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   9769篇
  免费   100篇
  国内免费   5篇
教育   6638篇
科学研究   1331篇
各国文化   60篇
体育   701篇
综合类   7篇
文化理论   95篇
信息传播   1042篇
  2022年   42篇
  2021年   84篇
  2020年   105篇
  2019年   168篇
  2018年   255篇
  2017年   312篇
  2016年   360篇
  2015年   232篇
  2014年   219篇
  2013年   1250篇
  2012年   306篇
  2011年   319篇
  2010年   218篇
  2009年   156篇
  2008年   225篇
  2007年   210篇
  2006年   165篇
  2005年   797篇
  2004年   616篇
  2003年   409篇
  2002年   228篇
  2001年   186篇
  2000年   179篇
  1999年   166篇
  1998年   66篇
  1997年   54篇
  1996年   74篇
  1995年   67篇
  1994年   63篇
  1993年   57篇
  1992年   119篇
  1991年   97篇
  1990年   89篇
  1989年   126篇
  1988年   83篇
  1987年   81篇
  1986年   89篇
  1985年   106篇
  1984年   78篇
  1983年   79篇
  1982年   80篇
  1981年   62篇
  1980年   65篇
  1979年   80篇
  1978年   76篇
  1977年   63篇
  1976年   64篇
  1974年   51篇
  1973年   45篇
  1969年   42篇
排序方式: 共有9874条查询结果,搜索用时 15 毫秒
51.
Automatic detection of source code plagiarism is an important research field for both the commercial software industry and within the research community. Existing methods of plagiarism detection primarily involve exhaustive pairwise document comparison, which does not scale well for large software collections. To achieve scalability, we approach the problem from an information retrieval (IR) perspective. We retrieve a ranked list of candidate documents in response to a pseudo-query representation constructed from each source code document in the collection. The challenge in source code document retrieval is that the standard bag-of-words (BoW) representation model for such documents is likely to result in many false positives being retrieved, because of the use of identical programming language specific constructs and keywords. To address this problem, we make use of an abstract syntax tree (AST) representation of the source code documents. While the IR approach is efficient, it is essentially unsupervised in nature. To further improve its effectiveness, we apply a supervised classifier (pre-trained with features extracted from sample plagiarized source code pairs) on the top ranked retrieved documents. We report experiments on the SOCO-2014 dataset comprising 12K Java source files with almost 1M lines of code. Our experiments confirm that the AST based approach produces significantly better retrieval effectiveness than a standard BoW representation, i.e., the AST based approach is able to identify a higher number of plagiarized source code documents at top ranks in response to a query source code document. The supervised classifier, trained on features extracted from sample plagiarized source code pairs, is shown to effectively filter and thus further improve the ranked list of retrieved candidate plagiarized documents.  相似文献   
52.
53.
Nullis in verba was chosen as the motto of the Royal Society, as it embodied the culture of transparency and collaboration that were the hallmarks of the Royal Society and of the scientific method it promoted. Communication, using the tools of the day, was essential to this community of scientists as they created and shared new knowledge. Almost three hundred years later, libraries continue to advance principles relating to the importance of collaboration and transparency. This two-part article series, published jointly in International Information and Library Review and Technical Services Quarterly explores notions of transparency and collaboration in research and how these ideas are impacting the world of librarianship – from information creation, organization and access perspectives.  相似文献   
54.
The mere perception that news has given certain problems more coverage can lead the audience to assume that those problems are more important. Given that the news media, at times, obsesses over relatively trivial matters, and given that the audience is increasingly able to filter media exposure, it is worth asking what happens when audience members perceive that recent media coverage has not emphasized any very important problems. In such cases, audience members might assume that any problems facing the nation must not be particularly important. We explicate this attitude of political complacency, test whether perceived media agendas lacking important problems can influence it, and explore whether complacency helps explain political disengagement. We also explore whether these effects generalize beyond news, to new media gatekeepers such as Twitter. Two experiments tested effects of a perceived absence of important problems in recent news or Twitter content. In the case of news, but not Twitter, this increased complacency in both studies. Study 2 added a no-exposure control and found that effects on complacency were driven by the cueing of nonproblem stories, not by the absence of problem story cues. Both studies validated complacency as a predictor of political disengagement.  相似文献   
55.
56.
57.
With the rise of microfluidics for the past decade, there has come an ever more pressing need for a low-cost and rapid prototyping technology, especially for research and education purposes. In this article, we report a rapid prototyping process of chromed masks for various microfluidic applications. The process takes place out of a clean room, uses a commercially available video-projector, and can be completed in less than half an hour. We quantify the ranges of fields of view and of resolutions accessible through this video-projection system and report the fabrication of critical microfluidic components (junctions, straight channels, and curved channels). To exemplify the process, three common devices are produced using this method: a droplet generation device, a gradient generation device, and a neuro-engineering oriented device. The neuro-engineering oriented device is a compartmentalized microfluidic chip, and therefore, required the production and the precise alignment of two different masks.  相似文献   
58.
59.
Published in 1951,The Catcher in the Rye encapsulated teenage angst. Some time ago David Belbin mused about the influence of Catcher on the proliferation and popularity of YA literature. Salinger's recent death has sparked a renewed interest in his work and more attention on Holden and his inheritors. This article discusses how five recent adolescent novels, with male protagonists, mirror Holden's adolescent paralysis. They exist in a liminal state between childhood and adulthood, attempting to understand the phonies around them. These protagonists help define the nature of the ‘lost’ adolescent in the current golden age of YA literature.  相似文献   
60.
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