遗传算法用于化学结构图的同态研究

提出一种采用整数串编码和基于节点基因交换方式的遗传算法,并应用于化学结构图的同态研究.遗传算法在一组随机生成的表示目标结构与查询结构节点间映射关系的整数串中进行逐步优化,直到找出与查询结构匹配的映射,从而实现化学结构图的同态匹配,并实现多重匹配.     

谈化学教学过程中生成性教学资源及利用

课堂生成性教学资源是教学活动前不能预设的、在教学过程中动态生成的有利于教学目标实现的各种因素。化学生成性教学资源产生于动态的化学教学过程;学生是化学教学资源的重要构成者和动态生成者;教师是化学生成性教学资源的开发者和课堂教学资源的重组者。化学教学过程中教师应对生成性教学资源加以识别、开发和利用。     

卫校化学教学中的信息加工模式探讨

结合加涅运用信息加工理论模拟的学习过程结构,分析了化学教学信息传输的基本条件,影响教学信息传输和接受的因素,教师对教学信息的编码变换,学生对教学信息的编码变换(译码),教学过程中信息的贮存和使用,教学过程中信息的反馈和控制。在化学教学过程,总结出化学信息加工模式:信源(教科书、实践实物等)→编码(知识的获得并形成相应的记忆痕迹)→信道(知识传输途径)→译码(学习或重组掌握认知)→信宿(学生认知结构的构建)。教师应指导学生将化学知识信息按一定的逻辑联系组织编码起来,使其更为系统化,成为具有一定结构的、井然有序的知识整体,利于实现化学教学过程的优化。     

有机化学结构信息处理Ⅰ.基于环的化学结构编码的转称算法

本文从化学结构编码时化学涵义完整性的要求出发,根据结构中环结构化学涵义的原子性,运用图论的方法,提出了一种基于环的结构编码转换算法。该算法实现了从原子级编码到超原子级编码的转换,从而可实现从任意编码向另一编码的转换。     

有机化学结构信息处理：Ⅰ.基于环的化学结构编码的转称算法

本文从化学结构编码时化学涵义完整性的要求出发,根据结构中环结构化学涵义的原子性,运用图论的方法,提出了一种基于环的结构编码转换算法。该算法实现了从原子级编码到超原子级编码的转换,从而可实现从任意编码向另一编码的转换。     

“卓越化学教师教育实验教学研究”课程探微

在对化学实验操作进行编码的基础上对高中化学课程标准中有关实验进行统计分析,以分析结果为依据对卓越化学教师教育实验教学研究课程中的实验内容进行优选,为化学教师教育学科课程的科学决策奠定基础。     

化学学习中的认知策略

在化学学习中,学生应获得和学会应用注意策略、编码策略、理解-控制策略、问题解决策略、情感策略等认知策略,从而学会学习。     

铑催化合成气转化为乙醇反应中甲酰基中间体的化学捕获

本文采用化学捕获法对铑基催化剂上合成气转化反应中的甲酰基中间体进行了化学捕获,在CO+2D_2反应后,用CH_3I进行的化学捕获反应中生成了CH_3CHO、CH_3CDO两种形式的乙醛;补充的Ar吹扫实验显示DCO的甲基化反应对生成的CH_3CDO有重要贡献。因此,甲酰基的确是合成气反应中的C_1含氧中间体。根据这一结果,初步探讨了合成气反应中CH_x物种的生成途径。     

师范院校开设《化学文献检索》课及其三类教学模式讲评

我校按原教育部要求，于１９８６年起对各科学生开设了正规的《化学文献检索及利用》（１９９２年以后改称《化学文献检索》）课。至今１１年中，已在校内外，对本科生、研究生、专科生和夜大学生按不同对象和规格，进行了教学。根据来自不同方面的反映。教学总效果良好；...     

配合物生成反应速率常数与平衡常数之间的直线自由能关系 铜(Ⅱ)—α,α′,-联吡啶-氨基酸体系

配合物的生成常数与配位体的酸性离解常数之间存在直线自由能关系,已有不少报道.本文报告配位化学中存在的另一种直线自由能关系,即配合物生成反应速率常数与其生成反应的平衡常数及其与配位体的离解常数之间亦存在直线自由能关系,即在配位化学中首次发现了存在着Bronsted均相酸碱催化定律式的直线自由能、     

Molecular challenges in modern chemometrics

Since the very beginning of the discipline, chemometrics has mainly focussed on analytical chemical problems such as calibration. With the growing importance of databases and applications in medicinal and computational chemistry, the domains of analytical chemistry and chemometrics have been enlarged significantly in recent years. Especially the relation between molecular structure and function has become of considerable interest. Despite the huge quantities of data that are available nowadays, it is often difficult to recognise and extract relevant chemical information for the problem at hand. One of the main obstacles is the definition of an appropriate representation of a molecule. Although a variety of different representations are used, none are generally applicable.

This paper focuses on the challenges that arise in the chemometrical analysis of molecular structures, the relation between structure and function and the relation between molecular representation and chemometrical modelling. Exciting opportunities for further research are illustrated using an example concerning the prediction of co-crystallisation behaviour for small organic molecules with cephalosporin antibiotics.     

