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   22475篇
  免费   396篇
  国内免费   30篇
教育   16218篇
科学研究   1987篇
各国文化   203篇
体育   1712篇
综合类   34篇
文化理论   190篇
信息传播   2557篇
  2022年   132篇
  2021年   229篇
  2020年   363篇
  2019年   491篇
  2018年   699篇
  2017年   772篇
  2016年   717篇
  2015年   429篇
  2014年   576篇
  2013年   4228篇
  2012年   563篇
  2011年   634篇
  2010年   481篇
  2009年   458篇
  2008年   519篇
  2007年   501篇
  2006年   441篇
  2005年   385篇
  2004年   364篇
  2003年   327篇
  2002年   379篇
  2001年   425篇
  2000年   396篇
  1999年   403篇
  1998年   212篇
  1997年   238篇
  1996年   264篇
  1995年   213篇
  1994年   210篇
  1993年   193篇
  1992年   302篇
  1991年   300篇
  1990年   329篇
  1989年   311篇
  1988年   295篇
  1987年   248篇
  1986年   256篇
  1985年   322篇
  1984年   267篇
  1983年   255篇
  1982年   196篇
  1981年   206篇
  1980年   176篇
  1979年   240篇
  1978年   214篇
  1977年   194篇
  1976年   160篇
  1975年   128篇
  1974年   120篇
  1973年   147篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Abstract

Previous, analytical-empirical case studies of national Agricultural Knowledge Systems (AKSs) have produced a list of factors which are typical for successful AKSs. The aim of the present paper is to investigate (1) in how far these factors exist in the Swiss AKS, (2) in what ways the unique, confederal system of Switzerland has had an influence on its AKS, and (3) whether additional, generalizable factors can be identified, which could add to the efficiency of the national AKSs.

The federal system of Switzerland with its relatively small cantons which are responsible for law enforcement and agricultural extension (but not for research) imposes special conditions on its AKS and makes it difficult to manage them. Informal communication devices help to overcome this drawback.

The investigation of the Swiss AKS corroborates the list of criteria for well functioning AKSs that were identified in earlier research, and added two new points: (1) the need for “relais” stations to overcome interfaces between research and extension, especially when these two subsystems function at different organisational levels, or when extension is split up into small units; (2) the value of networking among different national AKSs.  相似文献   
992.
993.
994.
995.
The book market in European countries is different than the U.S. market for various political, geographical, and cultural reasons. The authors outline these differences and provide background on the move to electronic commerce and future. The article includes many electronic and print sources of and bibliographic tools for locating books in the European market.  相似文献   
996.
The pilot issue of the data collection of the All-Russian Institute of Scientific and Technical Information of the Russian Academy of Sciences “Industry of Nanosystems and Nanomaterials” gives an approximate view of the state of this field of science at the beginning of 2007. The topics of articles in the pilot issue are analyzed. The directions of development of nanotechnologies are shown. The basic types of nanomaterials, the methods of their production, and their properties and applications are given.  相似文献   
997.
998.
999.
Five women and 5 men were studied to examine the effects of submaximal exercise on thermoregulatory and hemodynamic variables during recovery in two environments: (a) control (C), 22 degrees C, 33% rh; and (b) hot humid (H), 32 degrees C. The participants exercised on a cycle ergometer at 60% of peak oxygen consumption for 35 min prior to 90 min of seated recovery. Sessions were identical, except for environment. Variables evaluated (p < .05) were: core temperature (TR), mean skin temperature (Ts), sweat rate (SR), heart rate (HR), stroke index (SI), cardiac index (CI), forearm blood flow (FBF), systolic blood pressure (SBP), and diastolic blood pressure (DBP). Men and women exhibited similar patterns of TR, Ts, and SR in both environments. Ts and SR (collapsed means for gender) were higher in the H than in the C. DBP was higher in men than in women throughout recovery in both environments. With combined means for gender, HR was higher in the H than in the C. CI, SI, FBF, and SBP were similar in both environments and returned to baseline within 15 min into recovery. These data suggest that heat dissipation during extended recovery was accomplished with similar contributions of cutaneous vasodilation and sweating in M and F. Furthermore, the moderate exercise level did not influence hemodynamics beyond 15 min of recovery in either environment.  相似文献   
1000.
Project GRAD (Graduate Ready for Activity Daily) evaluates a university course to promote physical activity. In a randomized study, 338 university seniors participated in either an intervention or control course for academic credit, and posttest data were collected on 321. The control course was knowledge-oriented. The intervention course taught behavior change skills in weekly lectures and peer-led labs. Physical activity was assessed with 7-Day Physical Activity Recall interviews. The intervention had no significant effects on men. Among women, the intervention increased total physical activity during leisure, strengthening exercises, and flexibility exercise. This university course had the intended effects of promoting healthful patterns of physical activity among women, but no effects were observed on men, who were more active than women at baseline.  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