安全认证技术在“软件人”系统中的应用

简要介绍了“软件人”的概念、其安全性问题以及几种安全认证技术,并且提出了基于公钥密码体制的“软件人”系统的安全认证方案。文中详细介绍了安全认证方案中的关键算法——RSA算法的一种实现,并分析了其安全性。     

pH对砖红壤和黄棕壤Cu2 吸附与解吸的影响

从土壤中分离得到的120个菌株中，筛选出对黄瓜角斑病菌有较强抑菌活性的拮抗细菌B9。温室盆栽防治试验结果表明：该菌株显著抑制角斑病的发生，防治效果达72．1％；拮抗细菌B9在28℃、pH值7．0生长最好，培养60h时，其OD值可达到1．708。经初步鉴定，该拮抗菌株属于黄杆菌属（Flavobacterium　sp.）。     

STM脉冲电压极性对材料微细加工影响的研究

利用扫描隧道显微镜（SIM）可对不同材料表面进行纳米级微细加工。在选取高定向裂解石墨（HOPG）和有机电双稳材料Ag-TCNQ分别进行直接刻蚀和电学改性的研究中，发现SIM脉冲电压极性对实验结果有影响。本文为此构建了物理模型，分析表明在不同极性的脉冲电压下，分别主要呈现电场效应或电子轰击效应。需要针对具体材料的具体加工要求，选择卿相应的脉冲电压极性。     

热门数码单反相机镜头专栏（10）——EF-S17～85mm F4.0～5．6 IS USM镜头

佳能EF—S17～85mmF4.0～5.6 IS USM镜头是2004年6月推出的又一款高性价比的数码单反黑相机专用镜头。网络和很多书刊通常都推荐该镜头配置在佳能20D机身上使用，我是将这只镜头装在350D机身上使用，不论视觉上还是使用上也都很协调。     

Effect of low temperature aging on microstructure and mechanical properties of super-high strength aluminum alloy

The effects of heat treatment on the microstructure and mechanical properties of two alloys, namely Al- 12.2%Zn-2.48%Cu-2.0%Mg-0.15%Zr-0. 166%Ag（alloy 1）, and Al-9.99%Zn-1.72%Cu-2.5%Mg-0.13%Zr（alloy 2） were investigated. The results show that low temperature aging after promotive solution treatment can increase elongation without the loss of strength for the studied alloys. The optimum aging treatment （T6） for alloy 1 and alloy 2 is 100 ℃/80 h and 100 ℃/48 h, respectively. Compared with other heat treatment alloys, alloy 1 and alloy 2 show super-high tensile strength up to 753 MPa and 788 MPa, remaining 9.3% and 9.7% elongation under T6 condition, respectively. During aging, trace addition of Ag enhances the formations of GP zone and metastable phase, and stabilizes GP zone and metastable phase to a higher temperature. Trace addition of Ag prolongs the aging time of reaching the peak strength and delays over-aging condition of the alloy. However, trace addition of Ag promotes the formation of coarse constituent in the alloy and consumes hardening alloying elements of Zn and Mg. Moreover, the addition of the transition element Zr in 7000 series super-high alloy forms incoherent Al3 Zr dispersoid which can serve as nucleation sites for nonuniform precipitation of η phase during aging process. The higher the aging temperature, the greater the tendency for nonuniform precipitation of η phase.     

Optimization of extraction and determination of emodin from Polygonum cuspidatum Sieb. et Zucc. products by HPLC-DAD

A uniform experimental design procedure was used to investigate the effects of some operating parameters on the extraction of emodin from Polygonum cuspidatum Sieb. et Zucc. products. Variables tested were volume ratio of material to solvent, size of material, extraction time and temperature and composition of extraction solvent （mixtures of acetone-water）. Each variable was tested at seven levels; 7 experiments were performed in random order. Analyses of the extracts were performed by high-performance liquid chromatography with diode array detection（HPLC-DAD）. Analytical responses were processed by using a forward regression analysis, in order to find polynomial function describing the relationship between variables and responses. For all the analytes the experimental conditions for providing the highest extraction yield inside the experimental domain considered were found. Finally, a simple, rapid and accurate analytical method was developed for the determination of emodin by high performance liquid chromatography. The separation is achieved within 25 rain on an ODS column using methanol and water as gradient mobiles. Emodin can be quantified by using external standard method detecting at 436 nm. Good linearity is obtained with correlation coefficient exceeding 0.9986 and the detection limit and the quantification limit are 1.53 and 3.23 mg/L respectively. This method shows good reproducibility for the quantification of the emodin with intra-day and inter-day relative standard deviation less than 2.3% and 5.6% respectively. Under optimized extraction conditions, the recovery of the standard is 96.5%. The validated method is successfully applied to quantify the emodin in seven Polygonum cuspidatum sieb. Et zucc. products, which provided an idea for the pre-treatment of determination of active compounds in traditional Chinese medicines.     

基于UML／Power Designer的信息系统分析方法

本文主要针对基于UML／Power Designer的信息系统分析方法进行研究：在基于面向对象UML的平台上，以CRM客户关系管理信息系统为研究对象，对其需求模型。总体设计模型和详细设计模型进行了分析设计，并采用了基于UML建模语言的CASE工具Power Designer进行进一步的辅助分析和设计，得到了CRM的相关实现模型。本文的研究对管理信息系统的分析方法提供了一种实用的技术途径。     

戴尔推出最高性能PowerEdge服务器

戴尔近日宣布面向国内市场推出采用英特尔最高性能至强5100系列（即Woodcrest）处理器的第九代PowerEdge服务器——再度体现戴尔致力降低数据中心复杂度的承诺。[编者按]     

基于WEB的教材管理系统的设计与实现

文章通过对教材管理过程的分析,提出了基于WEB的网上教材管理系统的设计思想,阐述了该系统的功能和相关的技术。     

U型管地热换热器中介质轴向温度的数学模型

基于能量平衡原理,经过分析与推导,得出了流体在U型埋管换热器流动过程中无量纲温度沿无量纲深度变化的关系式.根据埋管换热器的入口温度,能更为精确地求出流体的出口温度,为进一步分析影响地热换热器性能的因素提供了条件.