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   11995篇
  免费   11篇
  国内免费   11篇
教育   9183篇
科学研究   1307篇
各国文化   8篇
体育   378篇
综合类   29篇
文化理论   385篇
信息传播   727篇
  2024年   1篇
  2023年   2篇
  2022年   7篇
  2021年   13篇
  2020年   12篇
  2019年   10篇
  2018年   2178篇
  2017年   2085篇
  2016年   1570篇
  2015年   123篇
  2014年   143篇
  2013年   116篇
  2012年   252篇
  2011年   720篇
  2010年   862篇
  2009年   463篇
  2008年   666篇
  2007年   1174篇
  2006年   90篇
  2005年   418篇
  2004年   464篇
  2003年   369篇
  2002年   141篇
  2001年   16篇
  2000年   28篇
  1999年   10篇
  1998年   4篇
  1997年   25篇
  1996年   12篇
  1995年   7篇
  1994年   8篇
  1993年   3篇
  1992年   3篇
  1991年   8篇
  1990年   2篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1980年   1篇
  1978年   1篇
  1976年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
912.
913.
914.
本文首先从对象和类的基本概念出发,论述了面向MIS对象设计的主要内容,指出MIS系统实质上是对象类系统的结论。然后,给出了一个对象类--浏览对象类的具体程序。  相似文献   
915.
916.
917.
918.
Rats confronted with the onset of a light gradient display a transient increase in locomotion called theactivity response (AR) and a dark preference (Godsil & Fanselow, 2004). These experiments demonstrate that the magnitude of the AR can be blunted with Pavlovian fear-conditioning procedures via associative and nonassociative fear. Although manifested in decreased locomotion, the blunted AR effect was not due to increased freezing or immobility behaviors. Instead, rats displayed reduced rearing and an increase in a class of behaviors calledstationary activity. These results suggest that the lighting differential supplied by the cue influences the topography of defensive behavior and reduces the expression of freezing. This procedure provides a means by which to examine learned and unlearned defensive responses to the same stimulus.  相似文献   
919.
To analyse the association of high sensitivity C-reactive (hsCRP) protein levels and −717A/G single nucleotide polymorphism of CRP with acute myocardial infarction (AMI) in the Indian population. Study population included 100 MI cases wherein 32 patients had experienced previous MI (MI-Group-1), 68 MI cases were recruited at presentation (MI-Group-2) and equal number of age and gender matched healthy individuals. hsCRP levels were determined by ELISA and genotyping of −717A/G was carried out by polymerase chain reaction-based restriction digestion method. The −717A/G genotypes did not influence hsCRP level and their distribution did not differ between groups. However, in the present study hsCRP demonstrated significant correlation with BMI in controls of both the genders and with triglycerides in females of AMI at presentation who otherwise are with low risk profile. Identifying traditional risk factors associated with inflammation may help in controlling the acute event.  相似文献   
920.
Breast cancer is one of the most frequent malignancies in the world. Available staging procedures to detect breast cancer are bone scan, chest X-ray, liver ultrasonography, computerized tomography, estimation of tumor markers like carbohydrate antigen (CA15-3) and carcino embryonic antigen. These procedures are expensive and may not be required in all cases. Out of 70 patients studied, 55 had normal CA15-3 and 15 had elevated levels of Ca15-3. Eight (14.5%) of the 55 patients with normal CA15-3 had abnormal bone scan. Fifteen patients had CA15-3 levels above the normal range and among these 9 (60%) had abnormal bone scan. While prime facie it would appear that a high level of CA15-3 correlate with abnormal bone scan, it is also true that the numbers are small at present and conclusions about the validity of CA15-3 as marker of bone metastasis may be premature.  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