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31.
The versatility of palladium(II) acetate and palladium on activated charcoal catalysts with triethylsilane has been investigated in the hydrogenation and the isomerization of carbon–carbon double bond of 1‐alkenes. The reduction of 1‐alkenes was carried out in the presence of triethylsilane, ethanol and a catalytic amount of palladium(II) acetate or palladium on activated charcoal, at room temperature. This facile and efficient method affords high yields for hydrogenation of unsaturated alkenes to the corresponding alkanes. Then the carbon–carbon double bond isomerization of 1‐alkenes was tested using the same catalysts in the absence of solvent. The system palladium(II) acetate‐triethylsilane was found to be more effective compared with palladium on an activated charcoal–triethylsilane system at room temperature, while comparable results were obtained at 50 °C for both catalysts. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
32.
Hazem A. Attia 《Heat and Mass Transfer》2006,42(9):779-787
In the present paper the unsteady flow and heat transfer of a dusty conducting fluid between two parallel plates with temperature dependent viscosity and thermal conductivity are studied. A constant pressure gradient and an external uniform magnetic field is applied. The governing coupled momentum and energy equations are solved numerically using finite differences. The effect of the variable viscosity and thermal conductivity of the fluid and the uniform magnetic field on the velocity and temperature fields for both the fluid and dust particles is discussed.On leave from Department of Mathematics and Physics, Faculty of Engineering, El-Fayoum University, Egypt 相似文献
33.
The method developed by Debiane and Kharif for the calculation of symmetric gravity-capillary waves on infinite depth is extended to the general case of non-symmetric solutions. We have calculated non-symmetric steady periodic gravity-capillary waves on deep water. It is found that they appear via bifurcations from a family of symmetric waves. On the other hand we found that the symmetry-breaking bifurcation of periodic steady class 1 gravity wave on deep water is possible when it approaches the limiting profile, if it is very weakly influenced by surface tension effects. To cite this article: R. Aider, M. Debiane, C. R. Mecanique 332 (2004). 相似文献
34.
M.?M.?Al-DabbasEmail author K.?Al-Ismail R.?Abu-Taleb F.?Hashimoto I.?O.?Rabah K.?Kitahara K.?Fujita T.?Suganuma 《Chemistry of Natural Compounds》2011,47(1):17-21
A new isolated flavone, 4′-hydroxy-3,5,6,7-tetramethoxyflavone (6), together with seven known 3-O-methylated flavones isolated from the ethanol extract of the aerial parts of Varthemia iphionoides, were studied for DPPH free radical-scavenging and cytotoxic activities. Flavones 2, 3, 4, and 8 were the most active DPPH free-radical scavengers with inhibition percentage of 63.5, 42.9, 47.9, and 55.6, respectively,
at a concentration of 100 μg/mL. Flavones 2 and 8 were the most active as inhibitor for human leukemia HL-60 cells; the IC50 values after 48 h incubation were 20.5 and 23.9 μg/mL, respectively. 相似文献
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36.
Rabah Labbas Ahmed Medeghri Boubaker-Khaled Sadallah 《Applied mathematics and computation》2002,130(2-3):511-523
We prove the optimal regularity, in Sobolev spaces, of the solution of a parabolic equation set in a triangular domain T. The right-hand term of the equation is taken in Lebesgue space Lp(T). The method of operators sums in the non-commutative case is referred to. 相似文献
37.
In this paper we present a new and numerically efficient technique for designing 2-D linear phase octagonally symmetric digital filters using Schur decomposition method (SDM) and the diagonal symmetry of the 2-D impulse response specifications. This technique is based on two steps. First, the 2-D impulse response matrix is decomposed into a parallel realization of k sections, each comprising two cascaded linear phase SISO 1-D FIR digital filters. It is shown that using the symmetry property of the 2-D impulse response matrix and the fact that the left and right eigenspaces obtained by SDM are transpose of each other, the design problem of two 1-D digital filters is reduced to the design problem of only one 1-D digital filter in each section. 相似文献
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Actis P Manesse M Nunes-Kirchner C Wittstock G Coffinier Y Boukherroub R Szunerits S 《Physical chemistry chemical physics : PCCP》2006,8(42):4924-4931
This paper describes the functionalization of oxidized boron-doped diamond (BDD) electrodes with N-(3-trimethoxysilylpropyl)pyrrole (TMPP) and the influence of this layer on the electrochemical transfer kinetics as well as on the possibility of forming strongly adhesive polypyrrole films on the BDD interface through electropolymerization. Furthermore, localized polymer formation was achieved on the TMPP-modified BDD interface using the direct mode of a scanning electrochemical microscope (SECM) as well as an electrochemical scanning near-field optical microscope (E-SNOM). Depending on the method used polypyrrole dots with diameters in the range of 1-250 microm are electrogenerated. 相似文献