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   37435篇
  免费   415篇
  国内免费   16篇
教育   27395篇
科学研究   3263篇
各国文化   281篇
体育   2505篇
综合类   14篇
文化理论   576篇
信息传播   3832篇
  2022年   196篇
  2021年   306篇
  2020年   453篇
  2019年   699篇
  2018年   3043篇
  2017年   2956篇
  2016年   2391篇
  2015年   666篇
  2014年   896篇
  2013年   5257篇
  2012年   979篇
  2011年   1464篇
  2010年   1381篇
  2009年   1001篇
  2008年   1275篇
  2007年   1710篇
  2006年   556篇
  2005年   859篇
  2004年   893篇
  2003年   776篇
  2002年   530篇
  2001年   522篇
  2000年   456篇
  1999年   408篇
  1998年   242篇
  1997年   260篇
  1996年   282篇
  1995年   263篇
  1994年   216篇
  1993年   230篇
  1992年   356篇
  1991年   332篇
  1990年   319篇
  1989年   311篇
  1988年   272篇
  1987年   314篇
  1986年   281篇
  1985年   321篇
  1984年   261篇
  1983年   227篇
  1982年   202篇
  1981年   178篇
  1980年   166篇
  1979年   266篇
  1978年   192篇
  1977年   172篇
  1976年   161篇
  1975年   150篇
  1974年   155篇
  1971年   140篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
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   
83.
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   
84.
85.
86.
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   
87.
The issues related to funding of public research organizations are explored. The history of scientometric information systems is outlined. The advantages and disadvantages of a bibliometric approach to financing of research organizations are analyzed. The link between the assessment of the scientific and technological potential of an institution and the optimal allocation of funds is investigated. Recommendations on how to improve the efficiency of public resources allocated for scientific research are presented.  相似文献   
88.
Modern global eco-dynamics problems are discussed. It is noted that global changes are mostly characterized by several key features, such as their multicomponent nature, as well as interactivity and nonlinearity. These features challenge various forecast estimates in such a way that the concept of forecasting has been replaced over the last few years by a much more ambiguous concept of scenarios. The vagueness of scenarios is due to the problem of global climate change. A global climate–nature–society system model is outlined.  相似文献   
89.
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   
90.
History and case study are two diachronic research strategies commonly used to study political discourse as it relates to public libraries. Though suitable for some studies, these strategies are inexhaustive. A new, blended research strategy is therefore needed to accomplish what history and case study alone cannot. This hybrid strategy, historical case study, must analyze cases from the distant past to the present, using eclectic data sources, in order to produce both idiographic and nomothetic knowledge. To develop historical case study, the universal components of diachronic analysis are first identified. A general research design for historical case study is then introduced. Finally, historical case study is tested in an actual research project. Findings from this project reveal that historical case study is a successful diachronic research strategy. Historical case study is a new and valuable research design suitable for addressing questions related to change, continuity, development, and evolution.  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