全文获取类型
收费全文 | 24624篇 |
免费 | 427篇 |
国内免费 | 32篇 |
专业分类
教育 | 17809篇 |
科学研究 | 2096篇 |
各国文化 | 236篇 |
体育 | 1976篇 |
综合类 | 35篇 |
文化理论 | 235篇 |
信息传播 | 2696篇 |
出版年
2022年 | 162篇 |
2021年 | 284篇 |
2020年 | 456篇 |
2019年 | 632篇 |
2018年 | 895篇 |
2017年 | 942篇 |
2016年 | 871篇 |
2015年 | 525篇 |
2014年 | 691篇 |
2013年 | 4730篇 |
2012年 | 641篇 |
2011年 | 684篇 |
2010年 | 532篇 |
2009年 | 498篇 |
2008年 | 558篇 |
2007年 | 537篇 |
2006年 | 478篇 |
2005年 | 406篇 |
2004年 | 385篇 |
2003年 | 343篇 |
2002年 | 398篇 |
2001年 | 437篇 |
2000年 | 413篇 |
1999年 | 410篇 |
1998年 | 224篇 |
1997年 | 240篇 |
1996年 | 272篇 |
1995年 | 222篇 |
1994年 | 220篇 |
1993年 | 198篇 |
1992年 | 309篇 |
1991年 | 307篇 |
1990年 | 338篇 |
1989年 | 319篇 |
1988年 | 298篇 |
1987年 | 251篇 |
1986年 | 260篇 |
1985年 | 325篇 |
1984年 | 268篇 |
1983年 | 259篇 |
1982年 | 197篇 |
1981年 | 210篇 |
1980年 | 178篇 |
1979年 | 242篇 |
1978年 | 216篇 |
1977年 | 198篇 |
1976年 | 163篇 |
1975年 | 134篇 |
1973年 | 149篇 |
1972年 | 121篇 |
排序方式: 共有10000条查询结果,搜索用时 2 毫秒
991.
Clinical librarianship: a systematic review of the literature 总被引:2,自引:2,他引:0
992.
The development of services provided by the National Library of Medicine (NLM), which dates back to 1836, is described. MEDLINE, a database of 10-plus million references and abstracts to the world's biomedical literature, was put on the World Wide Web for free searching in 1997 as a system called PubMed, whose use has grown to over 250 million searches per year. PubMed features a variety of links between MEDLINE references and related information – full-text journal articles, DNA sequence data, medical knowledge bases, etc. – at websites within and outside NLM. PubMed is a major component of a larger NLM system, Entrez, which integrates access to a number of genome-related databases with linking features similar to those of PubMed. The newest linked service, which became a reality in February 2000, is PubMed Central, the National Institutes of Health's free repository for primary research reports in all the life sciences. 相似文献
993.
994.
995.
The aim of this study was to establish whether asymmetry of the strength of the leg and trunk musculature is more prominent in rowers than in controls. Nineteen oarsmen and 20 male controls matched for age, height and body mass performed a series of isokinetic and isometric strength tests on an isokinetic dynamometer. These strength tests focused on the trunk and leg muscles. Comparisons of strength were made between and within groups for right and left symmetry patterns, hamstring: quadriceps ratios, and trunk flexor and extensor ratios. The results revealed no left and right asymmetries in either the knee extensor or flexor strength parameters (including both isometric and isokinetic measures). Knee extensor strength was significantly greater in the rowing population, but knee flexor strength was similar between the two groups. No difference was seen between the groups for the hamstring: quadriceps strength ratio. In the rowing population, stroke side had no influence on leg strength. No differences were observed in the isometric strength of the trunk flexors and extensors between groups, although EMG activity was significantly higher in the rowing population. Patterns of asymmetry of muscle activity were observed between the left and right erector spinae muscles during extension, which was significantly related to rowing side (P < 0.01). These observations could be related to the high incidence of low back pain in oarsmen. 相似文献
996.
997.
Three soccer header types (shooting, clearing and passing) and two heading approaches (standing and jumping) were manipulated to quantify impact forces and neck muscle activity in elite female soccer players. The 15 participants were Division I intercollegiate soccer players. Impact forces were measured by a 15-sensor pressure array secured on the forehead. The electromyographic (EMG) activity of the left and right sternocleidomastoid and trapezius muscles was recorded using surface electrodes. Maximum impact forces and impulses as well as the EMG data were analysed with separate repeated-measures analyses of variance. Impact forces and impulses did not differ among the header types or approaches. Higher values were found for jumping versus standing headers in the mean normalized EMG for the right sternocleidomastoid. In addition, the integrated EMG was greater for the right sternocleidomastoid and right and left trapezius (P < 0.05). The sternocleidomastoid became active earlier than the trapezius and showed greater activity before ball contact. The trapezius became active just before ball contact and showed greater activity after ball contact. The increased muscle activity observed in the neck during the jumping approach appears to stabilize the connection between the head and body, thereby increasing the stability of the head-neck complex. 相似文献
998.
Research methods in sport and exercise psychology: quantitative and qualitative issues 总被引:1,自引:1,他引:0
Biddle SJ Markland D Gilbourne D Chatzisarantis NL Sparkes AC 《Journal of sports sciences》2001,19(10):777-809
Contemporary aspects of research methods in sport and exercise psychology are discussed in this wide-ranging review. After an introduction centred on trends in sport and exercise psychology methods, the review is organized around the major themes of quantitative and qualitative research. Our aim is to highlight areas that may be problematic or controversial (e.g. stepwise statistical procedures), underused (e.g. discriminant analysis), increasingly used (e.g. meta-analysis, structural equation modelling, qualitative content analysis) and emergent (e.g. realist tales of writing). Perspectives range from the technical and speculative to the controversial and critical. While deliberately not providing a 'cookbook' approach to research methods, we hope to provide enough material to help researchers to appreciate the diversity of potential methods and to adopt a more critical perspective in their own research consumption and production. 相似文献
999.
Researchers and practitioners require guidelines for using electronic pedometers to objectively quantify physical activity (specifically ambulatory activity) for research and surveillance as well as clinical and program applications. Methodological considerations include choice of metric and length of monitoring frame as well as different data recording and collection procedures. A systematic review of 32 empirical studies suggests we can expect 12,000-16,000 steps/day for 8-10-year-old children (lower for girls than boys); 7,000-13,000 steps/day for relatively healthy, younger adults (lower for women than men); 6,000-8,500 steps/day for healthy older adults; and 3,500-5,500 steps/day for individuals living with disabilities and chronic illnesses. These preliminary recommendations should be modified and refined, as evidence and experience using pedometers accumulates. 相似文献
1000.