微波辐射法合成丙二酸甲(乙)烷酯

丙二酸甲(乙)烷酯类是一些药物和天然产物合成的中间体,一般由丙二酸二甲(乙)酯经部分水解得到丙二酸单甲(乙)酯钠盐,再通过酸化、酰氯化和酯化反应制得[1],该方法路线较长、酰氯化反应会产生有毒尾气。羧酸(包括烷酸和芳酸)酯可由其盐和卤代烃直接反应制得[2-4],而且可利用无溶剂相转移催化的条件进一步加速反应和提高产率。微波技术用于有机合成[5-7]具有操作简便、产率高和速度快等优点。我们参考文献[2-4]方法,应用微波技术合成了标题化合物。1　实验部分1 1　仪器ＢｒｕｋｅｒＤＰＸ 300ＦＴ ＮＭＲ型核磁光谱仪,ＴＭＳ为内标;ＩＲ…     

γ射线对A172胶质瘤细胞的生物学效应

以不同剂量照射后的细胞存活率、 微核率和微核细胞率作为生物学终点, 研究了γ射线对A172细胞的生物学效应. 结果表明: 细胞存活率与剂量之间满足回归方程lgY=-0.064 27X+1.833 54, 其回归系数r=-0.988 6, P<0.01. 剂量为1 Gy时微核率和微核细胞率达到最大值, 此时的微核率为（66.75±3.564）%, 微核细胞率为（53.9±0.784 9）%, 微核率和微核细胞率均随着剂量的增大先增大后减小, 并分别维持在42%和37%左右. To study the biological effectiveness in A172 glioma cells induced by γ ray irradiation, the survival fraction and the micronucleus frequency of A172 cells was measured. The result showed that the survival fraction was negatively correlated to the radiation dose. At 1.0 Gy, the micronucleus frequency peaked about (66.75±3.564)%, and the frequency of micronucleus cells peaked about (53.9 ±0.784 9)%. As the radiation dose increasing, the micronucleus frequency and the frequency of micronucleus cells decreased and finally kept steady about 42% and 37%, respectively.     

银原子在液体基底上的凝聚特性

研究了沉积在液体基底表面上的银原子的扩散和凝聚特性．实验结果表明：银原子在液体表面先形成准圆形的团族，然后通过无规扩散而逐渐凝聚成具有分枝状的凝聚体．准圆形团簇的平均半径以及凝聚速率均随沉积速率的变化而变化．还提出了一个凝聚速率概率模型，计算结果与凝聚速率的实验曲线相符合． 关键词：     

储存环上的放射性核束流品质计算

为给兰州重离子加速器冷却储存环（ＨＩＲＦＬ－ＣＳＲ）注入放射性核束（ＲＩＢ）提供初始参数，及为ＣＳＲ上ＲＩＢ分离谱仪的物理设计提供依据，对最近几年发展起来的利用弹核碎裂（ＰＦ）、双消色散分离谱仪在线获取和分离所需ＲＩＢ的参数计算方法，进行了系统的总结；给设计中的ＣＳＲ－ＲＩＢ分离谱仪设定一组束流光学参数，在此基础上对一组具有代表性的反应道的部分参数进行了初步计算，并用ＧＡＮＩＬ发展的相关程序ＬＩＳＥ进行了验证．理论与实验均表明，在目前对ＰＦ反应机制尚不能精确描述的情况下，对ＲＩＢ产额的计算结果达到１～２数量级的精度；对ＲＩＢ横向发射度和动量散度的计算结果相对准确. The calculation of the parameters of RIB produced by the projectile fragmentation and separated by an achromatic spectrometer is firstly summarized. The calculation method to the RSPC(the RIB spectrometer between CSR main ring and the experimental ring) is then described. The final results of the yield, the energy spread and the transversal emittance of some typical RIB has been obtained.     

Phase Separation and Magnetoresistance in Nd0.52Sr0.48MnO3

Polycrystalline Nd0.52Sr0.48MnO3 ceramic is prepared by a Pechini process. Its electron spin resonance spectra,magnetic and transport properties have been investigated experimentally. At temperature above 270K, the compound is paramagnetic insulator, while in temperature between 160 K and 270 K, the compound is separated into a paramagnetic insulator and a ferromagnetic metal coexisting state. Below 160 K, the ferromagnetic phase coexists with an antiferromagnetic state, but the ferromagnetic phase remains to be dominant. This makes the compound exhibiting a metallic character even at temperature far below TN.     

纳米X_1-Y_2SiO_5∶Eu的制备与格位选择激发下的光致发光研究

采用溶胶凝胶法制备了纳米微晶Ｘ１Ｙ２ＳｉＯ５∶Ｅｕ，研究了室温和１５Ｋ下的光致发光特性．透射电子显微镜的测量结果表明，样品的平均粒径为５０ｎｍ．通过低温下的格位选择激发，分别得到Ｘ１Ｙ２ＳｉＯ５∶Ｅｕ中两种格位的Ｅｕ３＋离子各自的光致发光光谱，确定了谱峰位置．在格位选择激发下，两种格位的发光衰减均呈很好的单指数关系，５Ｄ０能级的寿命分别为３００和２１８ｍｓ．     

激光远场焦斑测试技术研究

激光远场分布测量一直存在两方面的困难：一方面是由于波面畸变具有不确定性，使得焦平面位置不易确定；另一方面是焦斑“主瓣”和“旁瓣”光能密度相差悬殊，无如此大动态范围的探测器。此文针对现有的激光远场测试的3种常用方法(长焦距透镜法、列阵相机法、Rame Pair法)进行了实验研究。首先需要建立一个实验平台，3种激光远场测试方法在相同的测试条件下对激光束的相同位置进行测试，以减少比对误差。光路排布如图1所示。图1中虚线所包围的部分即3种测试方法的光路排布，由这3种方法分别测得的焦斑和焦斑列阵并通过一定的算法重构焦斑，所得结果比对如图2。     

HIRFL—CSR电子冷却装置上的横向电子束温度

从磁场中单电子的轨道运动方程出发，分析并推出了ＨＩＲＦＬ－ＣＳＲ电子冷却装置上的横向电子束温度，并得到了一些重要结论。     

SUPPRESSION OF BALLISTIC ELECTRON TRANSMISSION THROUGH A SEMICONDUCTOR Π-STRUCTURE BY AN EXTERNAL TRANSVERSE ELECTRIC FIELD

We have conducted numerical studies of ballistic electron transport in a semicon-ductor II-structure when an external transverse electric field is applied. The device conductance as a function of electron energy and the strength of the transverse electric field is calculated on the basis of tight-binding Green's function formalism. The calculations show that a relatively weak electric field can induce very large decrease in the electron transmission across the structure. When the transverse electric field is sufficiently strong, electrons can hardly be transported through the device. Thus the performance of the device can be greatly improved for it is much easier to control electron transport through the device with an external transverse electric field.     

基于辐射加热源的材料高温发射率测量方法

材料高温辐射特性参数是量化研究热输运过程中的基本参数。本文将高能流太阳能聚集模拟器引入到材料高温发射率测量中,利用高能流太阳能聚集模拟器产生的可见光及近红外光谱辐射直接对样品进行加热,建立了材料中红外波段的高温发射率测量方法,避免了常规测量中封装窗口及高温炉体自身光谱辐射对测量的影响。基于该方法,采用红外热像仪、FTIR光谱仪等设备,搭建了实验平台,理论上可实现1700 K以内的样品发射率测量。采用该装置对某型钢进行了实验测量,获得了材料7~25μm波段内不同温度下的发射率曲线。