新手熟手初中化学教师课堂教学行为特征的比较研究*——以“酸和碱”单元教学为例

通过对新手化学教师和熟手化学教师各4节“酸和碱”单元常态课堂中教师使用教学行为链、教学行为对在时间和频次等方面的特征进行对比分析发现,在教学行为链上,新、熟手化学教师都会在较高水平的教学行为链上花费更多的时间,熟手化学教师高水平教学行为链在频次上的占比要优于新手化学教师,在不同教学行为链时间安排上的合理性要更高一些;在教学行为对上,新、熟手化学教师都多以“问”和“讲”,学生多以“答”的方式来展开课堂活动,熟手化学教师在每一次“动”和“思”上所用时间要明显高于新手化学教师,学生参与课堂的水平上,熟手化学教师要优于新手化学教师。得出如下启示:与熟手化学教师相比,新手化学教师应有效地组织和安排课堂教学行为,注重对“酸和碱”学科内容本身及其教学的驾驭。无论是熟手还是新手化学教师均应进一步给予学生课堂参与的机会。     

新手-熟手化学教师课堂教学行为及其所用时间的比较研究

通过对新手教师和熟手教师的6节常态课堂中教学行为及其所用时间进行对比分析,发现了熟手教师无论在课堂教学行为链的数目比例分配还是所用时间比例分配上均要好于新手教师。新手教师为了更好地完成向熟手教师的转变,在平时的课堂教学中应当注重合理安排各类型的教学行为链的数目比例和所用时间比例,应当多采用一些高水平的教学行为链以及多投入一些时间在高水平的教学行为链上。     

新手-熟手化学教师课堂教学基元系统有效性的比较研究

依据课堂教学系统CPUP模型理论和课堂教学基元系统有效评价量表,通过对24位新手教师和熟手教师的24节常态课堂中基元系统有效性进行对比分析。结果发现,新手教师与熟手教师的主要差别表现在"教学行为链实施质量"和"资源和技术的使用质量"2个维度上,熟手教师显著高于新手教师;而在"时间利用的合理性""匹配度"和"基元内容的合理性"3个维度上,2者不存在显著差异。     

新手-熟手教师化学课堂教学有效性比较研究——以“离子反应”为案例

利用《课堂教学基元系统有效性评价量表》,对新手教师和熟手教师"离子反应"课堂教学中基元系统有效性进行评价,并进行对比分析。发现2者在"时间利用的合理性""教学行为链实施质量"和"匹配度"3个维度上存在显著性差异,熟手教师比新手教师表现要好;在"资源和手段使用质量"和"基元内容的合理性"2个维度上不存在显著性差异,2者在"资源和手段使用质量"上均表现不理想,在"基元内容的合理性"上均表现良好;在基元系统有效性总分上2者表现出了显著性差异,整体上而言,熟手教师的课堂教学基元系统有效性高于新手教师。     

新手-熟手高中化学教师PCK个案比较研究* ——以“氧化还原反应”主题为例

采用访谈法与质性资料分析法,测查了6名(3名新手与3名熟手)高中化学教师关于氧化还原反应主题的PCK。结果表明:(1)新手教师与熟手教师在CTO,KoL与KoS组分上存在较明显的差异。新手教师倾向于采用“教师-传授”教学取向,对学生知识的把握相对不足,更强调使用习题巩固策略;而熟手教师倾向于采用“学生-建构”教学取向,对学生知识的把握更为全面,更强调学生自主建构知识的过程。(2)新手教师与熟手教师在KoC与KoA组分上存在较明显的相似之处。在课程知识方面,教师对课程标准与教材中氧化还原反应主题内容具有较好的理解,但对化学基本观念、学科核心素养认识尚浅;在评价知识方面,教师偏向于传统的评价方式,且集中在形成性评价和总结性评价,但相对缺乏对学生的课前诊断性评价。文末据此对我国化学教师教育及其研究提出相关建议。     

