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61.
Seed of Litchi chinensis Sonn. is a traditional Chinese medicine, having curative effects on gastric disease, diabetes,and relieving pain.[1] Two new compounds 4-O-p-coumaroylquinic acid butyl ester (1) and 3-O-p-coumaroylquinic acid butyl ester (2), along with five known compounds: 5-O-p-coumaroylquinic acid butyl ester (3),[2] 3-O-p-coumaroylquinic acid methyl ester (4),[3] n-butyl-1-β-D-fructopyranoside (5),[4] D-1-O-methylmyo-inositol (6)[5] and 1H-imidazole-2,3-dihydro-2-oxo-4-carboxylic acid methyl ester (7)[5] were isolated and purified from the ethanol extracts of the seed of L.chinensis Sonn. Their structures, shown in Figure 1, were elucidated by ESI-MS, 1H NMR and 13C NMR, including 2DNMR spectroscopy. 相似文献
62.
A series of 4,6-disubstituted pyrimidines were synthesized via Suzuki and Kumada coupling reaction of 4,6-dichloropyrimidine. 相似文献
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65.
采用淋洗液发生器阴离子交换-抑制电导检测法,同时分离和检测阿思巴甜、甜蜜素、安赛蜜和糖精4种常见的甜味剂.由于采用了淋洗液发生器,使背景电导大大降低,可以实现甜味剂的高灵敏度检测和分离.该方法具有良好的重现性、线性关系和较低的检测限.阿思巴甜、甜蜜素、安赛蜜和糖精的检测限分别是:1.27、0.045、0.033、0.063 mg/L;样品测定的回收率分别为99.7%、102.8%、98.6%、103.5%. 相似文献
66.
ChujiangCai ZhigangShen MingzhuWang ShulinMa YushanXing 《中国颗粒学报》2003,1(4):156-161
This paper reports the use of a colloidal Pd^0 catalysis system to metallize the surface of precipitators separated from coal fly-ash, and metals such as Cu, Ni etc. are deposited on the precipitators surface. Alternatively, according to the characteristic surface of cenospheres, an Ag coating catalysis system is adopted to first deposit Ag on the cenospheres surface, followed, if necessary, by the deposition of other metals such as Cu, Ni, etc. on the Ag coating to produce monolayer and multilayer metal-coated cenospheres. The surface characteristics and the morphologies of the metal coatings are examined in detail with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) techniques. It can be shown that the quality of metal coatings derived from the Aa coatina catalysis system, is better than that of the colloidal Pd^0 catalysis system. 相似文献
67.
68.
Richards模型在蔬菜生长预测中的应用 总被引:6,自引:0,他引:6
本文从 Richards模型的数学表达出发 ,阐述了模型中各参数初始值的确定以及优化过程 .并利用菜花和菠菜的试验数据建立其“最优”生长模型 . 相似文献
69.
We experimentally studied the in-plane thermal and electrical properties of a suspended platinum nanofilm in thickness of 15 nm. The measured results show that the in-plane thermal conductivity, the electrical conductivity and the resistance-temperature coefficient of the studied nanofilm are much less than those of the bulk material, while the Lorenz number is greater than the bulk value. Comparing with the results reported previously for the platinum nanofilm in thickness of 28 nm, we further find that the in-plane thermal conductivity, the electrical conductivity and the resistance-temperature coefficient decrease with the decreasing thickness of the nanotilm, while the Lorenz number increases with the decreasing thickness of the nanofilm. These results indicate that strong size effects exist on the in-plane thermal and electrical properties of platinum nanofilms. 相似文献
70.
Frame Wavelets with Compact Supports for L^2(R^n) 总被引:1,自引:0,他引:1
De Yun YANG King Wei ZHOU Zhu Zhi YUAN 《数学学报(英文版)》2007,23(2):349-356
The construction of frame wavelets with compact supports is a meaningful problem in wavelet analysis. In particular, it is a hard work to construct the frame wavelets with explicit analytic forms. For a given n × n real expansive matrix A, the frame-sets with respect to A are a family of sets in R^n. Based on the frame-sets, a class of high-dimensional frame wavelets with analytic forms are constructed, which can be non-bandlimited, or even compactly supported. As an application, the construction is illustrated by several examples, in which some new frame wavelets with compact supports are constructed. Moreover, since the main result of this paper is about general dilation matrices, in the examples we present a family of frame wavelets associated with some non-integer dilation matrices that is meaningful in computational geometry. 相似文献