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   14572篇
  免费   231篇
  国内免费   11篇
教育   10136篇
科学研究   1752篇
各国文化   131篇
体育   1033篇
综合类   17篇
文化理论   190篇
信息传播   1555篇
  2022年   101篇
  2021年   144篇
  2020年   214篇
  2019年   287篇
  2018年   414篇
  2017年   457篇
  2016年   405篇
  2015年   268篇
  2014年   384篇
  2013年   2548篇
  2012年   346篇
  2011年   330篇
  2010年   315篇
  2009年   272篇
  2008年   297篇
  2007年   309篇
  2006年   281篇
  2005年   247篇
  2004年   279篇
  2003年   239篇
  2002年   261篇
  2001年   315篇
  2000年   343篇
  1999年   264篇
  1998年   158篇
  1997年   187篇
  1996年   187篇
  1995年   129篇
  1994年   137篇
  1993年   122篇
  1992年   209篇
  1991年   195篇
  1990年   231篇
  1989年   218篇
  1988年   190篇
  1987年   204篇
  1986年   182篇
  1985年   229篇
  1984年   166篇
  1983年   159篇
  1982年   147篇
  1981年   135篇
  1980年   139篇
  1979年   202篇
  1978年   159篇
  1977年   136篇
  1976年   105篇
  1975年   100篇
  1974年   109篇
  1971年   98篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Background: Somali Bantu refugees, with unique health information needs, created challenges for health and social service providers. Objectives: A service innovation was developed (i) to raise awareness, especially among local health and social service providers, about the Bantu refugees’ presence in the community, their culture, and their information needs and (ii) to deliver needed health information, emphasizing child health, to the Bantu mothers in their homes. Methods: The project consisted of: (i) a community conference targeting local health and social service providers, describing the refugees’ presence in the community, their culture, and information needs. (ii) Focus groups conducted with members of the Bantu population elicited additional information needs. (iii) Curriculum was developed based on identified needs, and (iv) the curriculum was delivered to the refugees in their homes. A clinical informationist and MP3 technology enhanced the project. Findings: Conference attendees’ evaluation responses indicated improved understanding of Bantu culture. Focus groups’ identification of health information needs provided a framework for the health education curriculum. A project website made educational materials available to other healthcare providers. Conclusions: The project raised awareness of the Bantus’ presence, culture, and information needs. Identification of other unmet needs demonstrated that additional support for refugees is required.  相似文献   
83.
84.
This study extended validity evidence for multidimensional measures of coaching competency derived from the Coaching Competency Scale (CCS; Myers, Feltz, Maier, Wolfe, & Reckase, 2006) by examining use of the original rating scale structure and testing how measures related to satisfaction with the head coach within teams and between teams. Motivation, game strategy, technique, and character building comprised the dimensions of coaching competency. Data were collected from athletes (N = 585) nested within intercollegiate men's (g = 8) and women's (g = 13) soccer and women's ice hockey (g = 11) teams (G = 32). Validity concerns were observed for the original rating scale structure and the predicted positive relationship between motivation competency and satisfaction with the coach between teams. Validity evidence was offered for a condensed post hoc rating scale and the predicted relationship between motivation competency and satisfaction with the coach within teams.  相似文献   
85.
Although angiogenetic therapy using recombinant growth factors holds much hope for the treatment of ischaemic diseases, there are still many unanswered questions, including the method of administration, the correct dose of these factors, and the duration of the therapeutic approach. Exercise has also been suggested to induce neovascularizaiton in muscles. We evaluated the angiogenetic effects of the intramuscular administration of basic-fibroblast growth factor (b-FGF) and acidic-fibroblast growth factor (a-FGF) in rat heart, compared with rats who exercised daily. In conclusion, both the intramuscular administration of b-FGF and exercise increased significantly angiogenesis in the heart in contrast to the intramuscular administration of a-FGF, which was ineffective.  相似文献   
86.
87.
In this paper a variety of optimal control (OC) problems for distributed- parameter (DP) systems are approached using mathematical programming (MP). First, the principal DP models in current use are given, a variety of DP objective functions is provided, and the OC problems based on them are formulated. Second, these models and objective functions are converted in algebraic form, as required by MP, and the solution procedure of the OC problems via MP is outlined. Third, a representative set of nonlinear programming results applied to DP systems is presented, and finally, a numvber of application examples is given.  相似文献   
88.
A sequence of metrics {DN} is said to be additive and matched to a discrete memoryless channel (DMC) if DN is the sum on its coordinates of N single letter metrics and if the maximum likelihood decoder for sequences of length N is a minimum DN-distance decoder. Necessary and sufficient conditions on the transition probabilities of a DMC for the existence of a sequence of additive metrics matched to it are given. In the case of the binary channel these are shown to be equivalent to the channel being symmetric. Explicit transition probabilities are given for a large class of ternary DMCs with an associated sequence of additive matched metrics. The problem solved here may be considered a generalization of the problem of finding the DMCs matched to the Lee metric solved by Chiang and Wolf in 1971 (2).  相似文献   
89.
Necessary and sufficient conditions are obtained for the realization of an m-variable positive real function (PRF) as the impedence function of a resistively-terminated ladder network of m lossless two-ports connected in cascade. Each two-port is a single-variable lossless ladder with all of its transmission zeros either at the origin or at finity. Conditions are also obtained when each of the two-ports is a Fujisawa-type lowpass ladder.  相似文献   
90.
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