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目的估测人体运动过程中参与工作的各子系统的能耗,建立较为精细的人体运动能耗分配关系。方法研究对13名大学生(男性)进行了功率自行车设定负荷下的运动代谢实验、多域多维心功能检测以及动作技术影像拍摄和解析,并对人体运动能量系统和做功进行了建模分析。结果受试者在给定的相同负荷功率下以不同转速蹬功率自行车时的运动能耗差异显著;总搏功两两之间均无显著性差异(P>0.05);无用功两两之间比较差异显著(P<0.001)。结论心脏做功仅与负荷量(输出功率)有关,而在给定负荷情况下心脏做功与速度大小无关;运动参数的改变显著影响运动无用功,也影响总能量消耗;在中等强度踏蹬自行车运动中,呼吸系统、循环系统、骨骼肌系统分别消耗总能量的11.02%,52.86%,5.36%;剩余30%左右的能量为对外做功和移动肢体做功(分别为25.72%和5.04%)。研究还为估测运动能耗在不同系统间的分配关系提供了一种可行方法。 相似文献
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Road criterium and track bicycle racing occur at high speeds, demand repeated high power outputs, last 10–90?min, and offer little chance for recovery after the event. Consecutive evenings of criterium and track racing are respectively known as speed-week or six-day events and take place in evening hours over the course of a week. Given the schedule and timing of these competitions, return to homeostasis can be compromised. No recommendations exist on how to optimize recovery for cyclists participating in these types of repeated evening competitions. Criterium and track cyclists spend considerable time, near and above the individual lactate threshold and therefore mostly utilize carbohydrate as their chief energy substrate. Henceforth, pre – and post-race nutrition and hydration is examined and recommendations are brought forward for carbohydrate, protein, and fluid intake. As evening high-intensity exercise perturbs sleep, strategies to optimize sleep are discussed and recommendations for an optimal sleep environment are given. Active recovery is examined, and the benefits of a short duration low intensity exercise reviewed. Passive recovery methods such as compression garments and cold water immersion are recommended, while evidence for massage, pneumatic compression devices, and neuromuscular electrical stimulation is still lacking. Optimizing recovery strategies will facilitate a return to the resting state following strenuous night competition. 相似文献
24.
公路自行车多日赛赛段的设计非常重要,要使环青海湖大赛更具有吸引力、观赏性和挑战性,赛段的设计应充分体现科学性和艺术性,因此,赛段设置的编排就显的尤为重要。 相似文献
25.
《European Journal of Sport Science》2013,13(3):259-264
AbstractCarbohydrate (CHO) mouth rinse has been shown to improve time trial performance. Although the exact mechanism remains un-established, research postulates that there are oral cavity receptors which increase neural drive. Increasing the duration of the mouth rinse could potentially increase stimulation of these receptors. The aim of the current investigation was to determine whether the duration of mouth rinse with 6.4% CHO affected 30-min self-selected cycling performance. Eleven male participants (age =24.1±3.9 years) performed three 30-min self-paced trials. On one occasion water was given as a mouth rinse for 5 s without being ingested placebo (PLA), on the other two occasions a 6.4% CHO solution was given for 5 and 10 s. Distance cycled, heart rate, ratings of perceived exertion, cadence, speed and power were recorded throughout all trials. The main findings were that distance cycled during the 10-s mouth rinse trial (20.4±2.3 km) was significantly greater compared to the PLA trial (19.2±2.2 km; P<0.01). There was no difference between the 5- and 10-s trials (P=0.15). However, 10 out of 11 participants cycled further during the 5-s trial compared to PLA, and eight cycled further during the 10-s trial compared to the 5 s. In conclusion, although there was an improvement in distance cycled with the 5-s mouth rinse compared to the PLA it was only significant with 10 s suggesting a dose response to the duration of mouth rinse. 相似文献
26.
《European Journal of Sport Science》2013,13(8):671-680
AbstractWe sought to examine whether the relationship between recovery–stress factors and performance would differ at the beginning (Stage 1) and the end (Final Stage) of a multi-stage cycling competition. Sixty-seven cyclists with a mean age of 21.90 years (SD?=?1.60) and extensive international experience participated in the study. The cyclists responded to the Recovery–Stress Questionnaire for Athletes (RESTQ-Sport) and rated their performance (1?=?extremely poor to 10?=?excellent) in respect to the first and last stage. Two step-down multiple regression models were used to estimate the relationship among recovery (nine factors; e.g. Physical Recovery, Sleep Quality) and stress factors (10 factors; e.g. Lack of Energy, Physical Complaints), as assessed by the RESTQ-Sport and in relation to performance. Model 1 pertained to Stage 1, whereas Model 2 used data from the Final Stage. The final Model 1 revealed that Physical Recovery (β?=?.46, p?=?.01), Injury (β?=??.31, p?=?.01) and General Well-being (β?=??.26, p?=?.04) predicted performance in Stage 1 (R2?=?.21). The final Model 2 revealed a different relationship between recovery–stress factors and performance. Specifically, being a climber (β?=?.28, p?=?.01), Conflicts/Pressure (β?=?.33, p?=?.01), and Lack of Energy (β?=??.37, p?=?.01) were associated with performance at the Final Stage (R2?=?.19). Collectively, these results suggest that the relationship among recovery and stress factors changes greatly over a relatively short period of time, and dynamically influences performance in multi-stage competitions. 相似文献
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28.
