"云娜"台风暴雨的Q矢量与螺旋度诊断分析

利用非地转ω方程说明了Q矢量散度的物理意义,并通过计算台风“云娜”影响过程中的Q矢量散度和高低空螺旋度,分析了这两个物理量的演变特征及其与台风、台风暴雨的关系,指出低层等压面上Q矢量散度场及相对螺旋度对台风暴雨预报具有较好的参考价值。     

“闭眼投篮”练习方法教学效果探讨

人体的运动技能是在多种感受机能的参与下完成的,在视觉、听觉、位觉、触觉、本体感觉中,本体感觉是运动技术形成的基础。在我院篮球专项班学生在教学中增加“闭眼投篮”的练习,运用“闭眼投篮”练习与传统的投篮教学方法相结合进行教学,有助于迅速掌握投篮基本技术、技巧,建立正确的动力定型,而且能够改善学生的心理品质,克服心理障碍,有利于提高投篮的命中率,是提高篮球教学质量的有效手段。     

1999年全国体操锦标赛男子自由体操比赛浅析

目前在自由体操项目上, 运动员的成套动作出现了 “两多一少”现象, 这是规则导向的结果, 但并非动作发展的必然趋势。我国运动员在完成自由体操动作中, 尚存在着起评分偏低、训练水平欠缺和动作完成准确性等问题, 应予以重视     

问题与策略:我国省级综合档案馆微信公众号移动服务研究

由于具有互动营销功能,微信可作为档案移动服务平台建设的重要选择之一.本文以《档案移动服务平台建设指南》为依据,采用网络调查法调查了我国省级综合档案馆微信公众号开展档案查询、档案展厅、档案资讯、互动交流等移动服务的现状,在此基础上分析了其中存在的问题,并以部分优秀微信公众号和移动服务平台为例提出了相应的优化策略.     

Fatigue increases ankle sprain risk in badminton players: A biomechanical study

ABSTRACT

Ankle sprains are the most common injury in regular badminton players and usually occur at the end of a match or training. The purpose of the present study was to examine the influence of fatigue produced by badminton practice on the lower limb biomechanics of badminton players. It was hypothesized that fatigue induces ankle kinematic and lower leg muscle activity changes which may increase the risk of ankle sprain. Ankle kinematics, ankle kinetics and muscles activities of 17 regular badminton players were recorded during lateral jumps before and after an intense badminton practice session. Post-fatigue, ankle inversion at foot strike and peak ankle inversion increased (+2.6°, p = 0.003 and +2.5°, p = 0.005, respectively). EMG pre-activation within 100 ms before foot landing significantly decreased after fatigue for soleus (?23.4%, p = 0.031), gastrocnemius lateralis (?12.2%, p = 0.035), gastrocnemius medialis (?23.3%, p = 0.047) and peroneus brevis (?17.4%, p = 0.036). These results demonstrate impaired biomechanics of badminton players when fatigue increases, which may cause a greater risk of experiencing an ankle sprain injury.     

Mediating effects of resistance training skill competency on health-related fitness and physical activity: the ATLAS cluster randomised controlled trial

The purpose of this study was to examine the mediating effect of resistance training skill competency on percentage of body fat, muscular fitness and physical activity among a sample of adolescent boys participating in a school-based obesity prevention intervention. Participants were 361 adolescent boys taking part in the Active Teen Leaders Avoiding Screen-time (ATLAS) cluster randomised controlled trial: a school-based program targeting the health behaviours of economically disadvantaged adolescent males considered “at-risk” of obesity. Body fat percentage (bioelectrical impedance), muscular fitness (hand grip dynamometry and push-ups), physical activity (accelerometry) and resistance training skill competency were assessed at baseline and post-intervention (i.e., 8 months). Three separate multi-level mediation models were analysed to investigate the potential mediating effects of resistance training skill competency on each of the study outcomes using a product-of-coefficients test. Analyses followed the intention-to-treat principle. The intervention had a significant impact on the resistance training skill competency of the boys, and improvements in skill competency significantly mediated the effect of the intervention on percentage of body fat and the combined muscular fitness score. No significant mediated effects were found for physical activity. Improving resistance training skill competency may be an effective strategy for achieving improvements in body composition and muscular fitness in adolescent boys.     

中国皮划艇国家二队功能动作筛查的应用研究

运用文献资料法、测试法、问卷调查法、专家访谈法和数理统计法对国家皮划艇青年队进行功能动作筛查测试,根据测试结果为备战2020年奥运会提供数据及理论的支持。通过研究发现:划艇运动员的总分情况整体优于皮艇运动员;大部分运动员髋、膝、踝三关节在单一的运动平面中具有较好的协调和稳定性,但在两个以上的运动平面中完成动作的稳定和控制能力有待提高;运动员的髋关节、肩关节及股四头肌柔韧性存在不平衡现象,左侧链与右侧链在多运动平面中协调稳定性也存在不平衡现象;运动员的损伤率较高,且损伤的主要部位是肩和腰。     

Effect of gender on trunk and pelvis control during lateral movements with perturbed landing

In lateral reactive movements, core stability may influence knee and hip joint kinematics and kinetics. Insufficient core stabilisation is discussed as a major risk factor for anterior cruciate ligament (ACL) injuries. Due to the higher probability of ACL injuries in women, this study concentrates on how gender influences trunk, pelvis and leg kinematics during lateral reactive jumps (LRJs). Perturbations were investigated in 12 men and 12 women performing LRJs under three different landing conditions: a movable landing platform was programmed to slide, resist or counteract upon landing. Potential group effects on three-dimensional trunk, pelvic, hip and knee kinematics were analysed for initial contact (IC) and the time of peak pelvic medial tilt (PPT). Regardless of landing conditions, the joint excursions in the entire lower limb joints were gender-specific. Women exhibited higher trunk left axial rotation at PPT (women: 4.0 ± 7.5°, men: ?3.1 ± 8.2°; p = 0.011) and higher hip external rotation at both IC and PPT (p < 0.01). But women demonstrated higher knee abduction compared to men. Men demonstrated more medial pelvic tilt at IC and especially PPT (men: –5.8 ± 4.9°, women: 0.3 ± 6.3°; p = 0.015). Strategies for maintaining trunk, pelvis and lower limb alignment during lateral reactive movements were gender-specific; the trunk and hip rotations displayed by the women were associated with the higher knee abduction amplitudes and therefore might reflect a movement strategy which is associated with higher injury risk. However, training interventions are needed to fully understand how gender-specific core stability strategies are related to performance and knee injury.     

用热力学浅析几个“反常”问题

通过对化学几个“反常”问题的浅析,说明热力学是一种非常有用的理论工具.     

论党在早期工人运动中解决帮会问题的策略

中国共产党成立以后就着手开展工人运动 ,首先遇到的障碍是帮会。由于在工厂、码头、矿山、货栈等有劳苦工人的地方 ,几乎都有帮会的活动 ,又由于帮会在思想上禁锢着工人群众的觉悟 ,在组织上限制着工人群众的自由 ,阻碍工人运动的发展。为此 ,我党制定了一系列妥善处理帮会的策略 ,排除了帮会对工人运动的干扰 ,有力地推动了中国革命。