全文获取类型
收费全文 | 2525篇 |
免费 | 42篇 |
国内免费 | 45篇 |
专业分类
教育 | 1644篇 |
科学研究 | 212篇 |
各国文化 | 1篇 |
体育 | 453篇 |
综合类 | 249篇 |
文化理论 | 2篇 |
信息传播 | 51篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 28篇 |
2020年 | 29篇 |
2019年 | 41篇 |
2018年 | 25篇 |
2017年 | 46篇 |
2016年 | 30篇 |
2015年 | 51篇 |
2014年 | 132篇 |
2013年 | 166篇 |
2012年 | 134篇 |
2011年 | 147篇 |
2010年 | 118篇 |
2009年 | 114篇 |
2008年 | 141篇 |
2007年 | 198篇 |
2006年 | 203篇 |
2005年 | 201篇 |
2004年 | 175篇 |
2003年 | 150篇 |
2002年 | 108篇 |
2001年 | 113篇 |
2000年 | 73篇 |
1999年 | 42篇 |
1998年 | 16篇 |
1997年 | 28篇 |
1996年 | 21篇 |
1995年 | 17篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1989年 | 6篇 |
1988年 | 1篇 |
排序方式: 共有2612条查询结果,搜索用时 15 毫秒
871.
Juliano Dal Pupo Jonathan Ache Dias Rodrigo Ghedini Gheller Daniele Detanico Saray Giovana Dos Santos 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):259-271
This study analysed the modulation of jump performance, vertical stiffness as well as joint and intralimb coordination throughout a 30-s vertical jump test. Twenty male athletes performed the test on a force plate while undergoing kinematic analysis. Jump height, power output, ground contact time, vertical stiffness, maximum knee and hip flexion angles, and coordination by continuous relative phase (CRP) were analysed. Analysis of variance was used to compare variables within deciles, and t-tests were used to compare CRP data between the initial and final jumps. Results showed reduction in jump height, power output, and vertical stiffness, with an increase in contact time found during the test. Maximum knee and hip flexion angles declined, but hip angle decreased earlier (10–20% of the test) than knee angle (90–100%). No changes were observed in CRP for thigh–leg coupling when comparing initial and final jumps, but the trunk–thigh coupling was more in-phase near the end of the test. We conclude that fatigue causes reduction in jump performance, as well as changes in stiffness and joint angles. Furthermore, changes in intralimb coordination appear at the last 10% of the test, suggesting a neuromotor mechanism to counterbalance the loss of muscle strength. 相似文献
872.
Gavin L. Moir Jared M. Gollie Shala E. Davis John J. Guers Chad A. Witmer 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):492-506
To investigate the effects of different loads on system and lower-body kinetics during jump squats, 12 resistance-trained men performed jumps under different loading conditions: 0%, 12%, 27%, 42%, 56%, 71%, and 85% of 1-repetition maximum (1-RM). System power output was calculated as the product of the vertical component of the ground reaction force and the vertical velocity of the bar during its ascent. Joint power output was calculated during bar ascent for the hip, knee, and ankle joints, and was also summed across the joints. System power output and joint power at knee and ankle joints were maximized at 0% 1-RM (p < 0.001) and followed the linear trends (p < 0.001) caused by power output decreasing as the load increased. Power output at the hip was maximized at 42% 1-RM (p = 0.016) and followed a quadratic trend (p = 0.030). Summed joint power could be predicted from system power (p < 0.05), while system power could predict power at the knee and ankle joints under some of the loading conditions. Power at the hip could not be predicted from system power. System power during loaded jumps reflects the power at the knee and ankle, while power at the hip does not correspond to system power. 相似文献
873.
Paul Comfort Paul A. Jones Rebecca Udall 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):139-156
Power is a fundamental component for many sporting activities; while the load that elicits peak power during different exercises and differences between sexes remains unclear. This study aims to determine the effect of sex and load on kinematic and kinetic variables during the mid-thigh clean pull. Men (n = 10) and women (n = 10) performed the mid-thigh clean pull at intensities of 40%, 60%, 80%, 100%, 120%, and 140% of one repetition maximum (1RM) power clean in a randomised and counter-balanced order, while assessing bar velocity, bar displacement, power, force, and impulse. Two-way analysis of variance revealed that men demonstrated significantly greater (p < 0.05) values for all variables across loads, excluding bar velocity. Men demonstrated significantly greater (p < 0.05) bar velocities with 40–80% 1RM; in contrast, women demonstrated significantly (p < 0.05) higher velocities with 120–140% 1RM. Irrespective of sex significantly greater (p < 0.05), system peak power, bar velocity, and displacement occurred with 40% 1RM. In contrast, peak force and impulse were significantly (p < 0.05) greater with 140% 1RM. When performing the mid-thigh clean pull, to maximise system power or bar velocity, lower loads (40–60% 1RM) are recommended. When training force production or impulse, higher loads (120–140% 1RM) are recommended, when using the mid-thigh clean pull. 相似文献
874.
