Synthesis and crystal structure of the trimetallic erbium tetrahydride complex [Li(THF)4][{(ButCp)2Er(μ-H)} 3-(μ3-H)]

Reaction of [(Bu′tCp)2Er(μ-CI)]2 with Bu′Li in 1:1 molar ratio in THF at -78℃, after work-up, afforded the trimetallic erbium tetrahydride complex [Li(THF)4][{(Bu′Cp)2Er(μ-H)}3(μ3-H)] (1) by β-hydrogen elimination reaction. Crystal structure determination reveals that complex 1 has discrete ion pair structure. The anion is composed of three (Bu′Cp)2Er units to form a triangle array connected by three bridged hydrogen atoms, and the fourth hydrogen atom coordinated to three Er^3 ions. The coordination num-ber for each Er^3 ion is 9.     

中学化学教学方法初探

本文通过具体教学实例阐述了"四环节教学法"和"问题教学法"两种教学方法的实施过程。     

坚持正确导向,贯彻"四个统一"

本文就如何贯彻落实“四个统一”,如何把“四个统一”与高等教育工作的实际联系起来,努力培养德、智、体全面发展的合格人才,进行了比较全面的论述。     

金属间化合物环境氢脆的研究进展

总结了不同合金元素对Ll2型金属间化合物环境氢脆的影响.证明硼对Ni3Al的韧化主要是由于硼强烈降低氢的沿晶扩散,从而抑制由水汽诱发的环境氢脆.但硼在相同结构的Co3Ti中并没有上述作用,这是由于硼不偏聚在Co3Ti晶界上,不能有效降低氢的扩散系数.而Fe却可有效抑制Co3Ti中由水汽诱发的环境氢脆,其机理是Fe抑制了合金与水汽的表面反应速度.     

推广"四进家"活动 构筑农村大文化

随着社会主义市场经济体制的完善和农村改革的不断深化,如何赋予农村精神文明以新的内容和形式,是许多理论工作者和实际工作者需要不断探索的新课题。宜昌市在这方面作了有益的尝试,其“四进家”活动启示我们,农村精神文明建设要抓住根本,突出重点;找准载体,形成氛围;强化管理,务求实效。     

临氢条件下CO偶联合成草酸二乙酯反应的原位红外研究

利用原位红外光谱技术测定了临氢条件下CO和亚硝酸乙酯在催化剂上吸附的红外光谱,发现氢气会影响CO在催化剂活性中心上的吸附,且氢气与CO会发生甲烷化反应,氢气与亚硝酸乙酯反应生成乙醇和少量的乙腈,因此,CO催化偶联反应中加入氢气后,CO的转化率和草酸二乙酯选择性均降低。     

论英语形容词的理解及其两种基本翻译方法

本文就如何在理解英语形容词的基础上,运用汉语的叠词和四字结构,"忠实、通顺"地将其进行翻译的方法上进行了探讨.在就所应注意的若干问题进行分析和研究的同时,提出了自己的观点.     

一个类似于Dedekind和的四次均值公式

利用Dedekind和的性质,Dirichlet L—函数的性质以及解析方法研究一个类似于Dedekind和的四次均值,给出了一个较精确的渐进公式。     

Electrochemical hydrogen storage of aligned multiwalled carbon nanotubes

Hydrogen storage of aligned multi-walled carbon nanotubes (a-MWNTs),non-aligned MWNTs(n-MWNTs) and graphite electrodes are studied by the electro-chemical measurements .The electrodes are prepared by mixing carbon nanotubes (CNTs) copper powder and ptfe binder in a weight ratio of 1:5:3 and compressing the mixture into porous nickel collector,The results show that the electrochemical hydrogen storage capacity of the a-MWNT electrode is up to 1625 mAh/g corresponding to a high hydrogen storage of 5.7 wt% ,which is 10 times that of graphite electrode and is 13 times that of n-MWNT electrode, suggesting that a-MWNTs are promising materials for electrochemical hydrogen storage.     

NMR study on self-assembled cage complex of hexamethylenetetramine and cucurbit[n]urils

Self-assembled complexes between cage com-pounds cucurbit[n = 5—8]urils and hexamethylenetetramine were studied by using NMR techniques. Experimental results reveal that hexamethylenetetramine can lid cucurbit[5]uril to forming self-assembled capsules in which nothing is encap-sulated yet; the cavity of the cucurbit[7]uril can accommo-date a hexamethylenetetramine molecule to form a self- assembled host-guest inclusion. Moreover, both the cavity interaction of the cucurbit[7]uril with hexamethylenetetra-mine稨Cl and the portal interaction of the dipole carbonyl of the cucurbit[7]uril with hexamethylenetetramine稨Cl lead to form self-assembled capsules in which the hexamethylene-tetramine稨Cl are encapsulated in the hexamethylenetetra-mine稨Cl lidded cucurbit[7]uril. Although the structures of the portal and cavity to cucurbit[5]uril are similar, there is no obvious interaction between decamethylcucurbit[5]uril and hexamethylenetetramine, and also between cucurbit [6]uril or cucurbit[8]uril and hexamethylenetetramine.