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991.
A procedure for fast determination of the total content of arenes in reformer naphthas by 1H NMR spectroscopy was developed and tested. Their content is determined from the ratio of the integral intensities of the signals of aromatic protons and alkane methyl protons, using a calibration plot constructed on the basis of GLC data. 相似文献
992.
T. T. Kucherenko P. V. Muzyka É. B. Rusanov A. N. Chernega V. A. Kovtunenko A. K. Tyltin F. S. Babichev 《Chemistry of Heterocyclic Compounds》1992,28(5):515-518
An unusual path for the reaction of 2-aryl-1-dimethylamino-2H-isoindoles with N-R-maleimides, leading to the imides of l,2-dihydronaphthalene-2,3-dicarboxylic adds, was established by x-ray crystallographic analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 614–618, May, 1992 相似文献
993.
994.
The synthesis of 2,8-dimethyl 3,9-dichloro 6-sila[5.5] spiro undecatetra 2.4,8,10-ene is described. The thermal decomposition of the adduct formed by the reaction of this product with methyl acetylene dicarboxylate is studied. From the characterization of the copyrolysis products, two possible mechanisms are proposed which imply the formation of digonal silicon such as 2-silaallene and 2-silaketene. 相似文献
995.
The crystal structure of 12,13-dibromopseurotin has been determined by single crystal X-ray analysis. The crystals belong to space group P21 with a = 16.75, b = 9.63, c = 7.42 Å, β 95.9°, Z = 2. The structure was solved by the heavy atom technique and refined to R = 0.062 with 819 significant reflexions for 299 parameters. 相似文献
996.
997.
998.
Vibrational circular dichroism (VCD) in the past two decades has developed into a powerful new structural tool. A concise review of the applications of VCD to determine the structures of various biological molecules, namely peptides and proteins, nucleic acids and carbohydrates, is provided. 相似文献
999.
Coupling of gradient capillary electrochromatography (gradient CEC) and capillary zone electrophoresis (CZE) with nuclear magnetic resonance spectroscopy (NMR) was performed using a recently developed capillary NMR interface. This technique was applied for the analysis of pharmaceuticals and food. An analgesic was investigated using isocratic and gradient continuous-flow CEC-NMR. Comparison of the results demonstrated the superiority of gradient CEC over isocratic CEC. Aspartame and caffeine, both ingredients of soft beverages, were separated and analyzed by continuous flow CZE-NMR. The order of elution could be reversed by altering the pH. This reversal led to an increased sample concentration in the NMR detection cell, thus allowing the acquisition of a totally correlated spectroscopy (TOCSY) two-dimensional (2-D) spectrum of the synthetic peptide aspartame. 相似文献
1000.
A. N. Dmitrievskii A. A. Pribylov N. A. Skibitskaya L. A. Zekel’ A. P. Kubyshkin M. Ya. Shpirt 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(7):1099-1104
Isotherms of sorption of butane, propane, ethane, methane, and carbon dioxide on an asphaltene sample of known elemental composition were measured. The effect of the pressure and temperature on the shape the sorption isotherms for all the adsorption systems studied was examined. The values of the initial heat of sorption were determined and compared to the energies of interaction of the molecules with asphaltene. The results obtained suggest that asphaltene is a swellable amorphous sorbent. 相似文献