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991.
Rapid resolution liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry was developed for simultaneous determination of twelve saponins in Radix et Rhizoma Notoginseng (RRN) with macranthoidine A as internal standard. All calibration curves showed good linear regression (r 2 > 0.9935) within test range. The limits of detection of the twelve compounds were in the range of 1.53–5.08 ng mL−1. This method was successfully applied to analyze the saponins in fifteen samples of RRN.
相似文献992.
高校教学质量评价的属性识别法 总被引:2,自引:1,他引:1
郭奇 《数学的实践与认识》2008,38(6):9-13
阐述了高校教学质量评价的属性识别法.并应用此方法对普通高等学校的教学质量进行评价,指出了属性识别理论与模糊综合评判方法相比的优越之处.为普通高等学校教学质量评价提供了一种量化处理的方法. 相似文献
993.
Cucurmosin 2, a type 1 ribosome-inactivating protein (RIP) isolated from sarcocarp of Cucurbita moschata, has been crystallized by the vapor-diffusion method using PEG6000 as the precipitant. The crystals belong to the orthorhombic space group P212121, with unit cell parameters a = 55.853, b = 65.507, c = 91.754 А, and have one molecule per asymmetric unit. X-ray data have been collected to 1.8А, using a synchrotron source. 相似文献
994.
Jianhua Liu Yusong Wang Qi Fu Xiangyang Zhu Wenfang Shi 《Journal of polymer science. Part A, Polymer chemistry》2008,46(4):1449-1459
A simple mathematic model for the free radical polymerization of chain transfer monomers containing both polymerizable vinyl groups and telogen groups was proposed. The molecular architecture of the obtained polymer can be prognosticated according to the developed model, which was validated experimentally by homopolymerization of 4‐vinyl benzyl thiol (VBT) and its copolymerization with styrene. The chain transfer constant (CT) of telogen group in a chain transfer monomer is considered to play an important role to determine the architecture of obtained polymer according to the proposed model, either in homopolymerization or copolymerization. A highly branched polymer will be formed when the CT value is around unity, while a linear polymer with a certain extent of side chains will be obtained when the CT value is much bigger or smaller than unity. The CT of VBT was determined to be around 15 by using the developed model and 1H NMR monitored experiments. The obtained poly(VBT) and its copolymers were substantiated to be mainly consisted of linear main chain with side branching chains, which is in agreement with the anticipation from the developed model. The glass transition temperature, number average molecular weight, and its distribution of those obtained polymer were primarily investigated. This model is hopefully to be used as a strategy to select appropriate chain transfer monomers for preparing hyperbranched polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1449–1459, 2008 相似文献
995.
996.
用T和Dγ(0 ≤ γ ≤ 1)分别表示变量核奇异积分和分数次微分算子.T*和T#分别为T的共轭算子及拟共轭算子.利用球调和多项式展式,本文得到了TDγ-DγT和(T*-T#)Dγ在?q,λω(Rn)上的有界性.同时也得到了变量核奇异积分的积T1T2和拟积T1°T2的加权范不等式. 相似文献
997.
Substituted 2-halomethyl-2,3-dihydrobenzofurans were synthesized in one pot and in mild yield from substituted o-allylphenols with diacetoxyiodobenzene in the presence of 12 or Br2 in dry CH2Cl2 under reflux. 相似文献
998.
Z H Qi J Yan W J Xiong J G Yuan S Song C Q Xue L W Cai 《Science in China. Series B, Chemistry, life sciences & earth sciences》1989,32(9):1082-1086
On the basis of sequencing the large DNA-fragments which have been inserted into M13mp8, we design a simple strategy to determine the complete nucleotide sequence of HBV adr NC-1 DNA with chain termination method. The whole genome is 3195 nucleotides long. Five reading frames are observed. The gene location and organization are shown. 相似文献
999.
1000.