低应变法检测桥梁嵌岩桩的评价

用低应变法检测嵌岩桩 ,若桩底出现明显同相反射 ,多数因桩底缺陷引起。而区分是桩还是持力层的缺陷 ,主要看反射的起跳时间在 2 L/ C之前还是之后。当桩的变径及入岩反射对测试影响很大时 ,应进一步用钻芯法检验。     

男子青少年体操运动员肘、腕关节劳损性伤痛的防治

男子青少年体操运动员肘关节、腕关节劳损性伤痛是训练中的一种常见多发性运动损伤，严重阻碍了训练计划的执行和运动技术的提高。本文分析和研究了伤痛形成的各种原因，并提出了预防、治疗的基本方法。     

肌肉拉伤的临床和基础理论研究

肌肉拉伤是运动损伤中的常见病。在临床上认为,大多数肌肉拉伤是由于肌肉性质改变造成的局部损伤,可以诊断出损伤的位置,多发生于靠近肌肉—肌腱连接处的肌纤维。生物力学研究表明:当肌肉受到的拉伸力大于其最大等长收缩力时将会引起损伤。比较肌肉在被动拉伸和有神经刺激收缩的主动拉伸时发现,在损伤时拉伸力有小量增加,应变没有变化,但吸收能量的能力却有很大的变化。实验还证实了肌肉的粘弹性。这些研究成果说明:肌肉吸收能量的能力和粘弹性的改变对于预防肌肉损伤是非常重要的。     

对速滑蹬冰加速理论的质疑与思考

对蹬冰的加速理论研究进行分析的结果认为:从前提出的加速理论,在反映高水平运动员加速能力时是有条件的,并且,认为Ingen Schenau所提出的加速理论,还有待于经过实验加以验证.因此,单纯从获得速度改变量大小的角度来推断蹬冰加速的机制,并不是重心沿前进方向加速的唯一条件.     

钢结构材料在高温(火灾)条件下的力学性能试验研究

从基本的钢结构材料在高温下的力学性能着手 ,进行高温条件下钢结构材料的性能试验 ,建立高温下钢材的屈服强度、极限强度、弹性模量和极限应变随温度变化的力学模型 ,为高温 (火灾 )条件下钢结构的结构分析提供依据。     

混合药膜包膜系统释放动力学研究

存储混合型是目前研究较多的控制释放体系 ,但由于其机理较为复杂 ,目前尚未建立合理实用的动力学模型 .以混合药膜包膜体系为研究对象 ,建立了释放动力学的简化模型并获得了解析解 .实验数据表明 ,该模型适用于描述药物装填量大于饱和溶解度的药物释放动力学行为 (相对偏差小于 3 % ) .根据该模型还从理论上分析了两种限定条件 (Dm Df和 Dm Df)下药物的释放特征 :当 Dm Df时 ,释放速率变为常数 ,达到零级释放 ,其释放速率与药膜无关 ,这为零级释放缓释体系如何控制释放速率和药物释放量提供了理论依据 :当 Dm Df时 ,药物的释放速率与药膜中的释放系数、溶解度和药物的装填量有关 ,与包膜过程无关 ,其释放过程类似于混合药膜缓释体系     

Is there really an eccentric action of the hamstrings during the swing phase of high-speed running? part I: A critical review of the literature

It is widely assumed that there is an eccentric hamstring muscle fibre action during the swing phase of high-speed running. However, animal and modelling studies in humans show that the increasing distance between musculotendinous attachment points during forward swing is primarily due to passive lengthening associated with the take-up of muscle slack. Later in the swing phase, the contractile element (CE) maintains a near isometric action while the series elastic (tendinous) element first stretches as the knee extends, and then recoils causing the swing leg to forcefully retract prior to ground contact. Although modelling studies showed some active lengthening of the contractile (muscular) element during the mid-swing phase of high-speed running, we argue that the increasing distance between the attachment points should not be interpreted as an eccentric action of the CE due to the effects of muscle slack. Therefore, there may actually be no significant eccentric, but rather predominantly an isometric action of the hamstrings CE during the swing phase of high-speed running when the attachment points of the hamstrings are moving apart. Based on this, we propose that isometric rather than eccentric exercises are a more specific way of conditioning the hamstrings for high-speed running.     

Examining coaches’ perceptions of how their stress influences the coach–athlete relationship

This study extends recent coach stress research by evaluating how coaches perceive their stress experiences to affect athletes, and the broader coach–athlete relationship. A total of 12 coaches working across a range of team sports at the elite level took part in semi-structured interviews to investigate the 3 study aims: how they perceive athletes to detect signals of coach stress; how they perceive their stress experiences to affect athletes; and, how effective they perceive themselves to be when experiencing stress. Following content analysis, data suggested that coaches perceived athletes able to detect when they were experiencing stress typically via communication, behavioural, and stylistic cues. Although coaches perceived their stress to have some positive effects on athletes, the overwhelming effects were negative and affected “performance and development”, “psychological and emotional”, and “behavioural and interaction” factors. Coaches also perceived themselves to be less effective when stressed, and this was reflected in their perceptions of competence, self-awareness, and coaching quality. An impactful finding is that coaches are aware of how a range of stress responses are expressed by themselves, and to how they affect athletes, and their coaching quality. Altogether, findings support the emerging view that coach stress affects their own, and athlete performance.     

Exploring athletes’ perceptions of coach stress in elite sport environments

The present study aimed to extend research that has focused on the identification of stressors associated with coaching practice by systematically evaluating how such stressors effect athletes, and more broadly, the coach–athlete relationship. A total of 13 professional- and national-level athletes were interviewed to address the three study aims: how they detect when a coach is encountering stressors, how coach experiences of stress effects them as an athlete, and how effective the coach is when experiencing stress. Following content analysis, the data suggested athletes were able to detect when a coach was experiencing stress and this was typically via a variety of verbal and behavioural cues. Despite some positive effects of the coach experiencing stress, the majority were negative and varied across a range of personal influences on the athlete, and effects on the general coaching environment. It was also the broad view of the athletes that coaches were less effective when stressed, and this was reflected in performance expectations, perceptions of competence, and lack of awareness. The findings are discussed in relation to the existing theory and with reference to their implications for applied practice, future research, and development of the coach–athlete relationship.     

武术教学中教师应变能力的研究

武术教学中应变能力的合理运用是教师的一项基本素质。为了体现出高质量的武术教学,文章分别通过教师自身、课程组织中各种教学失误及学生突发事件,就应变的运用做出分析,并提出相对合理的对策,为完善武术教师的综合素质提供一定参考。