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   29344篇
  免费   388篇
  国内免费   74篇
教育   21167篇
科学研究   2614篇
各国文化   302篇
体育   2197篇
综合类   50篇
文化理论   182篇
信息传播   3294篇
  2021年   305篇
  2020年   409篇
  2019年   605篇
  2018年   830篇
  2017年   886篇
  2016年   832篇
  2015年   535篇
  2014年   755篇
  2013年   5627篇
  2012年   715篇
  2011年   753篇
  2010年   657篇
  2009年   599篇
  2008年   674篇
  2007年   618篇
  2006年   630篇
  2005年   558篇
  2004年   466篇
  2003年   436篇
  2002年   396篇
  2001年   756篇
  2000年   543篇
  1999年   466篇
  1998年   277篇
  1997年   299篇
  1996年   301篇
  1995年   249篇
  1994年   284篇
  1993年   239篇
  1992年   383篇
  1991年   366篇
  1990年   407篇
  1989年   387篇
  1988年   331篇
  1987年   328篇
  1986年   339篇
  1985年   369篇
  1984年   326篇
  1983年   306篇
  1982年   250篇
  1981年   258篇
  1980年   232篇
  1979年   343篇
  1978年   282篇
  1977年   229篇
  1976年   213篇
  1975年   210篇
  1974年   197篇
  1973年   204篇
  1971年   204篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Previous studies have shown that weeding a library collection benefits patrons and increases circulation rates. However, the time required to review the collection and make weeding decisions presents a formidable obstacle. This study empirically evaluated methods for automatically classifying weeding candidates. A data set containing 80,346 items from a large-scale weeding project running from 2011 to 2014 at Wesleyan University was used to train six machine learning classifiers to predict a weeding decision of either ‘Keep’ or ‘Weed’ for each candidate. The study found statistically significant agreement (p?=?0.001) between classifier predictions and librarian judgments for all classifier types. The naive Bayes and linear support vector machine classifiers had the highest recall (fraction of items weeded by librarians that were identified by the algorithm), while the k-nearest-neighbor classifier had the highest precision (fraction of recommended candidates that librarians had chosen to weed). The variables found to be most relevant were: librarian and faculty votes for retention, item age, and the presence of copies in other libraries.  相似文献   
82.
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   
83.
As academic libraries' budgets remain flat while their expenditures rise, library leaders must seek out alternative sources of funding. One option is a mandatory student fee dedicated to the library. This article presents the results of a survey of 152 deans and directors of public R1 and R2 research universities that were asked whether their libraries benefit from mandatory student fees. While a library-specific fee is unusual, nearly half of responding libraries are eligible to receive some portion of another mandatory student fee. Study results can serve as evidence for libraries preparing to make a case for the significant, positive impact possible through even a modest library fee.  相似文献   
84.
85.
The current state of the Russian Science Citation Index is analyzed. Several areas for its further development identified by long-standing active users, such as data searching, refinement, and storage; current user alerts; data input with the Science Index license; patent information; and the application programming interface (API) are investigated.  相似文献   
86.
The study explored the role of second-screen use and binge-watching in moderating entertainment education (EE) effects. A pretest/posttest experiment of 273 viewers of East Los High measured the effects of exposure to three subplots, concerning alcohol abuse, abortion, and immigration. The effect of identification with characters on change in attitudes was significantly moderated by second-screen use and binge-watching. In particular, second-screening tended to enhance the positive impact of identification; whereas, among respondents who binge-watched the show, the effects of identification were weaker.  相似文献   
87.
Is the reluctance to share bad news (i.e., the MUM effect) motivated more by a public display or private concern, and does it benefit mainly the messenger or the recipient? An experiment (N = 309) that crossed good/bad news with three communication channels (face-to-face, text messaging, e-mail) revealed that messenger reluctance was greatest under conditions of bad news and did not vary based on the channel through which the recipient contacted the messenger. In contrast with earlier work, this MUM effect was more consistent with a private fear of distressing the recipient. Theoretical implications and limitations are discussed.  相似文献   
88.
ABSTRACT

Course: Mixed-Method Communication Research Methods

Objective: The purpose of this semester-long activity is to provide students with opportunities to cultivate mixed-method communication research skills through a social justice-informed service-learning format. Completing this course, students will be able to: recognize the unique strengths of quantitative and qualitative research methods; locate, evaluate, and utilize scholarly literature for a literature review; conduct an original research project using quantitative and qualitative research methods to gather and analyze data; and raise self and community awareness about a social issue through collaboration with a community organization.  相似文献   
89.
双星滑动聚束模式合成孔径雷达(SAR)既保持了双星SAR的灵活性、可靠性和稳定性,同时还可产生高分辨率的图像对,对于观测和测绘具有巨大的潜力.这种模式下需要兼顾双星成像与多普勒带宽显著增加的问题.分析双星滑动聚束SAR系统下目标的多普勒特性,结合双星成像算法与频谱分析法,提出一种基于双曲等效的双星滑动聚束SAR 2步成...  相似文献   
90.
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