质点组内力的功改变质心动能的条件

讨论了质点组内力的功是可以改变质心动能的，以及所满足的条件．     

Remote effects of lower limb stretching: preliminary evidence for myofascial connectivity?

The skeletal muscles and the fibrous connective tissue form an extensive, body-wide network of myofascial chains. As fascia can modify its stiffness, strain transmission along these meridians is supposable. The goal of this trial therefore was to collect pilot data for potential remote effects of lower limb stretching on cervical range of motion (ROM). Twenty-six healthy participants (30 ± 6 years) were included in the matched-pairs intervention study. One group (n = 13) performed three 30 s bouts of static stretching for the gastrocnemius and the hamstrings, respectively. An age- and sex-matched control group (CG; n = 13) remained inactive. Pre- and post-intervention, maximal cervical ROM in flexion/extension was assessed. A repeated measures ANOVA revealed systematic differences between groups (P < .05). ROM increased following stretching (143.3 ± 13.9 to 148.2 ± 14°; P < .05) but remained unchanged in the CG (144.6 ± 16.8 to 143.3 ± 16.8°; P > .05). Our data point towards existence of a strain transfer along myofascial meridians. Further randomised controlled studies on conditions, factors and magnitude of tensile transmission are warranted.     

我国体育人文学科研究的发展与成果评述

体育人文学科在体育美学、体育人类学和体育休闲娱乐理论的科研成果显著,主要集中在独特的体育人类学方法论、中西文化结合的体育人文价值观、凝聚人类终极理想的体育审美观、具有强烈社会责任感的体育改革发展观等方面。中国人文体育思想发展折射出中国体育改革发展的思想历程,学科所产生的学术影响深远,对于体育改革与发展具有长远指导价值。     

国外对中小学生家庭环境影响的研究及其启示

20世纪60年代中期以来,国外有关中小学生家庭环境对学习成绩影响的研究成果丰硕,国外对中小学生家庭环境影响的研究大致经历了从家庭环境结构维度到家庭环境过程维度再到家庭环境资本维度的历史演变过程,梳理这些研究成果对我国目前正在进行的教育改革有着重要的启示。     

卢瑟福模型中电子运动分析

关于卢瑟福模型中电子的运动是加速还是减速,不同文献给出不同描述,甚至是截然相反的描述.本文分别从能量和力的角度定量、定性地分析了卢瑟福模型中电子的运动情况,得出了卢瑟福模型中电子绕原子核旋转、辐射能量时作加速运动的结论.     

试析当前湖北劳动力素质结构

近年来，湖北经济增长率结束了长时期的下降而开始出现回升，经济发展的状况对全省劳动力就业形势构成了较大影响。表现为经济结构的调整带来了就业形势的变化，并进而影响劳动力素质结构的变化。     

The influence of shoe drop on the kinematics and kinetics of children tennis players

This study investigated the immediate effects of reducing the shoe drop (i.e. the difference between the heel and the forefoot height) on the kinematics and kinetics of the lower extremities of children tennis players performing a tennis-specific movement. Thirteen children tennis players performed a series of simulated open stance forehands wearing 3 pairs of shoes differing only in the drop: 0 (D0), 6 (D6) and the control condition of 12?mm (D12). Two embedded forceplates and a motion capture system were used to analyse the ground reaction forces and ankle and knee joint angles and moments of the leading lower limb. In D6 compared with D12, the peak impact force was reduced by 24% (p?=?.004) and the ankle was less dorsiflexed at foot strike (p?=?.037). In D0 compared with D12, the peak impact force was reduced by 17% (p?=?.049), the ankle was less dorsiflexed at foot strike (p?=?.045) and the knee was more flexed at foot strike (p?=?.007). In addition, 4 out of 13 participants (31%) presented a forefoot strike pattern for some of the trials in D0. No difference was observed across shoe conditions for the peak knee extensor moment (p?=?.658) or the peak ankle plantarflexor moment (p?=?.071). The results provide preliminary data supporting the hypothesis that for children tennis players, using a 6-mm lower shoe drop might reduce heel impact forces and thus limit potentially impact-related injuries.     

历史研究是一切社会科学的基础

2018年1月3日,中国历史研究院成立。习近平总书记代表党中央致信祝贺。贺信特别强调了历史研究的重要价值。历史研究之所以重要,是因为“世界的今天是从世界的昨天发展而来的。     

Enhancing Teaching and Learning: Libraries and Open Educational Resources in the Classroom

Academic libraries continually adjust services to adapt to the ever-changing landscape in higher education. In response to the broken textbook market, libraries are becoming actively involved in the open educational resources (OER) movement. Although there is not a formal program in place, librarians at Utah State University explored a collaborative approach to integrate OER in faculty members' courses. One goal of the effort was to work closely with faculty to consider course objectives and learning outcomes when evaluating and incorporating OER. This article identifies a streamlined process for targeting courses most suited for OER adoption and outlines a process of collaborating with teaching faculty to integrate relevant OER. The paper includes a detailed workflow that other libraries can easily adapt to make OER part of their faculty outreach toolkit.     

Teaching Them to Teach: Programmatic Evaluation of Graduate Assistants’ Teaching Performance

Academic libraries are one of the most important sources of “on the job” training for future library instructors. Librarians who supervise and assess these future library instructors (often in graduate assistant positions) often choose to provide observations and feedback each semester to these instructors in training. Scholarly literature, however, provides little information on whether this system helps graduate assistants to develop as teachers. The authors of this article assessed graduate assistants’ performance as teachers over three semesters using a system of observation and self-assessment. They analyzed both patterns and areas of growth and discuss the strengths and weaknesses of this system.