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   16620篇
  免费   284篇
  国内免费   13篇
教育   11346篇
科学研究   1425篇
各国文化   220篇
体育   1793篇
综合类   23篇
文化理论   132篇
信息传播   1978篇
  2021年   140篇
  2020年   279篇
  2019年   402篇
  2018年   465篇
  2017年   523篇
  2016年   509篇
  2015年   332篇
  2014年   412篇
  2013年   3082篇
  2012年   351篇
  2011年   390篇
  2010年   303篇
  2009年   332篇
  2008年   332篇
  2007年   309篇
  2006年   289篇
  2005年   258篇
  2004年   496篇
  2003年   401篇
  2002年   405篇
  2001年   272篇
  2000年   275篇
  1999年   224篇
  1998年   118篇
  1997年   139篇
  1996年   164篇
  1995年   155篇
  1994年   148篇
  1993年   137篇
  1992年   195篇
  1991年   201篇
  1990年   177篇
  1989年   225篇
  1988年   190篇
  1987年   216篇
  1986年   186篇
  1985年   242篇
  1984年   203篇
  1983年   180篇
  1982年   158篇
  1981年   144篇
  1980年   114篇
  1979年   184篇
  1978年   150篇
  1977年   128篇
  1976年   142篇
  1975年   107篇
  1974年   125篇
  1973年   97篇
  1971年   110篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
131.
This paper describes the procedures used at the Library of the College of Physicians of Philadelphia to divide its ninety-year-old dictionary card catalog. The division was necessitated by overcrowding, obsolete subject headings, and lack of a complete authority list which resulted in like materials being scattered throughout the catalog under several headings. Two catalogs were created: the historical-biographical catalog, representing all works published before 1950 and all works of historical or biographical nature; and the current catalog, containing all works published from 1950 on, excepting historical or biographical materials. The 1950- catalog was further divided into name and subject catalogs, and the subject section was revised according to MeSH. The project was completed in about two years. As a result, searching time has been much reduced, and the library is able to take advantage of the annual revisions of MeSH to update the subject catalog.  相似文献   
132.
133.
Millions of Canadians residing in Canada's northern, isolated, rural, and remote communities do not have broadband Internet access. This situation has led to a national “broadband divide.” That is, the deployment of wireline broadband is very limited in Canada's northern, isolated, rural, and remote areas because of the significant expense of installation and maintenance of the wired infrastructure needed to reach dwellings in these locations.Terrestrial broadband wireless technology, on the other hand, does not entail the same kind of physical infrastructure. As a result, there are dramatic changes in how spatial considerations affect the provision of broadband Internet services (BIS) to areas beyond the urban zone. In particular, the spatial question is now focused on assessing the capacity for different technological solutions to reach profitable population bases, and brings to the forefront organizations that are developing non-line-of-sight (NLOS) technologies that would permit wireless Internet access over much greater distances than current solutions.We begin this paper by establishing the importance of broadband connectivity to Canada's northern, isolated, rural, and remote communities. This discussion comments on the role of the Government of Canada in the provision of broadband connectivity to residents of these communities, and outlines the current regulatory issues that govern wireless services and policy formulation.The second part of the paper illustrates the use of geographic information system (GIS) approaches in the study of wireless broadband planning and deployment. Case study findings suggest that GIS applications can make a significant contribution to the analysis of wireless deployment planning, to the understanding of the relationships between wireless signal sources and consumers, and to the spatial configuration of terrestrial wireless broadband networks. We conclude the paper by discussing how the GIS approach employed could be used to inform the public policy process with regard to increasing access to broadband Internet services in all regions of the country, and thereby providing the opportunity for all Canadians, regardless of location, to fully participate in the Information Society.  相似文献   
134.
Drawing on components of agenda-setting theory and the two-step flow of information from mass media to news audiences, this study examines the effects of mass and interpersonal communication on breast cancer screening practices among college- and middle-aged women (n = 284). We theorized that screening behaviors among younger women would be influenced more by interpersonal sources of information while screening among middle-aged women would be more influenced by exposure to mass-mediated information. Findings supported anticipated patterns, revealing important and varying roles for both mass and interpersonal communication in the health behaviors of women. Implications for health practitioners and campaign planners, as well as recommendations for future research, are discussed.  相似文献   
135.
