全文获取类型
收费全文 | 3820篇 |
免费 | 23篇 |
国内免费 | 89篇 |
专业分类
教育 | 2245篇 |
科学研究 | 507篇 |
各国文化 | 6篇 |
体育 | 677篇 |
综合类 | 40篇 |
文化理论 | 7篇 |
信息传播 | 450篇 |
出版年
2024年 | 11篇 |
2023年 | 26篇 |
2022年 | 34篇 |
2021年 | 28篇 |
2020年 | 33篇 |
2019年 | 21篇 |
2018年 | 32篇 |
2017年 | 10篇 |
2016年 | 22篇 |
2015年 | 43篇 |
2014年 | 131篇 |
2013年 | 92篇 |
2012年 | 253篇 |
2011年 | 352篇 |
2010年 | 155篇 |
2009年 | 109篇 |
2008年 | 228篇 |
2007年 | 214篇 |
2006年 | 257篇 |
2005年 | 207篇 |
2004年 | 200篇 |
2003年 | 161篇 |
2002年 | 162篇 |
2001年 | 126篇 |
2000年 | 118篇 |
1999年 | 112篇 |
1998年 | 39篇 |
1997年 | 44篇 |
1996年 | 25篇 |
1995年 | 33篇 |
1994年 | 34篇 |
1993年 | 39篇 |
1992年 | 44篇 |
1991年 | 47篇 |
1990年 | 36篇 |
1989年 | 58篇 |
1988年 | 20篇 |
1987年 | 35篇 |
1986年 | 40篇 |
1985年 | 39篇 |
1984年 | 20篇 |
1983年 | 22篇 |
1982年 | 33篇 |
1981年 | 23篇 |
1959年 | 12篇 |
1958年 | 11篇 |
1957年 | 11篇 |
1956年 | 11篇 |
1954年 | 11篇 |
1953年 | 9篇 |
排序方式: 共有3932条查询结果,搜索用时 15 毫秒
991.
992.
993.
Volianitis S Dawson EA Dalsgaard M Yoshiga C Clemmesen J Secher NH Olsen N Nielsen HB 《Journal of sports sciences》2012,30(2):149-153
Reduced hepatic lactate elimination initiates blood lactate accumulation during incremental exercise. In this study, we wished to determine whether renal lactate elimination contributes to the initiation of blood lactate accumulation. The renal arterial-to-venous (a-v) lactate difference was determined in nine men during sodium lactate infusion to enhance the evaluation (0.5 mol x L(-1) at 16 ± 1 mL x min(-1); mean ± s) both at rest and during cycling exercise (heart rate 139 ± 5 beats x min(-1)). The renal release of erythropoietin was used to detect kidney tissue ischaemia. At rest, the a-v O(2) (CaO(2)-CvO(2)) and lactate concentration differences were 0.8 ± 0.2 and 0.02 ± 0.02 mmol x L(-1), respectively. During exercise, arterial lactate and CaO(2)-CvO(2) increased to 7.1 ± 1.1 and 2.6 ± 0.8 mmol x L(-1), respectively (P < 0.05), indicating a -70% reduction of renal blood flow with no significant change in the renal venous erythropoietin concentration (0.8 ± 1.4 U x L(-1)). The a-v lactate concentration difference increased to 0.5 ± 0.8 mmol x L(-1), indicating similar lactate elimination as at rest. In conclusion, a -70% reduction in renal blood flow does not provoke critical renal ischaemia, and renal lactate elimination is maintained. Thus, kidney lactate elimination is unlikely to contribute to the initial blood lactate accumulation during progressive exercise. 相似文献
994.
Scafoglieri A Tresignie J Provyn S Marfell-Jones M Reilly T Bautmans I Clarys JP 《Journal of sports sciences》2012,30(8):777-785
The aim of the present study was to develop and cross-validate anthropometrical prediction equations for segmental lean tissue mass (SLM). One hundred and seventeen young healthy Caucasians (67 men and 50 women; mean age: 31.9 ± 10.0 years; Body Mass Index: 24.3 ± 3.2 kg · m(-2)) were included. Body mass (BM), stretch stature (SS), 14 circumferences (CC), 13 skinfolds (SF) and 4 bone breadths (BB) were used as anthropometric measurements. Segmental lean mass of both arms, trunk and both legs were measured by dual energy X-ray absorptiometry as the criterion method. Three prediction equations for SLM were developed as follows: arms = 40.394(BM) + 169.836(CCarm-tensed) + 399.162(CCwrist) - 85.414(SFtriceps) - 39.790(SFbiceps) - 7289.190, where Adj.R (2) = 0.97, P < 0.001, and standard error of estimate (SEE) = 355 g;trunk = 181.530(BM) + 155.037(SS) + 534.818(CCneck) + 175.638(CCchest) - 88.359(SFchest) - 147.232(SFsupraspinale) - 46522.165, where Adj.R(2) = 0.97, P < 0.001, and SEE = 1077g; and legs = 55.838(BM) + 88.356(SS) + 235.579(CCmid-thigh) + 278.595(CCcalf) + 288.984(CCankle) - 84.954(SFfront-thigh) - 53.009(SFmedial calf) - 28522.241, where Adj.R (2) = 0.96, P < 0.001, and SEE = 724 g. Cross-validation statistics showed no significant differences (P < 0.05) between observed and predicted SLM. Root mean squared errors were smallest for arms (362 g), followed by legs (820 g) and trunk (1477 g). These new prediction equations allow an accurate estimation of segmental lean mass in groups of young adults, but estimation errors of 8 to 14% can occur in certain individuals. 相似文献
995.
