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   38761篇
  免费   578篇
  国内免费   134篇
教育   27432篇
科学研究   4137篇
各国文化   323篇
体育   2981篇
综合类   23篇
文化理论   372篇
信息传播   4205篇
  2022年   244篇
  2021年   345篇
  2020年   558篇
  2019年   865篇
  2018年   1656篇
  2017年   1630篇
  2016年   1390篇
  2015年   660篇
  2014年   918篇
  2013年   6756篇
  2012年   946篇
  2011年   1143篇
  2010年   898篇
  2009年   803篇
  2008年   898篇
  2007年   940篇
  2006年   653篇
  2005年   713篇
  2004年   680篇
  2003年   640篇
  2002年   565篇
  2001年   669篇
  2000年   631篇
  1999年   574篇
  1998年   326篇
  1997年   343篇
  1996年   404篇
  1995年   383篇
  1994年   288篇
  1993年   323篇
  1992年   493篇
  1991年   481篇
  1990年   495篇
  1989年   516篇
  1988年   433篇
  1987年   488篇
  1986年   446篇
  1985年   511篇
  1984年   435篇
  1983年   395篇
  1982年   341篇
  1981年   318篇
  1980年   294篇
  1979年   464篇
  1978年   351篇
  1977年   323篇
  1976年   286篇
  1975年   252篇
  1974年   269篇
  1973年   246篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
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   
182.
This research analyzed a dataset of academic libraries' posts on Facebook. It applied a text and data analytics approach to a dataset collected from the Facebook posts of academic libraries at the top 100 English-speaking universities, as listed by the 2014 Shanghai World University Rankings. The dataset is from a two-year posting history of 18,333 unique posts, 113,621 likes, and 3401 comments. Less than a quarter of the libraries had more than 2000 post-related likes, and only seven received more than 100 comments on their postings. Content analysis identified the most prevalent single word (unigrams), bigrams (two-word sequences), and trigrams (three-word sequences) in high and low engagement content. Semantic analysis identified the semantic categories for posts with high and low engagement. The findings can assist academic libraries in their social media strategies for engagement, marketing, and visibility.  相似文献   
183.
The purpose of this ecological study was to examine the impact of a library credit course on graduation rates and GPA using pre-existing records. Over 20?years of aggregate institutional data were analyzed to evaluate the course's impact on first-time-full-time, white, and black students. Results were mixed: students who took the course were less likely to graduate than their peers who did not take the course but enjoyed slightly higher GPAs at graduation. It was discovered that students taking the course are not representative of the overall student body and struggle academically. Implications for revisions to the library credit course are discussed.  相似文献   
184.
This paper analyses the publication patterns of researchers in the field of applied sciences at Universities of Technology in South Africa. Aspects investigated include publications in SCOPUS-listed journals; number of citations and countries of publication. Collaborative research patterns at national and international levels were also investigated. A bibliometric analysis approach was followed using SCOPUS as the main source of data and analysing the articles published in selected applied science disciplines. Results show that researchers in the field of applied sciences in universities of technology have increased their number of publications over the past 10?years and are also working in conjunction with other researchers both nationally and internationally. The analysis is an important addition to the field in South Africa which helps in measuring how institutions are positively responding to government incentives in research. The results are also important to information professionals who are increasingly playing an important role in research impact assessments.  相似文献   
185.
186.
187.
This paper identifies individuals’ accumulated history with Information and Communication Technologies (ICTs) as a replacement for the contested and outdated term ‘digital divide.’ We propose that an individual’s ability to benefit from their technological history consists of four factors: awareness, knowledge, access, and technological capacity of the user’s social collective. Together, these factors make up the individual’s level or amount of Technological Capital. The development of this construct was based on empirical research conducted in Soweto, South Africa, and through an analysis of the literature on assessing individuals’ accumulated histories. The concept of technological capital has the potential for application in fields in which ICTs are used for communication, capacity building, and identifying barriers to adoption of new technologies. The use of the concept may have implications for policy decisions, resource allocation, and future research into differences among individuals’ and communities’ ability to benefit from the introduction of new technologies.  相似文献   
188.
189.
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   
190.
Although the USSR and the United States had a comparable number of employees in the field of scientific information, there was a substantial difference in funding, which resulted in a lack of information support for Soviet scientists. While 90% of the publications in the United States were available almost immediately after their release, in the USSR they were delayed by 1.5 to 2 years. Since the publication of the Abstracts Journal by VINITI (AJ), its content was consistently expanding and reached its peak in 1990 (1.5 million documents per year). The next quarter of a century was characterized by a decline in both the composition of the AJ and the time required for its document coverage. The steps for restructuring VINITI activities are discussed. The focus is made on improving the limited coverage of the Russian-language part of the global flow of scientific information by Western information systems.  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