浅析氢键及其对物质性质的影响

本文主要论述了氢键的本质、种类及其对物质性质的影响,阐述了分子间氢键与分子内氢键对物质性质影响的差异.     

氢键对物质性质的影响及应用

氢键不属于化学键,也不属于范德华力,是介于化学键和范德华力之间的一种由氢原子参与成键的特殊键型.氢键的键能较小,但其存在却对物质的性质,结构等方面有很大影响.故对氢键的研究应用也为人们所关注.     

氢键的形成条件及对物质性质的影响

氨键是一种最常见也是最重要的分子间或分子内的相互作用,这种作用比共价键弱得多,对描述分子的许多行为以及决定物质的物理性质起到重要作用。本文对氢键的形成条件及对物质性质的影响做了较详细的论述.     

关于分子间,内氢键及对物质性质影响的讨论

本阐明了形成分子间与分子内氢键的条件,并比较了物质形成分子间与分子内氢键后对物质性质的影响及其差异。     

浅析氢键对物质性质的影响

近年来氢键在化学前沿领域应用颇广,比如超分子设计、晶体材料合成与结构分析、生物体现象分析等,而这些也正是化学命题中信息题型的情境素材的极好来源,也是学科内综合、跨学科综合试题的命题热点。     

氢键对含氮有机化合物性质和结构的影响

氢键广泛存在于气体、液体和晶体等各种状态之中，影响着物质的性质和结构。本文仅就氢键对含氮有机化合物的性质、化学反应和结构的影响作进一步的分析论证。     

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。     

试论氢键及其性质

1 氢键的定义 氢键是一种特别强的偶极—偶极相互作用。在氢键中,一个氢原子在两个电负性原子间起一种桥梁作用。它与电负性极强的元素(如F、O、N等)以共价键结合,又以纯粹的静电力和另一个分子中电负性极强的原子结合而形成的。一般可表示为X—H…Y,式中X和Y均代表电负性较大的原子。 氢键的强弱与X和Y原子的电负性大小及原子半径有关,一般来说,电负性越大,原子半径越小,则形成的氢键就越强,此外还与成键方向有关,只有当X—H…Y在同一直线上时,氢键最强。     

浅谈分子间氢键对有机化合物性质的影响

有机化合物的性质主要由化合物的结构所决定，但分子间的氢键对化合物的物理性质、光谱性质、有机化学反应、有机化合物的酸碱性等有较大影响。     

浅析氢键对物质物理性质的影响

氢键对物质的物理性质产生不同程度的影响 ,本文结合具体事例论述氢键的形成、特征及对物质熔点、沸点、溶解度、粘度、硬度等物理性质的影响     

论教育沟通及其过程特性

教育沟通是指教育者与受教育者之间通过有效语言和其它方式 ,运用合理协调方式达成共识的一种人际沟通。与一般的人际沟通相比 ,它具有二分的确定性、目的的先在性、资源的倾斜性、方式的潜隐性和网络性等特点。从发生机制看 ,教育沟通具有伴生性、均衡性、转换性等过程特性     

试析人类对自然界的干预及后果

人类自诞生之时起便开始了对自然界的干预.在渔猎文明时代,人类对自然界的过度干预使得许多哺乳动物灭绝;农业文明在取得对自然界胜利的同时也使植被减少、土地沙漠化,古文明湮没;工业文明的巨大进步,却意外导致了天空、陆地、海洋的全方位危机,使人与自然的关系陷入严重的冲突与矛盾之中.     

