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A. A. Akhrem N. A. Borisevich O. V. Gulyakevich A. L. Mikhal'chuk T. F. Raichyonok S. A. Tikhomirov G. B. Tolstorozhev 《Journal of fluorescence》1999,9(4):357-361
The specific fluorescence properties as well as picosecond transient absorption features have been studied for two 8-azasteroids. It is shown that at various excitation wavelengths the essentially different final excited electronic states are realized. Because of the multicenter character of 8-azasteroids the spectroscopic data obtained may be analyzed on a basis of the mesomeric tautomerism model taking into account the dynamic combination of cis- and trans-configurations. The dependence of fluorescence spectral characteristics on the solvent nature is a manifestation of intermolecular H-bond interactions. 相似文献
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N. A. Borisevich O. V. Gulyakevich A. L. Mikhal'chuk I. V. Skornyakov 《Journal of Applied Spectroscopy》2003,70(1):27-33
We have investigated the intermolecular interactions of 8-aza-D-homogona-1,3,5(10),13-tetrane-12,17a-dione and 2,3-dimethoxy-8-azagone-1,3,5(10),13-tetran-12,17-dione with CHCl3, binary solvents CHCl3–CH3OH, CCl4–CHCl3, and CCl4–CH3OH and also in the solid phase, which manifest themselves in the IR spectra. When the C=O groups of the studied 8-azasteroids form hydrogen bonding with the OH groups of alcohol, the frequencies (C=O) change insignificantly. We have found that they are higher than the corresponding frequencies in the IR absorption spectra of solid-phase samples, which is attributable not only to the effect of the medium but also to the possible shortened contacts of the C=O groups with the CH3 and CH2 groups of the molecules under study. 相似文献
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N. A. Borisevich I. V. Skornyakov V. A. Khripach G. B. Tolstorozhev V. N. Zhabinskii 《Journal of Applied Spectroscopy》2007,74(5):673-680
We have analyzed the IR spectra obtained for steroidal phytohormones 24-epibrassinolide, 24-epicastasterone, 28-homobrassinolide,
and 28-homocastasterone. The characteristic frequencies of the stretching vibrations of the hydrocarbon groups CH3, CH2, and CH and also the C=O groups in the spectra of brassinolides are higher than in the spectra of castasterones, which makes
it possible to identify them from the IR spectra. Study of the spectra of these brassinosteroids in different media (pressed
samples in KBr, films, solutions in CHCl3 and CDCl3) allowed us to establish the presence of intermolecular interactions in which C=O and OH groups, OH-OH groups participate,
and also the possible formation of intramolecular hydrogen bonds between the OH groups of the molecules.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 610–616, September–October, 2007. 相似文献
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In order to analyze the intensity of the circulating flow in the rarefaction zone near the axis of a rapidly rotating cylinder, the problem of gas flow in a cylinder with a stationary upper end face is solved for intermediate Knudsen numbers by the direct statistical modeling method. The effect of the rarefaction of the gas on the intensity of the secondary flow is investigated. The contribution of the self-excited thermal circulation of the gas to the total circulating flow is analyzed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 186–188, May–June, 1990. 相似文献