pH对席夫碱在玻碳电极上电化学氧化还原的影响

合成了一种席夫碱（N-苯基苯甲亚胺）,利用循环伏安法对这种席夫碱溶液在玻碳电极上的电化学氧化还原进行了研究,并考察了pH对这种席夫碱的电化学氧化还原反应的影响．结果表明：该席夫碱的循环伏安图上,在-1．590V电位下出现了一个-CH=N-基团不可逆的还原峰,这说明在玻碳电极上此席夫碱可以被还原;在不同pH的缓冲溶液中,此席夫碱的-CH=N-基团还原峰的峰电位随着H^＋浓度的增大向负方向移动,并对H^＋对席夫碱-CH=N-基团的电化学氧化还原影响的机理进行了推断．     

Problems in Teaching the Topic of Redox Reactions: Actions and Conceptions of Chemistry Teachers

Although there is growing interest in studies of teachers' actions and conceptions, little is known about content-related teaching problems arising in science classrooms. This article presents a case study of problems which can occur when teaching the topic of redox reactions to Grade 11 students. Two chemistry teachers, a senior and a junior teacher, were involved in the study. Their reflective comments on the teaching problems were also investigated. Research data were obtained from classroom observations and audiotaped recordings of classroom practice. After the lessons, we conducted semistructured interviews with the teachers. The teaching problems are reported in terms of teaching activities causing difficulties for students in considering new conceptions to be necessary, intelligible, plausible, or fruitful. Analyses of the teachers' comments on these teaching activities clarifies a number of reasons why they acted as they did. It can be concluded that teachers' scientific expertise is an important source of difficulties when teaching redox reactions. Implications for an improvement of current chemistry classroom practice and content-related teacher training are offered.     

氧化还原反应产物的推断及反应方程式的书写方法

本文主要介绍应用元素电势图推断氧化还原反应产物并根据推断产物书写相应反应方程式的方法.对拓宽氧化还原理论在无机元素化学中的应用有实际意义.     

Effect of Marangoni Convection on Mass Transfer in Liquid Phase

Marangoni effectis of interestto the chemical en-gineers from both scientific and practical points ofview[1—6]. The Marangoni convection contributes tothe renewal of the interfacial surface and is capable ofincreasing the mass transfer rate, resulting in intensi-fication of separation processes such as distillation,extraction, absorption, and desorption. The theoretical studies of Marangoni instability inthe past were focused on determining the critical tran-sition point. The critical condit…     

Analysis on the Role of Mass Media in the Development of Tibet Tourism

In this paper, I will briefly analyze the role of mass media in the development of Tibet tourism. Through some exam?ples and some theoretical analysis we will mainly discuss the problems and the prospe...     

Analysis on the Role of Mass Media in the Development of Tibet Tourism

In this paper, I will briefly analyze the role of mass media in the development of Tibet tourism. Through some examples and some theoretical analysis we will mainly discuss the problems and the prospects of Tibet tourism media. I sincerely hope this thesis will provide some good suggestions and views to the developing of Tibet tourism.     

论新时期教师角色的转变

在当今社会发展和教育改革的背景下,传统的教师角色面临着极大的挑战,教师角色的转变已成为必然趋势。文章讨论了教师角色的内涵、传统教师角色在新时代的不适应以及教师角色转变的趋向等问题。     

Mass Transfer of MTBE in Groundwater During Air Sparging

A one-dimensional column is set up to study the mass transfer during air sparging process for methyl tertiary butyl ether(MTBE) removal in saturated soil and groundwater, with the condition of different airflow and soil penetrability. It is shown that the removal rate of MTBE can reach 80%, 90% and 95% when airflow is 0.05 m3/h, 0.085 m3/h and 0.10 m3/h, respectively. Increasing airflow will help to increase the removal rate of dissolved MTBE, but eventually a threshold removal rate is reached, above which further increasing air injection rates does not increase the removal rate. Fine sand allows the injected air to travel in bubble form, while coarse sand and medium sand allow the injected air to travel in the form of discrete channels; the greater the soil grain size is, the more extensive the channel net work forms, which in turn leads to higher removal rate. A tailing effect of lingering residual contaminant concentrations occur within the fine sand. About 20% of MTBE cannot be removed.     

The Role of the Mass Media in the Integration of Migrants

The media have a profound effect on the worldview of their consumers and should be carefully considered in matters of immigration. Often, migrants are portrayed through a negative lens by the media and most usually as a homogenous group rather than as individuals. This article examines the portrayal of migrants in one particular context (Germany) and questions what the best ways would be for handling these negative images, especially but not only in education systems. The author concludes that perhaps the combination of viewing migrants as individual people, rather than as a homogenous group, as well as more positive media portrayal of migrant people, would lead to a more positive representation of migrants in society.     

