400米运动员全程步长的诊断及其训练

全程步长是影响400米运动成绩的重要因素；400米教练员面临着如何诊断全程步长以及采取哪些方法对其进行训练的现实问题。     

体外反搏对运动员血流动力学影响的研究

１２名游泳运动员，配对后随机分成实验组和对照组，实验组每人进行２周共１０次体外反搏，于反搏前、反搏后即刻和２周后测定血流动力学指标，同时对与之配对的对照组队员进行测定。结果表明：体外反搏后即刻心输出量增加，左心室有效泵力提高，体循环外周阻力下降，微循环状态改善；进行两周反搏后的第二天，上述良好变化继续存在，而对照组各项指标前后变化不大，提示体外反搏对提高运动员心功能，改善血循环状况从而增加重要器官的血液供应，加速代谢产物的排泄方面有良好的作用。     

Do children spend too much time in schools? Evidence from a longer school year in Indonesia

I examine the effects of a longer school year in Indonesia on grade repetition, educational attainment, employability, and earnings. I exploit an arbitrary rule that assigned students to a longer school year in Indonesia in 1978–1979, which fits a fuzzy regression discontinuity design. I find the longer school year decreases the probability of grade repetition and increases educational attainment; it also increases the probability of working in formal sectors and wages later in life. These results suggest the length of school years in Indonesia is not too long.     

一种高频高跨导JFET的研制

本文研究了一种硅高频高跨导JFET的设计和制造技术，测量结果表明，所研制的器件性能基本达。到了国际上先进公司同类产品的指标参数。     

单点与双点拉剪点焊试样的疲劳特性比较

对单点与两点焊拉剪点焊疲劳试样分别进行了疲劳试验,观测了疲劳裂纹的形状和萌生位置,分析了两种试样的疲劳性能。通过有限元模型分析了同等载荷作用下两种试样的变形,对比两种试样的载荷幅寿命关系,认为两点试样的承载能力约为单点试样的两倍。基于此,使用单点试样的载荷幅寿命曲线,预测了两点试样的疲劳寿命,寿命预测结果与实验寿命结果一致。     

Relationship between the peak time of hamstring stretch and activation during sprinting

The purpose of this study was to investigate the time series relationships between the peak musculotendon length and electromyography (EMG) activation during overground sprinting to clarify the risk of muscle strain injury incidence in each hamstring muscle. Full-body kinematics and EMG of the right biceps femoris long head (BFlh) and semitendinosus (ST) muscles were recorded in 13 male sprinters during overground sprinting at maximum effort. The hamstring musculotendon lengths during sprinting were computed using a three-dimensional musculoskeletal model. The time of the peak musculotendon length, in terms of the percentage of the running gait cycle, was measured and compared with that of the peak EMG activity. The maximum length of the hamstring muscles was noted during the late swing phase of sprinting. The peak musculotendon length was synchronous with the peak EMG activation in the BFlh muscle, while the time of peak musculotendon length in the ST muscle occurred significantly later than the peak level of EMG activation (p < 0.05). These results suggest that the BFlh muscle is exposed to an instantaneous high tensile force during the late swing phase of sprinting, indicating a higher risk for muscle strain injury.     

大体积混凝土温度应力造成裂缝的控制

分析大体积砼温度裂缝 ,提出降低温度应力、防止大体积砼裂缝几项措施     

控制多层住宅小型砼空心砌块墙体裂缝的研究与实践

探究了多层住宅小型砼空心砌块墙体裂缝产生的原因及防治措施，对指导目前工程的设计及施工有一定的实用价值。     

短跑中影响步长步频的因素

论述了影响短跑步长、步频的主要因素，以便在短跑训练中改进方法，采用有效的手段进行针对性的训练，从而尽快提高短跑运动成绩。     

网络交通模型中考虑信号控制的行程时间函数模型

为了描述信号控制路段的行程时间,基于累计曲线法提出了城市基本道路的行程时间模型.首先利用交通波方法分析了路段排队形成及消散过程;然后构建路段入口和出口的累计曲线,通过累计曲线得到了单车道、稳定流量输入条件下的形成时间函数;最后考虑路段的拓扑结构特性,将多车道路段分解成多个单车道的组合,并得出了基本道路的行程时间模型.该...