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   43457篇
  免费   775篇
  国内免费   487篇
教育   28976篇
科学研究   5580篇
各国文化   257篇
体育   3447篇
综合类   1092篇
文化理论   354篇
信息传播   5013篇
  2022年   434篇
  2021年   824篇
  2020年   784篇
  2019年   846篇
  2018年   1593篇
  2017年   1632篇
  2016年   1328篇
  2015年   1102篇
  2014年   1559篇
  2013年   5564篇
  2012年   2062篇
  2011年   2346篇
  2010年   2037篇
  2009年   1829篇
  2008年   1860篇
  2007年   2010篇
  2006年   1647篇
  2005年   1522篇
  2004年   1065篇
  2003年   1024篇
  2002年   979篇
  2001年   1013篇
  2000年   768篇
  1999年   591篇
  1998年   359篇
  1997年   324篇
  1996年   335篇
  1995年   272篇
  1994年   215篇
  1993年   246篇
  1992年   359篇
  1991年   321篇
  1990年   317篇
  1989年   314篇
  1988年   257篇
  1987年   305篇
  1986年   269篇
  1985年   309篇
  1984年   249篇
  1983年   219篇
  1982年   192篇
  1981年   165篇
  1980年   155篇
  1979年   260篇
  1978年   182篇
  1977年   168篇
  1976年   156篇
  1975年   142篇
  1974年   147篇
  1971年   140篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
我国博物馆文创产品存在偏重消费者喜好和追求利润而忽视消费者文化需求差异的问题。本文通过对博物馆及其文化服务产品基本功能的深入分析,提出博物馆文创产品是博物馆教育的延伸,博物馆文创产品应该具有知识、文化、精神及能力内涵,评价博物馆文创产品的标准应强调满足公众的学习需求、引发公众的学习动机、激发学习行为的产生,并可以从文创产品的可读性、可操作性、可探究性三方面开展研发设计。北京自然博物馆的“中国恐龙展拼插模型”,以上述理念和思路进行开发设计,获得了市场和业界的认可。  相似文献   
992.
Satisfying clinical information needs remains a major challenge in medicine, underscored by recent studies showing high medical error rates and suboptimal physician adherence to evidence-based practice guidelines. Advanced clinical decision support systems can improve practitioner performance and patient outcomes. Similarly, integrating online information resources into electronic health records (EHRs) shows great potential for positively impacting health care quality. This paper explores the evolution and current status of knowledge-based resource linkages within EHRs, including the benefits and drawbacks, as well as the important role librarians can play in this process.  相似文献   
993.
Intelligent use of the many diverse forms of data available on the Internet requires new tools for managing and manipulating heterogeneous forms of information. This paper uses WHIRL, an extension of relational databases that can manipulate textual data using statistical similarity measures developed by the information retrieval community. We show that although WHIRL is designed for more general similarity-based reasoning tasks, it is competitive with mature systems designed explicitly for inductive classification. In particular, WHIRL is well suited for combining different sources of knowledge in the classification process. We show on a diverse set of tasks that the use of appropriate sets of unlabeled background knowledge often decreases error rates, particularly if the number of examples or the size of the strings in the training set is small. This is especially useful when labeling text is a labor-intensive job and when there is a large amount of information available about a particular problem on the World Wide Web.
Haym HirshEmail:
  相似文献   
994.
This article describes the first half century of the Communist government’s supervision and management of the central-government archives of the last two dynasties. Immediately with the Communist ascent to power in 1949, the new government took great interest in assembling and protecting the country’s archival documents, readying the Ming-Qing archives for access to scholars, and preparing for publication of selected materials. By the 1980s Beijing’s Number One Historical Archives, in charge of the largest holding of Ming-Qing documents, had become the first Chinese authority to complete a full sorting and preliminary catalogues for such a collection. Moreover, to facilitate searches, an attempt has recently begun to create a subject-heading system for these and other holdings in the country. In the first half century’s final decades, foreign researchers were admitted for the first time and tours and international exchanges began to take place.
Beatrice S. BartlettEmail:
  相似文献   
995.
