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171.
Zhidovinova M. S. Fedorova O. V. Rusinov G. L. Ovchinnikova I. G. 《Russian Chemical Bulletin》2003,52(11):2527-2528
The ultrasound effect accelerates the Biginelli reaction 40 and more times. A sonochemical method for the synthesis of ethyl 4-R-6-methyl-2-oxo- and 4-R-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates was developed. The target products were obtained within 2 to 5 min in 90—95% yields. 相似文献
172.
N. L. Ovchinnikova M. A. Kuchenkova T. D. Kasymova P. Kh. Yuldashev 《Chemistry of Natural Compounds》1978,13(5):566-569
Summary The amino-acid sequences of the chymotryptic peptides of the 7S globulin of cotton seeds have been determined.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 682–687, September–October, 1977. 相似文献
173.
S. N. Ovchinnikova N. P. Poddubnyi A. I. Maslii 《Russian Journal of Electrochemistry》2003,39(6):679-684
The work justifies the selection of a sulfosalicylate copper–nickel electrolyte and its composition for obtaining nanostructures comprising alternate magnetic and nonmagnetic layers by a single-bath method. According to calculations of an equilibrium composition of the electrolyte and electrodiffusion fluxes of discharging species, in a neutral region of pH copper exists in the form of multicharged anions CuSSA3–, and the migration effects must reduce the rate of the mass transfer of copper-containing species with increasing current of the parallel reaction of discharge of nickel ions. Dependences of the partial current density of copper deposition on the electrode potential are studied at various values of pH of the copper and copper–nickel electrolytes. Experimental results are analyzed on the basis of modeling concepts. It is shown that the drop of the partial current density of copper deposition below its limiting value at potentials of deposition of a magnetic layer is connected with the emergence of migration effects. 相似文献
174.
Ovchinnikova S. N. Aleksandrova T. P. Vais A. A. 《Russian Journal of Electrochemistry》2004,40(7):755-759
The cathodic deposition of copper on a gold electrode and its subsequent anodic dissolution in an acid chloride solution, where two successive stages of a one-electron transfer are distinguishable because of the stability of chloride complexes of Cu(I), is studied by voltammetry and quartz microgravimetry. The formation of a film of an intermediate compound of Cu(I) during the deposition and dissolution of copper is revealed experimentally. Techniques for identifying the intermediate solid species are suggested. During a cathodic polarization, a film of intermediate compound CuCl forms at a reduced concentration of chloride ions in the Cu(II)/Cu(I) process, while during the anodic dissolution of the copper deposit formed during the cathodic polarization the intermediates appear in the Cu(0)/Cu(I) process, the concentration of chloride ions notwithstanding. The change in the electrochemical behavior of the system caused by a decrease in the concentration of chloride ions is explained. 相似文献
175.
V. V. Antonova T. I. Ovchinnikova K. P. Bespalov T. N. Serova V. K. Promonenkov B. F. Ustavshchikov 《Chemistry of Heterocyclic Compounds》1982,18(3):280-283
The electronic structures of some pyridine bases are analyzed by means of 1H and 13C NMR spectroscopic data for substituted pyridines and the calculated bond orders in the pyridine ring. The differences in the chemical bonds in the pyridine ring of isomeric methylpyridines and the carbon—carbon bonds between the ring and the methyl groups in these compounds are in agreement with the experimental data on the thermal stability of the simplest pyridine bases and the gas-phase transformation of the isomeric methylpyridines on an industrial nickel—aluminum catalyst. The possibility of obtaining mono- or dialkylpyridines under these conditions, depending on the structure of the starting pyridine bases, is demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 371–374, March, 1982. 相似文献
176.
Drobot N. F. Noskova O. A. Ovchinnikova N. A. Zvereva G. A. Larin G. M. Krenev V. A. Trifonova E. N. Drobot D. V. 《Russian Journal of Coordination Chemistry》2003,29(7):474-477
IR and EPR studies of solutions formed after molybdenum chlorination in the medium of DMF revealed the diamagnetic Mo(VI) and paramagnetic Mo(V) complexes of composition R2[MoOCl5], where R is [(CH3)2NCOH2]+ (I) and [(CH3)2NH2]+ (II). The hydrolysis of complex II was found to give dimethyl-substituted ammonium chloride. 相似文献
177.
178.
Elena V. Ovchinnikova Tamara V. Andrushkevich 《Reaction Kinetics and Catalysis Letters》2008,93(2):203-210
The effect of the dioxygen and β-picoline concentrations on the oxidation of β-picoline to nicotinic acid was studied at 270°C
over a 20% V2O5-80% TiO2 (wt. %) catalyst. The study was performed in a differential reactor at constant concentrations of water and nicotinic acid.
A considerable excess of dioxygen was shown to be necessary for the formation of nicotinic acid. It was found that the rates
of β-picoline transformation into nicotinic acid, pyridine-3-carbaldehyde, pyridine-3-nitrile, pyridine and carbon oxides
as well as selectivities to products and the catalyst state depend strongly on the ratio of dioxygen to β-picoline concentrations.
The minimum admissible ratio of these concentrations under industrial conditions was determined. 相似文献
179.
Kocharova NA Kondakova AN Vinogradov E Ovchinnikova OG Lindner B Shashkov AS Rozalski A Knirel YA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(20):6184-6191
A lipopolysaccharide isolated from an opportunistic pathogen of the Enterobacteriaceae family Providencia rustigianii O34 was found to be a mixture of R-, SR-, and S-forms consisting of a lipid moiety (lipid A) that bears a core oligosaccharide, a core with one O-polysaccharide repeating unit attached, and a long-chain O-polysaccharide, respectively. The corresponding carbohydrate moieties were released from the lipopolysaccharide by mild acid hydrolysis and studied by sugar and methylation analyses along with one- and two-dimensional NMR spectroscopy and high-resolution electrospray ionization mass spectrometry. As a result, the structures of the core and the O-polysaccharide were established, including the structure of the biological repeating unit (an oligosaccharide that is preassembled and polymerized in biosynthesis of the O-polysaccharide), as well as the mode of the linkage between the O-polysaccharide and the core. Combining the structure of the carbohydrate moiety thus determined and the known structure of lipid A enabled determination of the full lipopolysaccharide structure of P. rustigianii O34. 相似文献
180.
A. A. Ovchinnikov M. Ya. Ovchinnikova 《Journal of Experimental and Theoretical Physics》1999,89(3):564-576
The properties of spin excitations superposed on a uniform ground state with antiferromagnetic (or spiral) spin structure
are studied in a 2D Hubbard model. Expressions are derived for the spin susceptibility in the random phase approximation (RPA) using split Hubbard
bands as a zeroth approximation. The calculated collective modes with dispersion ω(Q)=c|Q−(π, π)| near Q∼(π, π) reproduce well the characteristics of the spin excitations observed in undoped cuprates. For doped systems with an
antiferromagnetic structure of the ground state, calculating X″(Q,ω→0) gives the same mode with a peak at Q∼(π, π), regardless of the type of Fermi surface. It is shown that in doped systems with a spiral ground state spin structure,
X″(Q,ω→0) peaks occur with incommensurate quasimomenta Q that are coupled to the spirality vector.
Zh. éksp. Teor. Fiz. 116, 1058–1080 (September 1999) 相似文献