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   22546篇
  免费   397篇
  国内免费   31篇
教育   16261篇
科学研究   2003篇
各国文化   204篇
体育   1718篇
综合类   34篇
文化理论   189篇
信息传播   2565篇
  2022年   139篇
  2021年   232篇
  2020年   367篇
  2019年   499篇
  2018年   704篇
  2017年   778篇
  2016年   724篇
  2015年   432篇
  2014年   583篇
  2013年   4242篇
  2012年   569篇
  2011年   641篇
  2010年   488篇
  2009年   460篇
  2008年   522篇
  2007年   504篇
  2006年   444篇
  2005年   388篇
  2004年   365篇
  2003年   327篇
  2002年   378篇
  2001年   424篇
  2000年   396篇
  1999年   402篇
  1998年   210篇
  1997年   230篇
  1996年   254篇
  1995年   213篇
  1994年   210篇
  1993年   193篇
  1992年   302篇
  1991年   300篇
  1990年   330篇
  1989年   311篇
  1988年   295篇
  1987年   248篇
  1986年   256篇
  1985年   322篇
  1984年   266篇
  1983年   255篇
  1982年   196篇
  1981年   206篇
  1980年   176篇
  1979年   240篇
  1978年   214篇
  1977年   194篇
  1976年   160篇
  1975年   128篇
  1974年   120篇
  1973年   147篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
901.
902.
In 1990, the Republican Scientific-Medical Library (RSML) of the Ministry of Health of Armenia in collaboration with the Fund for Armenian Relief created a vision of a national library network supported by information technology. This vision incorporated four goals: (1) to develop a national resource collection of biomedical literature accessible to all health professionals, (2) to develop a national network for access to bibliographic information, (3) to develop a systematic mechanism for sharing resources, and (4) to develop a national network of health sciences libraries. During the last decade, the RSML has achieved significant progress toward all four goals and has realized its vision of becoming a fully functional national library. The RSML now provides access to the literature of the health sciences including access to the Armenian medical literature, provides education and training to health professionals and health sciences librarians, and manages a national network of libraries of the major health care institutions in Armenia. The RSML is now able to provide rapid access to the biomedical literature and train health professionals and health sciences librarians in Armenia in information system use. This paper describes the evolution of the RSML and how it was accomplished.  相似文献   
903.
904.
Selecting resources for physician assistants is challenging and can be overwhelming. Although several core lists exist for nursing, allied health, and medical libraries, judging the scope and level of these resources in relation to the information needs of the physician assistant is difficult. Medical texts can be highly specialized and very expensive, in essence, "overkill" for the needs of the physician assistant. This bibliography is meant to serve as a guide to appropriate medical texts for physician assistants. Titles were selected from the Brandon/Hill list, Doody's Electronic Journal, and various other reference resources. Resources were evaluated based on the subject and scope, audience, authorship, cost, and currency. The collection includes 195 titles from 33 specialty areas. Standard texts in each area are also included.  相似文献   
905.
906.
BACKGROUND: Cochrane-style systematic reviews increasingly require the participation of librarians. Guidelines on the appropriate search strategy to use for systematic reviews have been proposed. However, research evidence supporting these recommendations is limited. OBJECTIVE: This study investigates the effectiveness of various systematic search methods used to uncover randomized controlled trials (RCTs) for systematic reviews. Effectiveness is defined as the proportion of relevant material uncovered for the systematic review using extended systematic review search methods. The following extended systematic search methods are evaluated: searching subject-specific or specialized databases (including trial registries), hand searching, scanning reference lists, and communicating personally. METHODS: Two systematic review projects were prospectively monitored regarding the method used to identify items as well as the type of items retrieved. The proportion of RCTs identified by each systematic search method was calculated. RESULTS: The extended systematic search methods uncovered 29.2% of all items retrieved for the systematic reviews. The search of specialized databases was the most effective method, followed by scanning of reference lists, communicating personally, and hand searching. Although the number of items identified through hand searching was small, these unique items would otherwise have been missed. CONCLUSIONS: Extended systematic search methods are effective tools for uncovering material for the systematic review. The quality of the items uncovered has yet to be assessed and will be key in evaluating the value of the systematic search methods.  相似文献   
907.
OBJECTIVE: The research sought to examine the overlap in coverage between several health-related databases, thus enabling the identification of the most important sources for searching for information on the rehabilitation of people with severe mental illness. METHODS: The literature was searched within a systematic review. Several health-related databases were retrieved (Cumulative Index to Nursing and Allied Health Literature, The Cochrane Library, MEDLINE, PsycLIT, Sociofile, and Social Science Citation Index), noting their source and comparing results retrieved from each database. FINDINGS: The total number of studies retrieved from each database varied. Almost a third of the papers retrieved from each database were unique to that source. Forty-two percent of the papers were only found in one database. Restricting a search to one database alone would miss many papers and could affect the results of a systematic review. PsycLIT was the most useful database for this topic area, containing 44% of the papers. MEDLINE, the database of first choice for many health professionals, held only 29%. CONCLUSIONS: No database was determined to be significantly more useful than any other--each warranted inclusion in the study. Reliance cannot be placed on one database alone, and other methods such as hand searching should also be used. Although this may not be new information for information professionals, it is likely to be new for health professionals and researchers who are increasingly performing their own literature searches. Information professionals have an important role to play in conveying this message to those outside their profession.  相似文献   
908.
909.
910.
We examined the supposition that swimmers may exhibit an imbalance in bilateral arm power output during simulated swimming exercise. Ten competitive front crawl swimmers (5 males, 5 females; age 20.5+/-2.3 years; height 1.74+/-0.09 m; body mass 72.0+/-16.7 kg; 400 m freestyle swim time 278+/-20.5 s; mean +/- s) performed four incremental (10 W x min(-1)) swim ramp tests on a computer-interfaced biokinetic swim bench ergometer. External power output from each arm was measured continuously to exhaustion. The results showed that, throughout the course of the simulated swim, external power output clearly favoured the left arm (F1,9 = 12.5, P= 0.006). This was especially evident in the final 30 s to exhaustion, when 54.0+/-3.87% of external power output was derived from the left arm versus 46.0+/-3.87% from the right arm. The disparity in external power output was further highlighted when the participants were grouped into unilateral and bilateral breathers. Unilateral breathers (n = 5) produced 57.1+/-2.62% of external power output from the left armversus 42.9+/-2.62% from the right arm (P= 0.001). Bilateral breathers (n = 5) exhibited a more balanced external power output of 51.0+/-1.82% from the left arm and 49.0+/-1.82% from the right arm (P = 0.177). Evidence of power imbalance in the simulated swimming stroke may have important implications for optimizing swim performance. The observed power imbalance may be reduced when a bilateral breathing technique is adopted.  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