全文获取类型
收费全文 | 11716篇 |
免费 | 111篇 |
国内免费 | 19篇 |
专业分类
教育 | 7904篇 |
科学研究 | 1384篇 |
各国文化 | 117篇 |
体育 | 1156篇 |
综合类 | 7篇 |
文化理论 | 127篇 |
信息传播 | 1151篇 |
出版年
2021年 | 105篇 |
2020年 | 162篇 |
2019年 | 264篇 |
2018年 | 383篇 |
2017年 | 359篇 |
2016年 | 320篇 |
2015年 | 210篇 |
2014年 | 286篇 |
2013年 | 2146篇 |
2012年 | 246篇 |
2011年 | 245篇 |
2010年 | 223篇 |
2009年 | 195篇 |
2008年 | 222篇 |
2007年 | 238篇 |
2006年 | 198篇 |
2005年 | 185篇 |
2004年 | 171篇 |
2003年 | 191篇 |
2002年 | 161篇 |
2001年 | 180篇 |
2000年 | 181篇 |
1999年 | 186篇 |
1998年 | 98篇 |
1997年 | 86篇 |
1996年 | 129篇 |
1995年 | 89篇 |
1994年 | 108篇 |
1993年 | 106篇 |
1992年 | 176篇 |
1991年 | 167篇 |
1990年 | 160篇 |
1989年 | 161篇 |
1988年 | 136篇 |
1987年 | 133篇 |
1986年 | 161篇 |
1985年 | 155篇 |
1984年 | 132篇 |
1983年 | 145篇 |
1982年 | 132篇 |
1981年 | 118篇 |
1980年 | 111篇 |
1979年 | 180篇 |
1978年 | 125篇 |
1977年 | 125篇 |
1976年 | 121篇 |
1975年 | 92篇 |
1974年 | 101篇 |
1972年 | 84篇 |
1971年 | 80篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Avoiding versus seeking: the relationship of information seeking to avoidance, blunting, coping, dissonance, and related concepts. 总被引:1,自引:0,他引:1
Donald O Case James E Andrews J David Johnson Suzanne L Allard 《Journal of the Medical Library Association》2005,93(3):353-362
QUESTION: How have theorists and empirical researchers treated the human tendency to avoid discomforting information? DATA SOURCES: A historical review (1890-2004) of theory literature in communication and information studies, coupled with searches of recent studies on uptake of genetic testing and on coping strategies of cancer patients, was performed. STUDY SELECTION: The authors' review of the recent literature included searches of the MEDLINE, PsychInfo, and CINAHL databases between 1992 and summer of 2004 and selective, manual searches of earlier literature. Search strategies included the following subject headings and key words: MeSH headings: Genetic Screening/psychology, Decision Making, Neoplasms/diagnosis/genetics/psychology; CINAHL headings: Genetic Screening, Genetic Counseling, Anxiety, Decision Making, Decision Making/Patient; additional key words: avoidance, worry, monitoring, blunting, cancer. The "Related Articles" function in MEDLINE was used to perform additional "citation pearl" searching. MAIN RESULTS: The assumption that individuals actively seek information underlies much of psychological theory and communication practice, as well as most models of the information-seeking process. However, much research has also noted that sometimes people avoid information, if paying attention to it will cause mental discomfort or dissonance. Cancer information in general and genetic screening for cancer in particular are discussed as examples to illustrate this pattern. CONCLUSION: That some patients avoid knowledge of imminent disease makes avoidance behavior an important area for social and psychological research, particularly with regard to genetic testing. 相似文献
993.
A General Evaluation Framework for Topical Crawlers 总被引:10,自引:0,他引:10
Topical crawlers are becoming important tools to support applications such as specialized Web portals, online searching, and competitive intelligence. As the Web mining field matures, the disparate crawling strategies proposed in the literature will have to be evaluated and compared on common tasks through well-defined performance measures. This paper presents a general framework to evaluate topical crawlers. We identify a class of tasks that model crawling applications of different nature and difficulty. We then introduce a set of performance measures for fair comparative evaluations of crawlers along several dimensions including generalized notions of precision, recall, and efficiency that are appropriate and practical for the Web. The framework relies on independent relevance judgements compiled by human editors and available from public directories. Two sources of evidence are proposed to assess crawled pages, capturing different relevance criteria. Finally we introduce a set of topic characterizations to analyze the variability in crawling effectiveness across topics. The proposed evaluation framework synthesizes a number of methodologies in the topical crawlers literature and many lessons learned from several studies conducted by our group. The general framework is described in detail and then illustrated in practice by a case study that evaluates four public crawling algorithms. We found that the proposed framework is effective at evaluating, comparing, differentiating and interpreting the performance of the four crawlers. For example, we found the IS crawler to be most sensitive to the popularity of topics.Partially supported by National Science Foundation CAREER grant No. IIS-0133124/0348940. 相似文献
994.
995.
Home advantage is quantitatively defined and calculated for each season since the start of the main professional sports in North America and England. Over 400,000 games are analysed. The leagues represented are the National League (1876-2002) and American League (1901-2002) for baseball, the National Hockey League (1917-2003) for ice hockey, the National Football League (1933-2002) for American football, the National Basketball Association (1946-2003) for basketball, and the four levels of professional football, formerly called the Football League, in England (1888-2003). Problems caused by unbalanced playing schedules are considered. The results are presented graphically to show long-term trends and sudden changes. The highest levels of home advantage for all sports were in their early years of existence. Home advantage in ice hockey, basketball and football in England has declined over the last two decades. In baseball there has been very little change over the last 100 years, with home advantage consistently lower than in other sports. There was a large drop in home advantage in football in England following the 7-year suspension of the league during the Second World War. The trends and changes provide some evidence that travel and familiarity contribute to home advantage, but little in support of crowd effects. 相似文献
996.
Hertogh C Chamari K Damiani M Martin R Hachana Y Blonc S Hue O 《Journal of sports sciences》2005,23(9):937-942
In this study, we examined the effects of a prior run-up on intermittent maximal vertical jump performance. Seven regionally ranked male volleyball players volunteered to participate in the study. They performed three randomized tests: (1) six repeated intermittent maximal jumps (jump condition), (2) six repeated intermittent run-ups (run-up condition), and (3) six repeated run-ups followed by maximal jumps (run-up plus jump condition). All performances were assessed and blood lactate concentration and heart rate were measured before and after each of the tests. Mean ( +/- ) jump performance (64.7 +/- 2.3 cm) increased significantly (P = 0.02) over the course of the jump condition and was significantly higher (P < 0.001) than for the run-up plus jump condition (58.0 +/- 3.2 cm), which tended to decrease with repetition. Blood lactate concentration was significantly higher in the run-up plus jump condition (3.73 +/- 0.24 mmol . l(-1)) than in the jump (2.61 +/- 0.26 mmol . l(-1), P = 0.02) and run-up (2.86 +/- 0.18 mmol . l(-1), P = 0.03) conditions. The increase in heart rate was significantly higher both in the run-up plus jump condition (33 +/- 6 beats . min(-1), P = 0.05) and run-up condition (33 +/- 4 beats . min(-1), P = 0.02) than in the jump condition (21 +/- 3 beats . min(-1)). The results indicate that the addition of run-ups probably impeded performance in the repetition of vertical jumps. 相似文献
997.
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
998.
Educational technology research and development - 相似文献
999.
1000.