Application of the electronegativity indices of organic molecules to tasks of chemical informatics

An efficient structure filtration method for the operation with chemical databases containing information on the structures and properties of organic molecules was proposed. The technique involves the use of electronegativity indices for generation of identification keys and for isomorphism tests of the molecular graphs corresponding to the structural formulas. The test set for the method proposed included a total of 95,000,000 molecules containing up to sixty carbon atoms. Tests revealed a high discriminating capability of the electronegativity indices and high efficiency of the method for solving both general problems (recognition of chemical structures, chemical database management systems) and specific tasks (generation of molecular graphs, etc.) in chemical informatics. Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2166–2176, September, 2005.     

Information content in organic molecules: quantification and statistical structure via Brownian processing

Information and organic molecules were the subject of two previous works from this lab (Graham and Schacht, J. Chem. Inf. Comput. Sci. 2000, 40, 187; Graham, J. Chem. Inf. Computer Sci. 2002, 42, 215). We delve further in this paper by examining organic structure graphs as objects of Brownian information processing. In so doing, tools are introduced which quantify and correlate molecular information to several orders. When the results are combined with energy data, an enhanced informatic view of covalent bond networks is obtained. The information properties of select molecules and libraries are illustrated. Notably, Brownian processing accommodates all possible compounds and libraries, not just ones registered in chemical databases. This approach establishes important features of the statistical structure underlying carbon chemistry.     

Using the gini coefficient to measure the chemical diversity of small‐molecule libraries

Modern databases of small organic molecules contain tens of millions of structures. The size of theoretically available chemistry is even larger. However, despite the large amount of chemical information, the “big data” moment for chemistry has not yet provided the corresponding payoff of cheaper computer‐predicted medicine or robust machine‐learning models for the determination of efficacy and toxicity. Here, we present a study of the diversity of chemical datasets using a measure that is commonly used in socioeconomic studies. We demonstrate the use of this diversity measure on several datasets that were constructed to contain various congeneric subsets of molecules as well as randomly selected molecules. We also apply our method to a number of well‐known databases that are frequently used for structure‐activity relationship modeling. Our results show the poor diversity of the common sources of potential lead compounds compared to actual known drugs. © 2016 Wiley Periodicals, Inc.     

Tautomerism in chemical information management systems

Tautomerism has an impact on many of the processes in chemical information management systems including novelty checking during registration into chemical structure databases; storage of structures; exact and substructure searching in chemical structure databases; and depiction of structures retrieved by a search. The approaches taken by 27 different software vendors and database producers are compared. It is hoped that this comparison will act as a discussion document that could ultimately improve databases and software for researchers in the future.     

Computer generation of characteristic polynomials of edge-weighted graphs,heterographs, and directed graphs

The computer code developed previously (K. Balasubramanian, J. Computational Chem., 5 , 387 (1984)) for the characteristic polynomials of ordinary (nonweighted) graphs is extended in this investigation to edge-weighted graphs, heterographs (vertex-weighted), graphs with loops, directed graphs, and signed graphs. This extension leads to a number of important applications of this code to several areas such as chemical kinetics, statistical mechanics, quantum chemistry of polymers, and unsaturated systems containing heteroatoms which include bond alternation. The characteristic polynomials of several edgeweighted graphs which may represent conjugated systems with bond alternations, heterographs (molecules with heteroatoms), directed graphs (chemical reaction network), and signed graphs and lattices are obtained for the first time.     

计算(机)化学学科进展(2011-2013)

计算(机)化学已成为化学学科的重要组成部分,在理论计算、分子模拟、数据挖掘以及复杂体系分析中发挥了重要作用。本文总结了近年来化学信息学的研究进展,包括化学信息学方法、软件及数据库技术以及化学信息学在结构、性质、相互作用、反应机理,蛋白质及功能材料的性能研究,复杂体系化学数据分析中的应用。共引用参考文献78篇。     

Representation of the molecular topology of cyclical structures by means of cycle graphs. 3. Hierarchical model of screening of chemical databases

The increase in the size and complexity of chemical databases necessitates the proposal and development of efficient methods of classification and recovery of information, which supposes proposal of a model of classification of database records and the use of a compatible model of screening for inspection of clusters and recovery of the molecules that satisfy the search criterion. The cycle graphs model based on consideration of all the cycles and chains (and equivalent cycles and chains) present in the molecular structure has been proven appropriate for classification of chemical databases, giving rise to a generation of different classification levels depending on the structural elements (cycles and chains) that are considered. In this paper we propose a screening model, compatible with the cycle graphs model, based on a hierarchy of levels of abstraction. The set of molecules that satisfies a screening model (or selection criterion) diminishes as we advance in the hierarchy of levels of the model, which allows filtering of records and, therefore, an increase in the efficiency of the screening process. In the following work of this series we describe and validate the screening tool developed.     

Enumerating treelike chemical graphs with given path frequency

The enumeration of chemical graphs satisfying given constraints is one of the fundamental problems in chemoinformatics. In this paper, we consider the problem of enumerating (i.e., listing) all treelike chemical graphs from a given path frequency. We propose an exact algorithm for enumerating all solutions to this problem on the basis of the branch-and-bound method. To further improve the efficiency of the enumeration, we introduce a new variant of the compound enumeration problem by adding a specification on the number of multiple bonds to the input and design another exact enumeration algorithm. The experimental results show that our algorithms can efficiently solve instances with larger sizes that are impossible to solve by the previous methods. In particular, we apply the latter algorithm to the enumeration problem of the special treelike chemical structures-alkane isomers. The theoretical and experimental results show that our algorithm works at least as fast as the state-of-the-art algorithms specially designed for generating alkane isomers, however using much less memory space.