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   2215篇
  免费   36篇
  国内免费   4篇
教育   1593篇
科学研究   274篇
各国文化   25篇
体育   118篇
综合类   1篇
文化理论   39篇
信息传播   205篇
  2022年   14篇
  2021年   24篇
  2020年   34篇
  2019年   52篇
  2018年   75篇
  2017年   62篇
  2016年   55篇
  2015年   40篇
  2014年   45篇
  2013年   600篇
  2012年   48篇
  2011年   49篇
  2010年   34篇
  2009年   31篇
  2008年   44篇
  2007年   27篇
  2006年   33篇
  2005年   32篇
  2004年   39篇
  2003年   38篇
  2002年   34篇
  2001年   20篇
  2000年   27篇
  1999年   30篇
  1998年   24篇
  1997年   20篇
  1996年   27篇
  1995年   15篇
  1994年   20篇
  1993年   20篇
  1992年   20篇
  1991年   17篇
  1990年   19篇
  1989年   22篇
  1988年   14篇
  1987年   19篇
  1986年   14篇
  1984年   15篇
  1983年   16篇
  1982年   18篇
  1981年   19篇
  1980年   22篇
  1979年   17篇
  1978年   21篇
  1976年   12篇
  1974年   14篇
  1972年   12篇
  1968年   14篇
  1967年   14篇
  1966年   12篇
排序方式: 共有2255条查询结果,搜索用时 46 毫秒
1.
2.
3.
In this paper a summary is given of the various processes which have been proposed for making the potash in the natural silicates available as a fertilizer.Experimental trials of a new rotary kiln process for treating feldspar are described, which depends upon a previous treatment before furnacing, consisting of a method of aggregating or clumping the mix so that chemical contact of the reacting substances is brought about during the subsequent processing. The qualitative and quantitative results obtained on a number of experimental trials on a mill scale of operation are presented and discussed. It is shown that it is possible to economically manufacture a potash fertilizer containing free lime from feldspar, and for a sufficiently low cost to make an industry based upon the method worthy of consideration.  相似文献   
4.
5.
6.
The American Hospital Association (AHA) Resource Center indexes journals for the Health Planning and Administration (HEALTH) database and Hospital Literature Index (HLI). These journals, designated special list health journals, are selected to provide access to a wide and balanced coverage of hospital and health care administration and health policy literature. This article provides background information on HEALTH and HLI and describes special list health journals in detail (including historical information, information sources, and broad subject divisions). It also discusses AHA policies relating to journal and article selection and current subject distribution of special list health journals.  相似文献   
7.
Governments worldwide are increasingly using Web-based business models to enhance their service delivery. Yet the concept of the business model is unexplored within the context of e-government. Drawing upon the literature on e-commerce, we develop a taxonomy for analyzing Web-based business models for e-government. Based on a systematic survey of 59 e-government Web sites in the Netherlands, our findings indicate that most of the Web sites use the content provider or direct-to-customer business models, while only a few are using novel business models. Overall, the concept of business model is appealing and useful in the public sector. Specifically it compliments research on Web site quality by analyzing and describing Web sites using atomic e-government business models and suggesting improvements by using combinations of business models.  相似文献   
8.
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   
9.
Academic libraries and consortia are spending the vast majority of their material budgets on digital content, including ebooks. A review of ebook preservation activities for the North American library consortia is provided along with a look at the major preservation services such as Portico, CLOCKSS and HathiTrust. Publishers and ebook aggregators are also examined to provide a broad environmental scan of the current ebook preservation activities and risks.  相似文献   
10.
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