Abstract The velocity and acceleration at which the ball-carrier or tackler enters the tackle may contribute to winning the contest and prevailing injury free. Velocity and acceleration have been quantified in controlled settings, whereas in match-play it has been subjectively described. The purpose of this study was to determine the velocity and acceleration of the ball-carrier and tackler before contact during match-play in three competitions (Super 14, Varsity Cup, and Under-19 Currie Cup). Using a two-dimensional scaled version of the field, the velocity and acceleration of the ball-carrier and tackler were measured at every 0.1 s to contact for 0.5 s. For front-on tackles, a significant difference (P?0.05) between the ball-carrier (4.6?±?1 m · s(-1)) and tackler (7.1?±?3.5 m · s(-1)) was found at the 0.5 s time to contact interval in the Varsity Cup. For side-on tackles, differences between the two opposing players were found at 0.5 s (ball-carrier: 4.6?±?1.7 m · s(-1); tackler: 3.1?±?1.2 m · s(-1)) and 0.4 s (ball-carrier: 6.3?±?2.3 m · s(-1); tackler: 3.7?±?1.6 m · s(-1)) at Under-19 level. After 0.4 s, no significant differences (P?>?0.05) were evident. Also, the ball-carrier's velocity over the 0.5 s was relatively stable compared with that of the tackler. Results suggest that tacklers adjust their velocity to reach a suitable relative velocity before making contact with the ball-carrier. 相似文献
996.
The present study examined the extent to which scores on the Dispositional Flow Scale-2 (DFS-2) could differentiate individuals who frequently experience flow characteristics in physical activity from those who do not. A total of 993 participants completed the Japanese version of the DFS-2. Latent class factor analysis (LCFA), which combines the strengths of both latent class analysis and factor analysis, was conducted on the DFS-2 responses. Six classes were identified through a series of LCFAs and the patterns of the item-average scores for the nine flow attributes were found to be parallel among these classes. The top two and bottom two classes (19.3% and 13.4% of the whole sample) were considered the groups who experience flow characteristics frequently and seldom, respectively. These results indicated that individuals who often experience flow attributes in physical activity could be differentiated from those who do not based on their DFS-2 scores. 相似文献
997.
998.
999.
Vicedo M 《Isis; an international review devoted to the history of science and its cultural influences》2012,103(1):111-125
Starting in 1958, Harry Harlow published numerous research papers analyzing the emotional and social development of rhesus monkeys. This essay examines the presentation of Harlow's work in introductory psychology textbooks from 1958 to 1975, focusing on whether the textbooks erased the process of research, presented results without hedging, and provided a uniform account of Harlow's work and results. It argues that many textbooks were not passive vehicles of knowledge transmission; instead, they played a role similar to articles of meta-analysis and literature reviews. 相似文献
1000.
Stanley M 《Isis; an international review devoted to the history of science and its cultural influences》2012,103(2):254-277
Greek historical accounts of ancient eclipses were an important, if peculiar, focus of scientific attention in the nineteenth century. Victorian-era astronomers tried to correct the classical histories using scientific methods, then used those histories as data with which to calibrate their lunar theories, then rejected the histories as having any relevance at all. The specific dating of these eclipses--apparently a simple exercise in celestial mechanics--became bound up with tensions between scientific and humanistic approaches to the past as well as with wider social debates over the power and authority of science in general. The major figures discussed here, including G. B. Airy, Simon Newcomb, and T. H. Huxley, argued that the critical question was whether science could speak authoritatively about the past. To them, the ability of science to talk about the past indicated its power to talk about the future; it was also the fulcrum of fierce boundary disputes among science, history, and religion. 相似文献