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71.
以Cu^2^+和Na^+同时作为模板,用2,6-二甲酰基对甲苯酚直接与一定比例的乙二胺,二-1,2-亚乙基-三胺发生[2+2]型Schiff碱缩合,合成了含两个不同隔室Schiff碱大环配体(L^2^-)的铜钠异双核配合物[CuNaL(ClO~4)]。并对它进行了元素分析,UV-Vis,IR,^1HNMR,摩尔电导和ESR谱等项表征。ESR谱显示三个g值峰,对应的g~x,g~y,g~z值分别为1.987,2.168,2.233。单晶X射线四圆衍射分析表明,该配合物为单斜晶系,空间群P2~1/n,晶胞参数a=0.9255(3),b=1.7689(2),c=1.6055(2)nm,β=101.69(2)ⅲ,Z=4,V=2.574nm^3。Cu原子和Na原子分别位于大环配体L^2^-的'N~2O~2'四配位和'N~3O~2'五配位隔室。Cu^2^+的配位数为4,基本保持平面构型。Cu-O和Cu-N平均键长分别为0.1911,0.1926nm。Na^+除与L^2^-配位外,还与单齿高氯酸根结合,配位数为6。Na-O和Na-N的平均键长分别为0.2379,0.2468nm。Cu...Na间距离为0.3227nm。  相似文献   
72.
胡海泉  刘成卜 《化学学报》1998,56(12):1180-1183
用量子化学理论方法研究了硅杂环丙烯单重态的异构化反应。结果表明:该异构化反应的过渡态为三元环结构,该反应为氢迁移反应;反应的势垒高度为276.67kJ·mol^-^1[MP2/6-31G(d)]。通过内禀反应坐标(IRC)计算,获得了沿反应途径的势能剖面。  相似文献   
73.
《Nuclear Physics B》1996,477(1):3-26
We have calculated inclusive one- and two jet production in photon-photon collisions superimposing direct, single-resolved and double-resolved cross sections for center of mass energies of the LEP1, LEP2 and NLC range. The direct and single-resolved cross sections are calculated up to next-to-leading order. The double-resolved two-jet cross section is calculated only in LO with a k factor estimated from the NLO one jet cross section. Various differential cross sections as functions of transverse momenta and rapidities of the jets are evaluated.  相似文献   
74.
首次利用量子化学半经验AM1方法和从头算HF/6-31G方法对一种新型的苝醌类光? 艏?PQP)-菌生素(HMB)的结构及其分子内质子传递(IPT)进行了理论计算研究,并? 捎弥鸩皆黾硬嗔吹姆椒ㄉ杓屏艘幌盗心P突衔镆钥悸歉鞑嗔炊訦MBIPT的影响,? 峁推p醌(PQ)的IPT作了对比。同于HMB只有一个分子内氢键,此项研究对解释PQP的光敏活性有十分重要的意义。本研究主要结论:(1)基态时HMB的IPT势垒只有10.0180kJ/mol(反式)和37.9819kJ/mol(顺式),分子中存在着快速的IPT。(2)侧链对HMB的IPT势垒影响较小,IPT主要受它的大共轭结构和共振模式的影响。(3)过渡态时质子的电荷增加,质子传递势垒与它的电荷变化成线性关系,此关系可推广到其它质子传递体系。(4)HMB的IPT势垒和IPT过程中羟基氧氢键以及氢键的键长变化均成较好的线性关系。(5)虽然只有一个IPT模式,HMB的IPT以及共振模式仍然和PQ十分相似,这是HMB保持光敏活性的基础。  相似文献   
75.
伯胺N~1~9~2~3萃取硫酸铀酰的机理研究   总被引:3,自引:0,他引:3  
研究了伯胺N~1~9~2~3的正庚烷溶液从硫酸介质中萃取硫酸铀酰的机理。认为伯胺N~1~9~2~3的硫酸盐在有机相中形成了反向胶束(或胶团),并由红外光谱和透射电镜佐证。伯胺N~1~9~2~3和铀酰形成的萃合物主要存在于反向胶束准相中。可以较好地解释用斜率法无法解释的实验事实。  相似文献   
76.
This study investigated the targeting and ultrasound-triggered injury of cancer cells using anticancer drug-free liposomes that contained an emulsion of perfluoropentane (ePFC5) and were co-modified with avidin as a targeting ligand for cancer cells and the hemagglutinating virus of Japan (HVJ) envelope to promote liposome fusion with the cells. These liposomes are designated as ePFC5-loaded avidin/HVJ liposomes. ePFC5-loaded liposomes were sensitized to ultrasound irradiation. Liposomes modified with avidin alone (avidin liposomes) showed binding to MCF-7 human breast cancer cells, and liposomes modified with HVJ envelope alone (HVJ liposomes) were found to fuse with MCF-7 cells. The irradiation of MCF-7 cells with 1 MHz ultrasound (30 s, 1.2 W/cm2, duty ratio 30%) combined with ePFC5-loaded avidin/HVJ liposomes resulted in a decrease in cell viability at 1 h after irradiation to 43% of that of controls without ultrasound irradiation or liposomes. The cell viability was lower than that of cells treated with ultrasound irradiation with ePFC5-loaded avidin liposomes or ePFC5-loaded HVJ liposomes. This indicates that co-modification of liposome with avidin and HVJ envelope could enhance ultrasound-induced cell injury in the presence of ePFC5-loaded liposomes.  相似文献   
77.
We study and compare natural generalizations of Euclid's algorithm for polynomials with coefficients in a finite field. This leads to gcd algorithms together with their associated continued fraction maps. The gcd algorithms act on triples of polynomials and rely on two-dimensional versions of the Brun, Jacobi–Perron and fully subtractive continued fraction maps, respectively. We first provide a unified framework for these algorithms and their associated continued fraction maps. We then analyse various costs for the gcd algorithms, including the number of iterations and two versions of the bit-complexity, corresponding to two representations of polynomials (the usual and the sparse one). We also study the associated two-dimensional continued fraction maps and prove the invariance and the ergodicity of the Haar measure. We deduce corresponding estimates for the costs of truncated trajectories under the action of these continued fraction maps, obtained thanks to their transfer operators, and we compare the two models (gcd algorithms and their associated continued fraction maps). Proving that the generating functions appear as dominant eigenvalues of the transfer operator allows indeed a fine comparison between the models.  相似文献   
78.
对于一个由m个正整数构成的数组,若其中任意两个正整数的乘积都等于一个完全平方数减去1,则称这个数组为Diophantine m-tuples.最近,Dujella获得了关于Diophantine2-tuples及3-tuples个数的渐进公式.本文改进了的相关结果.  相似文献   
79.
利用锥上的不动点指数研究了一阶非线性常微分方程组的周期边值问题.在某些条件下,证明了上述周期边值问题正解的存在性.  相似文献   
80.
Based upon Il’yushin’s postulate and the plastic potential theory, a procedure for calculating the abrupt change in stresses from the peak strength surface to the residual strength surface is proposed. The stability criterion for a brittle-plastic body loaded proportionally is presented. Finally, three examples have been solved analytically and numerically, including an engineering example of the steep rock slope of a shiplock system for the Three Gorges hydroelectric power project in China.  相似文献   
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