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51.
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53.
A. P. Shubin 《Journal of Applied Mechanics and Technical Physics》1970,11(6):908-915
The article discusses plane stationary slowly varying flows of a nonviscous plasma with good conductivity in a channel in a transverse magnetic field; the flows are accompanied by blowing in and pumping plasma across solid metallic electrodes. The Hall effect is taken into consideration. It is shown that the potential jump near the anode, which appears in an accelerated plasma flow in an ordinary channel with solid electrodes, can be eliminated in flows accompanied by blowing in (pumping) of plasma. It is also shown that flows are possible in which the velocity, density, and the transverse electric field increase in the direction of the accelerator cathode.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 26–34, November–December, 1970. 相似文献
54.
G. I. Borodkin A. Yu. Vorob’ev M. M. Shakirov V. G. Shubin 《Russian Journal of Organic Chemistry》2011,47(6):889-896
Treatment of 2-X-substituted pyrazines [X = H, Me, Et, Pr, i-Pr, t-Bu, MeCH(OH), H2N, AcNH] with O-mesitylenesulfonylhydroxylamine gave the corresponding 2-X- and 3-X-(1-amino)pyrazin-1-ium mesitylenesulfonates. 2-Alkylpyrazines
(X = Me, Et, Pr, i-Pr) displayed a correlation between the logarithms of the concentration ratio of 2- and 3-substituted cations and substituent
steric constants. Wider series of substituted pyrazines [X = H, Me, Et, Pr, i-Pr, MeCH(OH), H2N, AcNH] conformed to a multiparameter correlation between the logarithms of the concentration ratio of 2- and 3-substituted
cations, on the one hand, and substituent constants σI, σRo, and E
so, on the other. The obtained data on the regioselectivity of amination of pyrazines were interpreted in terms of DFT/PBE/3Z
quantum-chemical calculations. 相似文献
55.
G. I. Borodkin A. Yu. Vorob’ev V. G. Shubin 《Russian Journal of Organic Chemistry》2011,47(6):897-903
Relative rates of the amination of 3-X- and 4-X-substituted pyridines (X = H, 3-Me, 4-Me, 3-F3C, 3-CN, 4-CN, 3-Cl, 3-Br, 4-MeO, 4-Me2N), pyrazine, quinoline, isoquinoline, 2,2′- and 4,4′-bipyridines, and 1,10-phenanthroline with O-mesitylenesulfonylhydroxylamine were estimated by NMR spectroscopy. Correlations were found between logarithms of the relative
amination rate constants and substituent constants σ or σI and σR for X-substituted pyridines. A wide series of nitrogen-containing heterocyclic compounds turned out to fit correlations between
logarithms of the relative amination rate constants, on the one hand, and relative stabilities of N-aminoazinium cations, energies of activation of the amination process, and gas-phase proton affinities, calculated by the
DFT/PBE/3z and DFT/B3LYP/L2 methods, on the other. 相似文献
56.
According to the NMR data, opening of the cyclopropane ring in carbocations derived from 9-cyclopropyl-10,10-dimethyl-9,10-dihydrophenanthren-9-ol
in acid medium follows two pathways, depending on the acidity. The first pathway is protonation of the cyclopropyl group;
it occurs in strongly acidic medium (HSO3F-SbF5-SO2ClF-CD2Cl2). The second pathway involves cyclopropyl-carbinyl rearrangement; it is typical of less acidic medium. 相似文献
57.
Molecular acidity is an important physiochemical property essential in many fields of molecular studies, but an efficient and reliable computational approach to make accurate predictions is still missing. In this work, based on our previous studies to use gas phase electronic properties such as molecular electrostatic potential and valence natural atomic orbitals of the acidic atom and leaving proton, we demonstrate here that different approaches can be employed to tackle this problem. To that end, we employ 196 singly, doubly, and triply substituted benzoic acids for the study. We show that two different approaches are possible, one focusing on the carboxyl group through its localized electronic properties and the other on the substituting groups via Hammett constants and their additivity rule. Our present results clearly exhibit that with the linear models built from the singly substituted species, one can accurately predict the pK(a) values for the doubly and triply substituted species with both of these two approaches. The predictions from these approaches are consistent with each other and agree well with the experimental data. These intrinsically different approaches are the two manifestations of the same molecular acidity property, both valid and complementary to each other. 相似文献
58.
Two fused thienoacene compounds with two-dimensional ring connectivity were synthesized, and their semiconducting properties were characterized. Both compounds have a crystal structure comprised of herringbone arrays of tight π-π stacks. Strong π-π interactions lead to self-assembly into well-defined crystalline thin films from the vapor phase for both compounds. Field effect transistors were fabricated, affording identical hole mobilities of 3.0 × 10(-3) cm(2)/(V s) and I(on/off) > 10(5). 相似文献
59.
60.
We study the long-time behavior of small solutions of the Cauchy problem for a Rosenau equation. For a class of nonlinearity of the perturbation, the global small solution was obtained, and the decay and scattering for small amplitude solution are established. 相似文献