变质量系统的能量转移和转化

本文研究了变质量系统的功能原理以及该系统的能量转移和转化问题.     

浅谈两侧性迁移在运动训练中的应用

在运动训练中两侧性迁移作为一种新的训练方式,对开发运动员的大脑潜力,提高运动智能,促进运动技术能的形成,提高运动成绩有积极的意义;同时为运动员"高原现象期"、肢体一侧受伤期的运动训练提供理论参考;为运动技术的更新提供了解决方案.     

Evaluating the Stability of Active Manganese Sites During Electrochemical Reactions by Cyclic Voltammetry

Manganese oxides are a promising class of electrocatalysts for renewable energy devices,such as fuel cells.Mn(Ⅲ) ions with e^g electron filling of-1 are the active sites for manganese-based electrocatalysts.However,Mn(Ⅲ) sites may be disproportionated during electrochemical reactions,thus reducing the number of Mn(Ⅲ) active sites and decreasing the catalytic activity of manganese oxides.In this work,we developed a facile cyclic voltammetry method to monitor the evolution of Mn(Ⅲ) sites...     

突发公共事件管理中媒体的角色地位

媒体信息是一种公共资源,理应在突发公共事件出现时起到信息传播、沟通和反馈的作用,最大限度地为增进公共福利而发挥最大效益。在突发公共事件管理中,媒体不仅可以及时监视可能导致突发公共事件发生的各种潜在因素,而且在突发公共事件发生过程中作为政府和公众的代言人,完全可以沟通信息、疏导情绪,发挥积极引导的作用。因此,突发公共事件管理的实质是信息传播的管理;突发公共事件管理需要正确的舆论导向;突发公共事件管理离不开广泛的社会沟通。     

大规模定制化生产在国际物流中的作用

企业在国际物流中有一定优势,大规模定制策略对国际物流作用明显。     

大众传播媒介在儿童社会化中的作用

一、大众传播媒介的主要特点当代儿童比以往任何一代儿童都更充分地享受了媒介资源 ,其成长也更多地受到了电视广播节目、报纸刊物和新兴电子媒介等大众传播媒介的影响。社会学家已将大众传媒列为除家庭、学校、同龄群体以外的影响儿童社会化的重要因素。传播学研究者指出 ,在儿童可塑性最强的时期 ,大众媒介为他们提供了一幅现实世界的图景和各种人生理想的模型。因而大众传播媒介对儿童的影响越来越受到人们的关注。一方面 ,大众媒介通过社会宣传有关法规政策 ,传播有益身体健康的信息 ,帮助儿童认识社会 ,帮助儿童成长。但另一方面 ,大众…     

论校园数字化中的大学教师角色转变

大学校园数字化的发展，对大学教师的素质提出新的要求。传统教师角色与校园数字化之间存在着冲突和矛盾。解决这一冲突和矛盾必须构建新的大学教师角色，确立新的激励机制。     

论新时期语文教师的角色转换

新时期要求语文教师进行角色转换:从知识的灌输者转换为学习的引导者;从课堂的主宰者转换为平等的交流者;从单向的传授者转换为互动的合作者;从呆板的经验者转换为教学的创新者。     

对于分子内电荷转移反应中盐效应改变其反应速率的动力学研究

Marcus-Levich理论[1][2]是在研究电荷转移反应领域中的一个标志,但是无法解释在某些分子内电荷转移反应中盐效应能够减少电子转移速率2-3个数量级的现象.自由能表达式的推导[3]是基于一个非平衡自由能函数,文章明确定义了这个表达式中的反应坐标,并由反应扩散方程的解导出了速率常数依赖于反应坐标的时间相关函数.理论计算结果与实验数据相符,并且此理论也可以扩展到在离子液体中的电荷转移反应.     

建环专业《热质交换原理与设备》精品课程建设探讨

为适应新时期高等教育培养目标的要求,本文从理论课教学、实验课教学及师资队伍建设等方面建设《热质交换原理与设备》精品课程,培育了一支高水平的教师队伍,培养了学生的综合能力,也为该课程能够健康持续地发展打下扎实基础,为培养高级应用型工程技术人才奠定良好的基础。     

幼儿科学活动中教师角色的定位与转换

要在幼儿园全面实施素质教育，幼儿教师就要不断学习贯彻新《规程》的播种，在了解儿童、尊重儿童、信任儿童的前提下，在适当的场合、恰当的时机扮演儿童的领导、儿童学习环境的构筑者、儿童的向导、儿童的倾听者、儿童的玩伴、儿童学习的观察者和研究者等多种不同的角色。幼儿科学活动要顺应儿童的需要，全面发展儿童各方面的素质，走出幼儿科学教育小学化、知识化的误区。