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排序方式: 共有133条查询结果,搜索用时 46 毫秒
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Z.M. Babar Wan Mohd Azizi Solachuddin JA Ichwan Qamar Uddin Ahmed Abul Kalam Azad Imranul Mawa 《Natural product research》2019,33(15):2266-2270
The current study provides a way of extraction for both active NSO and WSE from Nigella sativa seeds using 98% methanol. About 1?kg of ground seeds was macerated by 1:2.5 w/v (g/mL) for 72?hours. After rotary evaporation and 7 days of continuous drying and chilling at 50 and 4?°C, NSO and WSE were obtained at the same instant. Solubility tests of 24 solvents and 11 thin layer chromatographic analyses while 2, 2-diphenyl-1-picrylhydrazyl free radical scavenging assay of NSO (73.66) , WSE (33.32) and NSO?+?WSE (78.22) against ascorbic acid (IC50?=?4.28?mg/mL) was performed. WSE was found to be highly soluble in water and 5% NaOH exhibiting the same Rf value of 0.95 for EtOH:DMSO (9:1) against the honey. WSE has revealed more than twofold higher anti-oxidant activity than others. Formulation of WSE with Tualang honey may provide better targeted hydrophilic drug delivery systems. 相似文献
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Valdivia NP Williams EG Herdic PC 《The Journal of the Acoustical Society of America》2008,123(1):109-120
Boundary element methods (BEMs) based near-field acoustic holography (NAH) requires the measurement of the pressure field over a closed surface in order to recover the normal velocity on a nearby conformal surface. There are practical cases when measurements are available over a patch from the measurement surface in which conventional inverse BEM based NAH (IBEM) cannot be applied directly, but instead as an approximation. In this work two main approximations based on the indirect-implicit methods are considered: Patch IBEM and IBEM with Cauchy data. Patch IBEM can be applied with a continuation procedure, which as its predecessor patch NAH (a well known technique that can be used on separable geometries of the wave equation) continues the pressure field using an iterative procedure, or it can be applied by a direct procedure. On the other hand, IBEM with Cauchy data requires measurements over two conformal patches and it will be shown that this technique will be reliable regardless of the position of the source. The theory behind each method will be justified and validated using a cylindrical surface with numerical data generated by point sources, and using experimental data from a cylindrical fuselage excited by a point force. 相似文献
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An efficient and high-yielding approach for the asymmetric synthesis of calcimimetic (+)-NPS R-568 (1) has been developed. The key step of the synthesis is the highly diastereoselective addition of methyl Grignard to the (SS,E)-N-(3-methoxybenzylidene)-2-propanesulfinamide [5(S)], which afforded a single diastereoisomer in high yield in short reaction time. 相似文献
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Manuel Valdivia 《Mathematische Nachrichten》2001,231(1):169-185
In this paper we study some properties of basic sequences in the dual of a Fréechet space. As a consequence we obtain that if E is a Fréechet space with the property that for each closed subspace F of E and each bounded subset B of E/F there is a bounded subset A of E with φ(A) = B, where φ denotes the canonical surjection of E onto E/F, then one of the following conditions is at least satisfied: 1. E is a Banach space, 2. E is a Schwartz space, 3. E is the product of a Banach space by ω. Finally, we also obtain some results concerning totally reflexive spaces. 相似文献
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Brenden P. Epps Pablo Valdivia y Alvarado Kamal Youcef-Toumi Alexandra H. Techet 《Experiments in fluids》2009,47(6):927-939
Digital particle image velocimetry and fluorescent dye visualization are used to characterize the performance of fish-like
swimming robots. During nominal swimming, these robots produce a ‘V’-shaped double wake, with two reverse-Kármán streets in
the far wake. The Reynolds number based on swimming speed and body length is approximately 7500, and the Strouhal number based
on flapping frequency, flapping amplitude, and swimming speed is 0.86. It is found that swimming speed scales with the strength
and geometry of a composite wake, which is constructed by freezing each vortex at the location of its centroid at the time of shedding. Specifically, we find
that swimming speed scales linearly with vortex circulation. Also, swimming speed scales linearly with flapping frequency
and the width of the composite wake. The thrust produced by the swimming robot is estimated using a simple vortex dynamics
model, and we find satisfactory agreement between this estimate and measurements made during static load tests. 相似文献
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