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   29638篇
  免费   347篇
  国内免费   17篇
教育   20937篇
科学研究   2753篇
各国文化   318篇
体育   2623篇
综合类   9篇
文化理论   259篇
信息传播   3103篇
  2021年   287篇
  2020年   427篇
  2019年   649篇
  2018年   890篇
  2017年   798篇
  2016年   787篇
  2015年   483篇
  2014年   639篇
  2013年   5399篇
  2012年   601篇
  2011年   662篇
  2010年   510篇
  2009年   534篇
  2008年   585篇
  2007年   526篇
  2006年   502篇
  2005年   442篇
  2004年   496篇
  2003年   385篇
  2002年   393篇
  2001年   551篇
  2000年   591篇
  1999年   512篇
  1998年   314篇
  1997年   306篇
  1996年   365篇
  1995年   298篇
  1994年   301篇
  1993年   298篇
  1992年   425篇
  1991年   443篇
  1990年   422篇
  1989年   433篇
  1988年   401篇
  1987年   408篇
  1986年   401篇
  1985年   450篇
  1984年   360篇
  1983年   380篇
  1982年   322篇
  1981年   310篇
  1980年   320篇
  1979年   426篇
  1978年   334篇
  1977年   309篇
  1976年   264篇
  1975年   224篇
  1974年   241篇
  1973年   231篇
  1971年   221篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
This paper addresses several misunderstandings about the nature of the FBI's Central Records System. Although depicted in popular culture and much of FBI historiography as a tool for the Cold War suppression of American radicals, the FBI's records system grew out of Department of Justice systems already in place before J. Edgar Hoover became Director in 1924. The system grew in size and complexity according to the demands placed on it by the changing priorities of the FBI's criminal and intelligence missions, guided by a “progressive” drive for efficiency through centralization.  相似文献   
92.
The views of specialists (academics, librarians, publishers and information scientists) on trends in scholarly communications were canvassed by means of structured questions. A greater commonality of views was found than might have been expected.  相似文献   
93.
94.
OBJECTIVES: Medical Library Association (MLA) members were surveyed to gather background about the current state of expert searching in institutions. The survey results were intended to guide the recommendations of the Task Force on Expert Searching for promoting the importance of expert searching and implementing those recommendations. METHODS: MLA members were surveyed, and data obtained from the survey were compiled and analyzed to answer three general questions: what is the perceived value of searching skills to the institution, how do health sciences librarians maintain and improve their searching skills, and how are searching services promoted and/or mandated in the institution. RESULTS: There were 256 responses to the survey. Over 95% of the respondents saw their expert-searching skills were of value to their institutions, primarily through performing mediated searches and search consultations. Over 83% of the respondents believed that their searching skills had improved over the past 10 years. Most indicated that continued training was very important in maintaining and improving their skills. Respondents promoted searching services most frequently through orientations, brochures, and the libraries' Web pages. No respondent's institution mandated expert searching. Less than 2% of respondents' institutions had best practice guidelines related to expert searching, and only about 8% had guidelines or policies that identified situations where expert searching was recommended. CONCLUSIONS: The survey supports the belief that health sciences librarians still play a valuable role in searching, particularly in answering questions about treatment options and in providing education. It also highlights the need for more expert searching courses. There has been minimal discussion about the perceived need for expert-searching guidelines in the institutions represented by survey respondents.  相似文献   
95.
ABSTRACT

Lighting a cultural heritage artifact requires balancing visual perception with preventive conservation, by providing the best lighting (in terms of spectral distribution and quantity) to enable the viewer to appreciate details and color, while limiting photo-induced degradation. The paper outlines the methodology applied by a multi-disciplinary team while lighting the Shroud of Turin at its last public exhibition in 2015. The methodology considered the special requirements of the Shroud, including exposure to ultraviolet light, while providing appropriate display conditions that would meet audience expectations. The desired appearance (readability of the body image and color) was defined with the help of Shroud researchers and confirmed by subjective tests, while appropriate light levels for preservation were set in agreement with standard requirements and using knowledge of the degradation of linen in visible and UV light. The installation provided a controlled environment and a managed visitor route to the Shroud, assuring excellent perception of both details and color, with the lowest illuminance level about 15?lx.  相似文献   
96.
In 2008 Meier and Conkling first tested Google Scholar's coverage of the engineering literature against citations gathered from the Compendex database. Since that time, other studies have used the same methodology and found improvement in Google Scholar's coverage. This study uses engineering dissertations from Proquest Dissertations & Theses to create a data set of citations for the comparison of fee-based databases, Compendex and Scopus, against Google Scholar. From 1950 to 2017 Google Scholar outperformed both Compendex and Scopus in discoverability of citations in nine engineering subjects. These results have implications for collection management and information literacy program planning for librarians.  相似文献   
97.
ABSTRACT

The career path and significant professional accomplishments of librarian Valerie Bross (1954–2016) are described in this article. The awards and recognition she received are recounted and the influence of outside activities on her career is assessed. An attempt is made to capture what she was like as a professional, as well as what her unique characteristics were. A bibliography of her writings and a photograph are included.  相似文献   
98.
Inconsistency is often considered an indication of deceit. The conceptualization of consistency used in deception research, however, has not made a clear distinction between two concepts long differentiated by philosophers: coherence and correspondence. The existing literature suggests that coherence is not generally useful for deception detection. Correspondence, however, appears to be quite useful. The present research developed a model of how correspondence is utilized to make judgments, and this article reports on four studies designed to elaborate on the model. The results suggest that judges attend strongly to correspondence and that they do so in an additive fashion. As noncorrespondent information accumulates, an increasingly smaller proportion of judges make truthful assessments of guilty suspects. This work provides a basic framework for examining how information is utilized to make deception judgments and forms the correspondence and coherence module of truth-default theory.  相似文献   
99.
100.
Tracing the closure of oceans with irregular margins and the formation of an orocline are crucial for understanding plate reconstruction and continental assembly.The eastern Central Asian Orogenic Belt,where the Mongol-Okhotsk orocline is situated,is one of the world’s largest magmatic provinces.Using a large data set of U-Pb zircon ages,we updated the timing of many published igneous rocks,which allowed us to recognize tightly ’folded’ linear Carboniferous-Jurassic magmatic belts that wrap arou...  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