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   20006篇
  免费   248篇
  国内免费   56篇
教育   14702篇
科学研究   1514篇
各国文化   238篇
体育   1368篇
综合类   45篇
文化理论   124篇
信息传播   2319篇
  2021年   198篇
  2020年   255篇
  2019年   391篇
  2018年   563篇
  2017年   590篇
  2016年   558篇
  2015年   357篇
  2014年   496篇
  2013年   4196篇
  2012年   481篇
  2011年   509篇
  2010年   446篇
  2009年   453篇
  2008年   458篇
  2007年   430篇
  2006年   461篇
  2005年   394篇
  2004年   295篇
  2003年   284篇
  2002年   266篇
  2001年   408篇
  2000年   332篇
  1999年   284篇
  1998年   204篇
  1997年   195篇
  1996年   212篇
  1995年   193篇
  1994年   204篇
  1993年   186篇
  1992年   274篇
  1991年   260篇
  1990年   272篇
  1989年   256篇
  1988年   219篇
  1987年   229篇
  1986年   232篇
  1985年   231篇
  1984年   218篇
  1983年   207篇
  1982年   191篇
  1981年   170篇
  1980年   177篇
  1979年   234篇
  1978年   191篇
  1977年   137篇
  1976年   153篇
  1975年   148篇
  1974年   124篇
  1973年   126篇
  1971年   131篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
OBJECTIVES: The purpose of this study is to determine how personal digital assistants (PDAs) are used on an academic health sciences campus to define the level of training and support the library can provide to the students and faculty. METHOD: A Web-based questionnaire was developed. A total of 1,538 health sciences faculty and residents were sent an email message requesting participation. Data from the returned surveys were analyzed with SPSS. RESULTS: Sixty-one percent of survey respondents used PDAs. The address book, date book, and calculator were the most common uses reported for PDAs. Residents also reported a high use of drug databases on their PDAs. Most survey respondents indicated they would like to learn more about clinical resources for PDAs. CONCLUSIONS: Many opportunities exist for librarians to provide training and support for PDAs, in addition to evaluation and promotion of clinical software for PDAs.  相似文献   
52.
PURPOSE: The purpose was to determine the impact of online journals on the citation patterns of medical faculty. This study looked at whether researchers were more likely to limit the resources they consulted and cited to those journals available online rather than those only in print. SETTING: Faculty publications from the college of medicine at a large urban university were examined for this study. The faculty publications from a regional medical college of the same university were also examined in the study. The number of online journals available for faculty, staff, and students at this institution has increased from an initial core of 15 online journals in 1998 to over 11,000 online journals in 2004. METHODOLOGY: Searches by author affiliation were performed in the Web of Science to find all articles written by faculty members in the college of medicine at the selected institution. Searches were conducted for the following years: 1993, 1996, 1999, and 2002. Cited references from each faculty-authored article were recorded, and the corresponding cited journals were coded into four categories based on their availability at the institution in this study: print only, print and online, online only, and not owned. Results were analyzed using SPSS. RESULTS: The number of journals cited per year continued to increase from 1993 to 2002. The results did not indicate that researchers were more likely to cite online journals or were less likely to cite journals only in print. At the regional location where the number of print-only journals was minimal, use of the print-only journals did decrease in 2002, although not significantly. CONCLUSION/DISCUSSION: It is possible that electronic access to information (i.e., online databases) has had a positive impact on the number of articles faculty will cite. Results of this study suggest, at this point, that faculty are still accessing the print-only collection, at least for research purposes, and are therefore not sacrificing quality for convenience.  相似文献   
53.
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   
54.
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   
55.
56.
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   
57.
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   
58.
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   
59.
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   
60.
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