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   958篇
  免费   10篇
教育   729篇
科学研究   42篇
各国文化   36篇
体育   74篇
综合类   1篇
文化理论   5篇
信息传播   81篇
  2023年   2篇
  2021年   2篇
  2020年   18篇
  2019年   25篇
  2018年   46篇
  2017年   40篇
  2016年   24篇
  2015年   27篇
  2014年   26篇
  2013年   226篇
  2012年   28篇
  2011年   24篇
  2010年   30篇
  2009年   41篇
  2008年   27篇
  2007年   25篇
  2006年   22篇
  2005年   21篇
  2004年   22篇
  2003年   36篇
  2002年   11篇
  2001年   14篇
  2000年   21篇
  1999年   11篇
  1998年   20篇
  1997年   8篇
  1996年   12篇
  1995年   11篇
  1994年   12篇
  1993年   5篇
  1992年   16篇
  1991年   5篇
  1990年   14篇
  1989年   11篇
  1988年   7篇
  1987年   8篇
  1986年   4篇
  1985年   6篇
  1984年   5篇
  1983年   11篇
  1982年   6篇
  1981年   3篇
  1980年   4篇
  1979年   3篇
  1978年   4篇
  1977年   5篇
  1976年   3篇
  1919年   2篇
  1867年   1篇
  1838年   1篇
排序方式: 共有968条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
86.
87.
88.
89.
The purpose of this study was to determine the effects of short-term normoxic and hypoxic exercise on plasma endothelin-1 and nitric oxide levels, and the relationship of arterial compliance and pulmonary artery pressure to endothelin-1. Seven endurance-trained males completed two incremental and two steady-state exercise tests performed at ventilatory threshold in normoxia and hypoxia (fraction of inspired oxygen = 0.14). Plasma endothelin-1was measured throughout steady-state tests. Arterial compliance using applanation tonometry, plasma nitric oxide and pulmonary artery pressure using Doppler echocardiography were measured before and after exercise. Small arterial compliance and pulmonary artery pressure significantly increased following exercise. There were no main effects of condition or time for plasma endothelin-1and nitric oxide levels. There were no significant relationships between plasma endothelin-1 and arterial compliance or pulmonary artery pressure. In conclusion, mechanisms other than the endothelial system may play a role in the exercise-induced changes in small artery compliance in this study population. Moderate hypoxia and a 30-minute steady-state exercise have limited effects on plasma endothelin-1 in endurance-trained males.  相似文献   
90.
Nowadays, some virtual museums include 3D room scenes to show the models of its pieces, just like in real museums. Nevertheless, the generation and maintenance of this kind of scenes is generally difficult and should be done by an expert. For example, any change such as including a new piece or modifying the position of an existing fragment usually requires a different design and the creation of a new scene. In this paper we present a case study on the development of a web-based application to automatize this process. To this end, a database to store both graphic and non-graphic information about the pieces, and some 3D rooms to show them has been created. The designed scenes only contain some pieces of furniture to exhibit the fragments, which will be subsequently included. Thus, when a room is loaded in the web page, its associated pieces are obtained through a query in the database and its models are dynamically included in the original scene. Therefore, the position changes or the inclusion of new pieces are not performed in the 3D model, but in the database. Our application makes the transmission of the knowledge to the general public easier because any new discovered piece can be included in a existing museum effortlessly.  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