Study on the Quantitative Structure-toxicity Relationships for the Selected Esters by Using Molecular Electronegativity Interaction Vector （MEIV）

The molecular electronegativity interaction vector (MEIV) was used to describe the molecular structure of 30 selected esters. Two excellent QSTR models were built up by using multiple linear regression (MLR) and partial least-squares regression (PLS). The correlation coefficients (R) of the two models were 0.945 and 0.941, respectively. The models were evaluated by performing the cross validation with the leave-one-out (LOO) procedure. The cross-verification correlation coefficients (RCV) of the two models were 0.921 and 0.919, respectively. The results showed that the models constructed in this work could provide estimation stability and favorable predictive ability.     

分子电性距离矢量用于多溴联苯醚分子结构表达及色谱保留时间预测

应用分子电性距离矢量(MEDV)对多溴联苯醚(PBDEs)的209种同系物进行结构表征.通过多元线性回归的方法,建立了PBDEs定量结构-色谱保留(QSRR)关系的6个变量和5个变量的两种模型.两种模型的建模计算值复相关系数R均为0.995;用留一法(LOO)进行了交互检验,其复相关系数(R2cv)分别为0.987和0...     

A DFT Study of Thiophene Adsorption on the Rh（111） Surfaces

Thiophene adsorption on the Rh(111) surfaces has been investigated by density functional theory.The results show that the adsorption at the hollow and bridge sites is the most stable.The molecular plane of the thiophene ring is distorted,the C=C bond is stretched to 1.448  and the C-C bond is shortened to 1.390.The C-H bonds tilt 22～42oaway from the surface.The calculated adsorption geometries are in reasonable agreement with population analysis and density of states.The thiophene molecule obtains 0.74 electrons,reflecting the interaction between the lone pair of sulfur and the d-orbitals of metal.The reaction paths and transition states for desulfurization of the molecule have been investigated.The bridge adsorption structure of thiophene leads to a thiol via an activated reaction with an energetic barrier of 0.30 eV.This second step is slightly difficult,and dissociation into a C4H4 fragment and a sulfur atom is possible,with an energetic barrier of 0.40 eV.     

Ab initio Study on the Molecular Geometry,Electronic Structure and Thermodynamic Properties of Benzotrifuroxan(BTF)

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Density Functional Theory Study on the Structural and Electronic Properties of Ge（SiO_2）_n Clusters

The geometry,stability,binding energy and electronic properties of(SiO2)n and Ge(SiO2)n clusters(n = 7) have been investigated by Density functional theory(DFT).The results show that the lowest energy structures of Ge(SiO2)n are obtained by adding one Ge on the end site of the O atom or the Si near end site of the O atom in(SiO2)n.The chemical activation of Ge-(SiO2)n is improved compared with(SiO2)n.The calculated second-order difference of energies and fragmentation energies show that the Ge(SiO2)n clusters with n = 2 or 5 are stable.     

Theoretical Study on the Electronic Structures of Small TinNm （n ＋ m = 5, 6） Clusters

45 isomers of TinNm （n ＋ m = 5, 6） clusters, including linear, some planar and some stero configurations, have been predicted by density functional theory method. For five-atom clusters Ti3N2 and Ti2N3, the most stable structures are trigonal bipyramid in D3h symmetry, and for TiaN cluster, the isomer with one nitrogen atom occupying the center of quasi-tetrahedron is the most stable. In the isomers of Ti4N2 and Ti3N3, the planar networks are more stable, but for Ti2N4, the six-membered ring configuration is the most favorable. Most linear structures can form weak-strong bonds alternately with higher energy. As regards to planar structures, the more Ti-N bonds are formed, the more stable they will be; for stero closed polyhedral isomers, their energies are lower.     

QSAR Study on Some N-[5-（2-Furanyl）-2-methyl- 4-oxo-4H-thieno[2,3-d]pyrimidin-3-yl]-carboxamide and 3-Substituted-5-（2-furanyl）-2-methyl-3H-thieno- [2,3-d]pyrimidin-4-ones Using Three-dimensional Holographic Vector of Atomic Interaction Field

Study on the quantitative structure-activity relationship （QSAR） of 26 compounds, N-[5-（2-furanyl）-2-methyl-4-oxo-4H-thieno[2,3-d]pyrimidin-3-yl]-carboxamide and 3-substituted- 5-（2-furanyl）-2-methyl-3H-thieno[2,3-d]pyrimidin-4-ones, with three-dimensional holographic vector of atomic interaction field （3D-HoVAIF） was carried out. SMR-PLS QSAR models have been created and good correlation coefficients and cross-validated correlation coefficients were obtained. The result shows that the models have good prediction capability and favorable stability and the 3D-HoVAIF is applicable to the molecular structural characterization and biological activity prediction.     

