Trends in the CNDO/2 molecular orbital study of electronic structure in some neurotransmitter drugs

An investigation of electronic structure in some neurotransmitter drugs has been made using the CNDO/2 semi-empirical molecular orbital method.The electronic structure has been conveniently characterized by the electronic parameters nett atomic population (NAP) and bond index (BI). A variation of these electronic parameters with respect to conformation has been studied and has been found unlikely to exceed 0.1 e in most. cases. Further, the useful extent to which the electronic parameters of some commonly occurring functional groups may be regarded as conformationally invariant has been demonstrated. Also presented are (i) a discussion on the intramolecular close-approach of functional groups — the interaction between terminal —COO^? and ?NH₃⁺ groups of α-ω anaino acids is explicitly considered; (ii) an enquiry into the extension of ‘standard’ (idealized) geometry models in the elucidation of electronic structure.The implication of the results and observations presented here are briefly discussed with reference to classical and quantum structure-activity studies of drug molecules.     

某些有机物在氧化物载体表面的自发单层分散

自发单层分散原理已在载负型催化剂制备、再生等方面得到越来越广泛的应用[1，2]．许多氧化物和盐类可以在载体表面形成单层分散或亚单层分散．有些分散物与载体混合后在低于其熔点的温度下处理，就可以自发分散到载体表面[1，3]．这一现象通过XRD、LRS、XPS、SIMS、ISS、EXAFS     

A comparison of phototautomerism in different sites of free-base porphin (H2P) in n-alkane crystals

Selective laser-induced phototautomerism of free-base porphin in different n-alkanes (n-hexane, n-heptane, n-octane, nnonane, n-decane, n-undecane and n-dodecane) has been used to identify tautomer splittings in a number of sites in polycrystalline samples at 2 K. Pairs or lines arising from the two molecular orientations in each site can be reversibly transformed into each other. In the odd n-alkanes the occupation of different sites was not dependent on the rate at which the samples were frozen, but in the even n-alkanes metastable sites were only occupied following rapid quenching.     

程序涂渍柱“柱效能程序效应”的研究

本文从理论上给出程序柱“柱效能程序效应”的概念并导出了函数关系式,通过计算机可计算柱效能程序效应与柱内各变量之间的关系,实践证明实验数据的变化趋势与理论数据相符。     

拟静态法测定混合溶剂的汽化热和汽化熵

讨论了沸点升高法测定混和溶剂化热和汽化熵的原理，并用拟静态法测定了乙醇－丙酮，并－四氯化碳和苯，甲苯三组混和溶剂在不同组成下的正常沸点，根据沸点数据求得了混和泶微分汽化热和汽化熵，实验结果表明，二元混和溶剂与理想溶液偏离不大时，其正常汽化熵符合Ｔｒｏｕｔｏｎ规则。     

关于Aa-Bb型缩聚物网络结构的研究——溶胶凝胶分配理论

溶胶凝胶分配理论是在分子水平上表征交联网络结构的有效工具。由Flory等建立和发展起来的这一理论,由于引用了溶胶相无分子内环化反应的假定,特别是在理论推导中将分子内交联反应与分子间的链增长反应对两相分配的贡献未能加以区别,致使理论与实验不符。本文充分考虑了经典理论的这些缺欠,建立了更为符合客观实际的理论模型。同时,用十分简便的方法推导了反应溶胶分数,溶胶反应程度,分子内和分子间总反应程度等量宏观联系的参数方程组。以聚酯为模型化合物的实验研究与本文所得理论结果基本相符。     

取代基对氮和氧自由基稳定性影响的理论研究

用MNDO方法，全构型优化，研究了15个氮自由基4-RC6H4NH，和15个氧自由基4-RC6H4O（R＝－H；－OCH3，－Cl，－F，－CN，－COCH3，－NO2，－CH3，－CF3，－SCH3，－C6H5，－Nh2，－BH2，－PH2，－SiH3）的稳定化能．结果表明：－NH2，－CH3，－OCH3，－F基团对自由基起稳定化作用，－CF3，－NO2；－CN，－COCH3，－BH2基团对自由基起去稳定化作用．苯基对氧自由基有较大的稳定化作用，而对氮自由基的稳定性影响较小．－SCH3，－PH2，－SiH3，－Cl基团表现弱的去稳定化作用．计算和实验结果基本相符．     

Laser two-photon ionization of organic molecules in dielectric liquids

The ionization threshold of fluoranthene and of TMPD in n-pentane was determined by laser two-photon ionization (TPI) and found to be 4.50 ± 0.05 and 3.88 ± 0.05 eV respectively. For both molecules the TPI spectra show distinct structure due to autoionization. For fluoranthene the TPI spectrum suggests that the molecule dissociates via the first excited singlet state.     

关于统计学中一个新兴化学分支学科的建立、定义和教育

本文追溯了统计学发展、建立中的大事, 陈述了它的定义及其化学分支发展、建立的梗概; 鉴于化学界对该新兴化学分支学科的名称长期存在争议, 提出了以化学统计学而不以化学计量学为该学科名称的理由, 把化学统计学定义为一个研究有关数据的收集或产生、描述、分析、综合和解释, 以获得新化学知识或信息的学科; 阐明了许多公认属于统计学的方法, 如显著性检验、方差分析、回归和相关, 以及一些尚未认定属于统计学的方法, 如模型建立、蒙特卡罗方法、傅立叶变换和人工神经网络, 都含有统计学5 个内涵中的一个或多个; 探讨了化学统计学家成长的模式, 认为当务之急是把化学统计学纳入化学专业的教学计划, 以培养懂统计学的化学家。     

环形装置中三维MHD平衡与稳定性的计算机模拟

一、引 言 在聚变研究中,环形等离子体的磁约束起着重要作用。目前托卡马克研究的进展令人鼓舞,其理论与实验比较符合,定标关系清楚。但是无论从聚变的最终目标来看,还是从实验的安排考虑,完全轴对称的几何形状给各方面部带来许多不便。人们希望知道如果把环形几何中加进直线段,或者把圆环改成不具有对称性的环形,会对等离子体约束产生何种影响?