田径教科书中关于短跑途中跑存在问题商榷   总被引：1，自引：0，他引：1  

王吉夫 《体育学刊》2001,8(2):94-95

在短跑途中跑中，脚着地后髋关节并未弯曲，而是继续伸展：踝、膝关节是被动弯曲，而不是主动弯曲。此刻主动支撑会缩短制动时间，有利于制动冲量的减小。着地缓冲动作的细致划分，对全面正确地认识跑的原理是必要的，着地缓冲阶段应包括前蹬和后蹬的前一部分(垂直部位至最大缓冲)。摆动腿下压动作的作用有重要意义，应引起足够重视，在跑的划分中应有明确的界定。  相似文献   

运动性中枢疲劳机制的研究进展(综述)   总被引：6，自引：0，他引：6  

宋伟  王棣  付仅辉 《四川体育科学》2005,(4):47-50

本文采用文献资料研究法，对运动疲劳产生的中枢机制进行综合性分析．资料表明：一些特殊的神经生物学机制影响着中枢神经系统（CNS）发送和维持足够的神经冲动，成为疲劳产生的可能机制；另外，运动时CNS产生的神经递质、调质、神经激素：如5-羟色胺、多巴胺、氨类等物质，也是运动性中枢疲劳产生的敏感物质。  相似文献   

Activating lignite and sludge by electro-hydraulic impulse     

陈德淑 《重庆大学学报(英文版)》2003,2(2)

1. Introduction At present, it is necessary to use fertilizer to ensure the stable and high agricultural productivity. However, as we all know, the fertilizer not only decreases the self-fertility of soil, but also is accompanied with pesticide. Food poisoning caused by remnant pesticide in fruits and vegetables is often reported, and in such cases, chronic poisoning is the majority. The remnant pesticide accumulates in body gradually, and then induces kinds of disease. As reported, the Miyu…  相似文献   

α粒子散射公式的简易推导     

文石 《涪陵师范学院学报》1997,(3)

本文利用α粒子与靶核作弹性碰撞时,其动能、角动动量守恒并满足冲量定理,简明地推出α粒子散射公式。  相似文献   

脉冲噪声的自适应滤除方法   总被引：1，自引：0，他引：1  

武英 《南京晓庄学院学报》2005,21(5):25-27

为了在滤除图像噪声的同时更好的保护图像的细节,文中提出了一种基于非线性自适应滤波结构的改进算法。用中心加权中值滤波算法代替原方法中的中值滤波算法以及中值滤波代替均值滤波作为最终滤波结果输出。这种算法与同类算法相比,具有更好的滤波性能并能更好的保护细节,其效果明显优于中值滤波算法。  相似文献   

Motivation for online impulse buying: A two-factor theory perspective     

《International Journal of Information Management》2016,36(5):759-772

Impulse buying accounts for a large proportion of consumer shopping behavior in the bricks-and-mortar retail market. Online retailers also expect to profit from impulse buying. It is therefore interesting and beneficial to investigate the design elements of online stores and the sales promotion stimuli that e-retailers can use to either arouse consumers’ desire or decrease their self-control to evoke their purchase impulses. This study seeks to explicitly identify the factors associated with online store design and sales promotion stimuli that most affect online impulse buying behavior throughout the consumer decision-making process. Drawing on the two-factor theory, it successfully identifies the hygiene and motivation factors that trigger online impulse buying. The questionnaire responses of 239 valid respondents revealed that most of the hygiene factors are associated with the design of online stores, and all of the motivation factors are forms of sales promotion stimuli that effectively facilitate online impulse buying and present utilitarian or hedonic benefits to consumers. This study also identifies the most effective sales promotion stimuli and offers a comprehensive checklist for Web designers. Moreover, the distribution of motivation and hygiene factors for each stage of the EKB model is uneven, and some stages include only hygiene factors. The findings of this study demonstrate that the triggers of consumers’ online shopping behavior do not always apply to online impulse buying, and have important implications for impulse buying research and practice.  相似文献   

基于VAR模型通货膨胀影响因素的实证分析     

白金  蒋木子 《丹东师专学报》2011,(4):63-69

分析了十年我国两次比较严重的通货膨胀的成因,使用2001年1月—2010年9月的季度数据,在构建稳定的VAR模型基础上,通过建立协整方程,运用格兰杰因果检验以及脉冲响应函数的方法,对其进行分析。结果表明：经济增长、广义货币供给量、房地产销售价格指数、外汇储备与CPI之间存在长期的协整关系;长期内以房地产为代表的资产价格对CPI的冲击较大,短期内外汇储备推高CPI的效果最为显著。  相似文献   

Effect of a Brazilian Jiu-jitsu-simulated tournament on strength parameters and perceptual responses     

Daniele Detanico  Rodolfo André Dellagrana  Marina Saldanha da Silva Athayde  Rafael Lima Kons  Angel Góes 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):115-126

This study aimed to analyse the effects of a simulated Brazilian jiu-jitsu (BJJ) tournament on vertical jump performance, grip strength test and perceived effort responses. 22 male BJJ athletes participated in a simulated tournament consisting of three 7 min matches separated by 14 min of rest. Kimono grip strength test (KGST), counter movement jump (CMJ) and rate of perceived exertion (RPE) were measured before and after each match, while RPE of specific areas was assessed after three matches. ANOVA for repeated measures was used to compare strength parameters after each match with the level of significance set at 5%. The key results showed a significant decrease of jump height (p = 0.001) and net vertical impulse in the CMJ (p = 0.031), as well as a reduction of the number of reps in the KGST (p < 0.001). A significant increase of RPE was found throughout the matches (p < 0.001). Considering the RPE in specific areas, no differences were observed between the upper and lower body (p = 0.743). We conclude that the BJJ simulated tournament generated a decrease of performance in both upper and lower limbs and provoked a progressive increase in the effort perception over the matches.  相似文献   

用MF14万用表快速测定电视机行逆程脉冲幅值     

张启林 《河北北方学院学报(社会科学版)》1995,(6)

通过对MF14万用表结构的理论分析,推导出了电视机行脉冲幅度值与万用表指示值的关系,从而给出了一种快速测定行脉冲幅值的方法。  相似文献   

不同水平跳远运动员踏跳过程的生物力学分析   总被引：1，自引：0，他引：1  

车晓波  魏琳 《体育科学研究》1998,(1)

采用三维测力台实验方法对急行跳远踏跳过程测试,对健将,一级和二级跳远运动员踏跳中三维方向的踏跳力学特征进行探讨。从结果上分析认为：踏跳过程中起跳腿垂直方向波·谷力值和蹬伸力值虽然对跳远成绩影响较大,但运动员从缓冲到蹬伸阶段达到垂直冲量值最大值的时间长短是衡量运动员技术水平和成绩的另一重要指标,踏跳动作的实质是创造垂直速度的过程．  相似文献