教师与学生部分核心化学概念相异构想的比较研究

通过对化学教师部分核心化学概念相异构想的调查研究,并与高一学生的研究结果相比较,发现教师与学生整体回答的曲线大致平行;教师及学生在“宏观—微观”、“微观—符号”表征转换方面存在困难。为了促进教师与学生相异构想的转变,应促进教师教学的反思,充分利用教材的资源,丰富学生相异构想的调查。     

计算机模型应用于化学教学的若干策略

学生难以建立宏观-微观-符号三重表征及其它们之间的相互联系,造成大量的化学错误概念及学习障碍。为解决这一问题,国外学者广泛运用计算机模型于化学教学中,并取得良好效果,但国内相关研究相对滞后。论文在实证研究基础上,提炼出计算机模型应用于中学化学的若干教学策略,并结合具体教学案例加以阐述。这些策略包括：（1）创设问题情境,启发学生思维;（2）呈现宏微现象,理解科学知识;（3）训练科学方法,提高探究能力;（4）引导反思质疑,理解模型本质;（5）自主建构模型,增强建模技能。论文最后提出几条教学建议。     

多重表征教学:纸牌游戏中的化学平衡观

以多重表征模型为基础的问题解决教学将以跨学科的视域消解理论和实践的张力,防止理科课程与教学变革的内在异化。借助“纸牌游戏”活动开展关于化学平衡专题的教学实践,结果表明,该教学活动能够帮助学生通过微观表征使得符号表征深刻化,实现不同表征之间的转换和错误概念的转变,从而建构深刻的化学平衡的观念。     

化学概念的多重表征及教学建构——基于“氧化还原反应”概念的调查研究

从心理表征的角度看,“化学概念的理解”就是学习者对化学概念形成了恰当的心理表征。通过调查高三学生“氧化还原反应”概念的表征发现,学生对化学概念存在多重外部表征,但并非关于概念的真正理解。本文运用DeFT(Design,Functions,Task)概念框架建构教学,设计多重媒体学习环境以促进学生对抽象概念的理解。     

运用概念心理表征特点提高化学复习质量

做好化学基本概念的复习,教师必须了解学生对化学概念的掌握情况。教师要知晓化学概念的表征特点和学生在学习时的具体表征形式,才能在复习时有针对性地采用互补的表征方式、绘制化学概念图等策略,切实提高化学复习的效果。     

整合多重表征 促进概念深度理解——以“原电池”为例

有效整合多重表征,是促进学生科学概念深度理解的一种有效策略。本研究整合了科学教育领域中的3个多重表征框架的内容,对高中必修模块的“原电池”进行了教学设计。首先引导学生依次学习原电池的宏观装置、微观原理和电极符号,初步建构原电池概念,之后基于氢氧燃料电池关联表征,让学生建构原电池的装置原理二维模型图,理解原电池概念,最后依托生活中的纽扣电池应用二维模型图实现表征转换,解决实际问题,实现对原电池概念的深度理解。     

化学微观表征的方法与教学策略

将化学宏观现象进行形象、直观与动态的微观表征,能激发学生的学习兴趣,协助学生理解化学原理与规律。在几种不同形式的微观表征方法中,微观表征图能有效地消除相异构想,是建构化学三重表征的突破口,有利于化学三重表征的转化与融合。     

化学“四重表征”教学模式的理论建构与实践研究——从15年数字化手持技术实验研究的回顾谈起

回顾15年数字化手持技术实验研究中对“曲线表征”定量分析方法的论述,剖析化学“四重表征”教学模式理论的建构背景,采用文本分析法,从“四重表征”的理论创新、研究内容和应用案例3部分进行分析.以此为落脚点提出3点建议:提高教师的“四重表征”意识和转换水平;从心理机制层面研究学生迷思概念的成因;积极开发基于定量探究实验的教学案例,进而培养学生定量分析的思维,提高学生“四重表征”间转换水平和科学概念转变能力.     

