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   2480篇
  免费   44篇
  国内免费   3篇
教育   1735篇
科学研究   180篇
各国文化   57篇
体育   247篇
综合类   2篇
文化理论   34篇
信息传播   272篇
  2023年   11篇
  2022年   12篇
  2021年   29篇
  2020年   44篇
  2019年   67篇
  2018年   134篇
  2017年   115篇
  2016年   108篇
  2015年   77篇
  2014年   89篇
  2013年   541篇
  2012年   87篇
  2011年   80篇
  2010年   68篇
  2009年   68篇
  2008年   68篇
  2007年   59篇
  2006年   46篇
  2005年   52篇
  2004年   48篇
  2003年   42篇
  2002年   41篇
  2001年   26篇
  2000年   42篇
  1999年   26篇
  1998年   29篇
  1997年   28篇
  1996年   29篇
  1995年   33篇
  1994年   25篇
  1993年   33篇
  1992年   17篇
  1991年   12篇
  1990年   29篇
  1989年   15篇
  1988年   18篇
  1987年   18篇
  1986年   13篇
  1985年   20篇
  1984年   24篇
  1983年   15篇
  1982年   14篇
  1981年   17篇
  1980年   17篇
  1979年   12篇
  1978年   11篇
  1977年   10篇
  1974年   10篇
  1973年   12篇
  1972年   8篇
排序方式: 共有2527条查询结果,搜索用时 0 毫秒
141.
142.
143.
Although there has been a great deal of research into Collaborative Information Retrieval (CIR) and Collaborative Information Seeking (CIS), the majority has assumed that team members have the same level of unrestricted access to underlying information. However, observations from different domains (e.g. healthcare, business, etc.) have suggested that collaboration sometimes involves people with differing levels of access to underlying information. This type of scenario has been referred to as Multi-Level Collaborative Information Retrieval (MLCIR). To the best of our knowledge, no studies have been conducted to investigate the effect of awareness, an existing CIR/CIS concept, on MLCIR. To address this gap in current knowledge, we conducted two separate user studies using a total of 5 different collaborative search interfaces and 3 information access scenarios. A number of Information Retrieval (IR), CIS and CIR evaluation metrics, as well as questionnaires were used to compare the interfaces. Design interviews were also conducted after evaluations to obtain qualitative feedback from participants. Results suggested that query properties such as time spent on query, query popularity and query effectiveness could allow users to obtain information about team's search performance and implicitly suggest better queries without disclosing sensitive data. Besides, having access to a history of intersecting viewed, relevant and bookmarked documents could provide similar positive effect as query properties. Also, it was found that being able to easily identify different team members and their actions is important for users in MLCIR. Based on our findings, we provide important design recommendations to help develop new CIR and MLCIR interfaces.  相似文献   
144.
145.
146.
147.
A protocol of polymerase chain reaction-random amplified polymorphic DNAs (PCR-RAPDs) was established to analyse the gene diversity and genotype identification for clones of Sequoia sempervirens (D. Don) Endl. in Chile. Ten (out of 34) clones from introduction trial located in Voipir-Villarrica, Chile, were studied. The PCR-RAPDs technique and a modified hexadecyltrimethylammonium bromide (CTAB) protocol were used for genomic DNA extraction. The PCR tests were carried out employing 10-mer random primers. The amplification products were detected by electrophoresis in agarose gels. Forty nine polymorphic bands were obtained with the selected primers (BG04, BF07, BF12, BF13, and BF14) and were ordered according to their molecular size. The genetic similarity between samples was calculated by the Jaccard index and a dendrogram was constructed using a cluster analysis of unweighted pair group method using arithmetic averages (UPGMA). Of the primers tested, 5 (out of 60) RAPD primers were selected for their reproducibility and high polymorphism. A total of 49 polymorphic RAPD bands were detected out of 252 bands. The genetic similarity analysis demonstrates an extensive genetic variability between the tested clones and the dendrogram depicts the genetic relationships among the clones, suggesting a geographic relationship. The results indicate that the RAPD markers permitted the identification of the assayed clones, although they are derived from the same geographic origin. Project (No. CONICYT-FONDEF PROYECT D01 I 1008) supported by the National Commission of Science and Research of Chile  相似文献   
148.
All too often, strong opinions are held without regard to detailed knowledge of the subject involved. Current controversies show that the question of course content in professional broadcasting education is no exception. Regardless of the viewpoint held, a supply of adequate data relevant to the question should be welcomed by all. The Journal undertakes to supply as much data as possible relevant to broadcasting education, the most recent example being Harold Niven's “Fourth Annual Survey of Colleges and Universities Offering Course Work in Radio and Television, 1958–1959”; published in the Fallissue.  相似文献   
149.
150.
This study is designed to identify the underlying satisfaction dimensions gained through engagement in target shooting as a serious leisure pastime. The instrument design was based on the Leisure Satisfaction Scale. A total of 5502 useable surveys were collected through the Internet and a website related to target shooting and gun ownership. The results revealed eight dimensions: self-actualization, social interaction, location aesthetic, respite, physical benefit, connection and hedonic pleasure, which supplied the primary satisfiers of engaging in target shooting as a serious leisure activity. The demographic profile and dimensions of satisfaction may serve to dispel commonly held stereotypes of shooting hobbyists and those involved in gun ownership. The findings have important implications for leisure researchers and practitioners, to industry, both leisure and firearm related, and the target shooting community at large. This study adds to the literature of both target shooting and serious leisure.  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