S. A. Jobson A. M. Nevill S. R. George A. E. Jeukendrup L. Passfield 《Journal of sports sciences》2013,31(12):1269-1278
Abstract The aims of this study were to compare the physiological demands of laboratory- and road-based time-trial cycling and to examine the importance of body position during laboratory cycling. Nine male competitive but non-elite cyclists completed two 40.23-km time-trials on an air-braked ergometer (Kingcycle) in the laboratory and one 40.23-km time-trial (RD) on a local road course. One laboratory time-trial was conducted in an aerodynamic position (AP), while the second was conducted in an upright position (UP). Mean performance speed was significantly higher during laboratory trials (UP and AP) compared with the RD trial (P < 0.001). Although there was no difference in power output between the RD and UP trials (P > 0.05), power output was significantly lower during the AP trial than during both the RD (P = 0.013) and UP trials (P = 0.003). Similar correlations were found between AP power output and RD power output (r = 0.85, P = 0.003) and between UP power output and RD power output (r = 0.87, P = 0.003). Despite a significantly lower power output in the laboratory AP condition, these results suggest that body position does not affect the ecological validity of laboratory-based time-trial cycling. 相似文献
29.
Abstract Swain (1997) employed the mathematical model of Di Prampero et al. (1979) to predict that, for cycling time-trials, the optimal pacing strategy is to vary power in parallel with the changes experienced in gradient and wind speed. We used a more up-to-date mathematical model with validated coefficients (Martin et al., 1998) to quantify the time savings that would result from such optimization of pacing strategy. A hypothetical cyclist (mass = 70 kg) and bicycle (mass = 10 kg) were studied under varying hypothetical wind velocities (?10 to 10 m · s?1), gradients (?10 to 10%), and pacing strategies. Mean rider power outputs of 164, 289, and 394 W were chosen to mirror baseline performances studied previously. The three race scenarios were: (i) a 10-km time-trial with alternating 1-km sections of 10% and ?10% gradient; (ii) a 40-km time-trial with alternating 5-km sections of 4.4 and ?4.4 m · s?1 wind (Swain, 1997); and (iii) the 40-km time-trial delimited by Jeukendrup and Martin (2001). Varying a mean power of 289 W by ± 10% during Swain's (1997) hilly and windy courses resulted in time savings of 126 and 51 s, respectively. Time savings for most race scenarios were greater than those suggested by Swain (1997). For a mean power of 289 W over the “standard” 40-km time-trial, a time saving of 26 s was observed with a power variability of 10%. The largest time savings were found for the hypothetical riders with the lowest mean power output who could vary power to the greatest extent. Our findings confirm that time savings are possible in cycling time-trials if the rider varies power in parallel with hill gradient and wind direction. With a more recent mathematical model, we found slightly greater time savings than those reported by Swain (1997). These time savings compared favourably with the predicted benefits of interventions such as altitude training or ingestion of carbohydrate-electrolyte drinks. Nevertheless, the extent to which such power output variations can be tolerated by a cyclist during a time-trial is still unclear. 相似文献
30.
F. Chan-Dewar W. Gregson G. Whyte D. Gaze J. Waterhouse J. Wen 《Journal of sports sciences》2013,31(4):414-423
Abstract Twelve healthy participants performed two identical high-intensity 40 km cycling trials (morning and evening) under controlled laboratory conditions. Echocardiograms and venous blood samples were collected before and after each exercise bout. Cardiac electro-mechanical-delay (cEMD) was measured as QRS-complex onset to peak systolic (S’) and early diastolic (E’) tissue velocities. Myocardial strain and strain rates were assessed in longitudinal, circumferential and radial planes at the left ventricular apex and base. Cardiac troponin I (cTnI) and N-terminal Pro-Brain Natriuretic Peptide (NT-proBNP) were assessed as biomarkers of cardiomyocyte damage and wall stress. cEMD was lengthened after both morning (S’: 160 ± 30 vs. 193 ± 27; E’: 478 ± 60 vs. 620 ± 87, P < 0.05) and evening (S’: 155 ± 29 vs. 195 ± 31; E’: 488 ± 42 vs. 614 ± 61, P < 0.05) trials. A reduction in peak S’ (morning: 6.96 ± 1.12 vs. 6.66 ± 0.89; evening: 7.09 ± 0.94 vs. 7.02 ± 0.76) was correlated with cEMD (r = ?0.335, P < 0.05). Peak longitudinal strain was reduced, atrial strain rates were sporadically increased in both trials post-cycling. cTnI was elevated in only two participants (0.04 µg · L?1, 0.03 µg · L?1), whilst NT-proBNP was below the clinical cut-off point in all participants. Prolonged-cycling resulted in a lengthening of cEMD, small changes in aspects of left ventricular deformation and sporadic increases in cardiac biomarkers. None of these effects were moderated by time-of-day. 相似文献