3G的鲜花

直观地看,前年的各类通信设备展还是一个3G手机终端的大秀场,去年的一些通信设备展览则已经成为ICT(信息通信技术)的展示场所,各个厂商和运营商都更愿意拿出压箱底的技术和设备来吸引参观者, CDMA1x的准3G业务、GPRS增强型业务等推广,让2.5G、2.75G业务锋芒毕现,种种迹象表明,3G之花似乎有可能在今年绽放。     

负载型Ni-B/SiO2非晶态催化剂应用于菜籽油选择加氢的研究

研究了负载型Ni-B/SiO2非晶态合金催化剂对菜籽油的选择性加氢性能,考察了反应温度、反应时间及催化剂浓度对反应的影响,确定了适合菜籽油氢化的工艺条件,并初步探讨了温度对生成反式酸的影响.     

氨基磺酸催化合成环己酮1,2-丙二醇缩酮

以氨基磺酸为催化剂,对以环己酮和1,2-丙二醇为原料合成环己酮1,2-丙二醇缩酮进行了研究。较系统地研究了酮醇摩尔比,催化剂用量,反应时间诸因素对收率的影响。最佳反应条件为:n(酮)∶n(醇)=1∶1.5,催化剂用量为1 g,带水剂环己烷15 mL,反应时间60 m in。上述条件下,环己酮1,2-丙二醇缩酮的收率可达71.15%。     

Co2+: CaAl2S4吸收光谱的理论解释

MgAl2Sd，CaAl2S4，CO^2 MgAl2S4和Co^2 CaAl2S4晶体是典型的三重复合半导体材料，由化学输运反应的方法可以成功制备而得出，具有宽的能隙结构，因而在光电方面有着非常重要的应用而备受广泛的关注．采用Sugano-Tallabe强场近似理论，引入平均共价因子Ⅳ，利用经典晶场能量矩阵公式，在D2对称模型下计算出的结果较好符合了实验事实，从而纠正了S．K．Oh等人对Co^2 ：CaAl2S4吸收光谱的不合理解释。     

O(3 P)与C2H2反应机理的量子化学研究

用量子化学计算方法对O(^3P)与C2H2的反应进行了研究．在HF／6—311 G(d，p)，HF／6—311 G(3df，3pd)，MP2／6—311 G(d，p)和MP2／6—311 G(3df，3pd)计算水平上，优化了反应势能面上各驻点的几何结构．通过内禀反应坐标(IRC)计算和振动分析．对反应过渡态进行了确认，并确定了反应机理．     

铀与氢气的反应动力学

运用相对论有效原子实模型RECP和B3LYP方法计算了UH和UH₂的结构. 并在此基础上, 利用多体项展式理论方法, 导出三原子分子UH₂的解析势能函数. 根据UH₂势能函数, 采用准经典的Monte-Carlo轨线法研究了U+H₂体系的碰撞过程. 依据反应截面与能量之间的关系, 指出U+H₂(v = j = 0)是无阈能反应, 主要生成UH₂, 而反应H+UH(v = j = 0)生成UH₂的反应截面相对来说要小得多, 可以忽略. 如此证明铀与氢气反应生成UH3的中间产物是UH₂, 而不是UH. 这些结果为金属铀的抗氢化腐蚀研究提供了理论基础.     

A Novel Degradation Pathway of Zn（dmid） （ phen）2 in Pyridine

The light-oxidation degradation processes of Zn(dmid)(phen)2(dmid = 4, 5-dimercapto-1,3-dithiole-2 one, phen = 1,10-phenanthroaline) in pyridine solvent has been monitored, h has been found under the light, dmid^2- of Zn(dmid)(phen)2 in pyridine solution could generate NCS^- and NCS^-replaces dmid^2- to form Zn(NCS)2 (phen)2 simultaneously. The crystal structure of Zn(NCS)2 (phen)2 has been determined. In the crystal of Zn(NCS)2 (phen)2. two NCS^- ligands are arranged in syn-configuration, and there is strong π-π interaction between the two adjacent parallel phen.     

Stereo- and regio-selectivity in the photosensitized dimerization of 1, 3-dimethylthymine in solution

The effects of reaction pathway and temperature on stereo- and regio-selectivity of photocycloaddition of 1, 3-dimethylthymine (DMT) which gives four cyclobutane type dimers in solution using acetone as the photosensitizer, are investigated by measuring the product distribution. It is demonstrated that the ground-state aggregation between DMT molecules mainly leads to (h-t)dimers, and the diffusion-controlled triplet dimerization is favorable to the formation of (h-h) dimers.     

A template of rat brain based on fMRI T*2 imaging

The development of functional magnetic resonance imaging (fMRI) technology has made it possible to carry out functional brain imaging experiments in small animals. Usually, group data is required to form the assessment of population, which can not only increase the sensitivity of the overall experiment, but also allow the generalization of the conclusion to the whole population. In order to average the signals of functional brain images from different subjects, it is necessary to put all the mapping images into the same standard space (template image). However, up to now, most animal brain templates remain unavailable and it must be done by ourselves. In this study, a template image based on the brains of eight male Wistar rats is obtained, and it is successfully used in our present Alzheimer disease (AD)-like rat model studies as template for spatially normalizing images to the same stereotaxical space. The fMRI results processed with statistical parametric mapping (SPM99) software are in agreement with the results from immunohistochemical experiment, which proves that this method is universally applicable to the pathologic models of other small animals and to human brain lesion studies.     

基于J2EE数据库访问性能的优化方法

阐述了基于J2EE的应用系统中,改善数据库访问性能,提高执行效率的几种方法,为合理有效的开发软件系统提供设计标准和开发手段.