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Wafa I. Abdel-Fattah M.SH. Fayed SH.R. Gooda W.F.F. Mekky 《Journal of Sol-Gel Science and Technology》1998,13(1-3):981-985
-Eucryptite solid solution (LAS) Li2O : Al 2O3 : 3SiO2(113) was prepared via a sol-gel route. Complex solutions of lithium or aluminum salts in ethanol/water mixtures were catalysed by inorganic acids (catalyst/alkoxide ratio 0.1). Different ratios of H2SO4 catalyst were also used.TGA showed that the maximum % yield of LAS 113 occurred using H2SO4 catalyst. Above 400°C exothermic peaks occurred in DSC followed by the glass transition. XRD and IR showed a high crystallinity of -eucryptite solid solution using all acids at the 0.1 ratio with the highest crystallinity for the 0.05 H2SO4 ratio. SEM revealed similar grain sizes in spite of higher acid concentrations. XRD data indicated a change to a tetragonal modification with higher catalyst ratio. 相似文献
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Research on Chemical Intermediates - In the current work, an acidic ionic liquid ([{(IMC)-4-OMBH}BIM][HSO4]3) has been utilized as an effective and recyclable catalyst for the synthesis of... 相似文献
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M. M. Heravi Y. SH. Beneshtiha R. Hekmat Shoar N. Nami 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):285-289
Abstract The addition of dimethyl acetylenedicarboxylate (DMAD) to 6-menthy-1, 2,4-triazlne-3(2H)thione-5(4H)-one afforded 2-methoxylcarboxy-7-methyl-1,3-thiazino[3,2-b][1,2,4]triazine-4,8-dione. 相似文献
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Alexander Feinstein 《General Relativity and Gravitation》1988,20(2):183-190
The results of two different approaches to the late-time behavior of primordial gravitational radiation are compared. Using asymptotic expansion in time of the tetrad components of the Riemann tensor one finds that initially chaotic behavior transfers itself into a radiative gravitational field of Petrov typeN ast. On the other hand, to accomplish the physical picture, we study the high-frequency behavior of the field variables in the same formalism. We show that the background spacetime is of general Petrov type I, and then calculate the tetrad components of the stress-energy tensor induced by the disappeared radiation with the help of Newman-Penrose equations. 相似文献
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In a previous paper, the second author introduced a compacttopology r on the space of closed ideals of a unital Banachalgebra A. If A is separable, then r is either metrizable orelse neither Hausdorff nor first countable. Here it is shownthat r is Hausdorff if A is C1[0, 1], but that if A is a uniformalgebra, then r is Hausdorff if and only if A has spectral synthesis.An example is given of a strongly regular, uniform algebra forwhich every maximal ideal has a bounded approximate identity,but which does not have spectral synthesis. 1991 MathematicsSubject Classification 46H10. 相似文献
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