基于SOLO理论的思维导图建构三重表征整体关系的教学研究

以氯水的教学为案例,运用三重表征方式多元角度认识和理解物质,并用思维导图直观表示三重表征之间的联系。研究结果表明,SOLO分类理论可有效指导教师确定学生的学习最近发展区及有效的教学策略;运用思维导图可直观表示化学知识三重表征之间的逻辑关系,促进学生建构起三重表征的有机整体关系,加速以符号表征为桥梁进行三重表征之间的互译转换,促使学生将多点知识结构发展为关联知识结构、抽象拓展结构水平。因此,在教学中应用思维导图建构化学三重表征的整体关系,有利于提高学生学习结果的质量。     

学优生与学困生概念内部表征的差异研究——以离子反应为例

离子反应是高中化学的重点内容,也是学生学习的难点.通过调查发现:学优生与学困生对于离子反应的相关概念,在表征的数量、表征的形式、表征的程度以及角度方面都存在着差异.期望通过探究不同学生关于概念表征差异的原因,研究得出高质量的概念内部表征的特点,进而制订有效的概念转变策略,同时对影响概念表征的2个因素:学生已有认知结构和外部表征的结构化程度进行简单探讨,从而为教师的有效教学提供参考依据.     

On the Similarity of DNA Primary Sequences Based on 5-D Representation

We propose a 5-D representation of DNA sequences based on the classifications of the four basic acid bases A,T,G, and C. The use of the 5-D representation is illustrated by constructing sequence invariants based on the entries in derived sequence matrices restricted to a selected width of a band along the main diagonal. As an application, we make a comparison for the first exon of β-globin gene sequences belonging to eleven different species based on the 5-D representation.     

新加坡现行中学化学教科书视觉表征的文本研究*

借鉴Gkitzia等人编制的分析框架,采用内容分析法对新加坡现行中学化学教科书All About Chemistry ‘O' Level(2017年,Hodder Education出版)中的视觉表征进行文本分析。从视觉表征的类型(C1)、表面特征的注释(C2)、视觉表征与文本的关联(C3)、标题的存在与性质(C4)、多重表征的连接程度(C5)等5个维度进行编码统计分析,获得该教科书中的视觉表征信息。以期为我国后续中学化学教科书的编写提供借鉴与启示。     

Computation of electronic transition moments: the length versus the velocity representation

Summary We have compared transition moments (TMs) obtained using the length and velocity representations for transitions from the ground state of H₂ to the lowest two¹ _u and two¹ _u ⁺ Rydberg states, theA ¹–X ¹⁺ transition in BH, and theA ¹ _u –X ¹ _g ⁺ transition in C₂. For H₂, the TMs in the length and velocity representations agree well even in cases where the one-particle basis is incomplete and the TM has not converged. For BH and C₂ the TM in the length representation converges rapidly with improvements in the one-particle basis set and is insensitive to inner-shell correlation. In contrast, in the velocity representation convergence with improvements in the one-particle basis is much slower, especially for C₂, and the TMs are significantly changed by inner-shell correlation. Thus the difference between the TMs in the length and velocity representations would not appear to be a viable diagnostic of TM convergence.     

Sphericities of Double Cosets,Double Coset Representations,and Fujita’s Proligand Method for Combinatorial Enumeration of Stereoisomers

The concepts of double coset representations and sphericities of double cosets are proposed to characterize stereoisomerism, where double cosets are classified into three types, i.e., homospheric double cosets, enantiospheric double cosets, or hemispheric double cosets. They determine modes of substitutions (i.e., chirality fittingness), where homospheric double cosets permit achiral ligands only; enantiospheric ones permit achiral ligands or enantiomeric pairs; and hemispheric ones permit achiral and chiral ligands. The sphericities of double cosets are linked to the sphericities of cycles which are ascribed to right coset representations. Thus, each cycle is assigned to the corresponding sphericity index (a _d , c _d , or b _d ) so as to construct a cycle indices with chirality fittingness (CI-CFs). The resulting CI-CFs are proved to be identical with CI-CFs introduced in Fujita’s proligand method (S. Fujita, Theor. Chem. Acc. 113 (2005) 73–79 and 80–86). The versatility of the CI-CFs in combinatorial enumeration of stereoisomers is demonstrated by using methane derivatives as examples, where the numbers of achiral plus chiral stereoisomers, those of achiral stereoisomers, and those of chiral stereoisomers are calculated separately by means of respective generating functions.     