高中化学新手熟手教师学科教学知识对比研究*

以“化学平衡”教学主题为载体自编调查问卷,选取河北省79位在职高中化学新手教师和81位高中化学熟手教师进行学科教学知识测查。应用独立样本t检验对调研数据进行比较和分析,重点从内容知识、课程知识、学生知识、教学策略知识、评价知识等5个维度探讨新手与熟手教师PCK差异及差异形成的原因,并据此提出相关建议,为促进高中化学新手教师的快速专业化成长提供借鉴和参考。     

专家熟手新手教师在化学试题命制中的差异研究——以一道工艺流程题的命制为例

专家、熟手和新手教师基于相同文献命制高中化学工艺流程题,通过试题要素分析、实测结果对比和显著性差异检验,研究专家、熟手和新手教师在化学命题上的差异及差异表现,为提升教师的命题水平提供有益的参考。     

“沉淀-溶解平衡概念应用”课堂教学中专家与新手教师语言行为的比较研究

采用课堂观察和弗兰德斯互动分析系统(FIAS),对新课程背景下"沉淀-溶解平衡的概念应用"教学中新手与专家教师的课堂教学语言行为进行了比较研究.结果发现新手和专家教师在课堂语言结构、教师倾向或风格、教师与学生情感气氛和课堂教学语言行为的组合等方面都存在较大差异.针对专家和新手教师语言行为的特征和差异,对新手教师语言行为的改进提出了建议.     

专家-新手型教师“化学键”课堂教学行为特征分析

采用课堂观察和"教学行为对"分类理论,对新课程背景下新手与专家教师"化学键"课堂教学行为进行了个案比较研究。研究结果表明新手与专家教师在课堂教学行为方面存在较大差异。在总结新手和专家教师课堂教学行为特征和差异的基础上,对新手教师教学行为的改进提出了建议。     

专家—新手教师化学课堂“实验教学行为组合”结构特征的比较

运用专家—新手比较研究方法,对16位教师在常态课中化学实验"教学行为组合"的特征进行了比较。结果发现,新手教师的显著特征是"不提出实验问题"和"教师设计实验方案";专家教师的显著特征是"提出探究性实验问题"、"师生共同设计实验方案"和"师生共同进行实验操作"。     

“水上”(“on water”)有机反应

"水上"有机反应的发展是水相绿色合成反应研究领域中的一个突破。体系的非均相性质是"水上"反应的基本特征。水不仅是重要的绿色反应介质,在大多数"水上"有机反应中都能观察到水对反应的速度和选择性有明显的提升作用。采用"水上"反应的条件,可以使反应的规模扩大,有利于产物的分离、纯化。本文以反应的类型分类综述了近年来有关"水上"有机反应研究的进展,以及在绿色有机合成中的应用。     

营养化学课程翻转课堂的探索与实践

With its tailored learning content, flexible learning environment and directed teacher guidance, the flipped classroom in "nutrition chemistry" has effectively solved the problems of students' specialty, large number and limited time in the course of elective course. The teaching mode based on the cultivation of students' ability and the core of improving scientific literacy was constructed.     

"Dip-Pen" nanolithography on semiconductor surfaces

Dip-Pen Nanolithography (DPN) uses an AFM tip to deposit organic molecules through a meniscus onto an underlying substrate under ambient conditions. Thus far, the methodology has been developed exclusively for gold using alkyl or aryl thiols as inks. This study describes the first application of DPN to write organic patterns with sub-100 nm dimensions directly onto two different semiconductor surfaces: silicon and gallium arsenide. Using hexamethyldisilazane (HMDS) as the ink in the DPN procedure, we were able to utilize lateral force microscopy (LFM) images to differentiate between oxidized semiconductor surfaces and patterned areas with deposited monolayers of HMDS. The choice of the silazane ink is a critical component of the process since adsorbates such as trichlorosilanes are incompatible with the water meniscus and polymerize during ink deposition. This work provides insight into additional factors, such as temperature and adsorbate reactivity, that control the rate of the DPN process and paves the way for researchers to interface organic and biological structures generated via DPN with electronically important semiconductor substrates.     

