结合三维静电势参数研究二取代苯的定量结构－疏水性关系

对含有常见取代基的92个二取代苯化合物进行了结构优化和静电势及其导出参数的计算,运用多元线性回归方法对化合物的疏水常数与分子的结构参数进行了关联.结果表明,分子表面负静电势的加和ΣV－S、分子空间内最负的静电势Vmin、表面最大静电势Vs,max以及分子体积V、极性表面积APS和分子的偶极密度μ/V这六个参数,可以很好地用于表达这些化合物疏水性与分子结构间的定量关系,而不用具体考虑分子中极性基团间的相互作用.用建立起来的QSPR(quantitative structure-property relationship)关系式对111个类似化合物的疏水性进行了预测,获得了满意的结果.     

磁性纳米标记检测技术在生物医学即时检测领域的研究进展

基于磁性纳米材料的磁标记检测技术具有灵敏度高、线性范围广、信号检测便捷等优点。由于生物样品自身磁背景信号极低,相比于光学标记检测技术,磁标记检测技术在蛋白质、核酸、细胞、病原体及生物组织检测中均表现出更高的灵敏度,在生物医学即时检测领域展现了良好的应用前景。该文围绕磁性纳米粒在即时检测领域的最新研究进展,重点介绍了其在蛋白质、核酸以及几类病原体检测方面的应用,并对基于磁性纳米粒的即时检测技术发展方向及应用前景进行了展望。     

Structure-activity study of antiepilepticN-aryl-isoxazolecarboxamides/N-isoxazolylbenzamide analogs using Wiener's topological index

The relationship between Wiener's topological index and the antiepileptic activity of a series ofN-aryl-isoxazole carboxamides/N-isoxazolylbenzamide analogs has been investigated. Values of Wiener's topological index for 69 compounds constituting the training set were computed and an active range was identified. Each analog was subsequently assigned an activity which was then compared with the reported antiepileptic activity against the maximal electroshock seizure (MES) test. Due to significant correlation between antiepileptic activity and Wiener's topological index, it was possible to predict antiepileptic activity with an accuracy of 91 % in the active range.     

不饱和链烃沸点的拓扑研究

基于邻接矩阵与边价 (fi)定义边价连接性指数 ( mF) ,其中的0 F ,1 F与 2 94种不饱和链烃 (包括烯烃、炔烃及烯炔烃 )的沸点 (Tb)关联 ,得到良好的数学模型 :ln( 70 0 -Tb) =6 5 2 3 3 1-0 0 0 4880 F2 -0 3 46771 F0 5(n =2 94,R =0 9979,R2 =0 995 8,F =3 490 4,S =5 12 ) ,该回归模型经Jackknife法检验具有总体稳健性 .可以预示 ,该指数将在定量构效关系研究中成为重要参数 .     

一种新的三维氨基酸描述子及其在肽类药物QSAR中的应用

从20种天然氨基酸197个GETAWAY指数经主成分分析得出一种新3D氨基酸描述子——VSGETAWAY[vector of principal component scores for GETAWAY (geometry, topology and atom-weights assembly)]. 将其应用于48个苦味活性二肽、31个血管舒缓激肽促进剂和20个促凝血酶原激酶抑制剂结构表征并以偏最小二乘(PLS)对3个体系建立定量构效关系(QSAR)模型, 得复相关系数(Rcum2)与交互检验复相关系数(Qcum2)分别为0.887和0.753; 0.995和0.708; 0.999和0.802. 研究结果表明, VSGETAWAY描述子操作简便、结构表达能力强, 有望成为多肽药物QSAR研究中一种有效的结构表征方法.     

A quantitative evaluation of the electrostatic theory for ion pair chromatography

Summary A quantitative model for ion pair chromatography based on the electrostatic theory is described. The model is based on the solution of the linearised Poisson-Boltzmann equation in a cylinder. The obtained equations are compared with experimental data from a number of different systems. The agreement between theory and experiments is satisfactorily. Systematic deviations due to the use of the linearised equation and ion correlation effects are discussed.     

