基于自由树的中心的MAODV改进算法

MAODV路由协议是应用于移动Ad Hoc网络的一个组播路由协议,协议中的组长选取具有较大的随机性。本文分析了协议中组长的位置选取的相关特征,并在此基础上提出了基于自由树的中心的MAODV改进,改进算法避免了MAODV路由协议中组长处于组播共享树叶子结点的位置,减少了数据分组的传输次数,降低了网络传输的延迟。     

关于推进公共图书馆免费开放一些问题的思考

本文对公共图书馆实行免费开放的作用和意义作了阐述,并对免费开放后出现的一些问题作了分析,并提出相应的措施。     

不同药物对力竭游泳小鼠肾自由基代谢的影响

目的:旨在探讨人参茎叶、北冬虫夏草和辽东(楤)木对一次力竭游泳小鼠肾脏自由基代谢的影响及其机制.方法:昆明种雄性小鼠80只,随机分为五组:正常组(NC,n=16)、运动组(EC,n=16)、人参组(PG,n=16)、虫草组(CM,n=16)、(楤)木组(AE,n=16),经过6周灌胃后,进行一次性力竭游泳.采用分光光度法测定运动后即刻小鼠肾脏SOD、GSH-PX和MDA.结果:1)与NC组相比:EC组SOD、GSH-PX水平显著下降,MDA水平显著升高,P＜0.01.2)与EC组相比:PG组小鼠游泳至力竭的时间明显增加,MDA水平明显下降,P＜0.05;SOD、GSH-PX水平显著升高,P＜0.01.CM组小鼠游泳至力竭的时间明显增加,P＜0.05;SOD、GSH-PX水平显著升高,MDA水平显著下降,P＜0.01.AE组小鼠游泳至力竭的时间明显增加,GSH-PX明显升高,P＜0.05;SOD水平显著升高,MDA水平显著下降,P＜0.01.结论:1)一次性力竭游泳运动可引起小鼠肾脏抗氧化酶活性下降,脂质过氧化作用增强.2)人参茎叶提取物、北虫草发酵液和辽东(楤)木根皮提取物可改善小鼠肾脏抗氧化能力,在一定程度上预防了肾脏的脂质过氧化损伤.且这三种药物在预防肾运动源性自由基损伤方面的作用效果相似.     

股权分置改革改善现金股利掠夺效应的有效性

利用2003～2007年样本数据,研究了股权分置改革对现金股利掠夺效应的影响,结果发现股权分置改革改善了现金股利的利益输送行为,加强了自由现金流假说。     

免费能成为垄断平台的长期均衡策略吗？

在平台经济的发展中,“免费”已成为诸多平台企业常见的定价策略。本文将用户异质性偏好和产品质量差异引入到双边市场理论,探讨了平台长期对部分用户免费的可能性。研究发现：对于单边的垄断平台而言,用户间异质性的边际网络效应是平台实施长期免费策略的必要条件;在引入广告商或者平台竞争后,即使用户间获得的边际网络效应无差异,免费依然可能成为平台的均衡策略;随着边际网络效应的增强或产品间的质量差异扩大,对部分用户免费也更有可能成为平台的长期均衡策略。本文为平台定价策略和平台反垄断政策的制定提供有益借鉴。     

基于BIM的结构钢筋与机电系统翻模研究——以福州市规划院产业楼为例

基于建筑信息模型（Building Information Modeling, BIM)）概念,以福州市规划设计研究院新建大楼为实际案例,应用Autodesk Revit软件将原有CAD图纸进行BIM结构钢筋和机电模型建置,并提出BIM技术虚拟仿真过程中发现的问题。研究结果表明:（１）BIM技术可实际解决工程常常出现钢筋复杂节点、机电管道碰撞的问题;（２）机电系统进行Revit翻模时,不能按原CAD路径绘制,族库不全需建族完善。该研究成果可为后期施工决策提供技术支持,并有助于相关行业人士学习与借鉴。     

Effects of Conceptual Change and Traditional Confirmatory Simulations on Pre-Service Teachers’ Understanding of Direct Current Circuits

The objective of this research is to investigate the effects of simulations based on conceptual change conditions (CCS) and traditional confirmatory simulations (TCS) on pre-service elementary school teachers’ understanding of direct current electric circuits. The data was collected from a sample consisting of 89 students; 48 students in the experimental group who were taught simulations based on CCS, and 41 students in control group who followed the TCS. Subjects in both groups used open source software (Qucs) to simulate electric circuits. All students were administered Electric Circuits Concepts Test (DIRECT), Science Process Skills Test, Physics Attitude Scale, and Computer Attitude Scale before the treatment. Pre-test analyses revealed that there is no significant difference between experimental and control groups in terms of understanding of direct current electricity. After completing 3 weeks treatment, all students received the DIRECT again as a post-test. Analysis of covariance was used. Science process skills and attitudes toward computers were taken as covariates. The results showed that the conceptual change based simulations caused significantly better acquisition of conceptual change of direct current electricity concepts than the confirmatory simulation. While science process skills and attitudes towards computer made significant contributions to the variations in achievement, gender differences and interactions between gender and treatment did not. Eleven weeks later, the DIRECT was reapplied to the students in both groups. Eleven weeks delayed post-test results showed that the experimental group outperformed the control group in understanding of direct current electric concepts.     

《白鲸》中的存在主义意识解读

美国著名作家梅尔维尔的《白鲸》中以实玛利的出海、亚哈的反抗和结局的安排都蕴含着存在主义对于存在、荒谬、自由、选择的哲学阐释,这既反映了梅尔维尔创作的前瞻性,又揭示其见解的独特性。     

女子自由式摔跤跪撑技术的发展趋势

对2004年全国女子自由式摔跳锦标赛和冠军赛跪撑技术进行分析,认为女子自由式摔跤跪撑技术的发展是获得女子自由式摔跤比赛胜利的关键.同时指出,在跪撑技术的使用中应侧重于滚桥和交叉抱小腿这两种跪撑技术动作.     

A new solution to wireless sensor network density control problem

1 Introduction a At present, the research work on wireless sensor networks is based on the assumption that the energy of a sensor node is provided by the battery and can not be regenerated. The lifetime of the node is limited and ephemeral. Hence research…