用电磁打点计时器进行受迫振动实验--介绍我校的一个自学物理实验

介绍一种用简单的方法进行的受迫振动实验。     

高温超导体的结构组装

 在总结铜氧化物高温超导体晶体结构特点的基础上，提出了以无限层结构Cu-O钙钛矿为核心的结构组装概念，通过和相关结构的外延组合，衍生出了高温超导体的主要晶体构型。进一步运用此观念，建立了新的三元数命名法，并对高温超导体的晶体结构进行了归类。     

Crystal Structure of Adduct 2-Phenyl-imidazo [ 4,5-f ] 1,10-phenanthroline Methanol

The structure of the title adduct comprises a phenanthroline derivative 2-phenyl-imidazo[4,5-f]1,10-phenanthroline and a methanol.The composition of the crystalline adduct was characterized as C19H12N4.CH3OH.It belongs to orthorhombic system,space group Pna21 with a=1.3693(4)nm,b=2.2988(7)nm,c=0.51338(15)nm,V=1.6160(8)nm^3.Z=4,and final R1=0.0423.wR2=0.1012 .Crystal structure shows that all the 19 carbon atoms and 4 nitrogen atoms are coplanar.The bond length data indicated that a very extensive conjugation system was formed.This conjugation makes the compound being a potentially excellent energy transformer used for luminescent materials.     

液晶显示器用导电粉的扫描电镜图像

液晶显示器用导电粉的形状、尺寸及偏差对于液晶显示屏的质量控制来说是非常重要的。论述了液晶显示器(LCD)用导电粉的作用和性能要求。给出了液晶显示器用导电粉的扫描电镜图像。该图像对观测导电粉的粒径分布、导电粉在导电点中的浓度和分析导电点缺陷、提高液晶显示器的产品质量具有一定的意义。     

Hydrothermal Synthesis and Structure of [（PbCl2）μ-PyZ）1/2]n （Pyz = Pyrazine）

1 INTRODUCTION Because of the flexibility of Pb(II) coordination sphere and the nonstereospecific nature of halide anions[1], the chemistry of lead halide complexes has been developed in recent years. Especially PbX2- based coordination polymers with nitrogen-contain- ing Lewis bases have attracted renewed interest[2～11]. The choice of ligand and the reaction condition are of great importance in determining the final topo- logy of the supramolecular materials. But the avail- able struc…     

Synthesis and crystal structure of the octahedral cluster complex [Th(DMSO)8Cl][Re6Se7Cl7]

A cluster complex of the composition [Th(DMSO)₈Cl][Re₆Se₇Cl₇] has been obtained by interaction of ThCl₄ solution in DMSO with a water solution of K₃[Re₆Se₇Cl₇] and KCl. The compound crystallizes in the rhombic space group Pbcm with unit cell parameters a = 12.262(2) Å, b = 19.653(6) Å, c = 23.603(6) Å, V = 5688(2) ų, Z = 4, d _calc = 3.282 g/cm³. The structure is built from centrosymmetric cluster anions [Re₆Se₇Cl₇]^3? and complex cations [Th(DMSO)₈Cl]³⁺ possessing mirror-plane symmetry, half of the DMSO ligands being doubly disordered.     

Theoretical analysis of the onset of liquid entrainment for slots of finite width

The onset of liquid entrainment during discharge from large reservoirs containing a stratified mixture of two immiscible fluids through a side slot of a finite width is considered theoretically. A previously reported analysis in which the slot was approximated as a two-dimensional line sink has been extended to account for the finite width of the slot. The model resulting from the present analysis is expressed in terms of two simple algebraic equations suitable for hand calculations. According to the present results, the ratio of the critical height to the slot width is dependent only on the Froude number. Numerical results show that the present model approaches the correct physical limits at low Froude numbers and it converges to the predictions of the previously reported simple model at high Froude numbers.     

On‐line Determination of Particle Size Distributions in Flowing Dispersions

Emulsions are of great importance to industry. They are involved in many engineering operations, including chemical reactions, extraction, emulsification and suspension polymerization, etc. However, an important problem for these processes is how to control the size distribution of the dispersed phase. Indeed, off‐line analysis of the emulsion may generate uncertainties due to sampling and dilution of the product, which are likely to change the dispersion state and physico‐chemical properties. In this work, an on‐line optical method is proposed to characterize dispersed media in real flowing conditions. This method is based on the time‐analysis of back‐scattered light fluctuations. The present paper deals with the development of this method and its application to dispersions of alumina in water. The results obtained with the on‐line optical method are compared with those acquired by classical laser light scattering and microscopy.     

Crystallographic report: Bis(norfloxacin)dilead(II) tetranitrate, [Pb2(H‐Norf)2(ONO2)4]

The centrosymmetric binuclear structure of [Pb₂(H‐Norf)₂(ONO₂)₄]shows the geometry around each lead(II) atom to be distorted trigonal bipyramidal with Pb–O distances ranging from 2.357(3) to 2.769(4) Å. Copyright © 2003 John Wiley & Sons, Ltd.     

On an approach to the study of the Jaynes–Cummings sum in quantum optics

A new approach to the study of the Jaynes–Cummings sum, which determines the atomic inversion in quantum model of a single two-level atom interacting with a single mode of the quantized radiation field, based on the number theory theorems on approximation of trigonometric sums is presented.