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   27103篇
  免费   189篇
  国内免费   119篇
教育   19450篇
科学研究   3249篇
各国文化   109篇
体育   1683篇
综合类   11篇
文化理论   503篇
信息传播   2406篇
  2020年   209篇
  2019年   313篇
  2018年   2570篇
  2017年   2463篇
  2016年   1973篇
  2015年   376篇
  2014年   427篇
  2013年   2688篇
  2012年   529篇
  2011年   1085篇
  2010年   1101篇
  2009年   668篇
  2008年   907篇
  2007年   1435篇
  2006年   339篇
  2005年   657篇
  2004年   705篇
  2003年   614篇
  2002年   367篇
  2001年   259篇
  2000年   292篇
  1999年   274篇
  1998年   142篇
  1997年   159篇
  1996年   183篇
  1995年   169篇
  1994年   131篇
  1993年   142篇
  1992年   216篇
  1991年   228篇
  1990年   230篇
  1989年   258篇
  1988年   209篇
  1987年   225篇
  1986年   219篇
  1985年   250篇
  1984年   222篇
  1983年   211篇
  1982年   176篇
  1981年   168篇
  1980年   157篇
  1979年   244篇
  1978年   190篇
  1977年   180篇
  1976年   149篇
  1975年   132篇
  1974年   151篇
  1973年   132篇
  1972年   107篇
  1971年   119篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
131.
John Forge 《Metascience》2017,26(3):425-428
  相似文献   
132.
133.
134.
Quantum chemistry is based on the solution of the Schrödinger equation for a molecule. From starting data on the positions and nature of constituent atoms information is provided about the energy of the molecule and its electronic properties. The former can indicate what shapes drugs can adopt in binding to pharmacological receptors whilst electronic details, when compared using computer graphics, may highlight the factors responsible for biological activity. These techniques are beginning to show real successes in the design of drug molecules.  相似文献   
135.
Oxidative stress was studied by estimating plasma levels of malondialdehyde (MDA), beta carotene, vitamin E and erythrocytic superoxide dismutase(E-SOD) activity in 50 cases of carcinoma of upper digestive tract which included carcinoma of oral cavity, pharynx and oesophagus. While plasma MDA level was found to be increased (3.5±1.0 nmole/ml), a significant decrease in beta carotene (81.2±14.5mg%), vitamin E (8.5±1.1 mg/L) level and E-SOD activity (657.0±80.6 U/G Hb) were observed in carcinoma of upper digestive tract. Patients were treated with radiotherapy which itself was toxic enough and produced its deleterious effects by generation of reactive oxygen species (ROS). As antioxdiants can detoxify ROS, beneficial effect if any, of antioxidant administration during radiotherapy was studied in two groups of patients, group A (n=5, supplemented with antioxidants) and group B (n=5, without antioxidant supplementation). Plasma MDA level was found to be elevated in both the groups but the increase in group B was significant, compared to pretreatment level. Further, body weight was found to be significantly decreased in group B patients, which was maintained in group A patients. Moreover, group A patients showed significant elevation in beta carotene concentration, thus showing beneficial effect of administration of antioxidants during radiotherapy without disturbing the desirable therapeutic effect of radiotherapy.  相似文献   
136.
We present a new paradigm for the automatic creation of document headlines that is based on direct transformation of relevant textual information into well-formed textual output. Starting from an input document, we automatically create compact representations of weighted finite sets of strings, called WIDL-expressions, which encode the most important topics in the document. A generic natural language generation engine performs the headline generation task, driven by both statistical knowledge encapsulated in WIDL-expressions (representing topic biases induced by the input document) and statistical knowledge encapsulated in language models (representing biases induced by the target language). Our evaluation shows similar performance in quality with a state-of-the-art, extractive approach to headline generation, and significant improvements in quality over previously proposed solutions to abstractive headline generation.  相似文献   
137.
138.
This article offers a discussion of the connection between technology and values and, specifically, I take a closer look at ethically sound design. In order to bring the discussion into a concrete context, the theory of Value Sensitive Design (VSD) will be the focus point. To illustrate my argument concerning design ethics, the discussion involves a case study of an augmented window, designed by the VSD Research Lab, which has turned out to be a potentially surveillance-enabling technology. I call attention to a “positivist problem” that has to do with the connection between the design context and the use context, which VSD seems to presuppose, and I argue that it is necessary to clearly distinguish between the two, since the designers’ intentions do not always correspond with the users’ practice; in fact, the relation between design and use is very complex and principally unpredictable. Thus, a design theory must accept that foresight is limited to anticipation rather than prediction. To overcome the positivist problem, I suggest a phenomenological approach to technology inspired by Don Ihde’s concept of multistability. This argument, which is general in nature and thus applies to any theory of design ethics, is intended as a constructive criticism, which can hopefully contribute to the further development of design ethics.  相似文献   
139.
James Tabery 《Metascience》2007,16(1):143-146
  相似文献   
140.
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