Spectral representation of reduced protein models

We consider a spectrum-like two-dimensional graphical representation of proteins based on a reduced protein model in which 20 amino acids are grouped into five classes. This particular grouping of amino acids was suggested by Riddle and co-workers in 1997. The graphical representation is based on depicting sequentially the amino acids on five horizontal lines at equal separations. One-letter codes, B, O, U, X and Y, to which numerical values 1 to 5 have been assigned, are suggested as labels for the fictional amino acids that represent all the amino acids within each group. The approach is illustrated on ND6 proteins of eight species having from 168 to 175 amino acids. While visual inspection of the novel spectral graphical representations of proteins may reveal local similarities and dissimilarities of protein sequences, arithmetic manipulations of spectra offer an elegant route to graphic visualization of the degree of similarity for selected pairs of proteins.     

新版高中化学教科书视觉表征的文本研究*

以人民教育出版社和山东科学技术出版社2019年出版的4本化学必修教科书为研究对象,借鉴Gkitzia等人开发的分析框架,运用内容分析法对4本教科书中的视觉表征进行分析。从表征的类型、表面特征的注释、表征与文本的关联情况、是否存在合适标题、多重表征内各层表征间连接情况等5个维度对教科书进行编码统计,获得新版化学教科书中视觉表征的信息。     

Study of molecular orbitals in momentum space

Molecular orbitals are presented in configuration and momentum representations. We propose to minimize large oscillations present in calculated momentum wavefunctions by cancelling position factor phases. We illustrate the distortion introduced by different electron translation factors and show continuum states and dynamical wavefunctions in momentum coordinates. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001     

New 2D graphical representation of DNA sequences

We consider a 2D graphical representations of DNA sequences, which avoids loss of information associated with crossing and overlapping of the corresponding curve. We outline an approach, which is based on the construction of a three-component vector whose components are the normalized leading eigenvalues of the L/L matrices associated with DNA. The examination of similarities/dissimilarities among the coding sequences of the first exon of beta-globin gene of different species illustrates the utility of the approach.     

Efficient Implementation of High Dimensional Model Representations

Physical models of various phenomena are often represented by a mathematical model where the output(s) of interest have a multivariate dependence on the inputs. Frequently, the underlying laws governing this dependence are not known and one has to interpolate the mathematical model from a finite number of output samples. Multivariate approximation is normally viewed as suffering from the curse of dimensionality as the number of sample points needed to learn the function to a sufficient accuracy increases exponentially with the dimensionality of the function. However, the outputs of most physical systems are mathematically well behaved and the scarcity of the data is usually compensated for by additional assumptions on the function (i.e., imposition of smoothness conditions or confinement to a specific function space). High dimensional model representations (HDMR) are a particular family of representations where each term in the representation reflects the individual or cooperative contributions of the inputs upon the output. The main assumption of this paper is that for most well defined physical systems the output can be approximated by the sum of these hierarchical functions whose dimensionality is much smaller than the dimensionality of the output. This ansatz can dramatically reduce the sampling effort in representing the multivariate function. HDMR has a variety of applications where an efficient representation of multivariate functions arise with scarce data. The formulation of HDMR in this paper assumes that the data is randomly scattered throughout the domain of the output. Under these conditions and the assumptions underlying the HDMR it is argued that the number of samples needed for representation to a given tolerance is invariant to the dimensionality of the function, thereby providing for a very efficient means to perform high dimensional interpolation. Selected applications of HDMR's are presented from sensitivity analysis and time-series analysis.