Keisuke Fujii Shinsuke Yoshioka Tadao Isaka Motoki Kouzaki 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):28-44
We previously demonstrated the relationship between sidestepping performance and the preparatory state of ground reaction forces (GRFs). The present study investigated the effect of the preparatory state of GRFs on defensive performance in 1-on-1 subphase of basketball. Ten basketball players participated in 1-on-1 dribble game of basketball. The outcomes (penetrating and guarding) and the preparatory state of GRFs (non-weighted and weighted states, i.e. vertical GRFs below and above 120% of body weight, respectively) were assessed by separating the phases. In the non-weighted state and the weighted state to determine the outcome, the probability of successful guarding was 78.8% and 29.6%, respectively. The non-weighted state prevented delay of the defensive step in the determination phase. Both the non-weighted and weighted states, immediately before the determination phase, were likely to change to the weighted state in the determination phase; during this time, the defender's preparatory state would be destabilised, presumably by the dribbler's movement. These results revealed that the preparatory GRFs before the defensive step help to explain the outcome of the 1-on-1 subphase, and suggest a better way to prevent delaying initiation of the defensive step and thereby to guard more effectively against a dribbler. 相似文献
875.
Stefan Josef Lindinger Caroline Göpfert Thomas Stöggl Erich Müller Hans-Christer Holmberg 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):318-333
Diagonal skiing as a major classical technique has hardly been investigated over the last two decades, although technique and racing velocities have developed substantially. The aims of the present study were to 1) analyse pole and leg kinetics and kinematics during submaximal uphill diagonal roller skiing and 2) identify biomechanical factors related to performance. Twelve elite skiers performed a time to exhaustion (performance) test on a treadmill. Joint kinematics and pole/plantar forces were recorded separately during diagonal roller skiing (9°; 11 km/h). Performance was correlated to cycle length (r = 0.77; P < 0.05), relative leg swing (r = 0.71), and gliding time (r = 0.74), hip flexion range of motion (ROM) during swing (r = 0.73) and knee extension ROM during gliding (r = 0.71). Push-off demonstrated performance correlations for impulse of leg force (r = 0.84), relative duration (r = ? 0.76) and knee flexion (r = 0.73) and extension ROM (r = 0.74). Relative time to peak pole force was associated with performance (r = 0.73). In summary, diagonal roller skiing performance was linked to 1) longer cycle length, 2) greater impulse of force during a shorter push-off with larger flexion/extension ROMs in leg joints, 3) longer leg swing, and 4) later peak pole force, demonstrating the major key characteristics to be emphasised in training. 相似文献
876.
Matthew M. Doyle Andrew Lyttle Bruce Elliott 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(3):178-192
The aim of this study was to examine biomechanical variables relating to the force production of men's Lightweight (LW) and Heavyweight (HW) rowing pairs. Seven HW and seven LW coxless pairs were studied under a range of stroke rates, from 20 spm to race rating (average of 33.7 spm for the HWs and 33.9 spm for the LWs). Each crew was equipped with biomechanical apparatus allowing the measurement of gate force, horizontal oar angle, and boat velocity. The HW crews exhibited significantly higher (p < 0.05) values for all variables examined, at all rates. Peak handle force was 26.2% to 30.2% higher in the HW group. Average handle force ranged from 18.7% to 22.1% higher than the LW group. Work per stroke was found to be 26% to 28% higher for the HW crews, and Power Per Kilogram was also greater for the HW crews, from 24.0% to 29.2%. The LWs were observed to be consistently, but not significantly, slower than the HWs (from 96.9% at the race situation, to 98.7% at 28 spm). These observations are important when considering biomechanical performance indicators in rowing, as significant changes in performance indicators may lead to only minimal alteration in boat velocity. 相似文献
877.
从一个佯谬问题出发,利用数学计算的方法,得出了稳态电磁场动量守恒的结论.目的是加深对电磁场具有物质属性概念的理解. 相似文献
878.
自动存取款机混凝土机房一般在原有商业银行营业网点内改造而成.因其具有较大集中荷载,同时由于防盗防抢的要求需新增墙体作为维护结构,墙体线荷载也比较大,因此有必要对新增荷载进行分析,进而对楼板、次梁、框架梁进行内力分析、结构验算并进行结构加固. 相似文献
879.
本文首先简要介绍Austin言语行为理论尤其是言外行为和言外之力的定义,并据此引出语用模糊的概念,接着尝试从语用模糊的角度探讨了《哈姆雷特》主人公哈姆雷特的语言,从而发现了其语言魅力的部分原因在于灵活地运用了语用模糊。因而发现语用模糊在《哈姆雷特》中是一个行之有效的会话策略,这也为莎翁戏剧语言巨大魅力找到了一个新的语用学依据。 相似文献
880.
齿座开裂是我厂采煤机生产中存在的一大问题,齿座开裂直接影响到采煤机的产品质量,保证齿座在采煤机生产中安全使用,与采煤机滚筒设计,生产各个环节有密切的关系。拟对各个环节存在的问题做一分析。 相似文献