国外新型隐身材料的研究现状和发展方向

分析了隐身材料在隐身技术中的重要地位 ,较详细地介绍了手性材料、纳米材料、导电高聚物材料、多晶铁纤维材料的研究和应用现状 .最后指出 ,多频谱隐身材料和智能型隐身材料是隐身材料中的两个最主要发展方向     

4-氯代苯酐碱熔融法制备4-羟基苯酐

采用常温常压下的碱熔融法 ,由 4 -氯代邻苯二甲酸酐制备 4 -羟基邻苯二甲酸酐 ,测定了产物的理化性质和红外光谱、核磁共振氢谱 ,考察了温度和反应物、添加剂及碱用量等条件对产物收率和纯度的影响     

Transient and steady state results for two parallel queues

This paper lists numerical results for a system with two parallel queues in which arriving customers always join the shorter queue. These results enable us to discuss how fast the expected queue length converges toward its equilibrium, provided the arrivals are below the capacity of the service facility. It also shows how fast the expected queue length increases in case the traffic flow is at or above the capacity of the service facility. Finally, it is shown that the system under consideration behaves very similar to a two-server queue.     

Correlates of male condom use skills among high-risk women in South Africa

This exploratory study examined the performance of 295 South African women--who recently traded sex for goods or had unprotected sex--on a male condom use mastery index. Bivariate and multivariate logistic regression analyses were conducted to determine whether age, marital status, highest education obtained, male condom use at first penetrative sex, receiving prior demonstration of male condom use, recent sexually transmitted infection symptoms, and recently trading sex were significantly associated with index scores. Adjusted odds ratios indicated that age and sexually transmitted infection symptoms were negatively associated with condom skills; women who were older and had a higher number of recent sexually transmitted infection symptoms were more likely to have lower scores. Furthermore, participants executed, on average, approximately one third of condom use steps correctly. These findings suggest a need for increased behavioral skills training for women engaging in sexual risk behaviors because many lack the skills required to use a male condom properly.