全文获取类型
收费全文 | 3652篇 |
免费 | 64篇 |
国内免费 | 2篇 |
专业分类
教育 | 2696篇 |
科学研究 | 236篇 |
各国文化 | 34篇 |
体育 | 495篇 |
文化理论 | 74篇 |
信息传播 | 183篇 |
出版年
2023年 | 34篇 |
2022年 | 56篇 |
2021年 | 81篇 |
2020年 | 144篇 |
2019年 | 227篇 |
2018年 | 288篇 |
2017年 | 290篇 |
2016年 | 207篇 |
2015年 | 140篇 |
2014年 | 140篇 |
2013年 | 768篇 |
2012年 | 151篇 |
2011年 | 105篇 |
2010年 | 89篇 |
2009年 | 98篇 |
2008年 | 84篇 |
2007年 | 68篇 |
2006年 | 69篇 |
2005年 | 52篇 |
2004年 | 44篇 |
2003年 | 58篇 |
2002年 | 43篇 |
2001年 | 37篇 |
2000年 | 28篇 |
1999年 | 28篇 |
1998年 | 27篇 |
1997年 | 20篇 |
1996年 | 28篇 |
1995年 | 28篇 |
1994年 | 23篇 |
1993年 | 19篇 |
1992年 | 14篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 23篇 |
1988年 | 22篇 |
1987年 | 13篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 6篇 |
排序方式: 共有3718条查询结果,搜索用时 15 毫秒
941.
Dencker M Thorsson O Karlsson MK Lindén C Wollmer P Andersen LB 《Journal of sports sciences》2008,26(13):1397-1402
Maximal oxygen uptake VO(2max)) is considered the optimal method to assess aerobic fitness. The measurement of VO(2max), however, requires special equipment and training. Maximal exercise testing with determination of maximal power output offers a more simple approach. This study explores the relationship between [Vdot]O(2max) and maximal power output in 247 children (139 boys and 108 girls) aged 7.9-11.1 years. Maximal oxygen uptake was measured by indirect calorimetry during a maximal ergometer exercise test with an initial workload of 30 W and 15 W x min(-1) increments. Maximal power output was also measured. A sample (n = 124) was used to calculate reference equations, which were then validated using another sample (n = 123). The linear reference equation for both sexes combined was: VO(2max) (ml x min(-1)) = 96 + 10.6 x maximal power + 3.5 . body mass. Using this reference equation, estimated VO(2max) per unit of body mass (ml x min(-1) x kg(-1)) calculated from maximal power correlated closely with the direct measurement of VO(2max) (r = 0.91, P <0.001). Bland-Altman analysis gave a mean limits of agreement of 0.2+/-2.9 (ml x min(-1) x kg(-1)) (1 s). Our results suggest that maximal power output serves as a good surrogate measurement for VO(2max) in population studies of children aged 8-11 years. 相似文献
942.
García-López J Rodríguez-Marroyo JA Juneau CE Peleteiro J Martínez AC Villa JG 《Journal of sports sciences》2008,26(3):277-286
The aims of this study were to measure the aerodynamic drag in professional cyclists, to obtain aerodynamic drag reference values in static and effort positions, to improve the cyclists' aerodynamic drag by modifying their position and cycle equipment, and to evaluate the advantages and disadvantages of these modifications. The study was performed in a wind tunnel with five professional cyclists. Four positions were assessed with a time-trial bike and one position with a standard racing bike. In all positions, aerodynamic drag and kinematic variables were recorded. The drag area for the time-trial bike was 31% higher in the effort than static position, and lower than for the standard racing bike. Changes in the cyclists' position decreased the aerodynamic drag by 14%. The aero-helmet was not favourable for all cyclists. The reliability of aerodynamic drag measures in the wind tunnel was high (r > 0.96, coefficient of variation < 2%). In conclusion, we measured and improved the aerodynamic drag in professional cyclists. Our results were better than those of other researchers who did not assess aerodynamic drag during effort at race pace and who employed different wheels. The efficiency of the aero-helmet, and the validity, reliability, and sensitivity of the wind tunnel and aerodynamic field testing were addressed. 相似文献
943.
Relative age effect in Spanish association football: its extent and implications for wasted potential 总被引:1,自引:1,他引:0
Spain is one of the largest and most successful powers in international youth football, but this success has not extended to the national team. This lack of continued success seems to indicate a loss of potential. The relative age effect has been detected in football in many countries. Understanding the extent of this bias in the youth teams of Spanish elite clubs may help to improve selection processes and reduce the waste of potential. Comparisons between players from: the Spanish Professional Football League, all age categories of these clubs' youth teams, the Under-17 to Under-21 national teams, the national team, and the Spanish population, show a constant tendency to under-represent players from the later months of the selection year at all age groups of youth and Under-17 to Under-21 national teams. Professional and national team players show a similar but diminished behaviour that weakens with ageing, which suggests that talent identification and selection processes can be improved to help better identify potential talent early on and minimize wasted potential. 相似文献
944.