Theoretical Study on the Structure and Stability of Si5X （X = Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl） Clusters

1 INTRODUCTION In the later 60s of last century, silicon substituted for germanium to present as mainstream in semicon- ductor. The semi-conductive devices made by silicon have many advantages, for example, refractory pro- perty, high radioresistance, simple and stable process- ing technic, high machinability and low cost. So it was widely used to manufacture large power appara- tuses, for instance, digit and linear integrated circuit, large scale integrated circuit (LSI), etc. Thus, th…     

Structural Characterization and Retention Time Prediction for Components of Essential Oil of Meconopsis Integrifolia Flowers

A molecular structural characterization (MSC) method called reduced molecular electronegativity-distance vector (MEDVR) was used to describe the molecular structures of 55 components of meconopsis integrifolia flowers. By use of stepwise multiple regression (SMR) and partial least square (PLS) methods, a model with the correlation coefficient (R1) of 0.987 and the standard deviation (SD1) of 1.377 could be obtained. Then through multiple linear regression (MLR), another model with the correlation coefficient (R2) of 0.989 and standard deviation (SD2) of 1.395 could be constructed. Furthermore, in virtue of variable screening by the stepwise multiple regression technique (SMR), 8 vectors were selected to build up another model with its correlation coefficient (R3) and standard deviation (SD3) of 0.989 and 1.366, respectively. Then all the three models were evaluated by performing cross-validation with the leave-one-out (LOO) procedure, and the correlation coefficients (QCV) were 0.981, 0.976 and 0.979, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.     

Structural Characterization of Volatile Components of Rosa Banksiae Ait for Estimation and Prediction of Their Linear Retention Indices and Retention Times

The molecular electronegativity-distance vector （MEDV） was used to describe the molecular structure of volatile components of Rosa banksiae Ait, and QSRR model was built up by use of multiple linear regression （MLR）. Furthermore, in virtue of variable screening by the stepwise multiple regression technique, the QSRR models of 10 and 6 variables and linear retention index （LRI） 10, 7 and 6 varieables were built up by combinating MEDV with the Ultra2 column GC retention time （tR） of 53 volatile components of Rosa Banksiae Air. The multiple correlation coefficients （R） of modeling calculation values of QSRR model were 0.906, 0.906, 0.949, 0.943 and 0.949, respectively. The cross-verification multiple correlation coefficients （RCV） were 0.903, 0.904, 0.867, 0.901 and 0.904, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.     

有机磷酸酯类化合物气相色谱定量结构保留关系研究

采用分子电性距离矢量(MEDV)表征有机磷酸酯类化合物的分子结构,运用多元线性回归建立定量结构-色谱保留关系(QSRR)模型,同时采用逐步回归结合统计检测对模型进行变量筛选,建立了35个有机磷酸酯类化合物在3种不同固定相(OV-101,DB-1701和DB-WX)上气相色谱保留指数(RI)与MEDV的定量相关模型.在3种固定相上的QSRR模型的建模计算值复相关系数(R)、留一法(leave-one-out)交互校验复相关系数(QCV)分别为0.998 0和0.995 1(OV-101);0.996 3和0.989 6(DB-1701);0.993 7和0.984 1(DB-WX),表明模型具有良好估计能力与稳定性.     

多氯代二苯并呋喃在不同色谱柱上的气相色谱保留行为——定量结构-色谱保留关系(QSRR)的研究

 以一种拟原子的方式处理多氯代二苯并呋喃 (PCDFs)异构体中的苯环 ,将PCDFs异构体中的原子或基团分为 3类 ,即 :氯原子 (Cl) (记为“1”) ,氧原子 (O) (记为“2”)及拟原子 (B) (记为“3”)。在烷烃分子距边矢量的基础上 ,提出一种以基团为基准的分子距离边数矢量 (μ矢量 ) ,借助多元线性回归方法分别建立了多氯代二苯并呋喃在不同色谱柱上的色谱保留指数与表征其结构的 μ矢量间的定量结构 色谱保留关系 (QSRR)相关模型。各样本总体所建模型的相关系数均在 0 98以上。     

多环芳香硫化合物的定量结构-气相色谱保留指数关系

应用分子电性距离矢量(MEDV)对114个多环芳香硫化合物(PASHs)进行结构表征,通过多元线性回归建立了PASHs的气相色谱保留指数与MEDV参数之间的定量结构-保留值关系模型;同时采用逐步回归分析进行变量筛选,继而以留一法交互检验对所得优化模型进行预测能力评价,所建立的模型的相关系数为0.9947,交互检验相关系数为0.9940,表明该优化模型具有良好的稳定性和预测能力。此外,通过将样本集按2:1分成校准集和测试集预测,统计分析结果显示所建的模型具有良好的相关性和稳定性。本文所建的定量结构-保留值关系(QSRR)模型为预测PASHs的气相色谱保留指数提供了一个便捷有效的新方法。     

利用分子路径指数矢量对烷烃摩尔响应值的估计与预测

 利用分子路径指数矢量表示烷烃分子结构方法 ,结合多元线性回归算法及反传神经网络算法 ,对烷烃摩尔响应值进行处理 ,获得了比文献更佳的预测效果 ,交互校验的相关系数达 0 96 8以上。     

应用分子电性距离矢量预测烷烃和一元醇的折光指数

应用分子电性距离矢量对81个烷烃、22个一元醇进行了结构表征,通过多元线性回归与逐步回归的方法建立了分子电性距离矢量与折光指数的定量结构性质模型,模型的相关系数分别为0.980和0.979.采用留一法对模型进行交互检验复相关系数R2cv分别为0.927和0.898.说明定量结构性质模型具有很好的稳定性和预测功能.     

多环芳烃分子结构的距边矢量表征及其气相色谱保留指数预测

 从分子图论拓扑学角度出发 ,提出用六元素组成的分子距边矢量VMDE表达上百个多环芳烃化学结构 ,对 10 0种多环芳烃的毛细管气相色谱保留值进行定量相关性研究 ,发现存在良好的线性相关关系 :IR=a +bVMDE,n =10 0 ,r =0 .988,其中a ,b为回归系数 ,可用于多环芳烃的色谱保留指数的分子建模与定量预测。