不同瞄准点训练对篮球罚球命中率影响的实验研究

运用实验法,对罚球时选择不同瞄准点训练后命中率的变化进行对比分析。结果表明,经过分组训练,有确定瞄准点的实验组训练后罚球命中率具有显著提高,而没有确定瞄准点的实验组训练后命中率提高不明显。其中,以篮圈后沿为瞄准点的实验组训练后罚球命中率提高最大,而以篮圈前沿为瞄准点的实验组命中率提高次之,选择篮圈中心和没有固定瞄准点的对照组训练后罚球命中率增加不明显。     

多金属低贫矿石跳汰预选抛废试验研究

为了充分利用丰富的＂无开采价值＂低贫矿石资源,延长矿山服务年限,文章试验采用锯齿波跳汰机对多金属低贫矿石进行预选抛废研究,并取得了较佳的试验综合指标：预选抛废率高达61.24%;精矿富集比铅2.47、锌2.42、锡2.68;总金属回收率铅89.35%、锌85.88%、锡90.37%。项目成果为提高选厂主选流程的入选品位和原矿生产能力,实现低成本大规模生产创造了良好的前提条件。     

Timing of ball release in overarm throws affects ball speed in unskilled but not skilled individuals

We tested the hypothesis that variability in the timing of ball release in overarm throws affects ball speed. Nine unskilled and six skilled throwers made 30 throws fast and accurately from a sitting and standing position. Angular positions of finger and arm segments were recorded with search-coils at 1000 Hz; ball speed was measured with a radar gun. The time of ball release from the fingertips was measured with respect to seven arm kinematic reference points. Mean timing windows for ball release were 28?ms for unskilled throwers and 7?ms for skilled throwers. Mixed-model analyses of variance showed that a there was a statistically significant relationship between ball speed and the timing of ball release in unskilled throwers, but not in skilled throwers. This was presumably due to the difference in variability of the timing of ball release between the two groups. In contrast, skilled throwers showed a relationship between ball speed and peak forearm angular velocity (one measure of arm speed). We conclude that although variability in the timing of ball release can affect ball speed, this is only a major factor in unskilled throwers. When skilled throwers throw fast, variability in ball speed is due to variability in arm speed.     

The relationship between discus throwing performance and combinations of selected technical parameters

The aim of this study was to determine the relationship between discus throwing performance and the following technical parameters: hip–shoulder and shoulder–arm separation, trunk forward–backward tilt, throwing-arm elevation angles, and the absolute and relative throwing procedure phase times. Videographic data of 51 male and 53 female discus throwers' competitive performances were captured during major meets. The three-dimensional coordinates of 21 body landmarks and the discus were obtained for each thrower's best trial using direct linear transformation. The technical parameters were reduced from the three-dimensional data at six critical instants during the throwing procedure. Hierarchical stepwise multiple regression analyses were performed to determine the relative influence of linear combinations of the technical parameters on discus throwing performance. Specific techniques associated with linear combinations of certain technical parameters were identified using canonical correlations. Males and females were analysed separately. Suggestions for controlling the height of release and the vertical component of the speed of release using an effective technique are made.     

运用"链条式"教学优化篮球投篮技术教学的实验研究

高校专科篮球普修课,课时少而教学内容多的矛盾较为突出.运用"链条式"教学,结合篮球教学实际,设计出投篮技术教学链条模式,对投篮技术教学链条模式的特点进行的分析,并成功地进行了两轮投篮技术教学实验,结果显示"链条式"教学效果较为显著.     

标枪投掷的动作速度及其训练

随着运动训练的科学化、专门化及针对性的日益加强，我们认为掷标枪的技术与能力的结合是否完美，则集中体现在投掷的动作速度上。本文将围绕最后用力阶段的投掷动作速度问题，从决定动作速度的几个因素出发进行分析论证，并提出对标枪运动员的训练特点。     

85/86型标枪飞行特性的综合研究

利用力学原理和计算机对标枪飞行进行理论计算的方法，并以六运会男子标枪冠军纪占政和山东省运动员任军的投掷为例进行了计算。通过对运动员投掷参数的分析，从理论上为运动员指出了提高成绩的方向；并对如何提高成绩提出了具体的建议。     

掷铁饼技术训练中应注意的几个问题

分析掷铁饼技术的三个环节，提出掷铁饼技术训练中应注意的几个问题。     

Java程序异常及其处理

本文介绍面向对象Java语言中的异常、异常的处理的基本思想,异常处理的相关语句try~catch~finally,throw和throws的使用方法及其具体程序的实现。     

我国男子链球成绩滑坡的原因探析

采用文献法、调查法、数理统计法、分析与综合法，对我国男子链球成绩滑坡的原因进行了研究。认为导致我国男子链球成绩滑坡的原因是：技术进步迟缓。表现在技术主要环节上丰硕问题多年来一直未得到解决；专项身体素质明显下降；体重不断增加对成绩提高带来了不利影响。