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   20618篇
  免费   268篇
  国内免费   122篇
教育   14227篇
科学研究   2679篇
各国文化   145篇
体育   1608篇
综合类   19篇
文化理论   195篇
信息传播   2135篇
  2021年   147篇
  2020年   258篇
  2019年   393篇
  2018年   575篇
  2017年   589篇
  2016年   632篇
  2015年   427篇
  2014年   459篇
  2013年   3244篇
  2012年   509篇
  2011年   563篇
  2010年   361篇
  2009年   329篇
  2008年   381篇
  2007年   390篇
  2006年   380篇
  2005年   984篇
  2004年   817篇
  2003年   601篇
  2002年   404篇
  2001年   350篇
  2000年   334篇
  1999年   327篇
  1998年   168篇
  1997年   170篇
  1996年   211篇
  1995年   186篇
  1994年   148篇
  1993年   166篇
  1992年   237篇
  1991年   238篇
  1990年   247篇
  1989年   278篇
  1988年   240篇
  1987年   243篇
  1986年   235篇
  1985年   262篇
  1984年   236篇
  1983年   219篇
  1982年   189篇
  1981年   177篇
  1980年   166篇
  1979年   251篇
  1978年   195篇
  1977年   191篇
  1976年   161篇
  1975年   138篇
  1974年   158篇
  1973年   143篇
  1971年   124篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
921.
Zur Beherrschung der komplexen vernetzten und verteilten Funktionen von Automotive-Software ist eine Beschreibung des zu erstellenden Systems auf verschiedenen Abstraktionsebenen und schrittweise überg?nge zwischen diesen Ebenen notwendig. Neben der Definition geeigneter Ebenen werden zur Unterstützung echtzeitkritischer Systemanteile ein einheitliches Berechnungsmodell, ebenenspezifische Beschreibungstechniken, sowie methodische Regeln für diese Abstraktionsebenen eingeführt und in den Werkzeugprototypen AutoFocus integriert.  相似文献   
922.
This paper presents the results of a major investigation by questionnaire of author attitudes towards scholarly publishing, which was funded by the Publisher's Association. Altogether, the views of nearly 4,000 authors were obtained and this paper concerns just those thousand or so authors who accepted the invitation to write freely about their own personal feelings and experiences. Using QSR N6 textual analysis software, their comments were processed and themes extracted. While the rest of the questionnaire, which was formed of closed‐question, tick‐box type questions, clearly must have had some impact on their thinking, the authors had considerable latitude in regard to what they could say. The paper provides a unique opportunity to hear their views directly. The pressing topics turned out to be (in rough order of concern): the peer‐review system, copyright, journal prices, alternative business models for journal publishing, big deals, Elsevier, electronic publishing and digital journals.  相似文献   
923.
The logs of four universities using the OhioLINK journal system were evaluated for a period of fifteen months using deep log analysis methods in order to compare and contrast the information seeking behaviour of their users. Large differences were found, especially between the research and teaching universities. Methodological problems associated with making the comparisons are discussed in some detail especially in terms of defining online sessions.  相似文献   
924.
Design, implementation, and re-engineering of operating systems are still an ambitious undertaking. Despite, or even because, of the long history of theory and practice in this field, adapting existing systems to environments of different conditions and requirements as originally specified or assumed, in terms of functional and/or non-functional respects, is anything but simple. Especially this is true for the embedded systems domain which, on the one hand, calls for highly specialized and application-aware system abstractions and, on the other hand, cares a great deal for easily reusable implementations of these abstractions. The latter aspect becomes more and more important as embedded systems technology is faced with an innovation cycle decreasing in length. Software for embedded systems needs to be designed for variability, and this is in particular true for the operating systems of this domain. The paper discusses dimensions of variability that need to be considered in the development of embedded operating systems and presents approaches that aid construction and maintenance of evolutionary operating systems. CR subject classification  C.3; D.2.11; D.2.13; D.4.7  相似文献   
925.
926.
927.
928.
The aim of this study was to examine the maturation responses of young people to submaximal treadmill exercise. Body mass was controlled using both the conventional ratio standard and allometric modelling. Ninety-seven boys and 97 girls with a mean age of 12.2 years completed a discontinuous, incremental exercise test to voluntary exhaustion. We measured peak oxygen uptake (VO2peak) and VO2 when running at 8, 9 and 10 km x h(-1). Sexual maturation was assessed visually using Tanner's indices of pubic hair. Peak VO2 was significantly higher in boys (P<0.001); this was still the case when the influence of body mass was covaried out. During submaximal exercise, no significant differences in absolute VO2 were observed between the sexes (P>0.05); however, values of VO2, expressed both in ratio with body mass and adjusted for body mass using allometry, were significantly greater in boys than in girls (P<0.001). For absolute VO2, significant main effects (P<0.05) were seen for maturity at each exercise stage. With the influence of body mass controlled using either the ratio standard or allometry, no significant main effects (P>0.05) for maturity were observed. Our results indicate that boys are less economical than girls while running at 8-10 km x h(-1) and that, independently of body mass, maturation does not influence the VO2 response to submaximal exercise.  相似文献   
929.
Positive values for fairness in competition are supposed to undergird the behavior of athletes engaged in sport. Whether athletes' values actually develop over 4 years in a college that emphasizes character development is the focus of this study. Athletes' (N = 631) use of deontological ethics (Hahm, Beller & Stoll, 1989) in 21 sports value dilemmas were evaluated. At entrance, as well as near graduation, intercollegiate athletes' value scores were lower than intramural athletes' scores. Both groups' scores declined while they were in college. Individual-sport athletes had higher scores than team-sport athletes but manifested a greater decline over 4 years. The findings are consistent with other studies that show decreases in "sportsmanship orientation" and an increase in "professional" attitudes associated with participation in sport.  相似文献   
930.
The AIDS Library evolved out of consumer health activism in response to the need for the latest HIV information, materials, and technology. In 1998, staff implemented a microcomputer-based integrated automated library system with Web publishing capability to link catalogs, databases of Philadelphia regional services, online publications, and fact sheets. The Web site, , became "live" December 1, 1998. History leading to its development and future plans are presented.  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