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排序方式: 共有840条查询结果,搜索用时 15 毫秒
41.
Volodymyr Kysil Sergey Tkachenko Caroline Williams Marina Churakova 《Tetrahedron letters》2007,48(36):6239-6244
New trimethylchlorosilane (TMSCl) promoted multicomponent reaction (MCR) of ethylenediamine(s), diverse carbonyl compounds, and isocyanides is proposed for the synthesis of a variety of highly substituted 3,4,5,6-tetrahydropyrazin-2-amines including corresponding spirocyclic compounds. 相似文献
42.
43.
A. O. Turakulova A. N. Kharlanov A. V. Levanov V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(5):814-821
The oxidative dehydrogenation of propane on a supported vanadium catalyst was studied (the support was a complex oxide system consisting of a ceria–zirconia solid solution deposited on γ-Al2O3 (CeZrO/γ-Al2O3)). A comparative analysis of the properties of the support and the catalyst prepared on its basis was performed. The support and catalyst were characterized by the BET method, scanning electron microscopy, X-ray diffraction analysis, and Raman spectroscopy. The catalytic properties of the catalyst and support were studied in propane oxidation at 450 and 500°C with pulse feeding of the reagent. The effect of propane on the support was found to improve the oxidative properties of the latter. This behavior of the support is related to the preparation procedure, which leads to the formation on its surface of the crystalline phase of the ceria–zirconia solid solution and amorphous ZrO2 and Al2O3 phases and/or their solid solution. Similar processes occur with the catalyst support during the oxidative dehydrogenation, giving rise to additional active centers (CeVO4). 相似文献
44.
T. V. Povarnitsyna N. R. Popova K. G. Bogolitsyn A. L. Beloglazova A. N. Pryakhin V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(12):2051-2055
The kinetics of catalytic oxidation for ferulic acid with polyoxometalates used as catalysts was studied. The effect of pH
and concentrations of the principal reacting components on the process kinetics was studied. A kinetic scheme of oxidation
is proposed, and the values of a number of kinetic parameters of the process are determined. 相似文献
45.
A. N. Mitrofanova A. G. Khudoshin V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(7):1141-1146
The influence of Mn(II) ions on the rate of the reaction between ozone and model lignin compounds, guaiacol and veratrole,
was studied. The catalyst did not influence the rate of the destruction of the aromatic ring and intermediate ozonolysis products,
compounds with conjugated double bonds, in acid media but substantially increased the rate of oxidation of saturated carboxylic
acids, ketoacids, and aldehydes. Ozone consumption then increased from 2 to 5 moles per mole of the transformed substrate.
A mechanism of the catalytic action of Mn(II) in reactions between ozone and the compounds studied was suggested. 相似文献
46.
Stepan Oryshchyn Volodymyr Babizhetskyy Olga Zhak Jean-Yves Pivan Arndt Simon 《Journal of solid state chemistry》2010,183(11):2534-2543
The new ternary pnictides Er12Ni30P21 and Er13Ni25As19 have been synthesized from the elements. They crystallize with hexagonal structures determined from single-crystal X-ray data for Er12Ni30P21 (space group P63/m, a=1.63900(3) nm, c=0.37573(1) nm, Z=1, RF=0.062 for 1574 F-values and 74 variable parameters), and for Er13Ni25As19 (Tm13Ni25As19-type structure, space group P6?, a=1.6208(1) nm, c=0.38847(2) nm, Z=1, RF=0.026 for 1549 F-values and 116 variable parameters). These compounds belong to a large family of hexagonal structures with a metal-metalloid ratio of 2:1. HRTEM investigations were conducted to probe for local ordering of the disordered structure at the nanoscale. The magnetic properties of the phosphide Er12Ni30P21 have been studied in the temperature of range 2<T<300 K and with applied fields up to 5 T. The magnetic susceptibility follows the Curie-Weiss law from 4 to 300 K. The measured value of μeff=9.59 μB corresponds to the theoretical value of Er3+. 相似文献
47.
Violetta Kholomenyuk Volodymyr Mykhaylyuk Mikhail Popov 《Central European Journal of Mathematics》2011,9(6):1267-1275
We prove that if Köthe F-spaces X and Y on finite atomless measure spaces (Ω X ; Σ X , µ X ) and (Ω Y ; Σ Y ; µ Y ), respectively, with absolute continuous norms are isomorphic and have the property (for µ = µ X and µ = µ Y , respectively) then the measure spaces (Ω X ; Σ X ; µ X ) and (Ω Y ; Σ Y ; µ Y ) are isomorphic, up to some positive multiples. This theorem extends a result of A. Plichko and M. Popov concerning isomorphic classification of L p (µ)-spaces for 0 < p < 1. We also provide a new class of F-spaces having no nonzero separable quotient space.
相似文献
$\mathop {\lim }\limits_{\mu (A) \to 0} \left\| {\mu (A)^{ - 1} 1_A } \right\| = 0$
48.
We study irreducible representations of two classes of conformal Galilei algebras in 1-spatial dimension. We construct a functor which transforms simple modules with nonzero central charge over the Heisenberg subalgebra into simple modules over the conformal Galilei algebras. This can be viewed as an analogue of oscillator representations. We use oscillator representations to describe the structure of simple highest weight modules over conformal Galilei algebras. We classify simple weight modules with finite dimensional weight spaces over finite dimensional Heisenberg algebras and use this classification and properties of oscillator representations to classify simple weight modules with finite dimensional weight spaces over conformal Galilei algebras. 相似文献
49.
We generalize the results of Kahn about a correspondence between Cohen-Macaulay modules and vector bundles to non-commutative surface singularities. As an application, we give examples of non-commutative surface singularities which are not Cohen-Macaulay finite, but are Cohen-Macaulay tame. 相似文献
50.
We analyze a system of two different types of Brownian particles confined in a cubic box with periodic boundary conditions. Particles of different types annihilate when they come into close contact. The annihilation rate is matched by the birth rate, thus the total number of each kind of particles is conserved. When in a stationary state, the system is divided by an interface into two subregions, each occupied by one type of particles. All possible stationary states correspond to the Laplacian eigenfunctions. We show that the system evolves towards those stationary distributions of particles which minimize the Renyi entropy production. In all cases, the Renyi entropy production decreases monotonically during the evolution despite the fact that the topology and geometry of the interface exhibit abrupt and violent changes. 相似文献