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   12900篇
  免费   23篇
  国内免费   2篇
教育   9973篇
科学研究   1297篇
各国文化   5篇
体育   467篇
综合类   1篇
文化理论   397篇
信息传播   785篇
  2023年   13篇
  2022年   20篇
  2021年   24篇
  2020年   48篇
  2019年   70篇
  2018年   2254篇
  2017年   2153篇
  2016年   1633篇
  2015年   150篇
  2014年   191篇
  2013年   360篇
  2012年   242篇
  2011年   718篇
  2010年   871篇
  2009年   454篇
  2008年   666篇
  2007年   1167篇
  2006年   90篇
  2005年   407篇
  2004年   466篇
  2003年   373篇
  2002年   140篇
  2001年   29篇
  2000年   46篇
  1999年   24篇
  1998年   13篇
  1997年   18篇
  1996年   14篇
  1995年   8篇
  1994年   12篇
  1993年   8篇
  1992年   13篇
  1991年   19篇
  1990年   9篇
  1989年   13篇
  1988年   12篇
  1987年   8篇
  1986年   10篇
  1985年   14篇
  1984年   7篇
  1983年   9篇
  1980年   9篇
  1978年   15篇
  1977年   5篇
  1976年   10篇
  1974年   11篇
  1973年   6篇
  1972年   6篇
  1969年   5篇
  1965年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
932.
Landmarks     
Z. M. 《Prospects》1984,14(2):171-173
  相似文献   
933.
Landmarks     
Z. M. 《Prospects》1988,18(3):297-299
  相似文献   
934.
935.
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   
936.
Landmarks     
Z. M. 《Prospects》1991,21(2):139-141
  相似文献   
937.
Landmarks     
Z. M. 《Prospects》1988,18(2):151-153
  相似文献   
938.
Wang ZK  Zheng HY 《Biomicrofluidics》2012,6(1):12820-1282012
The study investigates the use of CO2 laser to induce glass strip peeling off to form microchannels on soda lime gass substrate. The strip peeling exhibits a strong dependence on the energy deposition rate on the glass surface. In spite of the vast difference in the combination of laser power and scanning speed, when the ratio of the two makes the energy deposition rate in the range 3.0-6.0 J/(cm2 s), the temperature rising inside glass will be above the strain point and reach the softening region of the glass. As a result, glass strip peeling is able to occur and form microchannels with dimensions of 20-40 μm in depth and 200-280 μm in width on the glass surface. Beyond this range, higher energy depsotion rate would lead to surface melting associated with solidification cracks and lower energy deposition rate causes the generation of fragment cracks.  相似文献   
939.
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   
940.
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