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21.
F. D. Polyak A. V. Eremeev M. P. Gavars A. P. Gaukhman I. B. Mazheika 《Chemistry of Heterocyclic Compounds》1988,24(7):733-735
The reaction of N-tritylproline methyl ester with tert-butyl hypochlorite gave 2,4-dichloro-2-methoxycarbonyl-5-pyrroline, which is readily converted to 2-methoxycarbonyl-4-chloropyrrole. The intermediate products were identified by Chromatographic mass spectrometry when the reaction was carried out at low temperatures.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 894–896, July, 1988. 相似文献
22.
R. I. Moshkina S. S. Polyak N. A. Sokolova I. F. Masterovoi A. B. Nalbandyan 《国际化学动力学杂志》1980,12(5):315-338
The kinetics of ethane oxidation was studied at 320, 340, 353 and 380°C, mixture composition 2 C2H6 + 1 O2, and total pressure 609 torr. It was found that at 320°C CH2O and CH3CHO were branching agents. A series of experiments was conducted on 2C2H6 + O2 oxidation in the presence of 0.7% 14C-labeled ethylene. The ethylene oxide was found to form only from C2H4, formaldehyde formed from C2H4 and C2H6; and CH3CHO, C2H5OH, and CH3OH formed only from ethane. The formation rates of C2H4, C2H4O, and CH2O were calculated by the kinetic tracer method. At 320°C the fraction of oxygen-containing products formed from C2H4 was 16–18%, and at 353 and 380°C it was 30–40%. 相似文献
23.
Eremeev A. V. Polyak F. D. Mishnev A. F. Bleidelis Ya. Ya. Liepin'sh É. É. Nasibov Sh. S. Chervin I. I. Kostyanovskii R. G. 《Chemistry of Heterocyclic Compounds》1982,18(11):1159-1164
The synthesis, investigation of the structure, separation, and x-ray diffraction analysis of diastereomeric aziridine-2-carboxylic acid derivatives obtained from 2,3-dibromopropionic acid methyl ester or amide and methyl esters of amino acids are described.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1495–1500, November, 1982. 相似文献
24.
The application of the fast gradient method to the dual quadratic programming (QP) problem leads to the dual fast projected gradient (DFPG) method. The DFPG converges with O(k ?2) rate, where k > 0 is the number of steps. At each step, it requires O(nm) operations. Therefore for a given ${\varepsilon > 0}$ an ${\varepsilon}$ -approximation to the optimal dual function value one achieves in ${O(nm\varepsilon^{-\frac{1}{2}})}$ operations. We present numerical results which strongly corroborate the theory. In particular, we demonstrate high efficiency of the DFPG for large scale QP. 相似文献
25.
A. N. Malinin N. N. Guĭvan L. L. Shimon A. V. Polyak N. G. Zubrilin A. I. Shchedrin 《Optics and Spectroscopy》2001,91(6):864-868
Results of a study of temporal characteristics of the emission of gas-discharge plasma of atmospheric pressure in multicomponent mixtures (mercury dibromide and dichloride with helium and additions of molecular nitrogen and xenon) of working media of HgBr/HgCl excimer lamps are presented. Gas-discharge plasma was produced and components of the working mixture were excited by high-frequency barrier and surface discharges occurring simultaneously. The repetition rate of the pumping pulse and its duration are 1000 Hz and ~100 ns, respectively. It is found that the amplitude and the length of emission pulses and their trailing edge are modified in HgBr2: HgCl2: Xe: He and HgBr2: HgCl2: N2: He mixtures when xenon and molecular nitrogen are added, as compared to a HgBr2: HgCl2: He mixture. Regularities observed in temporal characteristics of gas-discharge plasma emission are discussed. 相似文献
26.
V. I. Mikhailov L. E. Polyak V. M. Kanevsky A. S. Pisarev 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2014,8(2):308-311
The processes of the condensation and evaporation of a tellurium film produced by a molecular beam of Te2 on a sapphire surface are studied. It is experimentally shown that the desorption of tellurium from a surface upon growth under nonequilibrium conditions exceeds the equilibrium thermal desorption. If the beam intensity is less than the equilibrium value, then desorption is also lower than the equilibrium value. A model of this process with allowance for the transient states of tellurium in the adsorption layer is proposed. Within this model equilibrium and Langmuir beams are expressed in terms of the process parameters. The reflection coefficient of the beam is also a function of the process characteristics. The experimental data make it possible to estimate some of the basic parameters of the process, including the coverage and desorption rate in the adsorption layer. Taking these results into account is important for manufacturing perfect films not only of Te, but also of CdTe. 相似文献
27.
We analyze the spectral, integrated, and durability characteristics of radiation from atmospheric-pressure gas-discharge plasma based on multicomponent mixtures (mercury diiodide and dibromide with helium and small admixtures of molecular nitrogen and xenon). We produced the gas-discharge plasma and excited the components of the working mixture by a pulsed (pulse repetition rates 500, 2000, and 4000 Hz; pulse duration ~150 ns) barrier discharge. Visible radiation was detected from excimer molecules of mercury monoiodide and monobromide, nitrogen and helium molecules, and helium and mercury atoms. Patterns were found in the variations of optical plasma characteristics with pumping pulse repetition rate and with component and quantitative mixture composition. 相似文献
28.
S. K. Gularyan G. E. Dobretsov B. M. Polyak V. Yu. Svetlichny N. E. Zhukhlistova B. M. Krasovitskii L. I. Kormilova V. E. Zavodnik 《Russian Chemical Bulletin》2006,55(10):1737-1742
Ground-state RHF/6-311G(d,p) and density functional B3LYP/6-311G(d,p) quantum chemical calculations of 4-dimethylaminochalcone
(DMAC), a sensitive fluorescent probe, were carried out for vacuum and for solvents of different polarity. The effect of the
medium was included by the SCRF method in the framework of the polarization continuum model. The DMAC fragment comprising
the aniline and propenone groups has a nearly planar conformation. The phenyl group can lie in the same plane or rotate by
an angle within the limits of ±20° with a low barrier at 293 K. The results of calculations were confirmed by the data of
X-ray study, according to which the phenyl group in the crystal is rotated by 20°. Calculations with allowance for solvation
effects predict charge transfer from the dimethylamino group to the oxygen atom; the higher the medium polarity, the larger
the degree of charge transfer (atomic charge of oxygen increases by 0.07 e in acetone). The calculated dipole moment of the
DMAC molecule increases from 5.2 D (vacuum) to 5.9 D (heptane) and 6.9 D (acetone), which is in agreement with spectroscopic
data. The energy of the DMAC—environment interaction was calculated. Due to large dipole moment of the DMAC molecule, the
electrostatic component of this energy strongly depends on the environment polarity, which can be related to redistribution
of the probe between the aqueous phase and cells and lipid structures of lipoproteins. The electronic absorption spectra of
DMAC in solvents of different polarity were calculated; differences between the calculated and experimentally measured values
are at most 15 nm.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1674–1679, October, 2006. 相似文献
29.
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