首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4032篇
  免费   81篇
  国内免费   3篇
教育   3238篇
科学研究   151篇
各国文化   55篇
体育   195篇
综合类   1篇
文化理论   26篇
信息传播   450篇
  2022年   25篇
  2021年   45篇
  2020年   76篇
  2019年   100篇
  2018年   132篇
  2017年   166篇
  2016年   143篇
  2015年   100篇
  2014年   102篇
  2013年   971篇
  2012年   108篇
  2011年   122篇
  2010年   109篇
  2009年   99篇
  2008年   117篇
  2007年   115篇
  2006年   100篇
  2005年   97篇
  2004年   99篇
  2003年   80篇
  2002年   89篇
  2001年   67篇
  2000年   66篇
  1999年   52篇
  1998年   45篇
  1997年   58篇
  1996年   41篇
  1995年   44篇
  1994年   48篇
  1993年   47篇
  1992年   39篇
  1991年   37篇
  1990年   35篇
  1989年   36篇
  1988年   28篇
  1987年   27篇
  1986年   30篇
  1985年   40篇
  1984年   29篇
  1983年   28篇
  1982年   25篇
  1981年   17篇
  1980年   26篇
  1979年   26篇
  1978年   25篇
  1977年   25篇
  1976年   26篇
  1974年   12篇
  1971年   12篇
  1969年   12篇
排序方式: 共有4116条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
995.
Oil and allied industries have brought increasing wealth to the Middle East and a recognition by individual governments of pressing educational requirements. While sharing certain problems, such as overcrowded classes and a lack of specialist teachers, with Europe, other aspects of educational growth in this area are unique.  相似文献   
996.
OBJECTIVE: This article presents an updated review of the literature of Munchausen Syndrome by Proxy (Factitious Disorder by Proxy, MBP). METHOD: Four hundred fifty-one cases of MBP were analyzed from 154 medical and psychosocial journal articles. RESULTS: Typical victims may be either males or females, usually 4 years of age or under. Victims averaged 21.8 months from onset of symptoms to diagnosis. Six percent of victims were dead, and 7.3% were judged to have suffered long-term or permanent injury. Twenty-five percent of victims' known siblings are dead, and 61.3% of siblings had illnesses similar to those of the victim or which raised suspicions of MBP. Mothers were perpetrators in 76.5% of cases, but as knowledge of MBP grows a wider range of perpetrators is identified. In a small number of cases, MBP was found to co-exist with secondary gain or other inflicted injury. CONCLUSION: Although published cases form a non-random sample, they add to knowledge about MBP and validate claims that it occurs. More knowledge about non-medical aspects of MBP, and more pooling of data, is desirable.  相似文献   
997.
The aim of this study was to examine the consistency or reproducibility of measuring cycling peak power in children and adults. Twenty-seven pre-pubertal girls and boys and 27 female and male physical education students (age 9.8 +/- 0.5 and 24.4 +/- 4.3 years, respectively; mean +/- s) participated in the study. All participants performed five tests over 15 days and underwent a habituation session before the study. Each test included four sprints against four different braking forces. We found that braking forces of 7.5% of body weight in children and 10% of body weight in adults were too high for most of the participants to elicit maximal cycling power. Unlike the children, the physical education students improved their performance between session 1 and session 2 (1025 +/- 219 vs 1069 +/- 243 W; P < 0.001). Therefore, to obtain reproducible measures of cycling peak power, a habituation session including a complete test protocol (i.e. warm-up plus three sprints) is highly recommended. When the protocol included three sprints in children and at least two sprints in adults, measurement of cycling peak power was found to be highly reliable (test-retest coefficient of variation approximately 3%). Finally, to avoid performance fluctuations, especially over several consecutive evaluations (e.g. longitudinal studies), it is necessary to maintain high motivation in children.  相似文献   
998.
