脉宽调制型DC—DC变换器的线性描述函数分析法

介绍了一种分析开关变换器的新方法－线性描述函数法的理论证明及实验结果,这种方法具有精确度高的优点。     

DNA芯片技术

DNA芯片可用于核酸序列的测定及基因突变检测等,这里对DNA芯片的制作、作用原理、性能及用途等进行了综述。     

鲇鱼(Silurus asotus)产卵类型的研究

本文侧重研究了站鱼个体生殖力及产卵类型。结果表明：雌性个体1冬龄达性成熟,性腺一次成熟,卵子分批产出,产卵期是6—8月份,性成熟系数在7月份达高峰,8月份是产卵盛期,在产卵前的卵巢切片只发现有第4时相和第5时相卵母细胞,确定产卵类型为一次产卵。     

PSS码词组输入法及教学实践

本文介绍了PSS码（拼音、声调、首笔码）汉字输入法的词组编码及输入方法,并总结了PSS码作为一门选修课的教学效果。     

A gender comparison of HIV and drug use across the rural-urban continuum

Despite the central role of women drug users in escalating AIDS statistics, there is still a limited number of studies that examine the roles of gender and drug use type in HIV seroprevalence. This lacuna in the research literature has led to significant gaps in researchers' understanding of how and to what extent women may differ in their drug-using and HIV risk behaviors compared to their better-studied male counterparts. This study, derived from a sample of 3,555 out-of-treatment drug users residing in three South Florida urban and rural communities, attempts to compare the drug usage and needle and sexual risk behaviors of male and female drug users that put them at risk for HIV infection. The overall seropositivity rate for women drug users was 26.5% compared to 19.5% for their male counterparts. Results of multivariate analyses indicate that females compared to males were 1.4 times more likely to be HIV seropositive. Risk behaviors associated with this elevated seropositivity include living arrangements, homeless status, drug use, sexual trading behaviors, and history of STDs. Furthermore, there was a strong linear relationship between drug use type and HIV seroprevalence among women drug users. Compared to those who were neither crack smokers nor injectors of illicit drugs, those who were crack smokers only were 2 times more likely to be HIV seropositive, while those who were both crack smokers and injectors were 5 times more likely to be HIV seropositive, and those who were injectors only were 6 times more likely to be HIV seropositive. These findings indicate that among women, drug abuse and its associated risk behaviors, increase the vulnerability of this population for HIV and thus render them an extremely important priority population on which to focus HIV prevention and public health efforts and programs.     

高管层团队人口特征与公司业绩关系的实证研究

以沪深两市156家上市公司为研究样本,考察了我国企业高层管理团队人口特征与组织绩效之间的关系。研究发现,我国上市公司高管人员管理背景的多样性和平均年龄对企业业绩有显著的促进作用,但高管团队平均学历水平及学历水平的差异性对企业业绩的影响不显著。     

浅析经济新闻的民生视角

随着我国市场经济的迅猛发展并趋于成熟,经济新闻越来越为人们所关注、重视。目前中国政府提出"改善民生",为"民生视角"的新闻报道提供了大量素材和广泛受众。大势所趋,媒体应以"民生视角"来报道经济新闻。电视民生新闻的崛起为"民生视角"的广播报道提供了借鉴。而"小角度"报道、"百姓立场"关注、"零距离"解读和"大容量"覆盖则是可行的方式。     

论北宋天圣年间四川仕风的嬗变——三苏文章汇入北宋古文运动的地域背景

北宋天圣以前川民「怀土罕趋仕进」。天圣以后,「应时务用」的观念成为了时代的主导观念,因而促成了「通经学古,以西汉文词为宗师」的蜀学汇入时代的主流。这是三苏文章与欧阳修古文革新思想合拍的重要背景。     

基于VaR风险控制的半log-最优资产组合模型

通过建立基于VaR风险控制下的单周期半log-最优资产组合数学模型,证明了最优解的存在性与唯一性。利用遗传算法对半log-最优资产组合模型进行了实例计算与分析,并与log-最优资产组合模型进行了比较,结果表明半log-最优资产组合模型具有计算方便的特征。     

S2O82-/ZrO2-Ce2 O3固体超强酸的制备及催化合成环缩酮的研究

分别以H2SO4和(NH4)2S2O8为浸渍溶液,采用共沉淀法合成了固体超强酸SO42-/ZrO2、SO42-/ZrO2及SO42-/ZrO2-Ce2O3。用红外光谱和Hamm ett指示剂表征了合成的固体超强酸,并用环己酮和乙二醇的缩合反应为探针反应,研究了它们的催化活性。实验表明:(1)SO42-/ZrO2-Ce2O3在缩合反应中的催化活性比SO42-/ZrO2和SO42-/ZrO2要强;(2)引入适当数量的Ce2O3使得固体超强酸的酸强度增大;(3)当固体超强酸SO42-/ZrO2-Ce2O3的制备条件为焙烧温度550℃、焙烧时间4h、Ce2O3质量与ZrO2质量比2%时,酸对缩合反应的催化活性最高。