固体核磁共振研究固体酸催化剂酸性进展

酸性直接与固体酸催化剂的活性相关,因此研究固体酸催化剂的酸性受到了科研工作者的广泛关注. 固体核磁共振技术已经成为研究固体酸催化剂酸性的一种强有力的工具. 该文介绍了固体核磁共振的特点和各种常用技术,着重综述了固体核磁共振研究固体酸催化剂酸性的进展.     

化学演示实验操作中易被忽视的错误

化学演示实验不仅是传授知识的需要,也是对学生进行严谨科学的规范化操作最直观的教育。操作的规范化是化学教师的必备条件,应引起教师注意。     

Lattice Boltzmann simulation of fluid flows in two-dimensional channel with complex geometries

Boundary conditions (BCs) play an essential role in lattice Boltzmann (LB) simulations. This paper investigates several most commonly applied BCs by evaluating the relative L₂-norm errors of the LB simulations for two-dimensional (2-D) Poiseuille flow. It is found that the relative L₂-norm error resulting from FHML's BC is smaller than that from other BCs as a whole. Then, based on the FHML's BC, it formulates an LB model for simulating fluid flows in 2-D channel with complex geometries. Afterwards, the flows between two inclined plates, in a pulmonary blood vessel and in a blood vessel with local expansion region, are simulated. The numerical results are in good agreement with the analytical predictions and clearly show that the model is effective. It is expected that the model can be extended to simulate some real biologic flows, such as blood flows in arteries, vessels with stenosises, aneurysms and bifurcations, etc.     

A(B0.51B0.52)O3系统中三种有序态的稳定性初探

在A(BB_0.5¹B_0.5²)O₃钙钛矿型铁电陶瓷材料中,除了在较高温度下都能有稳定的<111>型超格子有序结构外,在室温和-150℃情况下,还分别观察到1/2<110>和1/2<100>型超格子有序结构,本文引入长程相互作用,并利用8点集团变分模型,在不同温度范围内分析了前面三种有序态的稳定性,所得结论与实验结果一致。 关键词：     

Slow-rise and fast-drop current feature of ultraviolet response spectra for ZnO-nanowire film modulated by water molecules

This study describes the fabrication of ZnO-nanowire films by electro-chemical anodization of Zn foil.The ZnO films are characterized by field emission scanning electron microscopy,X-ray diffraction patterns,and transmission electron microscopy,respectively.The ultraviolet(UV) photo-response properties of the surface-contacted ZnO film are studied through the current evolution processes under different relative humidities.Unlike the usually observed current spectra of the ZnO films,the drop time is shorter than the rise time.The photo-conductivity gain G and the response time τ are both increased with the increase of the applied bias.The photo-conductivity gain G is lowered with the increase of the environmental humidity,while the response time τ is increased.These results can be explained by considering three different surface processes:1) the electron-hole(e-p) pair generation by the UV light illumination,2) the following surface O2-species desorption,and 3) the photo-catalytic hydrolysis of water molecules adsorbed on the ZnO surface.The slow-rise and fast-drop current feature is suggested to originate from the sponge-like structure of the ZnO nanowires.     

PIXE应用于分析Si基片热扩Ni的深度分布

本文报告了PIXE(Proton Induce X-ray Emission)技术分析Si基片热扩Ni的深度剖面,质子能量为0.7至2.5MeV,比较了两种理论计算结果的差异,并与其它测量方法得的结果作了比较。     

[Bmim]ZnBr_3促进的烯胺酯和联烯酮的串联反应合成烟酸酯衍生物

发展了一种Lewis酸性离子液体[Bmim]Zn Br3促进的烯胺酯与联烯酮的新型串联反应,在二者缩合生成烟酸酯衍生物的过程中,这种离子液体既作为溶剂又起着催化剂的作用,并且可以回收再利用.该串联反应具有反应时间短、处理过程简单、环境友好、产率高等优点,可为含有烟酸酯结构单元的天然产物及复杂药物分子的合成提供简便的途径.     

基于教育游戏的翻转课堂教学设计——以“原电池的设计”为例

在国内外翻转课堂相关文献对比和教育游戏特点分析基础上,尝试进行了基于教育游戏的高中化学“原电池的设计”的翻转课堂教学设计,利用教学游戏,充分调动学生的学习兴趣,提高翻转课堂课前学习效率。     

含氮、磷四元不饱和杂环化合物的合成和表征

合成了含氮、磷四元不饱和化合物. 反应可能是通过phosphinidene对P—C＝N的1,3环加成反应过程进行的.     

Cr掺杂对Bi0.5Ca0.5MnO3磁性和电输运性质的影响

通过对M～T曲线、M～H曲线和P～T曲线的测量,研究了Bi0.5Ca0.5Mn1-xCrxO3(O≤x≤0.12)系列样品的磁性和电输运特性.结果表明,随Cr掺杂量的增加,反铁磁转变和电荷有序转变分别在x～0.03和x～0.12相继消失.低温下始终出现自旋玻璃或团簇玻璃行为,说明存在反铁磁与铁磁的相互竞争.对电阻率数据的拟合表明,所有组分载流子的电输运可用可变程跃迁描述.我们用相分离的图象解释了相关现象.