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   7640篇
  免费   71篇
  国内免费   41篇
教育   5066篇
科学研究   1661篇
各国文化   23篇
体育   266篇
综合类   277篇
文化理论   1篇
信息传播   458篇
  2024年   1篇
  2023年   21篇
  2022年   47篇
  2021年   151篇
  2020年   160篇
  2019年   682篇
  2018年   537篇
  2017年   262篇
  2016年   70篇
  2015年   280篇
  2014年   587篇
  2013年   549篇
  2012年   640篇
  2011年   649篇
  2010年   481篇
  2009年   427篇
  2008年   378篇
  2007年   455篇
  2006年   405篇
  2005年   274篇
  2004年   208篇
  2003年   198篇
  2002年   117篇
  2001年   80篇
  2000年   41篇
  1999年   11篇
  1998年   14篇
  1997年   10篇
  1996年   4篇
  1995年   3篇
  1994年   2篇
  1993年   1篇
  1992年   5篇
  1990年   1篇
  1989年   1篇
排序方式: 共有7752条查询结果,搜索用时 31 毫秒
21.
Searching online information resources using mobile devices is affected by small screens which can display only a fraction of ranked search results. In this paper we investigate whether the search effort can be reduced by means of a simple user feedback: for a screenful of search results the user is encouraged to indicate a single most relevant document. In our approach we exploit the fact that, for small display sizes and limited user actions, we can construct a user decision tree representing all possible outcomes of the user interaction with the system. Examining the trees we can compute an upper limit on relevance feedback performance. In this study we consider three standard feedback algorithms: Rocchio, Robertson/Sparck-Jones (RSJ) and a Bayesian algorithm. We evaluate them in conjunction with two strategies for presenting search results: a document ranking that attempts to maximize information gain from the user’s choices and the top-D ranked documents. Experimental results indicate that for RSJ feedback which involves an explicit feature selection policy, the greedy top-D display is more appropriate. For the other two algorithms, the exploratory display that maximizes information gain produces better results. We conducted a user study to compare the performance of the relevance feedback methods with real users and compare the results with the findings from the tree analysis. This comparison between the simulations and real user behaviour indicates that the Bayesian algorithm, coupled with the sampled display, is the most effective. Extended version of “Evaluating Relevance Feedback Algorithms for Searching on Small Displays, ” Vishwa Vinay, Ingemar J. Cox, Natasa Milic-Frayling, Ken Wood published in the proceedings of ECIR 2005, David E. Losada, Juan M. Fernández-Luna (Eds.), Springer 2005, ISBN 3-540-25295-9  相似文献   
22.
企业知识管理战略研究综述   总被引:4,自引:0,他引:4  
在对1997-2004年国内外部分核心期刊上发表的知识管理战略研究论文及代表性的知识管理战略著作进行系统检索和分析研究的基础上,对国内外有关知识管理战略的理论基础、内涵、基本流派、管理过程等理论研究现状和知识管理战略在不同企业与行业中的应用研究现状进行综述;结合知识管理战略未来的研究热点,指出我国知识管理战略研究目前存在的问题。  相似文献   
23.
哈佛大学自2007年重建工程与应用科学学院以来,采取了与传统工程学科大相径庭的发展路径,以解决人类面临重大挑战的前沿科学为重点发展方向,以机制保障为学科交叉融合提供土壤,以空间优化调整助力研究、孵化、成果转化一体化发展,取得了显著成绩。哈佛大学工学院发展路径正体现了新工科建设思路,对我国高校加快建设发展新工科,推动学科深度交叉融合,优化调整空间布局,服务科研创新、成果转化等具有重要启示。  相似文献   
24.
25.
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   
26.
Broad and discipline-specific information literacy competencies must be mastered by science, technology, engineering, and math (STEM) students. This study assessed changes in student perceptions of their competency in information literacy after continuous efforts in course curriculum. Data were gathered in 2015–2016 from first year interdisciplinary project-based courses with STEM students to assess changes in information literacy competencies. Analyses suggested there was a significant increase in students' perception of their familiarity with library resources, search strategies, citation use, and ability to evaluate source quality. There was no change in their perception of their ability to evaluate the variety of source and source relevance and a decrease in their perception of the ethical use of information. With faculty-librarian partnership and integrated instruction in a first year course, students showed the largest perceived increases in foundational information literacy skills but struggled with information literacy abilities. This study provides a baseline of information literacy competencies of first year students and provides recommendations for continuing education.  相似文献   
27.
Academic libraries invest millions of dollars to make electronic resources such as e-books available to students for free. However, free access might not necessarily result in students' sustained interest in and use of e-books. This interdisciplinary, mixed methods research investigates the factors influencing the intention of 279 undergraduate students to use e-books at a land-grant university in the southern US. Structural equation modeling of the survey responses suggests that organizational environment for information technology, external locus of control, subjective norm, perceived enjoyment (i.e., joyfulness), and information technology features play a significant role in influencing the intention of students to use e-books. Based on a combination of quantitative results and qualitative findings, this study identifies eight activities that libraries need to undertake in order to increase the use of e-books by undergraduate students.  相似文献   
28.
Autonomously motivated individuals tend to enjoy activities more than those who are extrinsically motivated, and they also tend to invest more effort. Grounded in basic psychological needs theory, the current study examines the motivation of students' autonomous information seeking and its relationship with the amount of effort invested in and enjoyment derived from information seeking. Autonomy support and perceived competence were found to explain 34.7% of the variance in autonomous motivation while autonomous motivation, in turn, explained 13.1% of variance in effort and 25.8% variance in enjoyment. The model indicates a positive relationship between basic psychological needs and autonomous motivation. Higher students' autonomy support and perceived competence levels lead to increases in autonomous motivation to seek information. Higher autonomous motivation levels, similarly, lead to higher levels of effort and enjoyment. Findings confirm that intrinsically motivated students enjoy information seeking more and invest more effort in the activity. This highlights the importance of encouraging students to engage in information seeking independently, while providing the necessary guidance that would increase their competence.  相似文献   
29.
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   
30.
The information practices of collaborative interdisciplinary researchers, especially in distributed environments, remain understudied. Embracing the naturalistic paradigm, this qualitative case study relies upon semi-structured interviews, snowball sampling, and grounded analysis. Based on interviews with 53 participants from 11 Digging Into Data 3 (DID3, 2014-2016) projects, this study examines the working practices of scholars (library and information science professionals, humanists, and computer scientists) engaging in collaborative, international, data-intensive, publicly-funded interdisciplinary research. Benefits of such work include avoiding redundancy, exploding disciplinary silos, and more ambitious, larger-scale outputs. Challenges and lessons learned center on innovation, flexibility, and failure, translation, intermediaries, divisions of labor and delegation of responsibilities and tasks, conflict resolution, technology, outputs and publication, and timeframe, sustainability, and infrastructure.  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