散手运动员赛前训练生理生化指标监测手段与方法

目的:研究散手运动员赛前训练中某些生理生化指标的变化规律。方法:选择8名男散手运动员作为研究对象,采用多时点连续采血进行测试,观察运动员赛前训练某些生理生化指标的变化规律。结果:血乳酸是反映散手运动员运动训练强度的敏感指标;血色素是评价运动员机能状态及贫血的生理指标;血尿素和肌酸激酶是监控运动员运动负荷的生化指标;血清睾酮是反映运动员的运动疲劳和选材的重要指标。     

改革开放34年西北五省区信息承载力定量评价及分析

评价改革开放34年西北五省区信息承载力的需求与供给,结果表明除陕西省外,西北五省区信息生态系统整体处于不均衡承载状态,信息压力远大于信息承载力,区域内部信息承载力分布极不均匀,亟需发展信息治理的核心能力与应用技术,特别是信息弹性力中的社会信用体系建设与信息能力中的信息咨询与决策、信息使能技术、信息协作能力等。     

Induced pluripotent stem cells: origins, applications, and future perspectives

Embryonic stem(ES)cells are widely used for different purposes,including gene targeting,cell therapy,tissue repair,organ regeneration,and so on.However,studies and applications of ES cells are hindered by ethical issues regarding cell sources.To circumvent ethical disputes,great efforts have been taken to generate ES cell-like cells,which are not derived from the inner cell mass of blastocyst-stage embryos.In 2006,Yamanaka et al.first reprogrammed mouse embryonic fibroblasts into ES cell-like cells called induced pluripotent stem(iPS)cells.About one year later,Yamanaka et al.and Thomson et al.independently reprogrammed human somatic cells into iPS cells.Since the first generation of iPS cells,they have now been derived from quite a few different kinds of cell types.In particular,the use of peripheral blood facilitates research on iPS cells because of safety,easy availability,and plenty of cell sources.Now iPS cells have been used for cell therapy,disease modeling,and drug discovery.In this review,we describe the generations,applications,potential issues,and future perspectives of iPS cells.     

讨论式教学法在士官大专《工程力学》课例中合理运用

讨论式教学法能够充分调动学员的学习热情,培养创新思维和多种能力,是一种实用性很强的教学方法,本文针对讨论式教学法在士官大专《工程力学》课程中的试点,结合用微积分关系法绘制剪力图和弯矩图的典型课例,详细论证了讨论式教学法的不同形式在该课例中的灵活运用,不但活跃了课堂气氛,而且取得了良好的教学效果。     

贫困大学生心理压力特征及心理健康的相关研究

以贵州籍贯的贫困大学生为被试,对其心理压力特征及心理健康的相互关系进行了统计学分析与研究.发现不同性别、学科、年级、母亲文化程度,是否兼职、独生子女的大学生在心理压力的5个因子得分上差异有统计学意义(P<0.05).来源地、父亲不同文化程度的大学生在心理压力5个因子得分上差异无统计学意义(P>0.05).心理压力的5个因子和心理健康的9个因子之间均呈现显著正相关(P<0.05).心理压力的五个因子对心理健康的9个因子有不同的预测力.     

动物血液的开发利用

阐述了利用动物血液提取超氧化物歧化酶、凝血酶、血红素的工艺及用途，介绍了在食品工业、饲料加工业中的应用。     

Effect of bag holding on the center of foot pressure and the lower leg muscle activities

Abstract

This study examined the influence of holding a bag with one hand on the center of foot pressure (COP) and the electromyographic responses in lower leg muscles. Thirteen healthy male adults participated in this study to keep an upright posture while holding a load with the dominant hand with four bag weight conditions (0%, 15%, 30%, and 45% of maximal voluntary contraction (MVC) of the jerk strength). Integrated Electromyography (iEMG) and mean power frequency (MPF) of EMG were calculated to estimate the degree of muscle activity and fatigue in the tibialis anterior and soleus that are involved in ankle joint control. Body sway was evaluated by the mean position of left-right (X) and front-back (Y) axis sway and the following 4 body sway factors; unit time sway factor (F1), front-back sway factor (F2), left-right sway factor (F3), high frequency band power spectrum factor (F4). When holding a bag at 45% MVC or more of the jerk strength with a single hand for one minute, muscle activity in the lower leg on the side of the bag increased markedly, and muscle fatigue was induced in the antigravity muscles of both legs. As a result, anteroposterior sway increased to a short, quick sway.     

Stresses in the plantar region for long- and short-range throws in women basketball players

Abstract

This study aimed to assess plantar pressure pattern modifications caused by short- and long-distance shots in women basketball players. To this end, 24 experienced national- and regional-level basketball players performed 3 trials of 4 technical gestures (free throw, jump stop shot, three-point shot and lay-up) barefoot on a pressure platform placed in fixed positions on the court. Raw data were processed to calculate location and magnitude of pressure peaks in three sub-regions (forefoot, midfoot and rearfoot), and the increase ratio was calculated relative to plantar pressure measured during a static bipedal and unipedal upright stance. The results showed significant increases (p<0.001) in plantar pressure peaks in forefoot (but not midfoot and rearfoot) for all the gestures that involved the use of both legs. Particularly large increases were detected for the three-point shot. All three sub-regions underwent significant changes of the pressure peak in the case of lay-up (forefoot and rearfoot: p<0.001, midfoot: p=0.002). The high levels of contact stress detected for routinely performed technical gestures suggest that a detailed knowledge of changes in the physiological patterns of plantar stresses that take place during play is crucial in reducing the risk of foot injuries and establishing proper training and rehabilitation protocols.     

Choking interventions in sports: A systematic review

ABSTRACT

Choking under pressure describes suboptimal sport performance in stressful situations, which has led to two fundamental ‘choking’ models: distraction and self-focus. The purpose of this review was to provide an overview of empirical studies that have tested interventions used to alleviate choking. The systematic review includes 47 empirical studies published up to April 2017, including experimental, quasi-experimental, and single-case studies with athletes. These studies encompassed a variety of interventions (n?=?13) that were either distraction based or self-focus based. In addition, a third group – acclimatisation interventions – was identified. The results indicate that, in general, choking interventions based on both choking models and on acclimatisation provide a benefit to performance under pressure. The most reported effective interventions were pre-performance routines, quiet eye training, left-hand contractions, and acclimatisation training. The use of dual task was beneficial for performance under pressure but harmful when used in training. Mixed evidence was found for analogy learning, and null effects were reported for goal setting, neurofeedback training, and reappraisal cues. These results may help athletes and coaches select and implement effective strategies and methods to improve performance under pressure.     

Choking under pressure: Illuminating the role of distraction and self-focus

ABSTRACT

Two dominant explanations of choking under pressure – self-focus and distraction – have been enduringly presented as competing mechanisms of motor skill failure under performance stress. Dual-task experiments designed to simultaneously assess both mechanisms have often favoured self-focus, whereas qualitative research and examinations of gaze behaviour suggest that distraction plays a role. Though both mechanisms remain plausible, several reviews of the choking literature have side-stepped how autonomous motor skill failure would play out under a distraction-based model or a dual-mechanism model. In this discussion, we contend that persistent experimental focus on the brief moments of motor execution, without adequate consideration of diverse preparatory cognitive activities that also characterise sporting expertise, has delayed understanding of distraction’s involvement. With an expanded scope in mind, we critically review the evidence for both mechanisms and describe how distraction alone or distraction in combination with self-focus might derail an expert motor skill under pressure. Different suggestions are made for self-paced and externally paced sports given their different attentional challenges.