径向基-偏最小二乘-贝叶斯方法及其在化学模式分类中的应用

提出一种用于模式分类的RBF-PLS—Bayes方法。它集成地应用径向基(RBF)变换与偏最小二乘(PLS)方法，从原有模式中提取出分类能力甚强的成分，然后进行贝叶斯(Bayes)判别。这种集成方法尤其适用于复杂化学信息的模式分类，本文将其应用于两种类型的化学模式分类问题，均取得了令人满意的效果。与经典的判别分析方法和单纯的神经网络方法相比，具有明显的优越性。     

Structure—activity relationships for <Emphasis Type="Italic">in vitro</Emphasis> oxime reactivation of chlorpyrifos-inhibited acetylcholinesterase

Organophosphorus pesticides parathion, chlorpyrifos, and malathion inhibit the enzyme acetylcholinesterase (AChE; EC 3.1.1.7) via phosphorylation of its active site. AChE reactivators and anticholinergics are compounds used as antidotes in the case of intoxication by these AChE inhibitors. In this work, chlorpyrifos, a representative member of this pesticide family, was used to inhibit the AChE activity of rat brain. The effect of twenty-one structurally different AChE reactivators was tested in vitro and subsequently, the relationship between their chemical structure and biological activity was outlined.     

The use of TG-FTIR technique for the assessment of hydrogen bromide emissions in the combustion of BFRs

The TG-FTIR technique was used in the present study to investigate the thermal degradation behaviour of materials containing brominated flame retardants under fire conditions. Time-temperature profiles and oxygen concentrations typical of selected fire scenarios were reproduced in the thermogravimetric analyzer, while the characterization of the gaseous products generated was performed by the simultaneous FTIR analysis. FTIR analysis combined with the use of specific calibration procedures allowed the quantitative estimation of the gaseous products evolved as a function of experimental conditions. The results obtained allowed the straightforward assessment and the comparison of the quantities of hydrogen bromide formed in the oxidation and thermal degradation of pure brominated flame retardants and of flame retarded materials of industrial interest. Hydrogen bromide yields resulted dependent on the experimental conditions used, such as oxygen concentration and heating rate. Although TG-FTIR experiments only provide a representation of the actual heterogeneous combustion products in real fire conditions, the coupled TG-FTIR technique proved to be a straightforward experimental methodology allowing one to obtain reference data on the nature and quantities of the macropollutants generated in a fire. This revised version was published online in July 2006 with corrections to the Cover Date.     

Surface diffusion in reversed-phase liquid chromatography using silica gels bonded with C1 and C18 ligands of different densities

Surface diffusion in reversed-phase liquid chromatography (RPLC) using silica gels bonded with C₁ and C₁₈ alkyl ligands of different densities was studied from the viewpoints of two extrathermodynamic relationships, i.e., enthalpy-entropy compensation (EEC) and linear free energy relationship (LFER). First, according to the four methods proposed by Krug et al., the values of surface diffusion coefficient (D_s) were analyzed to confirm that an actual EEC resulting from substantial physico-chemical effects takes place for surface diffusion. Then, it was also demonstrated that a LFER is observed between surface diffusion and the retention equilibrium. The establishment of EEC and LFER suggests a mechanistic similarity of molecular migration by surface diffusion, irrespective of the alkyl chain length and the densities of C₁ and C₁₈ ligands. Finally, a thermodynamic model for the LFER based on the real EEC was used to estimate D_s values under various RPLC conditions. The D_s values can be estimated with a mean square deviation of about 25–30%. The agreement between the D_s values estimated and those experimentally measured suggests that the total mass flux by surface diffusion consists of the two contributions due to C₁ and C₁₈ ligands and that the contribution of each ligand is proportional to the ligand density.