The derivatives of b -alkoxycarbonylethyltin trichlorides with diethyldithiocarbamate, ROCOCH2CH2Sn(S2CNEt2)Cl2, were synthesized and characterized by the means
Promoted by SmI3 β-diketones, β-ketoesters and α–cyano esters were added to α,β–unsaturated esters to form δ–carbonyl esters in mild conditions in mode
CO2-TPD was demonstrated an effective way to investigate the phase formation during pyrolysis for the preparation of composite oxides using metal-organic molecu
The photoinduced one-electron reduction of 1,4-dihydroxyanthraquinone(1,4-DHAQ) was studied by fluorescence, absorption and ESR spectroscopics.
在三维弹性接触边界元法基础上 ,采用不同形状板单元描述中间滚动体 ,并置于内环上 ,从而将多物体接触问题简化成两物体接触问题。对于板单元的弹性变形 ,用 Hertz接触公式 ,将其变形以等效间隙代入总体矩阵方程中 ,从而获得轧机滚动轴承负荷特性的三维分布。本方法具有计算模型直观、简单和较高的计算精度 ,因而成为设计和分析轧机滚动轴承负荷特性的有效数值方法
用从头算方法在B3LYP/ 6 31G 水平上对亚胺膦R3PNH(R =CH3,Cl)进行了理论计算研究。结果表明这两种亚胺膦的极性 ,P -N键性质及分子轨道存在明显差异 ,亚胺膦 (CH3) 3P =N
Condensation of 3,7-dichloromethyl-5-isopropyl-2-methoxytropone 4 with bis (mer-captoethyl) ether 5a and mono, di, and tri-ethylene glycol bis(mercaptoethyl) et
扼要介绍作者研制的包括前后处理的二维边界元法软件 THBEM2和三维边界元法软件 THBEM3,并通过算例介绍它们在复杂工程问题的线弹性应力分析 ,以及弹性力学辅助教学等方面的应用
词汇的学习包括理解、记忆和输出三个部分.理解是积累词汇的前提,没有理解的机械性记忆,在输出上会产生很大的困难,因此,必须运用灵活多样的教学方法和手段帮助学生理解单词