纳米材料及其应用

系统介绍了纳米材料的概念、分类、特性以及制备与合成方法，重点介绍了纳米材料在工业生产、医药、生活和环保中的应用，讨论了中国在纳米材料产业方面存在的问题，并指出了纳米材料产业发展前景，     

The influence of explicit nature of science and argumentation instruction on preservice primary teachers' views of nature of science

There exists a general consensus in the science education literature around the goal of enhancing learners' views of nature of science (NOS). An extensive body of research in the field has highlighted the effectiveness of explicit NOS instructional approaches in improving learners' NOS views. Emerging research has suggested that engaging learners in argumentation may aid in the development of their NOS views, although this claim lacks empirical support. This study assessed the influence of a science content course incorporating explicit NOS and argumentation instruction on five preservice primary teachers' views of NOS using multiple sources of data including questionnaires and surveys, interviews, audio‐ and video‐taped class sessions, and written artifacts. Results indicated that the science content course was effective in enabling four of the five participants' views of NOS to be improved. A critical analysis of the effectiveness of the various course components led to the identification of three factors that mediated the development of participants' NOS views during the intervention: (a) contextual factors (context of argumentation, mode of argumentation), (b) task‐specific factors (argumentation scaffolds, epistemological probes, consideration of alternative data and explanations), and (c) personal factors (perceived previous knowledge about NOS, appreciation of the importance and utility value of NOS, durability and persistence of pre‐existing beliefs). The results of this study provide evidence to support the inclusion of explicit NOS and argumentation instruction as a context for learning about NOS, and promote consideration of this instructional approach in future studies which aim to enhance learners' views of NOS. © 2010 Wiley Periodicals, Inc. J Res Sci Teach 47: 1137–1164, 2010     

Fostering connectedness to nature in higher education

Environmental thinkers and educators have argued for the importance of celebrating our connectedness to nature, or the perception of being part of, rather than separate from, the natural world. Using pre-and post-test measurements of Nature Relatedness and supplemental interviews, this study addresses the question of whether a particular introductory college-level ecology course can increase learners’ connectedness to nature, both independently and in comparison to a similar course. The results show that the course significantly increased participants’ connectedness, particularly their identification with nature and nature-focused worldview. Other environmental courses studied demonstrated no such changes, suggesting that environmental education does not automatically lead to connectedness. However, if woven into the goals and approach of teaching, connectedness to nature can indeed be fostered in higher education. This is a promising result for educators and others working towards a sustainable future.     

论中介的本质及其辩证法意义

中介具有三重的辩证法意义。其一 ,事物是互为中介而联为一体的 ,因而中介是普遍联系得以实现的联系环节 ;其二 ,事物的对立双方相互渗透而发生变化 ,因而中介是运动变化得以实现的过渡阶段 ;其三 ,中介是质变发展得以实现的转化条件。发展是辩证法的核心 ,因而作为转化的条件是中介的本质。中介的辩证法意义特别是它的本质意义在人与自然的关系演变中表现得尤为明显     

Making learning interesting and its application to the science classroom

Generations of students are graduating from secondary school disinterested in post-secondary study of science or pursuing careers in science-related fields beyond formal education. We propose that destabilising such disinterest among future students requires science educators to begin listening to secondary school students regarding their views of how science learning is made interesting within the science classroom. Studies on students’ interest in response to instructional strategies applied in the classroom communicate the opinions (i.e. the ‘voice’) of students about the strategies they believe make their classroom learning interesting. To this end, this scoping study (1) collects empirical studies that present from various science and non-science academic domains students’ views about how to make classroom learning interesting; (2) identifies common instructional strategies across these domains that make learning interesting; and (3) forwards an instructional framework called TEDI ([T]ransdisciplinary Connections; Mediated [E]ngagement; Meaningful [D]iscovery; and Self-determined [I]nquiry), which may provide secondary school science teachers with a practical instructional approach for making learning science genuinely interesting among their students within the secondary school science classroom context.     

科学人性观对教育的启示

人性是教育的起点,也是教育的终点.教育工作者只有树立科学的人性观,才能把学生培养成为人性丰满,主体性突出,有进取意识和创新精神的社会个体.     

胺的碱性强弱及其影响因素

从诱导效应，共轭效应，溶剂化效应及空间位阻效应讨论了对胺的碱性强弱变化的影响。