Previous papers on grey literature by the authors have described (1) the need for formal metadata to allow machine understanding and therefore scalable operations; (2) the enhancement of repositories of grey (and other) e-publications by linking with CRIS (Current Research Information Systems); (3) the use of the research process to collect metadata incrementally reducing the threshold barrier for end-users and improving quality in an ambient GRIDs environment. This paper takes the development one step further and proposes “intelligent” grey objects. The hypothesis is in 2 parts: (1) that the use of passive catalogs of metadata does not scale (a) in a highly distributed environment with millions of nodes and (b) with vastly increased volumes of R&D output grey publications with associated metadata; (2) that a new paradigm is required that (a) integrates grey with white literature and other R&D outputs such as software, data, products and patents (b) in a self-managing, self-optimizing way and that this paradigm manages automatically curation, provenance digital rights, trust, security and privacy. Concerning (1) existing repositories provide catalogs; harvesting takes increasing time ensuring non-currency. The end-user expends much manual effort/intelligence to utilize the results. The elapsed time of (1) the network (2) the centralized (or centrally controlled distributed) catalog server searches (3) end-user intervention becomes unacceptable. Concerning (2) there is no paradigm currently known to the authors that satisfies the requirement. Our proposal is outlined below. Hyperactive combines both hyperlinking and active properties of a (grey) object. Hyperlinking implies multimedia components linked to form the object and also external links to other resources. The term active implies that objects do not lie passively in a repository to be retrieved by end-users. They “get a life” and the object moves through the network knowing where it is going. A hyperactive grey object is wrapped by its (incrementally recorded) formal metadata and an associated (software) agent. It moves through process steps such as initial concept, authoring, reviewing and depositing in a repository. The workflow is based on the rules and information in the corporate data repository with which the agent interacts. Once the object is deposited, the agent associated with it actively pushes the object to the end-users (or systems) whose metadata indicate interest or an obligation in a workflowed process. The agents check the object and user (or system) metadata for rights, privacy, security parameters, and for any charges and assure compatibility. Alternatively the object can be found passively by end-user or system agents. The object can also associate itself with other objects forming relationships utilising metadata or content. Declared relationships include references and citations; workflowed relationships include versions and also links to corporate information and research datasets and software; inferenced relationships are discovered relationships such as between documents by different authors developed from an earlier idea of a third author. Components of this paradigm have been implemented to some extent. The challenge is implementing—respecting part two of the hypothesis—the integration architecture. This surely is harnessing the power of grey.
Anne AssersonEmail:
  相似文献   
996.
BACKGROUND: This study was undertaken to provide evidence that library outreach projects in the NHS in the Thames Valley Strategic Health Authority area were effective and could justify continued funding. Objectives: The object was to assess whether information literacy skills training taken up by health professionals impacts on their confidence and skills in using electronic sources of health information. METHOD: A total of 487 health professionals taking up training on a voluntary basis were assessed by completing a self-assessment questionnaire prior to and after training to establish their information literacy skills and confidence levels. Of these, 223 trainees (46%) also returned 6-week follow-up questionnaires. RESULTS: Results showed that 464 trainees (95%) intended to apply what they had learnt in a variety of ways; use of specific resources greatly increased after training and confidence in using them increased substantially. Use of search techniques increased considerably overall, whereas use of Google decreased. CONCLUSIONS: The major findings of this research are that training health-care personnel in the use of electronic resources impacts positively on their information literacy skills and confidence, and that the information available to them is considered to have potential value across health-care practice.  相似文献   
997.
998.
We used an appetitive sensory preconditioning procedure to investigate temporal integration in rats in two experiments. In Phase 1, rats were presented with simultaneous compound trials on which a 10-sec conditioned stimulus (CS) X was embedded within a 60-sec CS A. In Group Early, CS X occurred during the early portion of CS A, whereas in Group Late, CS X occurred during the latter portion of CS A. In Phase 2, CS X was paired simultaneously with sucrose. On a subsequent test with CS A, the rate of magazine entries peaked during the early portions of the stimulus in Group Early and during the latter portions of the stimulus in Group Late (Experiments 1 and 2). Similar response peaks were not observed on tests with a control stimulus that had been presented in compound with a stimulus that did not signal reward (Experiment 2).  相似文献   
999.
In two experiments, participants inspected and drank a series of drinks, half of which contained sugar and half unpalatable Tween20 (tween). Each sugar and tween drink had a particular flavor and color. Following this training, the flavors of the sugar drinks were assigned higher hedonic evaluations than were those of the tween drinks, even though the participants did not reliably report which flavors had been present in the sugar and tween drinks during training. Moreover, the evaluative conditioning of the flavors was unaffected by whether or not the colors alone had been pretrained to predict the presence of sugar or tween in the drinks. In accord with Baeyens, Eelen, van den Bergh, and Crombez (1990), we conclude that flavor-evaluative conditioning is not mediated by contingency learning.  相似文献   
1000.
In four experiments with rats, we examined the persistence of behavior when reinforcement was switched from immediate to delayed. In Experiment 1, lever pressing elicited by instrumental training with immediate reinforcement continued when a 20-sec delay of reinforcement was introduced (easy-to-hard condition), whereas when the delay condition was introduced from the start (hard-to-hard condition), responding remained low throughout. A similar result was obtained in Experiment 2, in which lever pressing was elicited by a classical conditioning (autoshaping) procedure. In Experiment 3, rats initially trained with delayed reinforcement continued to respond at a low rate when switched to immediate reinforcement (hard-to-easy condition). By measuring magazine entry (goal tracking) as well as lever pressing (sign tracking) in Experiment 4, we confirmed that such transfer effects at least partly involve the persistence of whatever type of behavior was initially dominant.  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