高中化学中物质熔沸点内容的教学探讨

在高中化学教学辅导书中,时常出现一些判断物质熔沸点的规律或判断熔沸点高低的题目.在分析、解决这类题目时,常常出现以偏概全的现象,抑或运用大学化学知识来进行解释,没有准确地定位教学的内容和难度.针对这种现象,在分析文献、课程标准、教材和高考试题的基础上,提出定位物质熔沸点教学内容及难度的重要性的建议.     

基于分子结构矩阵的链烷烃沸点的QSPR研究

根据链烷烃的分子结构图构建分子结构矩阵,依照分子结构矩阵行列向量的1—范数建立分子结构参数Pi,qj.对39种链烷烃的沸点进行定量关系—相关性研究,得多元线性回归方程:Tb=31.187p0+17.528p1+16.091p2+15.473p-1+7.313q2+11.255q3+3.479q4-3.376q5-142.475,r=0.997.研究结果表明,分子结构参数Pi,qj.简单易得,与链烷烃的沸点具有优良的相关性和较高的结构选择性.     

氢键对有机物性质和结构的影响

探讨了氢键的本质、种类及其对有机物结构和性质的影响。     

分子内氢键对化合物性质的影响

讨论了分子内氢键的形成对有机化合物的熔沸点、化合物的构象、稳定性、酸性及红外光谱产生的影响．     

卤代甲烷的沸点与分子结构之间的定量关系

探讨了卤代甲烷的沸点与其分子结构之间的关系 ,发展了一种既能计算卤代甲烷沸点、又能预测未知卤代甲烷沸点的方法 .对卤代甲烷的计算结果表明 ,沸点计算值与实验值的一致性令人满意 ,平均误差 1 75 % ,优于文献方法 .     

有理整函数的极值点和拐点的一个注记

给出了有理整函数的极值点和拐点的充分条件,得到了三次有理整函数的一个性质．     

一氟烷烃沸点与分子结构关系的理论探讨

用拓扑方法探讨了一氟烷烃的沸点与其分子结构之间的关系,提出了一个结构基础明确的定量关系式。应用这一定量关系,不仅能够合理表征一氟烷烃结构与沸点的关系,而且能够预测沸点。结果表明,沸点预测值都接近实验值,平均误差仅0.094％。     

不饱和链烃的沸点与分子结构之间定量关系的研究

根据分子中基团的特性和连接性，通过用距离矩阵和顶点矩阵表征基团的特性和连接性，发展了一种直接根据分子结构计算不饱和烃（包括烯烃、炔烃和烯炔混合烃）沸点的方法，对378种不饱和烃（C2－C40）的计算结果表明，沸点计算与实验值的一致性令人满意。     

Making sense of education: sensory ethnography and visual impairment

Education involves the engagement of the full range of the senses in the accomplishment of tasks and the learning of knowledge and skills. However both in pedagogical practices and in the process of educational research, there has been a tendency to privilege the visual. To explore these issues, detailed sensory ethnographic fieldwork was conducted in further education colleges, investigating the experiences of visually impaired students who use their non-visual senses and embodied actions to achieve their learning. The study found that the full sensory schemas of the students were not always appreciated or accessed by tutors, resulting in lost learning opportunities. Whilst particularly relevant for visually impaired students, these findings have implications for pedagogy for all students. Further the study highlighted the significance of sensory ethnography as a tool to explore the processes of teaching and learning.     

烷基苯和烷基联苯的沸点与其分子结构之间定量关系的拓扑化学研究

根据分子拓扑学原理，用距离矩阵表征分子中原子的连接性，通过区分苯环碳原子与烷基碳原子性质的差异，探讨了烷基苯和烷基联苯的沸点与其分子结构之间的关系。提出一个既能合理表征烷基苯和烷基联苯的结构性能关系，又能根据分子结构信息预测沸点的定量关系式，对190种烷基苯和烷基联苯（C6-C42)的计算结果表明，烷基苯和烷基联苯的沸点预测值与实验值之间的一致性令人满意，平均绝对误差3．92K，平均相对误差0．77％。     