Nine male student games players consumed either flavoured water (0.1 g carbohydrate, Na+ 6 mmol x l(-1)), a solution containing 6.5% carbohydrate-electrolytes (6.5 g carbohydrate, Na+ 21 mmol x l(-1)) or a taste placebo (Na+ 2 mmol x l(-1)) during an intermittent shuttle test performed on three separate occasions at an ambient temperature of 30 degrees C (dry bulb). The test involved five 15-min sets of repeated cycles of walking and variable speed running, each separated by a 4-min rest (part A of the test), followed by 60 s run/60 s rest until exhaustion (part B of the test). The participants drank 6.5 ml x kg(-1) of fluid as a bolus just before exercise and thereafter 4.5 ml x kg(-1) during every exercise set and rest period (19 min). There was a trial order effect. The total distance completed by the participants was greater in trial 3 (8441 +/- 873 m) than in trial 1 (6839 +/- 512, P < 0.05). This represented a 19% improvement in exercise capacity. However, the trials were performed in a random counterbalanced order and the participants completed 8634 +/- 653 m, 7786 +/- 741 m and 7099 +/- 647 m in the flavoured water (FW), placebo (P) and carbohydrate-electrolyte (CE) trials, respectively (P = 0.08). Sprint performance was not different between the trials but was impaired over time (FW vs P vs CE: set 1, 2.41 +/- 0.02 vs 2.39 +/- 0.03 vs 2.39 +/- 0.03 s; end set, 2.46 +/- 0.03 vs 2.47 +/- 0.03 vs 2.47 +/- 0.02 s; main effect time, P < 0.01). The rate of rise in rectal temperature was greater in the carbohydrate-electrolyte trial (rise in rectal temperature/duration of trial, degrees C x h(-1); FW vs CE, P < 0.05; P vs CE, N.S.). Blood glucose concentrations were higher in the carbohydrate-electrolyte than in the other two trials (FW vs P vs CE:rest, 4.4 +/- 0.1 vs 4.3 +/- 0.1 vs 4.2 +/- 0.1 mmol x l(-1); end of exercise, 5.4 +/- 0.3 vs 6.4 +/- 0.6 vs 7.2 +/- 0.5 mmol x l(-1); main effect trial, P < 0.05; main effect time, P < 0.01). Plasma free fatty acid concentrations at the end of exercise were lower in the carbohydrate-electrolyte trial than in the other two trials (FW vs P vs CE: 0.57 +/- 0.08 vs 0.53 +/- 0.11 vs 0.29 +/- 0.04 mmol x l(-1); interaction, P < 0.01). The correlation between the rate of rise in rectal temperature (degrees C x h(-1)) and the distance completed was -0.91, -0.92 and -0.96 in the flavoured water, placebo and carbohydrate-electrolyte conditions, respectively (P < 0.01). Heart rate, blood pressure, plasma ammonia, blood lactate, plasma volume and rate of perceived exertion were not different between the three fluid trials. Although drinking the carbohydrate-electrolyte solution induced greater metabolic changes than the flavoured water and placebo solutions, it is unlikely that in these unacclimated males carbohydrate availability was a limiting factor in the performance of intermittent running in hot environmental conditions.  相似文献   
999.
In primary care specialties, Morning Report is a traditional vehicle for expanding medical residents' training in diagnosis and treatment. At one academic medical center, residents and faculty in the Department of Family and Community Medicine use case-based teaching, centered around planning and reviewing patient management, to review intriguing cases from patient encounters in the department's hospital service. Seeking to improve the level of evidence-based information exchanged at Morning Report, department leaders invited reference librarians from the health sciences library to attend weekly Morning Report. The librarians saw this as an opportunity not only to improve residents' information-seeking skills, but also to improve librarians' teaching skills and understanding of the needs of users in clinical settings. This paper describes the evolution of librarians' involvement in Morning Report, examples of the kinds of contributions librarians have made in this setting, and changes made in Morning Report sessions to facilitate this activity.  相似文献   
1000.
Book reviews     
Journal Publishing By Gillian Page, Robert Campbell and Jack Meadows, Cambridge: Cambridge University Press, 1997, 420 pp £35.00, ISBN: 0 521 44137 4 Small Publishers A–Z: The guide to good publishing By Daphne Macara, West Molesey: Pandor House Publications, 1997, 44pp £6.50, ISBN: 1 871248 03 5  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号