城市森林效益与可持续性研究展望

正确认识城市森林的功能和效益 ,探索不同管理措施对城市森林效益的影响 ,对实现城市森林的可持续性具有十分重要的意义。本文综述了城市森林对生态环境和生态过程产生的影响及生态和社会效益 ;分析了城市森林可持续性的内涵及特征 ;对城市森林可持续性模式及评价标准、城市森林生态学等领域的研究成果和发展方向进行了归纳分析。在分析目前我国城市生态环境面临的问题的基础上 ,进一步提出城市森林是构建城市绿色空间的主体。建设可持续城市森林是实现城市经济和环境可持续发展的重要途径。     

浅谈网络环境下中学政治课研究性教学模式

基于网络环境下的研究性学习是目前研究性学习与信息技术的整合 ,尤其是与互联网技术整合的崭新课题 ,是当今国际教学改革的一个“亮点” ,探讨网络环境下中学政治课研究性教学模式的新课题。     

战略联盟--企业竞争新模式

战略联盟是企业之间为了一定目的 ,通过一定方式组成的网络式联合体。面对日趋激烈的市场竞争和外部环境的变化 ,企业之间既竞争又合作 ,战略联盟是一种全新的企业竞争模式     

法治及其与德治关系论

人类关于法的经验和原理,揭示了法治的含义与构成,法治在西方和非西方地区的历史和实践及其与德治的关系表明,法治之法应有道德性,但法治是现代社会的主流控制模式,是未来中国的必由之路。     

大小班结合的多媒体教学模式之实证研究

在从理论上探讨大小班结合的多媒体教学模式可行性的基础上,以三峡大学200名学生为研究对象,对该校一年半来采用该模式的授课效果进行了实证性研究。实验结果表明,大学英语采用大小班结合的多媒体教学模式比传统教学模式更有利于培养学生的综合运用能力,尤其是学生的听说能力。     

Type I error rates from likelihood‐based repeated measures analyses of incomplete longitudinal data

The last observation carried forward (LOCF) approach is commonly utilized to handle missing values in the primary analysis of clinical trials. However, recent evidence suggests that likelihood‐based analyses developed under the missing at random (MAR) framework are sensible alternatives. The objective of this study was to assess the Type I error rates from a likelihood‐based MAR approach – mixed‐model repeated measures (MMRM) – compared with LOCF when estimating treatment contrasts for mean change from baseline to endpoint (Δ). Data emulating neuropsychiatric clinical trials were simulated in a 4 × 4 factorial arrangement of scenarios, using four patterns of mean changes over time and four strategies for deleting data to generate subject dropout via an MAR mechanism. In data with no dropout, estimates of Δ and SE_Δ from MMRM and LOCF were identical. In data with dropout, the Type I error rates (averaged across all scenarios) for MMRM and LOCF were 5.49% and 16.76%, respectively. In 11 of the 16 scenarios, the Type I error rate from MMRM was at least 1.00% closer to the expected rate of 5.00% than the corresponding rate from LOCF. In no scenario did LOCF yield a Type I error rate that was at least 1.00% closer to the expected rate than the corresponding rate from MMRM. The average estimate of SE_Δ from MMRM was greater in data with dropout than in complete data, whereas the average estimate of SE_Δ from LOCF was smaller in data with dropout than in complete data, suggesting that standard errors from MMRM better reflected the uncertainty in the data. The results from this investigation support those from previous studies, which found that MMRM provided reasonable control of Type I error even in the presence of MNAR missingness. No universally best approach to analysis of longitudinal data exists. However, likelihood‐based MAR approaches have been shown to perform well in a variety of situations and are a sensible alternative to the LOCF approach. MNAR methods can be used within a sensitivity analysis framework to test the potential presence and impact of MNAR data, thereby assessing robustness of results from an MAR method. Copyright © 2004 John Wiley & Sons, Ltd.     

现代多媒体网络背景下的教与学

以Internet为背景的多媒体网络技术运用于教育,为有效整合教学内容、全面提高教育质量提供了先进的手段和技术支持,也为素质教育提供了环境支持。结合实际教学经验,探讨了多媒体网络技术在教育教学过程中的应用,认为多媒体网络技术促进了课件的开发和设计,实现了师生间的交互教学,利用网络教学技术平台软件实现教与学的交互。     

高校体育教育专业人才培养模式的现状与对策

文章对高校体育教育专业人才培养模式现状进行了分析,通过对修订培养目标、拓宽培养途径、优化课程设置、改革教学方法、提高师资力量等方面的研讨,进一步明确了高校体育教育专业人才培养模式改革的基本思路,以促进高校体育教育专业教学质量和人才质量的提高。     

Interpreting DNA Mixtures with Related Contributors in Subdivided Populations

Abstract.  In this paper, we study the statistical interpretation of forensic DNA mixtures with related contributors in subdivided populations. Compact general formulae for match probabilities are obtained for two situations: a relative of one tested person is an unknown contributor of a DNA mixture; and two related unknowns are contributors. The effect of kinship and population structure is illustrated using a real case example.     

非典与中国的电子商务

探讨了非典对于中国电子商务的影响以及电子商务在此期间发挥出的作用、存在的不足，进而提出了关于如何促进中国电子商务进一步发展的思考和建议．