全文获取类型
收费全文 | 10853篇 |
免费 | 118篇 |
国内免费 | 28篇 |
专业分类
教育 | 7226篇 |
科学研究 | 1173篇 |
各国文化 | 102篇 |
体育 | 1349篇 |
综合类 | 7篇 |
文化理论 | 120篇 |
信息传播 | 1022篇 |
出版年
2022年 | 83篇 |
2021年 | 112篇 |
2020年 | 158篇 |
2019年 | 239篇 |
2018年 | 326篇 |
2017年 | 334篇 |
2016年 | 310篇 |
2015年 | 193篇 |
2014年 | 275篇 |
2013年 | 1881篇 |
2012年 | 275篇 |
2011年 | 272篇 |
2010年 | 234篇 |
2009年 | 207篇 |
2008年 | 230篇 |
2007年 | 248篇 |
2006年 | 226篇 |
2005年 | 208篇 |
2004年 | 182篇 |
2003年 | 196篇 |
2002年 | 160篇 |
2001年 | 189篇 |
2000年 | 175篇 |
1999年 | 175篇 |
1998年 | 90篇 |
1997年 | 87篇 |
1996年 | 116篇 |
1995年 | 81篇 |
1994年 | 101篇 |
1993年 | 92篇 |
1992年 | 163篇 |
1991年 | 152篇 |
1990年 | 148篇 |
1989年 | 141篇 |
1988年 | 118篇 |
1987年 | 121篇 |
1986年 | 145篇 |
1985年 | 138篇 |
1984年 | 116篇 |
1983年 | 132篇 |
1982年 | 113篇 |
1981年 | 108篇 |
1980年 | 97篇 |
1979年 | 172篇 |
1978年 | 113篇 |
1977年 | 112篇 |
1976年 | 105篇 |
1975年 | 91篇 |
1974年 | 93篇 |
1971年 | 71篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Relationship between laboratory-measured variables and heart rate during an ultra-endurance triathlon 总被引:1,自引:1,他引:0
Laursen PB Knez WL Shing CM Langill RH Rhodes EC Jenkins DG 《Journal of sports sciences》2005,23(10):1111-1120
The aim of the present study was to examine the relationship between the performance heart rate during an ultra-endurance triathlon and the heart rate corresponding to several demarcation points measured during laboratory-based progressive cycle ergometry and treadmill running. Less than one month before an ultra-endurance triathlon, 21 well-trained ultra-endurance triathletes (mean +/- s: age 35 +/- 6 years, height 1.77 +/- 0.05 m, mass 74.0 +/- 6.9 kg, = 4.75 +/- 0.42 l x min(-1)) performed progressive exercise tests of cycle ergometry and treadmill running for the determination of peak oxygen uptake (VO2peak), heart rate corresponding to the first and second ventilatory thresholds, as well as the heart rate deflection point. Portable telemetry units recorded heart rate at 60 s increments throughout the ultra-endurance triathlon. Heart rate during the cycle and run phases of the ultra-endurance triathlon (148 +/- 9 and 143 +/- 13 beats x min(-1) respectively) were significantly (P < 0.05) less than the second ventilatory thresholds (160 +/- 13 and 165 +/- 14 beats x min(-1) respectively) and heart rate deflection points (170 +/- 13 and 179 +/- 9 beats x min(-1) respectively). However, mean heart rate during the cycle and run phases of the ultra-endurance triathlon were significantly related to (r = 0.76 and 0.66; P < 0.01), and not significantly different from, the first ventilatory thresholds (146 +/- 12 and 148 +/- 15 beats x min(-1) respectively). Furthermore, the difference between heart rate during the cycle phase of the ultra-endurance triathlon and heart rate at the first ventilatory threshold was related to marathon run time (r = 0.61; P < 0.01) and overall ultra-endurance triathlon time (r = 0.45; P < 0.05). The results suggest that triathletes perform the cycle and run phases of the ultra-endurance triathlon at an exercise intensity near their first ventilatory threshold. 相似文献
962.
Stability of pedalling mechanics during a prolonged cycling exercise performed at different cadences
The aim of this study was to analyse the effect of pedalling rate on the pattern of mechanical torque application and on neuromuscular fatigue during prolonged cycling exercise. Eleven well-trained individuals performed three 1-h pedalling sessions, at 50 rev.min-1, 110 rev.min-1 and a freely chosen cadence, at an intensity corresponding to 65% of their maximal aerobic power. The mechanical torque applied on the right pedal was recorded for 30 s every 5 min while pedalling. Contractile and neural properties of the quadriceps and hamstring muscles were analysed before and immediately after each of the three pedalling sessions. The post-exercise reduction in knee extensors maximal voluntary contraction was significant (P<0.01) irrespective of the cadence, but no difference was found between cadences. The use of a particular cadence did not lead to preferentially central or peripheral fatigue. An increase in cadence resulted in greater positive and negative work generated during pedalling. The mechanical pattern was not altered during the exercise, whatever the selected cadence. The present study demonstrates that despite the occurrence of neuromuscular fatigue, trained individuals maintained a stable pedalling pattern throughout an endurance cycling exercise for cadences ranging from 50 to 110 rev.min-1. 相似文献
963.
Educational technology research and development - 相似文献
964.
965.
966.
967.
Evidence supporting instructional sequences for and grade placements of concepts relating to the biological cell is given in this report on a pilot study. Is replication possible? 相似文献
968.
969.
970.