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991.
幂零群的若干充分条件 总被引:11,自引:0,他引:11
本文利用C-正规子群的性质,得到了若干有限群为幂零群的充分条件,推广了一些著名定理,如Thompson定理及It^o定理。 相似文献
992.
Chen Guo Hao Wen Huizhou Liu 《中国颗粒学报》2005,3(6):310-316
In this paper we review our work on self-assembly of the system, poly(ethylene oxide)-poly(propylene oxide)-poly(elhylene oxide) (PEO-PPO-PEO) block copolymers, which is a kind of macromolecular complex fluids. The control of self-assembly could be obtained by adding inorganic salts or aliphatic alcohols. By self-assembly of amphiphilic block copelymers a microemulsion phase is formed which could be applied in micelle extraction, such as hollow-fiber membrane micelle extraction, magnetic micelle extraction and immobilized micelle extraction. 相似文献
993.
994.
GuoQiangLI XiangLI ZhiWeiDENG HuaShiGUAN WenHanLIN 《中国化学快报》2005,16(4):494-496
Two new compounds, namely 7α, 10α-dimethyl-3β-isopropene-1, 2-ene-octahydro-naphthalene (1) and ethyl 5Z,8Z, 11Z, 14Z-nonadecatetraenoate (2) were isolated from the soft coralNephthea hainansis. Compound 1 was a pseutosesquiterpene and 2 was a polyunsaturated fattyacid ethylate. Their structures were established on the basis of spectroscopic methods. 相似文献
995.
Wen Hsiang Wei 《Annals of the Institute of Statistical Mathematics》2009,61(2):291-308
A class of regression model selection criteria for the data with correlated errors is proposed. The proposed class of selection
criteria is an estimator of weighted prediction risk. In addition, the proposed selection criteria are the generalizations
of several commonly used criteria in statistical analysis. The theoretical and asymptotic properties for the class of criteria
are established. Further, in the medium-sample case, the results based on a simulation study are quite consistent with the
theoretical ones. The proposed criteria perform well in the simulations. Several applications are also given for a variety
of statistical models. 相似文献
996.
Yu‐Liang Yang Dr. Wen‐Ying Liao Wan‐Yun Liu Chih‐Chuang Liaw Dr. Chia‐Ning Shen Dr. Zih‐You Huang Shih‐Hsiung Wu Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(43):11573-11580
Six photosensitive polyketides, malbranpyrroles A–F, were discovered from the thermophilic fungus Malbranchea sulfurea by using intact‐cell desorption/ionization on silicon mass (ICD‐MS) and LC‐SPE‐NMR. These two strategies facilitate the searching and structural determination of unstable natural products. The ICD‐MS indicated that only brown hyphae of M. sulfurea can produce malbranpyrroles. The biosynthetic pathway of malbranpyrroles was evidenced by 13C isotope precursors and amino acid feeding experiments. The cytotoxicity data revealed that the conformation of the conjugated system in malbranpyrroles does not affect cytotoxic potency against cancer cell lines. In addition, the chlorine atom was shown to be the pharmacophore for cytotoxicity. 相似文献
997.
基于传导变换的传导知识是一类重要的可拓知识.本文以传导变换和传导效应为基础,规定了传导度和传导知识的定义与类型,为研究传导知识的挖掘奠定理论基础. 相似文献
998.
Wen‐Na Zhao Lei Han Cheng‐Cai Luo 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(8):m280-m282
The title novel mixed μ2‐SH‐ and μ3‐SH‐bridged tetranuclear copper(I) complex, cyclo‐bis[μ2‐bis(diphenylphosphino)amine]di‐μ3‐sulfanido‐di‐μ2‐sulfanido‐tetracopper(I) methanol disolvate, [Cu4(SH)4(C24H21NP2)2]·2CH3OH, has crystallographically imposed centrosymmetry and affords a neutral Cu4S4 core with a distorted step‐like structure. The distances of 2.8458 (16) and 2.8179 (16) Å between copper(I) centres indicate the presence of ligand‐supported Cu...Cu interactions. Strong N—H...O and O—H...S hydrogen bonds between the tetranuclear cluster and methanol solvent molecules result in a two‐dimensional hydrogen‐bonded supramolecular network. This complex is the first example of a coinage tetranuclear metal complex with mixed μ2‐SH‐ and μ3‐SH‐bridged chromophores. 相似文献
999.
Eight series of chiral compounds with semi-fluorocarbon chains have been synthesized. The compounds were characterized by IR, 1H NMR, 19F NMR and mass spectroscopies and elemental analysis. Their phase transition behaviour was investigated by differential scanning calorimetry and polarizing optical microscopy. Their clearing points increase with an increase of the length of fluorocarbon chain. For a certain compound, when the terminal hydrogen atom in the semi-fluoroalkyl chain was substituted by a chlorine atom, both the clearing point and melting point were increased, and the thermal stability of the chiral smectic C (SmC*) phase was enhanced. However, the clearing point decreased and the melting point increased with the introduction of a triple bond into the core. 相似文献
1000.
Hua Ning LIU Wen Peng ZHANG 《数学学报(英文版)》2007,23(1):77-82
The main purpose of this paper is to use the generalized Bernoulli numbers, Gauss sums and the mean value theorems of Dirichlet L-functions to study the asymptotic property of one class of number-theoretic functions, and to give four interesting hybrid mean value formulae. 相似文献