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71.
72.
To study collective excitations in hot finite Fermi systems (atomic nuclei, metallic clusters), a method accounting for the influence of temperature and the collective excitation parameters of the system on the mean field is developed using the formalism of thermofield dynamics. The role of the Pauli principle is considered more correctly than in the standard thermal random-phase approximation. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 111, No. 2, pp. 279–288, May, 1997.  相似文献   
73.
A self-consistent version of the thermal random phase approximation (TSCRPA) is developed within the Matsubara Green’s function formalism. The TSCRPA is applied to the many-level pairing model, and the normal phase of the system is considered. The TSCRPA results are compared with the exact ones calculated for the grand canonical ensemble. Advantages of the TSCRPA over the thermal mean-field approximation and the standard thermal random phase approximation are demonstrated. Results for correlation functions, excitation energies, etc., as a function of temperature are presented.  相似文献   
74.
A method for specific gas-phase deuteration of unsaturated silicon-containing compounds over pre-heterogenized Wilkinson's catalyst (a solution of (Ph3P)3RhCl in Carbowax 20M coated on Chromaton) in the reaction column connected to the mass spectrometer is described. This method was employed to study the dissociative ionization of the corresponding saturated analogues. With the aid of the mass spectra of the dideutero derivatives thus obtained, the main electron-impact-induced reactions of 1,1-dimethyl-1-silacyclopentane, 1,1,2,2-tetramethyl-1,2-disilacyclohexane, 1-methyl-1-ethyl-1-silacyclobutane and ethyl triethoxysilane were elucidated.  相似文献   
75.
Eight proanthocyanidins have been isolated from the roots ofPolygonum coriarum. The structures of two dimers, two trimers, including an acylglycosylated one, a tetramer, and three oligomers have been determined. All the compounds isolated were polymers and copolymers of (-)epigallocatechin, (-)epigallocatechin gallate and (-)epicatechin with C-4C-8 interflavan bonds.Institute of the Chemistry of Plant Substances. Academy of Sciences of the Republic of Uzbekistan, Tashkent, Fax (3712) 62 73 48. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 233–244, March–April, 1994.  相似文献   
76.
Chemical transformations and spectral characteristics have enabled us to establish the structure and configurations of three coumarins: (+)-2,2-dimethyl-3-hydroxy-3,4-dihydropyrano(5,6:6,7)coumarin (I); (+)-4-hydroxy-5-(1-hydroxy-1-methylethyl)-4,5-dihydrofuro(2,3:6,7)coumarin (II); and (+)-4-hydroxy-5-(1-glucopyranosyloxy-1-methylethyl)-4,5-dihydrofuro(2,3:6,7)-coumarin (III) isolated from the roots ofSmyrnopsis aucheri Karjag. This is the first time that these compounds, which have been called smyrinol, smyrindiol, and smyrindioloside, have been detected in nature.Institute of Chemistry of Plant Substances, Uzbekistan Republic Academy of Sciences, Tashkent. Azerbaidzhan State University, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 36–40, January–February, 1992.  相似文献   
77.
The new flavanon lehmannin (I) has been isolated from the roots ofAmmothamnus lehmannii Bunge. On the basis of chemical transformations and with the aid of physicochemical characteristics it has been established that compound (I) has the structure of 2,4,7-trihydroxy-8-(2-isopropenyl-5-methylhex-4-enyl)flavanone. The alkaline cleavage of lehmannin gave ammothamnidin (V). The structure proposed previously for the chalcone ammothamnidin has been corrected. It has been shown that it has the structure of 2,2-4,4-tetrahydroxy-3-(2-isopropenyl-5-methylhex-4- enyl)chalcone. A comparative study of the13C NMR spectra of a number of flavanones has revealed an empirical law permitting the prediction of the presence or absence of substituents (OH and OCH3) at C-2 from the value of the chemical shift of the signal of the C-2 carbon atom.Institute of the Chemistry of Plant Substances of the Uzbek SSR Academy of Sciences, Tashkent. I. P. Pavlov Samarkand State Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 516–524, July–August, 1987.  相似文献   
78.
Conclusions The codimerization of either 1,3-butadiene or 1,3-pentadiene with ethylene in the presence of the catalyst system C5H5Ti[OSi(CH3)3]3-CH3MgI assures the selective synthesis of vinylcyclobutanes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2781–2783, December, 1978.  相似文献   
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