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Mechanisms for the formation of toxisterol A are suggested. The connection between the conformation of the initial previtamin and the stereochemistry of the reaction products is discussed.Lensoviet Leningrad Technological Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 225–229, March–April, 1989. 相似文献
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A. A. Mak E. A. Viktorov O. A. Orlov V. I. Ustyugov 《Radiophysics and Quantum Electronics》2004,47(10-11):743-746
We present the results of experiments with a CW single-mode Nd:YAG laser, tunable in the vicinity of 1064 nm, with an intracavity narrow-band Cs 2 vapor saturable absorber. It is shown that the laser dynamics is determined by both the pump level and detuning of the laser frequency from the absorption-line center. 相似文献
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Effect of a magnetic field on the starting stress and mobility of individual dislocations in silicon
M. V. Badylevich Yu. L. Iunin V. V. Kveder V. I. Orlov Yu. A. Osip’yan 《Journal of Experimental and Theoretical Physics》2003,97(3):601-605
The strong effect of a magnetic field on the starting stress and mobility of individual dislocations is discovered in silicon grown by the Czochralski method with a high concentration of dissolved oxygen. It is shown that exposure of dislocations preliminarily introduced into the sample to a magnetic field considerably reduces the starting stresses for the motion of these dislocations. The effect is not observed in samples with a low oxygen concentration. It is assumed that the magnetic field induces singlet-triplet transitions in thermally excited states of silicon-oxygen complexes in the dislocation core, thus stimulating a change in the state (atomic configuration) of oxygen already located at dislocations. As a result, the mean binding energy of oxygen with a dislocation decreases. 相似文献
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V. D. Orlov N. V. Getmanskii O. V. Shishkin E. E. Lakin V. P. Kuznetsov 《Chemistry of Heterocyclic Compounds》1993,29(3):301-306
By the reaction of 2-nitrochalcone with hydrazine hydrate, 5-(2-nitrophenyl)-3-phenyl-1H-2-pyrazoline (I) and the hydrazone of 3-(5-(2-nitrophenyl)-3-phenyl-2-pyrazolin-1-yl)-3-(2-nitrophenyl)propiophenol (II) have been prepared. The acylation of both compounds I and II leads to N-acyl derivatives of the first. The acylating ability of formamide and N,N-dimethylformamide was observed in reactions with pyrazoline I. An x-ray structural study was carried out on compound II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 360–366, March, 1993. 相似文献
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Orlov I. S. Moiseeva A. A. Butin E. P. Egorov M. P. 《Russian Chemical Bulletin》2002,51(10):1961-1962
An unusual reaction of diaminogermylene and diaminostannylene with sterically hindered phenols which leads to the formation of stable phenoxyl radicals in high concentrations was found. The reaction mechanism was proposed. Amides [(Me3Si)2N]2E (E = Ge, Sn) were investigated electrochemically. 相似文献