基于B/S结构的网络考试系统的设计与实现

本概述了基于B／S结构的网络考试系统的总体结构，介绍了系统的设计方法，论述了系统实现的关键技术，给出了应用实例。     

四周常压模拟高住低练对女子赛艇运动员血清睾酮、皮质醇及血睾酮／皮质醇的影响

目的:探讨4周常压模拟高住低练训练法对女子赛艇运动员血清睾酮、皮质醇及血睾酮/皮质醇等的影响。方法:系统观察了7名女子赛艇运动员(实验组)进行4周高住低练(2500m)训练前、训练期间第1周、第2周、第4周及训练后第1周和第2周这些指标的变化,并与6名低住低练运动员(对照组)进行比较分析。结果:(1)4周高住低练使女子赛艇运动员血清T水平呈先降后升之势,4周结束后仍低于实验前水平,并且至少持续2周;(2)4周高住低练期间运动员血清皮质醇水平降低,实验结束后2周恢复到实验前水平;(3)4周高住低练期间Hb和RBC的变化与T和T/C的变化并不一致,实验前后比较,前两者总体趋势是升高,而后两者总体趋势是下降。结论:4周高住低练使血清T水平先降后升,血清C水平降低,这可能与低氧刺激导致血液Hb和RBC逐渐升高以及机体合成代谢相对增强有关。     

网络应用程序的负载平衡问题

在现今网络时代,通过网络寻找信息的需求量越来越大,在网络节点上的服务器需要有相当的负载能力,而且越来越多的情况下还需要通过几台服务器来共同完成对需要的应答任务。介绍了一种多服务器共同负载并平衡工作的技术——负载平衡。首先概要性地描述了负载平衡的原理,并按照软件应用的执行过程,从软件层次至硬件平台,自上而下的顺序将常见的负载平衡方法分为软件级负载平衡、网络级负载平衡、硬件级负载平衡,并简明扼要地说明了各种负载平衡的使用范围、实现代价、可扩展性与及总体优缺点。     

“Students Get What Flows Downward”: District Leaders’ Rationalizations of the Standardized Testing of Children

What do students stand to gain from high-stakes, standardized testing? We consider answers to this question from the perspective of urban district leaders tasked with designing and overseeing the implementation of standardized testing policies. Results revealed variation in leaders’ framing of and rationale for standardized testing with respect to benefits for students and whether/why students should strive for high test scores. Implications for both approaches to standardized testing and broader improvement initiatives are discussed.     

项目教学法在UG应用软件CAD模块教学中的实践与探索

探讨了在UG应用软件教学中运用项目教学法的意义,并通过一个应用项目教学法实例的阐述,介绍了项目教学法在UG/CAD教学中所取得的良好效果,以此探索职业教育教学改革的方法。     

Polychlorinated dibenzo-p-dioxins and dibenzofurans in flue gas emissions from municipal solid waste incinerators in China

Polychlorinated dibenzo-p-dioxins and furalls(PCDD/Fs)emissions in flue gas from two types of municipal solid waste incinerators(MSWIs)most commonly used in China were investigated in this study.The selected incinerators include two grate-type MSWIs:MSWl-A(350 t/d)and MSWI-B(150 t/d),and two fluidized bed MSWIs:MSWI-C(400 t/d) and MSWI-D (400 t/d),which are all equipped with semi-dry lime scrubber and bag filter except MSWI-D equipped with cyclone and wet scrubber(WS)as air pollutant conffol device(APCD).Results indicated that the emission concentration and the international toxic equivalents(I-TEQs)of the PCDD/Fs from the stacks were in the range of 1.210～10.273 ng/Nm3 and 0.019～0.201 ngI-TEQ/Nm3,respectively.They were greatly lower than the emission regulation standard of PCDD/FS in China(1.0 ng I-TEQ/Nm3).However,only the PCDD/Fs emission Ievel from MSWI-C Was below 0.1 ng I-TEQ/Nm3.Although the homologue profiles were distinct,the contributions of the 2,3,7,8-subsituted congenem to the total I-TEQ were similar among all the investigated MSWIs.Two major 2,3,7,8-substituted congeners,2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDD,account for 47% and 9%(average values)of the total I-TEQ values,respectively.The correlation between PCDD/Fs levels and composition of flue gas Was also discussed.     

Editorial

This study reports data on the challenges and needs of girls engaged in delinquent behaviour and the effectiveness of services provided by a girls' home. Implications and suggestions for the planning and implementation of effective programmes and services in alternative educational settings are included. It concludes that alternative education is not just a change of educational environment for youths in trouble, an understanding of the unique needs of girls and female offenders must be translated into practice as educators continue to find solutions for helping girls who are engaging in risky or delinquent behaviours.     

水稻P1B型ATPase重金属转运蛋白的结构与功能研究进展

P1B型ATPase重金属转运蛋白（HMA）广泛存在于低等植物和高等植物中,参与植物生长发育过程中所必需的微量金属营养元素的运输.与双子叶植物拟南芥（Arabidopsis thaliana）AtHMA1-8的大量研究相比,单子叶植物中HMA转运蛋白的相关功能与研究极其有限.根据已有的研究成果对水稻（Oryza sativa L.）体内9种HMA转运蛋白的分类、结构、分子机制与转运功能进行了详细对比和归纳,对这些重金属转运蛋白在植物中的组织分布、亚细胞定位和金属特异性进行了阐述,推测了目前尚未明确功能的OsHMA1、OsHMA4、OsH-MA6、OsHMA7和OsHMA8的亚细胞定位及潜在的转运功能,以期为未来进一步的科学研究提供更多依据.     

现代电源技术实验平台研制

为构建完整的电力电子技术中使用各种电力电子器件进行功率变换的知识体系,研制了现代电源技术综合实验平台,其包括单端隔离型高频开关电源实验、隔离型桥式DC/DC实验和变频调速实验3个实验。对3个实验的核心控制电路进行了详细介绍,并给出对应的工作波形。该实验平台可满足电气工程高年级本科生、研究生实验的要求,同时也可给相关教师提供功率变换的科研平台。     

Dimensions of Socio-economic Status and their Relationship to Mathematics and Science Achievement at Individual and Collective Levels

Applying two-level structural equation modelling techniques, the current study examined the dimensionality of socio-economic status (SES) and its relationship with mathematics and science performance at student and school levels. Data were drawn from population 2 (13-year-olds) of 17 countries in the Third International Mathematics and Science study (TIMSS). A set of items about the ownership of household materials was used to measure the dimensions of SES. For most of the countries, a general economic dimension and a cultural dimension were identified at the student level. The cultural dimension had the greatest impact on students' mathematics and science achievement. At the school level, however, only a general economic dimension was found in most countries. This dimension was interpreted to represent community wealth. It was found to be highly related to school mean maths-science achievement, except for the countries where an additional cultural dimension is identified. This cultural dimension can be interpreted as the community cultural resources and atmosphere, and is strongly related to average school mathematics and science achievement. The current study confirmed that the ownership of a set of household materials can be used as SES indicators in exploring its multifaceted feature at both individual and school levels. A similar model structure is found in different countries by applying these indicators, despite the fact that the content of the set of household possessions is different. The findings show that the latent structure of SES at individual level is different from that at the school level, and that SES dimensions have different effects on mathematics and science achievement at individual and school levels.