136.
PURPOSE: This study describes the system architecture and user acceptance of a suite of programs that deliver information about newly updated library resources to clinicians' personal digital assistants (PDAs). DESCRIPTION: Participants received headlines delivered to their PDAs alerting them to new books, National Guideline Clearinghouse guidelines, Cochrane Reviews, and National Institutes of Health (NIH) Clinical Alerts, as well as updated content in UpToDate, Harrison's Online, Scientific American Medicine, and Clinical Evidence. Participants could request additional information for any of the headlines, and the information was delivered via e-mail during their next synchronization. Participants completed a survey at the conclusion of the study to gauge their opinions about the service. RESULTS/OUTCOME: Of the 816 headlines delivered to the 16 study participants' PDAs during the project, Scientific American Medicine generated the highest proportion of headline requests at 35%. Most users of the PDA Alerts software reported that they learned about new medical developments sooner than they otherwise would have, and half reported that they learned about developments that they would not have heard about at all. While some users liked the PDA platform for receiving headlines, it seemed that a Web database that allowed tailored searches and alerts could be configured to satisfy both PDA-oriented and e-mail-oriented users.  相似文献   
137.
Scale and Translation Invariant Collaborative Filtering Systems   总被引:1,自引:0,他引:1  
Collaborative filtering systems are prediction algorithms over sparse data sets of user preferences. We modify a wide range of state-of-the-art collaborative filtering systems to make them scale and translation invariant and generally improve their accuracy without increasing their computational cost. Using the EachMovie and the Jester data sets, we show that learning-free constant time scale and translation invariant schemes outperforms other learning-free constant time schemes by at least 3% and perform as well as expensive memory-based schemes (within 4%). Over the Jester data set, we show that a scale and translation invariant Eigentaste algorithm outperforms Eigentaste 2.0 by 20%. These results suggest that scale and translation invariance is a desirable property.  相似文献   
138.
Organizational communication scholars are increasingly called upon to use theoretical knowledge to address problematic processes in public institutions. This article reports a process improvement project focused on a university conflict of interest (COI) policy as an example of how scholars can engage theory to improve ongoing policy processes. The project team included communication scholars and research administration staff who designed, implemented, and evaluated the mixed-methods project guided by structurating activity theory. Baseline survey results were used to design the process improvement project. Results of the follow-up survey indicate that researchers who participated in some aspect of the process improvement project (i.e. attending a policy café, using the redesigned website, or reading the new Quick Reference Guide) reported higher levels of policy communication and knowledge and more positive attitudes toward the COI policy than researchers who had not engaged with process improvement efforts. We offer theoretical and practical implications of results for organizational communication scholars and practitioners.  相似文献   
139.
Academic libraries are increasingly seeking ways to demonstrate their impact on student learning. Acknowledgments - formal statements of indebtedness – in graduate theses and dissertations provide a rather unexplored area for demonstrating impact of the academic library on student learning. This study uses quantitative and qualitative methods to characterize acknowledgments of the Texas A&M University Libraries (TAMU Libraries) in theses and dissertations, both overall and for three disciplines specifically: civil engineering, geography, and history. This study also searched for mentions of the TAMU Libraries throughout the entire body of theses and dissertations. Overall, acknowledgments to the TAMU Libraries in theses and dissertations were less than 1%, though acknowledgments were found in all three disciplines with over a quarter of the history theses and dissertations containing an acknowledgment to libraries. There was no statistically significant difference found between the numbers of acknowledgments in theses versus dissertations. Acknowledgments to the TAMU Libraries were found in the theses and dissertations of 28 different departments. Mentions to the TAMU Libraries – not necessarily a formal acknowledgment – were found throughout the text of theses and dissertations with most concentrated in the acknowledgment, method, and bibliography sections.  相似文献   
140.
ABSTRACT

Social media is a powerful tool for building an online presence, but it asks a lot. While it affords plentiful opportunities for professional development and networking, building a professional brand in an online space is not without its drawbacks and risks. By working from a set of actionable principles and benchmarks, users can minimize frustrations and setbacks to build a useful professional presence, all while imbuing the web with the tenets of good information stewardship.  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