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921.
Model chromophores of 1.10-dihydroflavin and its 10.10a-ring opened derivative have been isolated. By comparison with enzymatic intermediates, reaction mechanisms of flavin-dependent oxygenase and luciferase are discussed in terms of chemical structure. 相似文献
922.
V. E. Kuzmin N. S. Novikova T. A. Sidelnikova L. P. Trigub 《Journal of Structural Chemistry》1994,35(4):471-477
The use of topological indices to reveal the relationship between molecular structure and mesomorphous properties is discussed.
Mathematical models for classification of mesophase types are proposed. The effect of molecular structure and attractive ability
on phase transition temperatures is described. Examples of using correlation equations to predict the properties of 2,5-disubstituted
1,3-dioxanes are given.
A. V. Bogatskii Physicochemical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Struktumoi Khimii, Vol. 35, No. 4, pp. 53–60, July–August, 1994.
Translated by L. Smolina 相似文献
923.
A simple and rapid method for the simultaneous microdetermination of iodine and sulfur in organic compounds is described. The procedure utilizes the Schöniger flask method for the combustion, the iodide ions titration with 0.01 N mercuric perchlorate solution and diphenylcarbazone as indicator and the sulfate ions titration with 0.01 M barium perchlorate solution and dimethylsulfonazo III as indicator. The results obtained are in good agreement with calculated values. 相似文献
924.
Carbon disulfide reacts with the α-anions of carboxylate salts and esters to form intermediate salts, provides a new pathway to two classes of compounds: dithioesters and ketene mercaptals. The reaction produced the first carboxylated derivatives of dithioesters and ketene mercaptals. Examples of 2-carboxylated dithioesters and ketene mercaptals as well as their decarboxylated derivatives have been prepared and characterized. 相似文献
925.
N. N. Khimich Yu. L. Zub L. A. Koptelova T. S. Mashchenko E. P. Troshina M. G. Voronkov 《Russian Journal of Applied Chemistry》2006,79(11):1769-1774
Sol-gel process of hydrolytic polycondensation of tetramethoxysilane with trimethoxysilyl derivatives of lanthanide phosphoramide
complexes was studied in order to obtain photoluminescent organic-inorganic hybrid materials.
Original Russian Text N.N. Khimich, Yu.L. Zub, L.A. Koptelova, T.S. Mashchenko, E.P. Troshina, M.G. Voronkov, 2006, published
in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 11, pp. 1789–1794. 相似文献
926.
The acceleration of the electrodeposition and anodic dissolution of copper in acid sulfate solutions, caused by sodium pyrophosphate, is found to be due to a chemical heterogeneous stage, which involves an adsorbed pyrophosphate ion (probably, H2P2O7
2–). The assumption about the presence of a surface complex on the surface of copper is substantiated. As follows from adsorption isotherms, obtained for strongly acid (to 2 M H2SO4) solutions from anodic Tafel plots, the effect of the acid concentration on the rate of the discharge–ionization of copper is caused by its effect on the surface coverage by the adsorbate. Measurements of the quasi-equilibrium potential of the freshly renewed surface of copper confirm the assumption about the inhibiting of the surface diffusion of adsorbed atoms by adsorbed pyrophosphate. 相似文献
927.
A method is described for the precise determination of carbon and hydrogen in milligram, amounts of sample. The method is based on the manometric measurement of the amounts of carbon dioxide and water formed on combustion. A precision mercury manometer is used in which pressures are converted to mercury volumes. The latter are measured with the aid of a commercial piston-type buret using a photo-electric level indication. 相似文献
928.
Plasma-Enhanced Chemical Vapor Deposition of Silicon Carbonitride Films from Volatile Silyl Derivatives of 1,1-Dimethylhydrazine 总被引:1,自引:0,他引:1
T. P. Smirnova A. M. Badalyan V. O. Borisov L. V. Yakovkina V. V. Kaichev A. N. Shmakov A. V. Nartova V. I. Rakhlin A. N. Fomina 《High Energy Chemistry》2003,37(5):303-309
Silicon carbonitride films were synthesized from new volatile precursors by plasma-enhanced chemical vapor deposition. Based on a detailed study of the morphology of film surfaces, it was found that the layer material was an amorphous matrix with inclusions of nanosized crystals. Calculation of the structure of the crystalline phase from synchrotron X-ray diffraction patterns demonstrated that the entire set of the diffraction peaks detected is indexed by a tetragonal structure with the lattice parameters a = 9.6 Å and c = 6.4 Å. This is consistent with the fact that the carbon 1s and nitrogen 1s core level X-ray photoelectron spectra exhibited only sp
3 bonding, which was expected for superhard carbon nitride phases. 相似文献
929.
The solubility of salts with alkali and alkaline-earth metal cations and its dependence on the anion radius were discussed. The theoretical results were confirmed by experimental data on solubility. The stability of complexes in the Mg2+–Ba2+ series was considered depending on the ligand charge and radius. The revealed tendencies were explained in terms of the competition between solvent and ligand in solution for a central ion. 相似文献
930.
Bistable ferroelectric liquid crystal photoswitch triggered by a dithienylethene dopant 总被引:1,自引:0,他引:1
The spontaneous polarization (PS) of a ferroelectric liquid crystal is modulated reversibly by photocyclization of the dopant 1,2-bis[5'-(4' '-heptyloxyphenyl)-2'-methylthien-3'-yl]perfluorocyclopentene. The magnitude of PS photomodulation increases with dopant concentration up to 3 mol %, and the resulting photoswitch is fatigue resistant and bistable. To the best of our knowledge, this is the first example of a bistable ferroelectric liquid crystal photoswitch to be reported in the literature. 相似文献