全文获取类型
| 收费全文 | 2921篇 |
| 免费 | 64篇 |
| 国内免费 | 1篇 |
专业分类
| 教育 | 2227篇 |
| 科学研究 | 140篇 |
| 各国文化 | 35篇 |
| 体育 | 228篇 |
| 文化理论 | 33篇 |
| 信息传播 | 323篇 |
出版年
| 2023年 | 15篇 |
| 2022年 | 32篇 |
| 2021年 | 34篇 |
| 2020年 | 57篇 |
| 2019年 | 105篇 |
| 2018年 | 117篇 |
| 2017年 | 135篇 |
| 2016年 | 129篇 |
| 2015年 | 78篇 |
| 2014年 | 102篇 |
| 2013年 | 682篇 |
| 2012年 | 79篇 |
| 2011年 | 71篇 |
| 2010年 | 69篇 |
| 2009年 | 64篇 |
| 2008年 | 77篇 |
| 2007年 | 69篇 |
| 2006年 | 57篇 |
| 2005年 | 54篇 |
| 2004年 | 44篇 |
| 2003年 | 51篇 |
| 2002年 | 50篇 |
| 2001年 | 46篇 |
| 2000年 | 59篇 |
| 1999年 | 43篇 |
| 1998年 | 27篇 |
| 1997年 | 21篇 |
| 1996年 | 25篇 |
| 1995年 | 25篇 |
| 1994年 | 20篇 |
| 1993年 | 33篇 |
| 1992年 | 36篇 |
| 1991年 | 36篇 |
| 1990年 | 29篇 |
| 1989年 | 24篇 |
| 1988年 | 22篇 |
| 1987年 | 25篇 |
| 1986年 | 20篇 |
| 1985年 | 27篇 |
| 1984年 | 17篇 |
| 1983年 | 14篇 |
| 1982年 | 19篇 |
| 1981年 | 25篇 |
| 1980年 | 15篇 |
| 1979年 | 22篇 |
| 1978年 | 22篇 |
| 1977年 | 11篇 |
| 1976年 | 13篇 |
| 1975年 | 10篇 |
| 1889年 | 9篇 |
排序方式： 共有2986条查询结果，搜索用时 15 毫秒
101.
The aim of this study was to assess the influence of three imposed crank rates on the attainment of peak oxygen consumption (VO2peak) and other physiological responses during incremental arm crank ergometry. Twenty physically active, although non-specifically trained, males volunteered for the study. They completed an exercise protocol using an electrically braked arm ergometer (Lode Angio, Groningen, Netherlands) at crank rates of 60, 70 and 80 rev x min(-1). The order of tests was randomized and they were separated by at least 2 days. Peak VO2 was significantly higher (P < 0.05) at 70 and 80 rev x min(-1) than at 60 rev x min(-1). Peak ventilation volume increased as a function of crank rate and was higher (P < 0.05) at 80 than at 60 rev x min(-1). Peak heart rate was higher (P < 0.05) at 70 and 80 rev x min(-1) than at 60 rev x min(-1). Furthermore, 70 and 80 rev x min(-1) resulted in an extended test time compared with 60 rev x min(-1). The greater physiological responses observed during the tests at the two faster crank rates might have been the result of a postponement of acute localized neuromuscular fatigue, allowing for more work to be completed. We recommend, therefore, that an imposed crank rate between 70 and 80 rev x min(-1) should be used to elicit VO2peak and other physiological responses in arm crank ergometry. 相似文献
102.
It has previously been shown that females incur less muscle damage than males after strenuous exercise, but limited data are available for humans. To determine possible differences between the sexes in humans, the response to high-force eccentric exercise was examined in a large sample of women (n = 83) and men (n = 82). The participants performed a bout of eccentric exercise of the elbow flexors consisting of 70 maximal repetitions. Isometric strength, resting elbow angle and muscle soreness were measured before, immediately after (except soreness) and then daily for 7 days after exercise. There was a significant loss in strength among both groups (69% for women and 63% for men) (P < 0.01) immediately after exercise; at 168 h post-exercise, women still had a 27% strength loss and men had a 24% strength loss. No significant difference in strength loss or recovery rate was found between men and women. Soreness reached peak values 32-48 h post-exercise (P < 0.01), with no significant difference between men and women. Range of motion decreased significantly until 3 days after exercise (14.6 degrees or 0.255 rad loss for women; 12.2 degrees or 0.213 rad loss for men) (P < 0.01); at 168 h post-exercise, the women and men still showed a loss of 4.8 degrees (0.084 rad) and 4.0 degrees (0.07 rad), respectively. There was a significant interaction of sex x time (P < 0.01); a post-hoc test indicated that the women experienced a greater loss in range of motion at 72 h than men and this difference was maintained to 168 h post-exercise (P < 0.01). Thus, our results do not support the contention that women have a lower response to eccentric exercise than men. 相似文献
103.
104.
105.
106.
107.
Describing the plastic deformation of aluminium softball bats 总被引：1，自引：1，他引：0
Hollow aluminium bats were introduced over 30 years ago to provide improved durability over wooden bats. Since their introduction,
however, interest in hollow bats has focused almost exclusively around their hitting performance. The aim of this study was
to take advantage of the progress that has been made in predicting bat performance using finite elements and apply it to describe
bat durability. Accordingly, the plastic deformation from a ball impact of a single-wall aluminum bat was numerically modelled.
The bat deformation from the finite-element analysis was then compared with experiment using a high-speed bat test machine.
The ball was modelled as an isotropic, homogeneous, viscoelastic sphere. The viscoelastic parameters of the ball model were
found from instrumented, high-speed, rigid-wall ball impacts. The rigid-wall ball impacts were modelled numerically and showed
good agreement with the experimentally obtained response. The strain response of the combined bat-ball model was verified
with a strain-gauged bat at intermediate ball impact speeds in the elastic range. The strain response of the bat-ball model
exhibited positive correlation with the experimental measurements. High-speed bat-ball impacts were performed experimentally
and simulated numerically at increasing impact speeds which induced correspondingly increased dent sizes in the bat. The plastic
deformation from the numerical model found good agreement with experiment provided the aluminium work hardening and strain
rate effects were appropriately described. The inclusion of strain rate effects was shown to have a significant effect on
the bat deformations produced in the finite-element simulations. They also helped explain the existence of high bat stresses
found in many performance models. 相似文献
108.
109.
110.