauk, Volume 326 (1992)

 Dokl. Akad. Nauk, Volume 327 (1992)

 Dokl. Akad. Nauk, Volume 328 (1993)

 Dokl. Akad. Nauk, Volume 329 (1993)

 Dokl. Akad. Nauk, Volume 330 (1993)

 Dokl. Akad. Nauk, Volume 331 (1993)

 Dokl. Akad. Nauk, Volume 332 (1993)

 Dokl. Akad. Nauk, Volume 333 (1993)

 Dokl. Akad. Nauk, Volume 334 (1994)

 Dokl. Akad. Nauk, Volume 335 (1994)

 Dokl. Akad. Nauk, Volume 336 (1994)

 Dokl. Akad. Nauk, Volume 337 (1994)

 Dokl. Akad. Nauk, Volume 338 (1994)

 Dokl. Akad. Nauk, Volume 339 (1994)

 Dokl. Akad. Nauk, Volume 340 (1995)

 Dokl. Akad. Nauk, Volume 341 (1995)

 Dokl. Akad. Nauk, Volume 342 (1995)

 Dokl. Akad. Nauk, Volume 343 (1995)

 Dokl. Akad. Nauk, Volume 344 (1995)

 Dokl. Akad. Nauk, Volume 345 (1995)

 Dokl. Akad. Nauk, Volume 346 (1996)

 Dokl. Akad. Nauk, Volume 347 (1996)

 Dokl. Akad. Nauk, Volume 348 (1996)

 Dokl. Akad. Nauk, Volume 349 (1996)

 Dokl. Akad. Nauk, Volume 350 (1996)

 Dokl. Akad. Nauk, Volume 351 (1996)

 Dokl. Akad. Nauk, Volume 352 (1997)

 Dokl. Akad. Nauk, Volume 353 (1997)

 Dokl. Akad. Nauk, Volume 354 (1997)

 
Contact us:
 Terms of Use  Registration  Logotypes © Steklov Mathematical Institute RAS, 2020