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101.
Yury Yu. Rusakov Leonid B. Krivdin Maxim V. Penzik Vladimir A. Potapov Svetlana V. Amosova 《Magnetic resonance in chemistry : MRC》2012,50(10):653-658
Stereochemical structure of nine Z‐2‐(vinylsulfanyl)ethenylselanyl organyl sulfides has been investigated by means of experimental measurements and second‐order polarization propagator approach calculations of their 1H–1H, 13C–1H, and 77Se–1H spin–spin coupling constants together with a theoretical conformational analysis performed at the MP2/6‐311G** level. All nine compounds were shown to adopt the preferable skewed s‐cis conformation of their terminal vinylsulfanyl group, whereas the favorable rotational conformations with respect to the internal rotations around the C–S and C–Se bonds of the internal ethenyl group are both skewed s‐trans. Stereochemical trends of 77Se–1H spin–spin coupling constants originating in the geometry of their coupling pathways and the selenium lone pair effect were rationalized in terms of the natural J‐coupling analysis within the framework of the natural bond orbital approach. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
102.
Lyashenko G. S. Medvedeva A. S. Yazovtsev I. A. Albanov A. I. Demina M. M. 《Russian Journal of Organic Chemistry》2002,38(2):147-149
The hydrosilylation of a number of acetylenes RCCH (R, R' = Ph, CH2OPh, CH2SPh) with -ethynylhydrosilanes Me2SiHCHCR' in the presence of H2PtCl6 was investigated. The addition did not occur regioselectively, but was stereospecific and afforded a mixture of - and trans--adducts. The replacement of phenyl substituent by phenoxymethyl both in the molecule of ethynylsilane and the acetylene substrate resulted in growing proportion of the -adduct in the reaction mixture up to 10-60%. 相似文献
103.
Bennink RS Wong V Marino AM Aronstein DL Boyd RW Stroud CR Lukishova S Gauthier DJ 《Physical review letters》2002,88(11):113901
We have observed transverse pattern formation leading to highly regular structures in both the near and far fields when a near-resonant laser beam propagates without feedback through an atomic sodium vapor. One example is a regular far-field honeycomb pattern, which results from the transformation of the laser beam within the vapor into a stable three-lobed structure with a uniform phase distribution and highly correlated power fluctuations. The predictions of a theoretical model of the filamentation process are in good agreement with these observations. 相似文献
104.
Solid-Phase Luminescence Determination of Ciprofloxacin and Norfloxacin in Biological Fluids 总被引:1,自引:0,他引:1
Svetlana Beltyukova Olga Teslyuk Alla Egorova Elena Tselik 《Journal of fluorescence》2002,12(2):269-272
A simple, rapid, and sensitive luminescence test method for the determination of ciprofloxacin (CIP) and norfloxacin (NOR) has been described. The method is based on the intramolecular energy transfer from organic acid to terbium (Tb3+) ion. Luminescence of terbium (III) complex with CIP (NOR), sorbed on the zeolite has been studied. Under optimized conditions the detection limit is 1 g/mL in urine and human plasma. 相似文献
105.
We derive for Hecke-Maass cusp forms on the full modular group a relation between the sum of the form at Heegner points (and
integrals over Heegner cycles) and the product of two Fourier coefficients of a corresponding form of half-integral weight.
Specializing to certain cycles we obtain the nonnegativity of theL-function of such a form at the center of the critical strip. These results generalize similar formulae known for holomorphic
forms.
Partially supported by NSF grant # DMS-9096262.
Partially supported by NSF grant # DMS-9102082. 相似文献
106.
I. D. Kalikhman O. B. Bannikova E. N. Medvedeva T. I. Yushmanova V. A. Lopyrev 《Russian Chemical Bulletin》1982,31(6):1275-1277
Conclusion The PMR method was used to determine the conformations of the 1,2-diformyl-, diacetyl-, and di(trifluoroacetyl)hydrazines and their 1-methyl and 1,2-dimethyl analogs. The effect of the structure and the medium, on the population of the conformers was discussed.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1428–1430, June, 1982. 相似文献
107.
V. G. Khesin M. A. Al'perovich P. I. Abramenko R. D. Raikhina T. D. Medvedeva 《Chemistry of Heterocyclic Compounds》1982,18(2):144-147
The pathways of thermal fragmentation of thiacyanine dyes with different lengths of the external polymethine chain were investigated. The results of thermolysis of the thiacyanines are compared with the results of quantum-chemical calculations of their molecules.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 188–192, February, 1982. 相似文献
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