PCN中信道的指配及计算机模拟

在ＰＣＮ中，应用时分多址方式（ＴＤＭＡ）和动态信道指配（ＤＣＡ）可提高频谱利用率，增大系统容量，由于同道干扰对系统性能影响很大，信道（包括载波与时隙）必须仔细地加以分配，本文应用离散随机事件的方法模拟了多路同时进行的链路，讨论了３种不同的信道分配方法并分析了系统性能。     

前寒武纪的划分

本文采用尹赞勋提出的地球历史发展的两大阶段:天文时期与地质时期,并同意废弃隐生宙与显生宙。本文着重讨论了生物的发展,从无机到有机,到蛋白质,到细胞,到后生动物的阶段性。建议地质时期代的划分,根据生物发展阶段特征,前寒武纪划分为无生代、隐生代、始生代与原生代。另把古生代下限延至900Ma,包括震旦纪。小壳动物应归属震旦纪,而不是寒武纪。     

Unusual discrepancy between TOMS and ground-based measurements of the total ozone in 2002—2003

Monitoring the atmospheric ozone is one of the key projects in the atmospheric and environmental sciences, and the decrease of ozone in stratosphere has aroused the interests of governments and public in the world. Mainly two methods are used to measure the total atmospheric ozone in the globe: ground-based observation mainly including Dobson and Brewer ozone instruments, and satellite measurement. The popular satellite products are the Total Ozone Mapping Spectrometer (TOMS) data provided by the National Aeronautics and Space Administration (NASA) of the United States of America.     

Theory and Practice of Agricultural Eco-engineering in China

Agricultural eco-engineering is not only the important content of eco-agriculture construction, but also the important measure for operating eco-agriculture construction. Applying principle of ecology, and combining the method of systemic engineering with the measure of modem technology, the essential of agriculture ecologic engineering is to build the production mode of using agriculture resource with high effectiveness, and technique system of realizing sustainable development. This article gives an introduction of what the agricultural eco-engineering is and the basic theory and the design principle of agricultural eco-engineering.     

Research progress in nonlinear analysis of heart electric activities

1INTRODUCTION THE WORLD IS NONLINEAR,AND THE HUMAN LIFE ACTIVITY IS ALSO NONLINEAR.FROM THE VIEWPOINT OF SYSTEM,HUMAN BEINGS(OR THE OTHER HIGHER ANIMAL)ARE THE MOST COM-PLEX SYSTEM IN THE NATURE.FOR SUCH A PHYSIOLOGICAL SYS-TEM WITH THE UTTERMOST COMPLEXI…     

我国利益集团政策参与的制约因素及解决对策

我国正处于由传统社会向现代社会转型的关键时期，由于社会利益的分化，我国利益集团的存在和对社会政治生活的参与已是一种客观存在的事实。但由于受到各种具体情况的制约和干扰，使得我国利益集团参与政治活动受到一定的限制。因此，分析我国利益集团政策参与的制约因素，并提出解决的对策，对于促进我国民主政治的发展．建设社会主义政治文明具有重要的意义。     

Windows登录口令安全增强平台的设计与实现

对Windows 2000／XP安全机制中的登录部分进行了研究和改进，首先分析了现有口令和生物特征匹配登录方式的优缺点，针对这些登录方式在安全性能方面存在的不足，通过对Windows提供的用户认证机制（包括GINA、认证包以及口令过滤器等模块）的研究和重构，设计出一个可以为各种登录方式提供接口的安全功能加强平台，通过调用该平台，用户每次成功登录操作系统后，Windows SAM库中的口令得到自动更换，可有效阻止口令被盗引起的重放攻击，同时规范了人员操作，增强了系统的安全性，同时，在该平台的架构设计中，将用户信息获取功能和验证功能进行剥离，使系统在应用和二次开发中具有更大的灵活性。     

"科普追求"九章

1 科普,简略地说,就是以"科"为基础,以"普"为目的的行为或活动.科普作品则是以作品形式表现的科普活动.     

Inhibiting Effects of S.acus Linnaeus Extracts on GLT-82 Tumor Cell Lines

Hailong S.acus Linnaeus was chosen as the experimental material in the experiments and changes of cell morphology, forming rate of clone and changes of division index were conducted to identify the inhibiting effects of Hailong extract on human tumor cell lines (GLT-82). Four days after medication, most of the cells changed their normal morphology of tumor cells and became round, broken and even broke into pieces. The inhibiting rates could reach 75.1% on the fourth day. The division index reduced strongly and the clone could not form or the forming rate was very low. With the extract concentration increasing and the time prolonging, the inhibiting effect increased. These results indicate that Hailong has striking anti-tumor effects and will have a perfect future in the fields of treatment and prevention of cancer.     

痕量锰的共沉淀分离富集和测定的研究

本研究了用PAN[1-(2-吡啶偶氮)-2-荼酚]共沉淀分离富集人发中的痕量锰．用微量注射进样火焰原子吸收光谱(FAAS)测定的方法。在pH10．5的试样溶液中．不需另加载体．PAN能定量地共沉淀痕量锰。溶液中锰的浓度在0-0．25μg／ml范围内时．标准曲线呈线性。人发中共存的其它元素不干扰测定。锰的标准加入回收率在96-104％之间。12次重复测定锰含量为2．72μg／g的发样的变异系数为4．8％。方法的特征浓度为1．0×10^-3μg／ml.本法简便稳定．用于人发中痕量锰的测定．获得了满意的结果．