We observed how sailors manage their sleep and alertness before and during competition in a long-haul yacht race. Global performance of the teams was also recorded. We assessed eight sailors aged 21-30 years, split into four teams, who competed in the Tour de France à la Voile 2002 yacht race. Two phases of the race were examined: two legs in both the Atlantic Ocean and Mediterranean Sea. Sleep length, sleep debt, and sleepiness before competition and on board during the race were assessed using ambulatory polysomnography. Intermediate and final rankings were considered as a reflection of performance. A significant correlation was observed between the sleep debt before competition and the total sleep time on board during the Atlantic legs. The greater the sleep debt, the more sleepy the participants were. During the Mediterranean legs, almost all the sailors were deprived of sleep and slept during the daytime competitions. We observed that the final ranking in the race related to the sleep management strategy of the participants. In extreme competitive conditions, the effect of a good night's sleep before competition on performance is important. The strategy of the winners was to get sufficient sleep before each leg so as to be the most alert and efficient during the race. 相似文献
945.
Upjohn T Turcotte R Pearsall DJ Loh J 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(2):206-221
The objectives of the study were to describe lower limb kinematics in three dimensions during the forward skating stride in hockey players and to contrast skating techniques between low- and high-calibre skaters. Participant motions were recorded with four synchronized digital video cameras while wearing reflective marker triads on the thighs, shanks, and skates. Participants skated on a specialized treadmill with a polyethylene slat bed at a self-selected speed for 1 min. Each participant completed three 1-min skating trials separated by 5 min of rest. Joint and limb segment angles were calculated within the local (anatomical) and global reference planes. Similar gross movement patterns and stride rates were observed; however, high-calibre participants showed a greater range and rate of joint motion in both the sagittal and frontal planes, contributing to greater stride length for high-calibre players. Furthermore, consequent postural differences led to greater lateral excursion during the power stroke in high-calibre skaters. In conclusion, specific kinematic differences in both joint and limb segment angle movement patterns were observed between low- and high-calibre skaters. 相似文献
946.
Previous studies have found that reduced stick stiffness increases puck velocity in young male ice hockey players. This study
investigates the hypothesis that female players are disadvantaged by using equipment that is designed for taller and stronger
players. The purpose of this study was to investigate if stick flexibility and puck weight affect puck velocity in standing
slap shots performed by female ice hockey players. There was a significant increase in puck velocity (4.1%, p = 0.037) when stick stiffness and puck weight were reduced. ANOVA revealed that there was a significant correlation between
stick, puck and the participant herself (R
2 = 0.987). Spearman’s correlation analysis revealed that participants with higher puck velocities benefitted the most when
the stick flexibility and puck weight were reduced (r = 0.648, p = 0.043). It was concluded that decreased stick stiffness and puck weight increased puck velocity in standing slap shots
for female ice hockey players. 相似文献
947.
The aim of this study was to examine the facilitating effects of physical exercise on the reaction process. Eleven participants with specific expertise in decision-making sports performed a choice reaction time task during moderate sub-maximal exercise (90% of their ventilatory threshold power). Participants were tested at rest and while cycling. During exercise, the participants were faster, without being more variable. We suggest that the effect of exercise on cognitive performance was due to a major generalized improvement of the whole distribution of response time and, although the benefit effect was small, it was consistent throughout the entire range of reaction times. 相似文献
948.
The aim of this study was to examine the time-course of and the relationships between muscle oxygenation, blood volume and myoelectrical manifestations during isometric exercise in children. Twelve healthy children aged 12.5 +/- 1.2 years (mean +/- s) performed an isometric knee extension at 50% of their maximal voluntary contraction (MVC) until exhaustion to assess endurance time (limit time, T(lim)). Changes in muscle oxygenation and blood volume were assessed by near infrared spectroscopy (NIRS). The root mean square (RMS) amplitude and the mean power frequency (MPF) from electromyogram (EMG) signals were obtained, as NIRS parameters, from the vastus lateralis. Mean T(lim) was 117 +/- 34 s. The muscle oxygenation and blood volume curves decreased immediately at the beginning of exercise. Maximal deoxygenation occurred at 50% T(lim), and fell by 76.9% from the resting value. Similarly, minimal blood volume was observed at 50% T(lim); it reached a plateau that lasted until the end of exercise. The kinetics of the MPF and RMS curves were inversely related to time. At the last set of exercises (after 75% T(lim)), a steeper RMS curve and an abrupt decrease in the MPF curve were observed. Significant correlations (r) between muscle oxygenation, blood volume, root mean square amplitude and mean power frequency were observed, which ranged from 0.72 to 0.99. These findings suggest that the fatigue resulting from sustained isometric exercise is related to a decrease in oxygenation and blood volume. 相似文献
949.
Recent experiments on the ski simulator produced ambiguous results and raised unanswered questions concerning the true nature of "novice" behavior and the occurrence of behavioral changes during learning. The aim of the present experiment was to analyze the evolving behavior of three beginners during six practice sessions on a ski simulator The position of the apparatus platform was recorded as time series and used for constructing dynamical models, including stiffness and damping functions. The results showed that novices tended to exploit a Rayleigh damping behavior during the first trials and then transition toward a van der Pol damping. These results replicate previous observations by Nourrit, Delignieres, Caillou, Deschamps, and Lauriot (2003) and suggest the transition to the expert behavior could arise early in practice, when the task is of moderate difficulty. The discussion focuses on the properties of the observed learning dynamics and proposes a global conceptualization for acquiring complex motor skills. 相似文献
950.