互联网上化学信息的检索

信息资源与信息服务是科研人员从事科学研究和科技创新工作的重要基础。在科学飞速发展的今天,科学研究工作首先要掌握准确可靠、全面快捷的资讯查找方法。信息资源既是过去经验的总结,又是未来工作的向导。化学化工是信息量大、信息种类多的一门学科。随着计算机网络技术的迅速发展,Internet正在成为化学信息的主要载体和信息服务的重要手段。利用全球信息网浏览和获取化学信息已成为化学工作者必须掌握的基本技能之一。如何从浩如烟海的信息空间里快速找到自己有用的信息资源？掌握一套有效的查询方法和技巧是关键。     

互联网+时代检索化学化工信息与获取原文的便捷方法

在探讨传统化学文献与网络化学化工信息之间关系的基础上,就快速、便捷地检索化学化工信息源线索,以及获得原始文献的策略与方法进行了翔实总结,为即将加入相关行业的学者与青年学子便捷或免费获取文献提供有价值的方法。     

基于知识图谱科技创新资源智能推荐模型的设计与实现北大核心CSCD

近年来,随着科学技术的快速发展,科技成果信息数据规模呈指数型增长。在这些海量数据中蕴含着大量有价值的知识信息,如何从中筛选、整合并发挥这些知识信息的价值受到广泛关注。在此背景下,知识图谱应运而生,其中知识图谱中的知识推理成为研究热点,目前这一研究热点已在语义搜索、智能问答等方面取得重大成就。     

化学教师自我教育导向：《化学教育》信息的利用

教师现代化是教育现代化的先决条件。教师现代化的基本途径是教师的终身自我教育。在信息社会 ,教师的自我教育主要是通过教育信息的获得与交流来进行的。教师如何利用教育信息资源 ,选择何种教育信息 ,对于教师的自我教育有着极其重要的影响。对于化学教师来说 ,《化学教育》期刊是诸多信息源中最核心的信息源。1　《化学教育》期刊信息的特点与功能1 .1　特点1 .1 .1　现代性教育信息的现代性是《化学教育》期刊的明显特征。如“化学与社会”栏目介绍化学与相关学科、社会、环境、技术和经济等方面的关系及其在各个领域中的应用 ;“知识介…     

WWW与化学

计算机和计算机网络的迅猛发展强烈冲击着科技领域，如何查找和利用计算机网络上的信息，已成为科技工作中的重要一环。本文介绍了Ｉｎｔｅｒｎｅｔ的基本概念，着重讲解通过ＷＷＷ获得化学信息的方法。     

如何通过化工基础实验提高学生的综合素质

从化工基础实验的教学目标出发，谈如何通过化工基础实验培养学生从事科学研究工作的基本素质，如数据处理能力以及观察问题、发现问题、处理问题的能力，并在此基础上培养学生的创新能力。     

碳纳米管原子力显微镜针尖对脱氧核糖核酸高分辨率成像研究

运用自制的碳纳米管原子力显微镜针尖,在液体中观察了脱氧核糖核酸（DNA）分子的精细结构。结果表明,运用碳纳米管针尖获得的DNA分子的高度与电子显微镜的结果非常接近,且没有造成样品的变形损伤;碳纳米管针尖得到的DNA分子的宽度与真实值相近,减小了原子力显微镜成像的增宽效应,这是用传统的硅针尖无法获得的。DNA分子精细结构的高分辨率图像的获得为研究其功能提供了有价值的信息。     

快速溶胶-凝胶法制备纳米介孔TiO2——一个大学化学开放性实验的设计

设计了一个大学化学开放性实验——介孔TiO2的快速溶胶-凝胶法制备。该实验结合本课题组的最新研究成果,内容涉及介孔TiO2的快速合成和材料表征分析。通过本实验可以拓宽学生的化学专业知识,激发学生对科学研究的兴趣,培养学生创新能力和独立从事科研工作的能力。     

光电子能谱(四)

2.天然与合成高分子化合物用光电子能谱研究高分子化合物,所得数据一般不及红外和核磁来得精细,但具有快速、方便和不破坏表面等优点。对难溶的聚合物或经各种化学和物理处理的高分子化合物表面(如氧化、氟化、溶剂或等离子体处理),以及聚合物的光降解,等离子聚合和辐射接枝等过程进行研究,可以获得许多有价值的信息。有些问题是用其它分析方法无法解决的。 2.1 表面处理 2.1.1.试剂处理使织物阻燃为了赋于棉织物良好的阻燃性能,可以先用 tetrakis (hydroxymethyl) phosphonium     

一种基于R语言的大孔吸附树脂预测模型的构建

针对精准筛选高选择性分离中药多糖的大孔吸附树脂时间冗长、操作繁琐的现状,该文构建了一种快速筛选大孔吸附树脂的预测模型.采用R语言建立大孔吸附树脂参数、葡聚糖分子量与吸附量之间的多源信息模型,利用多源信息模型快速预测和筛选对中药多糖具有最佳吸附效果的大孔吸附树脂类型.所建多源信息模型的相关系数(r2)为0.901 2,P...     