Making sense and facing tensions: an investigation of core practice complexities

Recently, scholars have called for a practice-based framework for teacher education and some have argued more narrowly for a framework built around ‘core practices of teaching.’ These efforts, in part, are intended to make teacher education practice public and available for collective improvement. The purpose of this paper is to highlight challenges and possibilities that arose during a core practice-oriented course redesign. Despite attention to the literature, the teacher educators faced dozens of inherent tensions and contextual challenges that distinguish their understanding of core practices from other teacher educators operating with common principles. Based on lessons learned, the author argues for greater attention to the details of core practice redesigns, rationales explaining redesign decisions, and empirical investigation of teacher candidate outcomes of such redesigned courses and programs.     

Ag纳米线熔化过程的计算模拟

利用分子动力学方法模拟了Ag纳米线的熔化和过热,模拟中采用了一种镶嵌原子势模型.结果表明：自由Ag纳米线的熔点比大块Ag的平衡熔点低,而被高熔点的Ni包覆的Ag纳米线的熔点比Ag的平衡熔点高,即有过热存在.这说明纳米线也可以过热,分析其原因是由于Ag/Ni半共格界面的存在抑制了熔化的形核和生长.     

一类n维自映射无异状点的充要条件

给出了可降的n维自映射无异状点的若干充要条件.     

一种新的拓扑指数与链烷烃的沸点

本文从距离矩阵和邻接矩阵出发,定义一种新的拓扑指数Hx,将它用于研究饱和链烃类化合物的沸点,获得比较满意的效果.与其它已有的拓扑指数相比较,该指数计算方法简单,并具有良好的性质相关性.     

拓扑指数与对饱和脂肪酯物理化学性质的预测

本采用改进的分子连接性指数^1x，建立了饱和脂肪醋物理化学性质P的定量公式：P=a b^1x，式中a,b是系数，对于某一物理化学性质为一定值。本预测了含12个碳原子以内的饱和脂肪翻的水溶解度、分配系数、保留体积、沸点和相对密度等五项物理化学性质。     

分子轨道对称守恒原理中的方法论

本文通过能级相关理论、前线分子轨道理论,论述了对称性方法在化学反应中的应用,同时论述了在分子轨道对称守恒原理中,对称与守恒的统一。     

重心坐标系下三次C样条奇拐点分析

介绍三次C样条和重心坐标,同时给出重心坐标系下三次C样条的参数表示形式,利用仿射不变量来研究三次C样条奇拐点存在判别条件,并且对仿射不变量p的各种情况进行讨论,同时简化奇拐点判别条件。     

用聚点来描述的数列的敛散性

通过对数列的聚点的讨论,给出并证明了一个判别数列敛散性的结论,然后应用结论证明数列收敛的单调有界定理与柯西收敛准则.     

点焊机器人的工作原理及其结构CAD技术

本文在机构学、机械设计的基础上,根据点焊接机器人的工作原理和技术特点,论述了其机构的焊接运动过程,以及此类机器人机械结构CAD系统的主要技术构成.     

Making sense of professionalism and being a professional in a Kenyan higher education context

The concept of the professional in the context of a rapidly expanding higher education sector in a developing country offers interesting insights into the values, attitudes and motivations of lecturers. The article charts the expansion of higher education and summarises the challenges that it faces. It goes on to examine through interviews with faculty (staff) in one private university in Kenya what they understand by professionalism, what constitutes professional (and less than professional) behaviour and whether they feel that the institution supports or militates against professionalism amongst the academic workforce. The findings suggest that their view is unproblematic and resides in their specialist knowledge and accompanying values and behaviours and is less concerned with status, autonomy or agency. Faculty are clear what a professional is and what constitutes professional behaviour, but appear to recognise and accept that this is a low-status profession where colleagues struggle to survive materially, often prioritise extra teaching for research and enjoy limited opportunities for professional development. The research suggests that Kenya, and other countries in a similar position, may well struggle to provide an environment where professionalism will flourish as staff face a range of challenges to grow and improve their higher education system.