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991.
D. I. Kiryanov M. D. Smolikov V. V. Pashkov A. G. Proskura E. V. Zatolokina I. E. Udras A. S. Belyi 《Russian Journal of General Chemistry》2007,77(12):2255-2264
Analysis of the modern state of catalytic reforming is performed. Comparative assessment of the efficiency of various technologies
of the process is given and their distribution in Russia and abroad is shown. Experience of the modernization of reforming
installations with periodic catalyst regeneration is summarized. The state of manufacture of reforming catalysts in our country
and accumulated experience of the development of catalysts of the PR series are presented. Results of industrial exploitation
of new domestic reforming catalysts are shown. On this basis comparative assessment of Russian and imported catalysts is given.
Original Russian Text D.I. Kiryanov, M.D. Smolikov, V.V. Pashkov, A.G. Proskura, E.V. Zatolokina, I.E. Udras, A.S. Belyi,
2007, published in Russkii Khimicheskii Zhurnal, 2007, Vol. 51, No. 4, pp. 60–68. 相似文献
992.
L. G. Shaidarova S. A. Ziganshina G. K. Budnikov 《Journal of Analytical Chemistry》2003,58(6):577-582
The electrocatalytic activity of ruthenium(IV) oxide incorporated into a carbon-paste electrode was studied in the oxidation of cysteine and cystine. The oxidation potentials of the amino acids decreased and the current peaks of their oxidation increased at a modified electrode as compared to an unmodified one. Procedures for the voltammetric determination of cysteine and cystine with the use of electrodes chemically modified with ruthenium(IV) oxide were proposed. 相似文献
993.
V. G. Berezkin E. Yu. Sorokina A. I. Sokolov B. A. Rudenko 《Journal of Analytical Chemistry》2003,58(1):61-67
The effects of the presence of water vapor in the carrier gas and the temperature on the retention of achiral and chiral compounds, enantioselectivity, and performance of an open-tubular column with a cyclodextrin-containing phase were studied. The use of a carrier gas containing water vapor in the determination of optically active isomers, such as camphor, slightly increases the retention factor. A substantial improvement of performance characteristics of the column was found: for hydroxy compounds, the column performance increased by two to three times and the peak symmetry improved by more than twice. 相似文献
994.
Chmutova G. A. Zverev V. V. Pudovik M. A. Khailova N. A. Pudovik A. N. 《Russian Journal of General Chemistry》2003,73(11):1696-1701
The stability of phosphorylated ureas and thioureas containing various substituents at the P and N atoms and the stability of their cyclization products, the corresponding diazaphospholidines and/or oxaza(thiaza)phospholines, was evaluated by PM3, MNDO, and DFT calculations. The thermal effects of cyclizations involving phosphorylated ureas (or thioureas) and of separate steps of their synthesis were calculated. According to the calculations, diazaphospholidine structures are preferably formed from substituted ureas and thiazaphospholine structures, from their thio analogs; formation of five-membered heterorings with the P-N bond is thermodynamically preferable as compared to their six-membered analogs. 相似文献
995.
F. De Meester J. M. Frre J. L. Piette P. Jacquemin L. Grooters G. Llabres S. Defays 《Journal of heterocyclic chemistry》1992,29(2):535-541
In an attempt to rationalize a synthesis of penicillin analogs modified at C(3), we have isolated the 3R(β)-carbinolamide derivative 4a. The trityl substituent on N(6′) seems to be responsible for the inversion of configuration which occurs at C(3) during the acid hydrolysis of the isocyanate intermediate. An hydrogen bond is formed on the β-face of the bell-shaped bicyclic skeleton between the N(6′)-nitrogen lone pair and the C(3) hydroxyl group. On standing, the carbinolamide analog slowly isomerizes to its expanded bicyclic isomer 4b , but the starting material may be easily recovered by treatment with acid. The postulated intermediate during isomerization, i.e., the open aldehyde form, does not accumulate. Substitutions of the hydroxyl group at C(3) lead to a variety of compounds with the biologically active 3S(α) configuration. These may be used to study the importance of the carboxyl group of penicillins in their interaction with β-lactamases at the molecular level. 相似文献
996.
Tsventarnyi E. G. Kravtsov V. I. Kurtova O. Yu. 《Russian Journal of Electrochemistry》2003,39(3):215-222
The electroreduction kinetics of Pd(en)2+
2 complexes (0.01 M) is studied on a rotating disk electrode of Pd by recording CVA at 25, 50, and 70°C in solutions of pH 12–13 at ethylenediamine concentrations of 0.03–1.0 M. Established is a diffusion nature of limiting currents, from which diffusion coefficients for Pd(en)2+
2 complexes are calculated. The Pd electrode capacitance, determined by a pulsed galvanostatic method, is used for taking into account the true surface areas of electrolytic Pd deposits. Parameters of the slow electrochemical stage, which involves Pd(en)2+
2 complexes, are determined. The temperature dependence of the rate constant of cathodic reduction of Pd(en)2+
2 complexes is used for calculating an apparent activation energy. An electroreduction mechanism of Pd(en)2+
2 complexes on a Pd electrode is discussed. 相似文献
997.
A method is suggested for isomerization of -acetylenic ketones with migration of the oxo group from position 1 to position 3 and of the triple bond from position 2 to position 1 of the ketoacetylenic fragment; it consists of addition of Et2NH at the triple bond of the ketone, conversion of the adduct to the imminium salt with POCl3, followed by alkaline hydrolysis. The isomerization is achieved in one preparative stage without isolation of intermediate compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2094–2098, September, 1990. 相似文献
998.
L. Kh. Bikchurina R. Kh. Yumagulova L. M. Khalilov E. V. Vasil'eva G. V. Leplyanin 《Russian Chemical Bulletin》1990,39(6):1287-1291
The reaction of the acid chlorides of alkylenebisphosphonic acids with ethylene glycol and ethylene chlorohydrin gave ethylene glycol and -chloroethyl esters of alkylenebisphosphonic acids. The quaternization of these products leads to choline esters of alkylenebisphosphonic acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1424–1429, June, 1990. 相似文献
999.
G. A. Golubeva L. A. Sviridova E. S. Besidskii G. S. Besidskaya 《Chemistry of Heterocyclic Compounds》1990,26(4):416-420
Unlike 3-acylindoles, 3-acyl-2-aminoindoles display high selectivity on being electrophilically attacked in the benzene ring, and are substituted at the 6-position. At the same time, an unco-subsitution of the acyl group takes place (to the greatest extent — the formyl group). Direct bromination of 3-acyl- and 3-cyano-2-aminoindoles provides the 6-bromo- and 6,4-dibromo-2-aminoindoles and their derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 486–490, April, 1990. 相似文献
1000.
In this article we derive a segment-level formula for the matrix elements of the U(2n) generators in a basis symmetry adapted to the subgroup U(n) × U(2) (i.e., spin-orbit basis), for the representations appropriate to many-electron systems. This enables the direct evaluation of the matrix elements of spin-dependent Hamiltonians. 相似文献