发展“模型认知”素养的教学实践*——以“化学方程式”为例

模型认知是重要的思维方法。基于模型认知进行教学设计,能促使教师从关注知识转向关注核心素养,从而使教学活动有效地促进学生思维能力的发展。在对模型及模型认知理解的基础上,以典型的符号模型“化学方程式”为例,阐明了教学思路和教学活动与学科观念的关系,形成了发展学生模型认知核心素养的教学设计。     

Switching "on" and "off" the expression of chirality in peptide rotaxanes

The hydrogen-bond-directed synthesis, X-ray crystal structures, and optical properties of the first chiral peptide rotaxanes are reported. Collectively these systems provide the first examples of single molecular species where the expression of chirality in the form of a circular dichroism (CD) response can selectively be switched "on" or "off", and its magnitude altered, through controlling the interactions between mechanically interlocked submolecular components. The switching is achievable both thermally and through changes in the nature of the environment. Peptido[2]rotaxanes consisting of an intrinsically achiral benzylic amide macrocycle locked onto various chiral dipeptide (Gly-L-Ala, Gly-L-Leu, Gly-L-Met, Gly-L-Phe, and Gly-L-Pro) threads exhibit strong (10-20k deg cm(2) dmol(-1)) negative induced CD (theta;) values in nonpolar solvents (e.g. CHCl(3)), where the intramolecular hydrogen bonding between thread and macrocycle is maximized. In polar solvents (e.g., MeOH), where the intercomponent hydrogen bonding is weakened, or switched off completely, the elliptical polarization falls close to zero in some cases and can even be switched to large positive values in others. Importantly, the mechanism of generating the switchable CD response in the chiral peptide rotaxanes is also determined: a combination of semiempirical calculations and geometrical modeling using the continuous chirality measure (CCM) shows that the chirality is transmitted from the amino acid asymmetric center on the thread via the macrocycle to the C-terminal stopper of the rotaxane. This understanding could have important implications for other areas where chiral transmission from one chemical entity to another underpins a physical or chemical response, such as the seeding of supertwisted nematic liquid crystalline phases or asymmetric synthesis.     

Theoretical study on "multilayer" nitrogen cages

The relative stabilities of nonisomers are investigated. Twenty-two species of nitrogen cage molecules N(2n) (N6 (D(3h)), N8 (Oh), N10 (D(5h)), N12 (D(6h)), N12 (D(3d)), N16 (D(4d)), N18 (D(3h)), N20 (Ih), N24 (D(3d)), N24 (D(4h)), N24 (D(6d)), N30 (D(3h)), N30 (D(5h)), N32 (D(4d)), N36 (D(3d)), N40 (D(4h)), N42 (D(3h)), N48 (D(4d)), N48 (D(3d)), N54 (D(3h)), N56 (D(4h)), and N60 (D(3d))), which are divided into four sets, have been studied in detail. The geometries and varieties of energies are examined extensively, and NBO analysis and AIM analysis are applied to investigate the bonding properties of the cage molecules. The introducing of the concept of "layer" can well assist in explaining why one nonisomer molecule is more stable than another one. The results show that the lengths of bonds, on both sides of which are five-membered rings (referred to as pentagons), are the shortest and the orbital energies are the lowest. The nonlocalized electron numbers of orbitals, on at least one side of which is a triangle, are the greatest. Pentagons play a major role in the stability of a cage molecule, and the three-membered rings (referred to as triangles) play the second one. The layers in nitrogen cage molecules also contribute to the relative stabilities.     

给超细金纳米粒子做“外科手术”

正近年来在纳米科学研究中,金属纳米团簇(metal nanoclusters,超细的金属纳米粒子,尺寸约1-3 nm)这一领域逐渐兴起并引起了研究者们的广泛关注~(1,2)。与尺寸更大且多分散的纳米粒子相比,纳米团簇取得了原子尺度上的精确,具有确定的分子式和X射线单晶结构~(3,4)。因此,研究纳米团簇使得人们可以从根本上理解一些纳米结构与性能的关系~(1-3),以及跟踪纳米世界里的某些