我国优秀女子举重选手挺举技术分析

为了促进我国女子举重技术水平的不断提高，继续保持我国在这个项目中的领先地位，对我国优秀女选手的举重技术进行了测试研究，并和国际优秀男选手技术进行比较，找到差距，提出问题，供我国教练员、运动员改进技术参考。     

排球快抹技术的应用研究

本文通过查阅文献资料、比赛技术统计和测试来分析快扶在快攻中的重要作用，快抹具有动作快，隐蔽性、控制能力、适应性强和落点刁钻等特点，增强了进攻的能力，运用效果良好，建议通过加强快抹技术的训练，促进其在排球运动中的发展。     

P中与归纳等价的几个条件

本文先给出命题逻辑P的所有合式公式组成的集合W上的一个偏序关系,从而得到一个偏序集,然后在这个偏序集上讨论了与P中关于合式公式结构的归纳法等价的几个方法.     

Besizer曲线曲面的实时动态交互设计技术

交互设计技术是曲线曲面造型应用研究的重要内容。基于OpenGL设计了Besizer曲线曲面的实时动态生成与显示系统。利用选择机制辅助设计人员选择窗口坐标系下的控制点,利用模拟变换技术获取该控制点投影变换后的Z坐标,利用鼠标拖放技术,将该点Z坐标与鼠标的窗口新位置进行逆变换,获取拖放后该控制点的世界坐标,在此基础上控制并绘制三维空间的Besizer曲线曲面。这一过程支持设计人员与曲线曲面图形的直接交互,满足实时绘制和动态调整的要求,提高了曲线曲面造型的效率。     

浅谈农村初中生非贫困辍学的原因及对策

近几年来,国家加大对贫困地区教育事业的投入,大力改善办学条件,资助贫困学生,“不能让一个学生因贫困而辍学”的目标基本实现。然而现实的问题是非贫困辍学的学生却越来越多。为什么会出现这样的情况？这种现象会有什么危害？如何解决这对矛盾？笔者认为应着力从政府、社会、学校、家长这几个层面去解决问题。     

Strategies to improve impact efficiency in football kicking

In football, kicking with high ball velocity can increase scoring opportunities and reduce the likelihood of interception. Efficient energy transfer from foot to ball during impact is important to attain a high ball velocity. It is considered impact efficiency can be increased by reducing the change in ankle plantarflexion during foot–ball impact. However, conflicting evidence exists, questioning its effectiveness as a coaching cue. The aim of the present study was to systematically analyse joint stiffness, foot velocity and impact location with a mechanical kicking machine to determine if change in ankle plantarflexion during foot–ball impact and ball velocity are influenced. Sagittal plane data of the shank, foot and ball were measured using high-speed video (4,000 Hz). Increasing joint stiffness reduced change in ankle plantarflexion and increased ball velocity from a greater effective mass. Increasing foot velocity increased change in ankle plantarflexion and increased ball velocity. Distal impact locations increased change in ankle plantarflexion and reduced ball velocity as coefficient of restitution decreased. These results identify that change in ankle plantarflexion is a dependent variable during foot–ball impact and does not directly influence ball velocity. Coaches can assess ankle motion during impact to provide feedback to athletes on their impact efficiency.     

荧光法用于痕量亚硝酸根的测定

基于亚硝酸根与碘化钾反应生成单质碘,碘可使异硫氰酸荧光素发生荧光猝灭的原理,采用流动注射连续可更新液滴荧光法测定亚硝酸根.体系的激发和发射波长分别为492nm和516nm,亚硝酸根含量在25~100μg/L范围内有良好的线性关系,检测限为3.9μg/L.本方法灵敏度高,选择性好,操作简单.用于环境水样中痕量亚硝酸根的测定,结果满意.     

The assessment of practical work in school science

In this paper we provide an overview of the literature on understandings of drop out/opt out from science, technology and mathematics (STM) higher education programmes. After outlining the literature on students leaving higher education programmes in general, we then explore the research on drop out/opt out from STM programmes in particular, with an emphasis on research since 2000. We show that most of the research focuses on overcoming deficits in students' prior knowledge, but that a more specific focus on identities as an analytical framework for understanding young people leaving STM higher education programmes is also emerging. We show that it is important to shift from considering drop out as an individual problem for the student to regard it as a feature of the relationship between students and their study programmes. In the same way, measures to increase retention rates must shift from focusing on individual student adaptation to studies addressing institutional change. However, this change is difficult since it is entwined with fundamental conceptions of science and teaching.     

贫困地区农村校外青少年教育状况调查

通过对我国十省贫困地区1843名农村校外青少年的问卷调查发现,部分农村青少年完成九年义务教育遇到挑战,要实现国家对农村地区"普九"的既定目标任重而道远;家庭贫困依然是贫困地区农村青少年辍学的主要原因,但厌学是辍学不容忽视的重要因素。     

“2017年顶级羽毛球赛”中外男子单打运动员得失分特征比较研究*

对“2017年顶级羽毛球赛”中男子单打运动员,20场（42局）比赛录像,进行系统分析与研究,探究中外男子单打运动员得失分的异同点,为男子单打的技战术训练提供参考依据。主要运用文献资料法、专家访谈法、录像观察法、数据统计法进行研究。研究结论为：（1）男子单打制胜需要在增加进攻的同时,减少失误。（2）男子单打运动员需在0-4拍（发接发阶段）稳定发球、接发球质量,减少失误率,争夺创造进攻机会;5~9拍（限制阶段）提高攻击力,减少主动失误;10~14拍（相持限制阶段）注意进攻节奏变化,增加对手失误率。15拍之后（多拍阶段）稳定出球质量,减少无为进攻。（3）男子单打主动得分技术较多的为杀球、封球、扑球,主动失误技术较多的为杀球、吊球、高球,非压迫性失误较多的为挑球、搓球、放球。