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排序方式: 共有98条查询结果,搜索用时 15 毫秒
1.
A.I. Olemskoi O.V. Yushchenko V.N. Borisyuk T.I. Zhilenko Yu.O. Kosminska V.I. Perekrestov 《Physica A》2012
A novel mechanism of new phase formation is studied both experimentally and theoretically in the example of quasi-equilibrium stationary condensation in an ion–plasma sputterer. Copper condensates are obtained to demonstrate that a specific network structure is formed as a result of self-assembly in the course of deposition. The fractal pattern related is inherent in the phenomena of diffusion limited aggregation. Condensate nuclei are shown to form statistical ensemble of hierarchically subordinated objects distributed in ultrametric space. The Langevin equation and the Fokker–Planck equation related are found to describe stationary distribution of thermodynamic potential variations at condensation. Time dependence of the formation probability of branching structures is found to clarify the experimental situation. 相似文献
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L. E. Kitaev Z. M. Bukina V. V. Yushchenko D. A. Ionin N. V. Kolesnichenko S. N. Khadzhiev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(3):381-385
The effect of the manner and conditions of introducing lanthanum cations into NH4-ZSM-5 zeolite on the properties of catalysts for the conversion of dimethyl ether into the mixtures of gasoline hydrocarbons is studied. The physicochemical properties of synthesized catalysts are studied by means of temperature-programmed ammonia desorption, the adsorption of benzene, atomic absorption spectroscopy, differential scanning calorimetry, and thermogravimetry. It is shown that the degree to which lanthanum cations are replaced by ammonium cations both depends on the conditions of ion exchange in the zeolite and affects its acidity spectrum and the selectivity of the formation of paraffin hydrocarbons with isostructure. It is concluded that an increase in the amount of introduced lanthanum leads to an increase in the content of iso-paraffins from 69 to 76 wt % and a decrease in the content of aromatic hydrocarbons from 10.5 to 5.5 wt % and that of durene from 1.5 to 0.2 wt % in the products. 相似文献
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Olga Kalchenko Sergiy Cherenok Olexander Yushchenko Vitaly Kalchenko 《Journal of inclusion phenomena and macrocyclic chemistry》2013,76(1-2):29-36
Host–Guest complexation process of calixarenehydroxymethylphosphonic acids with 10 amino acids in solution H2O/MeCN (99:1) had been studied. Binding constants of the inclusion complexes from the dependence between capacity factors of the Guest and the calixarene-Host concentration in the mobile phase had been calculated. It was shown the binding constants depend on the nature of the amino acid residue, conformation of the calixarene skeleton, quantity of phosphoryl groups at the upper rim. In accordance with molecular calculation the complexation is determined by the electrostatic interactions between the positively charged nitrogen atom of amino acid and the negatively charged oxygen atom of phosphonic group of calixarene molecule, hydrogen bonds, π–π, CH–π and solvatophobic, interactions. 相似文献
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Tsodikov M. V. Slivinskii E. V. Yushchenko V. V. Kitaev L. E. Kriventsov V. V. Kochubei D. I. Teleshev A. T. 《Russian Chemical Bulletin》2000,49(12):2003-2006
The data of temperature-programmed desorption of ammonia from the surface of oxide systems and IR spectroscopy were used to demonstrate that the strength of the surface acid sites in titanium oxides prepared by the alkoxo method and modified by aluminum decreases with respect to that in nonmodified titanium oxide. Modification of titanium oxide with P3+ ions from ethriol phosphite almost completely suppresses the acid properties. Modified oxides are able to chemisorb water. XANES data suggest that modification of titanium oxide with phosphorus ions increases the electron density on the titanium atoms and, correspondingly, the basicity of the materials. 相似文献
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We study bounded and unbounded *-representations of Twisted Generalized Weyl Algebras and algebras similar to them for different choices of involutions. 相似文献
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N. V. Kolesnichenko L. E. Kitaev Z. M. Bukina N. A. Markova V. V. Yushchenko O. V. Yashina G. I. Lin A. Ya. Rozovskii 《Kinetics and Catalysis》2007,48(6):789-793
Zeolite H-TsVM has been loaded with palladium by different methods. The properties of the resulting catalysts in gasoline synthesis from syngas via dimethyl ether depend on the way in which palladium was introduced. The catalysts have been characterized by ammonia temperature-programmed desorption (TPD), temperature-programmed reaction with hydrogen, and X-ray photoelectron spectroscopy. According to ammonia TPD data, use of a palladium ammine complex instead of palladium chloride reduces the concentration of strong acid sites and raises the concentration of medium-strength acid sites, thereby reducing the yield of C1–C4 hydrocarbons and increasing the yield of gasoline hydrocarbons. At T = 340°C, P = 100 atm, and GHSV = 2000 h?1, the dimethyl ether conversion is 98–99%, the gasoline selectivity is >60%, the isoparaffin content of the product is ~61%, and the arene content is not higher than 29%. 相似文献
10.
Ardanova LI Get'man EI Loboda SN Prisedsky VV Tkachenko TV Marchenko VI Antonovich VP Chivireva NA Chebishev KA Lyashenko AS 《Inorganic chemistry》2010,49(22):10687-10693
Polycrystalline hydroxyapatites Ca(10-x)REE(x)(PO(4))(6)(OH)(2-x)O(x) were synthesized and studied by X-ray powder diffraction, infrared absorption, diffuse-reflectance spectroscopy, and thermogravimetry. The solubility limits x(max) of rare earth elements (REE) in Ca hydroxyapatites decreases with an increasing REE atomic number from x(max) = 2.00 for La, Pr, and Nd to x(max) = 0.20 for Yb at 1100 °C. Refinements of X-ray diffraction patterns by the Rietveld method show that REE atoms substitute for Ca preferentially at the Ca(2) sites of the apatite structure. The substitution decreases the Ca(2)-O(4) atomic distances in the calcium coordination polyhedra and increases the Ca(2)-O(1,2,3) distances. This observation shows that interatomic distances depend not only on radii of the ions involved in the substitution but also on their charges. 相似文献