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1.
A. V. Kravtsov 《Computational Mathematics and Mathematical Physics》2007,47(11):1875-1884
A linear problem of parametric oscillations of a low-viscous two-layer fluid in a closed vessel partially filled with a porous medium is studied. An asymptotic solution is constructed on the basis of combined application of boundary functions and averaging methods. Approximate formulas for boundaries of instability domains in the case of subharmonic and harmonic resonances are derived. 相似文献
2.
A. S. Peregudov L. N. Usatova E. I. Smyslova E. I. Fedin D. N. Kravtsov 《Russian Chemical Bulletin》1995,44(8):1513-1519
It has been shown by the19F NMR method that the relative polarities of nitrogenelement bonds in 2-(4-fluorophenyl)benzimidazole and its PhHg and PPh3Au derivatives increase in the order N-H19F NMR. It has been found that these reactions occur by a bimolecular associative mechanism and that the N-H bond is substantially less reactive than the N-Hg and N-Au bonds, which have identical reactivities within the limits of sensitivity of the method used.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1574–1580, August, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No. 93-03-5528). 相似文献
3.
A microscopic theory of the Efetov supermatrix sigma-model type is constructed for the low-lying electron states in a mixed
superconductive-normal system with disorder. This technique is used for the study of the localized states in the core of a
vortex in a moderately clean superconductor with τ
−1≫ω
0∼Δ2/E
F
. At low energies ε≪ω
Th∼ (ω
0/τ)1/2, the energy level statistics is described by the “zero-dimensional” limit of this supermatrix theory, and the result for
the density of states is equivalent to that obtained within Altland-Zirnbauer random matrix model. Nonzero modes of the sigma
model increase the mean interlevel distance by the relative amount [2 ln (1/ω
0
τ)]−1.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 78–83 (10 July 1998)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
4.
O. Ya. Butkovskii Yu. A. Kravtsov E. D. Surovyatkina 《Journal of Experimental and Theoretical Physics》1998,86(1):206-212
The structure of the attraction zones of the final states associated with dynamical period doubling bifurcations is investigated.
It is found that on the “initial value—transition rate” plane the attraction zones of the two possible final states alternate
with each other and that a subdivision of the attraction regions occurs with a decrease in the transition rate. It is shown
that the boundaries of the attraction zones are smeared out because of the effect of noise and in this situation the fine
structure of the attraction zones is destroyed. As analytical and numerical calculations have shown, the critical value of
the noise variance, corresponding to the boundary between the dynamical (or predictable) and stochastic (or unpredictable)
modes, has a power-law dependence on the transition rate with a typical exponent value of one. The existence of “noise” invariants
is also observed: the integrated (over all initial values) probability of achieving the final state is invariant with respect
to the noise level.
Zh. éksp. Teor. Fiz. 113, 369–380 (January 1998) 相似文献
5.
6.
7.
Supramolecular isomerism in coordination compounds: nanoscale molecular hexagons and chains 总被引:1,自引:0,他引:1
Abourahma H Moulton B Kravtsov V Zaworotko MJ 《Journal of the American Chemical Society》2002,124(34):9990-9991
A nanoscale supramolecular hexagon, 1, and its supramolecular isomeric chain structure, 2, have been prepared from self-assembly of 5-NO2-bdc and Cu(II) cations. The hexagon is neutral and soluble and has outer and inner diameters of 3.1 and 0.8 nm, respectively. 相似文献
8.
Tsventarnyi E. G. Kravtsov V. I. Kurtova O. Yu. 《Russian Journal of Electrochemistry》2003,39(3):215-222
The electroreduction kinetics of Pd(en)2+
2 complexes (0.01 M) is studied on a rotating disk electrode of Pd by recording CVA at 25, 50, and 70°C in solutions of pH 12–13 at ethylenediamine concentrations of 0.03–1.0 M. Established is a diffusion nature of limiting currents, from which diffusion coefficients for Pd(en)2+
2 complexes are calculated. The Pd electrode capacitance, determined by a pulsed galvanostatic method, is used for taking into account the true surface areas of electrolytic Pd deposits. Parameters of the slow electrochemical stage, which involves Pd(en)2+
2 complexes, are determined. The temperature dependence of the rate constant of cathodic reduction of Pd(en)2+
2 complexes is used for calculating an apparent activation energy. An electroreduction mechanism of Pd(en)2+
2 complexes on a Pd electrode is discussed. 相似文献
9.
Nikiforova T. G. Kravtsov V. I. Alekseeva V. V. 《Russian Journal of Electrochemistry》2003,39(7):709-715
Kinetics of electroreduction of glycinate and alaninate complexes of Pd(II) is studied polarographically in a test mode at 15–50°C in solutions of pH 3, 5, 10, and 12 containing free ligands and NaF, Na2SO4, or NaClO4 supporting electrolytes. Diffusion coefficients for Pd(II) complexes are calculated from values of limiting currents. Specifically adsorbed Pd(II) complexes with a composition identical to that in the bulk solution take part in the slow electrochemical stage. The mechanism of reduction of the complexes is temperature-independent and identical to that established earlier at 25°C. The study confirms the earlier assumption as to the mechanism of hindering action of the perchlorate and alaninate ions specifically adsorbed on the positively-charged surface of a mercury electrode on the reduction of these complexes. 相似文献
10.
Marina S. Fonari Victor Ch. Kravtsov Yurii A. Simonov Edward V. Ganin Vladimir O. Gelmboldt Janusz Lipowski 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(1-2):85-89
The crystalline host–guest type complex [(18-crown-6NH4)2][SiF6]4H2Ohas been obtained as the result of the interaction of SiF42NH3 with 18-crown-6 (18C6) in an aqueous medium. Crystal data: monoclinic, space groupC 2 c, a=26.541(2), b=8.363(2), c=20.469(2) Å, = 122.43(1)°and Z=4. The final R-value is 0.070 for 3253 reflections with I 2(I).The crystals consist of the complex [NH418C6]+ cations, [SiF6]2-anions and water molecules. The ammonium cation is hydrogen bonded by three of its H-atoms to the crown ether oxygen atoms with N(1) O separations2.923(5)–2.940(5) Å and by the fourth H-atom to the fluorine atom of thehexafluorosilicate anion, the N(1)F(4) distance being 2.797(6) Å.The conformation of the macrocycle and the hydrogen-bond geometry in thecomplex cation closely resemble those in related adducts between 18-crown-6and ammonium salts. All crystal components are connected via a system of hydrogen bonds into a ribbon along the b axis in the unit cell. 相似文献