化学教学中的信息转换

教学的本质是信息的传输、加工和内化的过程。信息转换是知识再生产与生产新知识相融合的一个思维过程。分析了信息呈现的多种方式, 从“信息量多少、信息表征方式、信息的属性”等方面阐述了信息的转换方法策略。     

化学习题中文字信息的分类、解读与运用

以中学化学习题中文字信息为研究对象,从组成、物理性质和化学性质等3个角度进行剖析,解读文字信息的丰富内涵,并通过一个案例探讨综合信息的运用,最后总结信息解读应注意的3个问题。     

Comparison of Optimization Based on Information Theory with Optimization of Rs in Column Chromatography

Abstract

Optimization based on the function of mutual information (FUMI) is reviewed by comparison with optimization of Rs in column chromatography. The following variables are considered: mobile phase composition; pH; column length; the amount of internal standard; detection wavelength. FUMI is equivalent to the precision of measurements and takes a maximum at the optimal condition. However, Rs neither takes a maximum nor corresponds to the precision. This paper demonstrates that FUMI is a superior measure of chromatographic performance.     

Relative information in excited-state orbital-free density functional theory

Euler equations of the orbital-free excited-state density functional theory of Coulomb systems are derived for specific relative information. Derivation via variational extremization of the relative Fisher information is also presented. Relationships between the Fisher and Shannon information, the local wave vector, and the relative information are displayed.     

Optimization Based on Retention Prediction and Information Theory for Liquid-Chromatographic Analysis of Alkylbenzenes

Abstract

The mobile phase composition and column length are optimized for analyses of six alkylbenzenes in reversed-phase liquid chromatography with the aid of retention prediction and information theory. Optimal conditions selected according to the resolution Rs and information theory are evaluated from the viewpoint of the precision and analytical efficiency (rapidity) of chromatography. The combination of the information-theoretical optimization with the retention prediction will accelerate the development in the automation of liquid-chromatographic analysis.     

An information-theoretic characterization of partitioned property spaces

A methodology, derived by analogy to Shannon’s information-theoretic theory of communication and utilizing the concept of mutual information, has been developed to characterize partitioned property spaces. A family of non-intersecting subsets that cover the “universe” of objects represents a partitioned property space. Each subset is thus an equivalence class. A partition and it’s associated equivalence classes can be generated using any one of a number of procedures including hierarchical and non-hierarchical clustering, direct approaches using rough set methods, and cell-based partitioning, to name a few. Thus, partitioned property spaces arise in many instances and represent a very large class of problems. The approach is based on set-valued mappings from equivalence classes in one partition to those in another and provides a coarse-grained means for comparing property spaces. From these mappings it is possible to compute a number of Shannon entropies that afford calculation of mutual information, which represents that amount of information shared by two partitions of a set of objects. Taking the ratio of the mutual information with the maximum possible mutual information yields a quantity that measures the similarity of the two partitions. While the focus in this work is directed towards small sets of objects the approach can be extended to many more classes of problems that can be put into a similar form, which includes many types of cheminformatic and biological problems. A number of scenarios are presented that illustrate the concept and indicate the broader class of problems that can be handled by this method.     

Order,disorder, and geometrical information indices of molecules

Structural features of various molecular systems with symmetry of point groups ranging fromC ₁ to the icosahedral symmetry are analyzed in the framework of the model suggested previously for the evaluation of order and disorder in the arrangement of atoms in a molecule based on the equationQ = I -P/3n (whereQ is the index of order, andP is the number of independent coordinates needed to fix ann-atomic molecule in the Cartesian coordinate system). TheQ value depends on various structural parameters of the molecule: the number of atoms in it, the symmetry, the dimensionality, and the number of structural degrees of freedom. The disorder indexP/3n = 1 -Q correlates with Shannon's entropy of information, andQ correlates with negentropy or excess information; this makes it possible to useP/3n as a new geometrical information molecular index that is obtained by a nonprobabilistic method. Analysis of the relationship between order and chaos in molecular systems, as well as of the specific order indexq =Q/n, makes it possible to identify both general and specific features of molecules.Translated from Izvestiya Akadernii Nauk. Seriya Khimicheskaya, No. 8, pp. 191219-121927, August, 1996.     

Segmentation techniques in image analysis: A comparative study

Nowadays, the detection, localization, and quantification of different kinds of features in an RGB image (segmentation) is extremely helpful for, e.g., process monitoring or customer product acceptance. In this article, some of the most commonly used RGB image segmentation approaches are compared in an orange quality control case study. Analysis of variance and correspondence analysis are combined for determining their most relevant differences and highlighting their pros and cons.     

Translation of genetic information on the ribosome

The information for protein structure that is contained in the base sequence of the nucleic acids is translated on the ribosome into the amino acid sequence. This translation can be divided into chain initiation, chain growth, and chain termination. Several specific protein factors and nucleic acids are involved in each section.—For chain initiation, start complexes are formed from the initiating amino acyl-tRNA, mRNA carrying the start signal, and the small and large subunits of a ribosome. GTP and the initiating factors are also involved in this process.—In chain elongation, one amino acid at a time is transferred, in a reaction cycle, from the linkage with tRNA into a linkage with the polypeptide chain. The amino acid to be incorporated is initially bound to the ribosome as amino acyl-tRNA, a process for which GTP and protein factors are necessary. The subsequent formation of a peptide linkage is catalyzed by the peptidyl transferase of the large ribosomal subunit. The peptidyl-tRNA with its newly added amino acid residue is then transferred from the amino acyl-tRNA acceptor site A to the peptidyl donor site P of the ribosome. This requires another protein factor and cleavage of GTP into GDP and phosphate.–Ghain termination begins as soon as one of the three terminator triplets UAA, UAG, or UGA in the mRNA reaches the ribosome. The mRNA is moving in relation to the ribosome from the 5′ end to the 3′ end. Release of the completed polypeptide chain from the ribosome is dependent on release factors. Before initiation of a new polypeptide chain, the ribosomes dissociate into their subunits.