四角场S=2离子ZFS高阶微扰公式的收敛性

本文以~５Ｂ＿２为基态，在强场图象下用微扰理论推导出了轴向零场分裂参量Ｄ的１到４阶微扰计算公式（~５Ｄ近似），并就公式的微扰收敛性进行了系统的讨论．通过计算和分析表明，当第一激发态靠近基态使得其能量与旋轨耦合常数ζ可比拟时．微扰公式是发散的．这时，微扰近似方法将不再有效。但在大多数情况下，公式保持有较好的收敛性．同时，给出了使微扰松式有效的晶场参量Ｄ＿９、δ和μ的近似取值范围，为~５Ｄ近似公式的应用提供了有价值的参考。     

时分复用倍乘光脉冲重复率的新型光纤耦合器环状连接法分析

提出并详细分析了一种基于时分复用技术倍乘光脉冲重复率的方法：在２×２光纤耦合器的一个输入口与一个输出口间，接入时延为脉冲列半周期奇数倍的一段光纤使之形成环状连接循环耦合，而在另一输出口获得光脉冲。详细分析了该系统中光纤耦合器耦合比、插入损耗、时延光纤长度的要求，偏差的影响及其调节法，给出了理论公式、结果的计算机模拟与实验介绍；与经典的马赫陈德尔干涉仪接法及近年提出的Ｓａｇｎａｃ环接法进行了比较。该方法特别适用于对窄脉冲列进行串接复用实现重复率的多次倍乘，从而得到数千兆赫至上百千兆赫的高重复率光脉冲     

Gamma-rays from Mössbauer sources: a low-dose approach to cancer therapy

Summary A new approach to cancer treatment using low-energy gamma-rays is discussed. Cultures of bone marrow mononuclear cells collected from normal donors and patients with chronic myelogenous leukaemia have been studied after the addition of hematin, at different concentrations, and irradiation by a M?ssbauer gamma-ray source. Growth stimulation has been observed when hematin is added to normal bone marrow cultures, while growth inhibition is observed when hematin is added to leukaemic cultures. The effect becomes then more pronounced when hematin is used in combination with M?ssbauer gamma-rays.     

Preservice Elementary Teachers' Use of Mathematics in a Project‐Based Science Approach

The use of a project‐based science (PBS) approach to teaching encourages students to integrate mathematics and science in meaningful ways as they create projects. As a beginning study of how students use mathematics in such an approach, an analysis of 23 projects developed by preservice elementary teachers enrolled in an elementary science course was conducted. Findings showed that students made a number of different types of mathematical errors and underutilized data representation and summary forms. Implications included the importance of developing methods for supporting the use of mathematical tools in utilizing a project‐based approach and considering ways that such tools mediate scientific thinking.     

农村移民职业教育培训与万州区实施城市化战略的思考

重庆市万州区城市化战略能否顺利实现,除了受制于人口管理,就业机会、土地制度、政府职能等因素外,很大程度上取决于广大农村移民人口的科学文化素质和文明程度.区政府要从提高移民的自身素质和职业能力出发,加强"三教"统筹,发挥城市教育资源的优势,完善农村移民职业教育培训体系,加大对农村移民劳动力转移培训的扶持力度,通过各种形式的培训,促进农村移民的城市化转变.     

分子生物学设计性实验与七年制学生能力培养

通过分子克隆设计性实验,充实学生的基础理论和基本技术,引导学生独立设计实验、查阅资料解决存在的问题,促进医学专业七年制学生的能力培养.     

梁大牙: 一个另类英雄 --评小说《历史的天空》

英雄人物的成长离不开具体的历史时代环境。随着对“文学即人学”观念的深入思考,当代军旅作家们开始注重在作品中展示英雄人物的成长与具体历史时代环境的关系,塑造了一批具有个性和丰富内涵的英雄形象。徐贵祥在《历史的天空》中塑造了一位另类英雄人物——梁大牙(梁必达)形象。文章从四个方面对梁大牙的出身、经历、性格和情感进行分析,揭示了其体现出的人性复杂性和创新意义。     

Surface modifications of ITO electrodes for polymer light-emitting devices

Surface modifications were performed on the indium tin oxide (ITO) substrates for polymer light-emitting devices, using the different treatment methods including solvent cleaning, hydrochloric acid treatment and oxygen plasma. The influence of modifications on the surface properties of ITO electrodes were investigated by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle, and four-point probe. The surface energies of the ITO substrates were also calculated from the measured contact angles. Experimental results demonstrate that the surface properties of the ITO substrates strongly depend on the modification methods, and oxygen plasma more effectively improves the ITO surface properties compared with the other treatments. Furthermore, the polymer light-emitting electrochemical cells (LECs) with the differently treated ITO substrates as device electrodes were fabricated and characterized. It is observed that the surface modifications on ITO electrodes have a certain degree of influence upon the injection current, luminance and efficiency, but hardly upon the turn-on voltages of current injection and light emission which are close to the measured energy gap of electroluminescent polymer. Oxygen plasma treatment on the ITO electrode yields the better performance of the LECs, due to the improvement of interface formation and electrical contact of the ITO electrode with the polymer blend in the LECs.     

A Mössbauer spectroscopic study of an industrial catalyst for dehydrogenation of etylbenzene to styrene

Iron oxide catalyst with spinel structure used for dehydrogenation of ethylbenzene is one kind of important catalyst in petrochemical industry. In this work several series of industrial catalyst were prepared with different components and different manufacturing processes. Mössbauer Spectroscopy has been used to determine the optimal components and the better manufacturing process for spinel structure formation. The results may prove useful for producing the industrial dehydrogenation catalyst with better catalytic property.     

Photodecomposition of several compounds commonly used as sunscreen agents

The photolysis reactions of three compounds commonly used as a sunscreen agents, Parsol 1789 (1-[4-(1,1-dimethylethyl)phenyl]-3-(4-methoxyphenyl)-1,3- propanedione), Oxybenzone ((2-hydroxy-4-methoxyphenyl)phenyl-methanone) and Padimate O (2-ethylhexyl-4-(dimethylamino)benzoate), were investigated to provide a chemical background to aid in the understanding of the photosensitization of the sunscreen agents. Photolysis was carried out in cyclohexane for 70–140 h using a mercury vapor lamp (450W) without excluding oxygen.

Irradation of Parsol 1789 in cyclohexane yielded tert-butylbenzene, p-tert-butylbenzoic acid and p-methoxybenzoic acid; products obtained from the combination of the sunscreen with the solvent included the cyclohexyl esters of p-methoxybenzoic acid, p-tert-butylbenzoic acid and methanoic acid; products obtained from the solvent included cyclohexanol, cyclohexanone and dicyclohexyl ether.

Irradiation of Oxybenzone in the cyclohexane for 100 h produced no detectable products by either gas or liquid chromatographic analysis. Oxybenzone was recovered unchanged and no products were observed from the photoinitiated reaction of oxygen with the solvent.

Irradiation of Padimate O in cyclohexane yielded the ethylhexyl esters of p-aminobenzoic acid, p-monomethylaminobenzoic acid and p-dimethylamino (o/m)-methylbenzoic acid, as well as products from the photoinitiated reaction of oxygen with the solvent.