双杠大回环屈体后空翻2周成挂臂动作的运动学分析     

李伟  姚侠文  王向东 《北京体育大学学报》2006,29(6):856-858

通过运动学分析揭示了双杠大回环屈体后空翻2周成挂臂动作的运动学规律和技术特点,为我国运动员发展和改进此类动作提供理论依据和参考数据.  相似文献   

Reciprocal Versus Nonreciprocal Assessment of Knee Flexors and Extensors in Concentric Actions Using the CON-TREX Multijoint Isokinetic Dynamometer: A Reliability Study     

Alex Bliss  Jeanne Dekerle 《Measurement in physical education and exercise science》2019,23(2):118-123

Knee flexor and extensor muscular assessment via isokinetic dynamometry is common practice and established in the research literature. However, reporting assessment methodology regarding reciprocal and nonreciprocal movements is often vague or absent. Such methodological issues are crucial for accurate assessments. Therefore, knee extensor and flexor peak moment using either reciprocal movement or nonreciprocal modalities was assessed. Fifteen participants performed three blocks of five concentric muscle actions at three angular velocities [1: nonreciprocal (maximal active flexion followed by passive extension); B2: reciprocal (maximal active extension followed by maximal active flexion); B3 nonreciprocal (maximal active extension followed by passive flexion)]. ANOVA revealed statistically significant within-subject modality effects for peak knee extensor moment and flexor velocity and modality differences (p < .05). Reciprocal and nonreciprocal assessments give significantly different results, with nonreciprocal giving higher peak moments. Reporting which modality is used is crucial to allow for greater clarity for the reader and practitioner.  相似文献   

轴流泵叶片的水动力性能研究     

Zhong Shao Xiang 《大连大学学报》1995,(4)

根据叶片绕流理论,用保角变换和级数展开的方法推导出由变换系数表示的叶片表面的速度分布,给出了轴流泵可调叶片的水动力矩数学模型及可靠性分析。最后,对某泵可调叶片的水动力矩进行了计算。研究表明,方法是可靠的,结果令人满意。  相似文献   

论债权人的代位权     

任春野 《沈阳教育学院学报》2006,8(4):35-37

围绕代位权这一内容，结合司法实践，就该制度的几个基本理论与实践问题加以讨论。  相似文献   

应用大挠度薄板功的互等定理求解四边固定矩形板的挠曲方程     

夏茂辉  毕晓华  常锦才 《唐山学院学报》2004,17(2):77-80

应用大挠度弯曲薄板的第二类功的互等定理,求解均载四边固定大挠度弯曲矩形板的挠曲面方程。  相似文献   

滚翻垫球后“再后倒”现象的讨论     

王凤玲 《石家庄学院学报》2000,(4)

对滚翻垫球后“再后倒”现象进行理论分析 ,可找出出现问题的根源 ,以便在教学中解决这一问题  相似文献   

论刚体对坐标轴转动惯量的平移和旋转变换     

于志明 《洛阳师范学院学报》2007,26(5):50-52

本文导出了刚体对坐标轴的转动惯量的平移和旋转变换一般式。  相似文献   

Dependence of nucleotide physical properties on their placement in codons and determinative degree     

Berezhnoy AY  Duplij SA 《Journal of Zhejiang University. Science. B》2005,6(10):948-960

INTRODUCTION It is well-known from the genetic code structure that there exists a connection between codons and physical and chemical amino acid properties (Lewin, 1983). Codon properties in turn are defined by physical properties of the nucleotides from which they are compounded (Ratner, 1985; 2000). The most important properties of nucleotides as complex three-dimensional molecules are their dipole moment, heat of formation and energy of the most stable con- formation (Schneider and Be…  相似文献   

Estimates of Central Moments for One Kind of Exponential-Type Operators     

宋占杰  杨振东  叶培新 《天津大学学报(英文版)》2011,17(2):85-88

In this paper,the explicit estimates of central moments for one kind of exponential-type operators are derived.The estimates play an essential role in studying the explicit approximation properties of this family of operators.Using the proposed method,the results of Ditzian and Totik in 1987,Guo and Qi in 2007,and Mahmudov in 2010 can be improved respectively.  相似文献   

金属标准拉伸试验中"反走"现象机理     

唐亮  杨昌棋 《实验室研究与探索》2011,30(5)

针对金属标准拉伸试验中,上下夹具偏心所导致的试验初期变形曲线往负方向延伸的"反走"现象,建立了一套考虑夹具偏心及夹持偏角的试样受力理论模型.特别对常用的楔形夹具在试验过程中产生的零夹持角和非零夹持角情况进行了分析,推导出试样应变与夹持力间的关系.分析了试验中产生变形值"反走"现象的机理,通过ABAQUS有限元软件对引伸计-试样联合模型进行了数值仿真.结果表明,理论分析、实验实测,以及有限元数值模拟所得结果具有良好的一致性.得出:试验初期在偏心所产生的误差占主导地位的并不是通常认为的偏心弯矩,而是上下楔形夹具夹持方式产生的侧向力以及附加弯矩的联合作用,解释并模拟了变形的"反走"现象,为进一步提高变形测量精度提供了新的思路.  相似文献