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   708322篇
  免费   49112篇
  国内免费   1299篇
耳鼻咽喉   9222篇
儿科学   23371篇
妇产科学   17615篇
基础医学   110737篇
口腔科学   20023篇
临床医学   63994篇
内科学   134911篇
皮肤病学   16186篇
神经病学   49676篇
特种医学   25850篇
外国民族医学   76篇
外科学   104738篇
综合类   14842篇
现状与发展   2篇
一般理论   161篇
预防医学   51535篇
眼科学   16374篇
药学   54074篇
  9篇
中国医学   2377篇
肿瘤学   42960篇
  2021年   5556篇
  2018年   7899篇
  2017年   6137篇
  2016年   6861篇
  2015年   7584篇
  2014年   10318篇
  2013年   15456篇
  2012年   20599篇
  2011年   21584篇
  2010年   12786篇
  2009年   11986篇
  2008年   20068篇
  2007年   21588篇
  2006年   21987篇
  2005年   20525篇
  2004年   20064篇
  2003年   19018篇
  2002年   18512篇
  2001年   36398篇
  2000年   36939篇
  1999年   30424篇
  1998年   7897篇
  1997年   6685篇
  1996年   6997篇
  1995年   6644篇
  1994年   6118篇
  1993年   5611篇
  1992年   22982篇
  1991年   22947篇
  1990年   22337篇
  1989年   22097篇
  1988年   20057篇
  1987年   19447篇
  1986年   18481篇
  1985年   17316篇
  1984年   12702篇
  1983年   10753篇
  1982年   5928篇
  1979年   11532篇
  1978年   8132篇
  1977年   6836篇
  1976年   6603篇
  1975年   7278篇
  1974年   8510篇
  1973年   8150篇
  1972年   7665篇
  1971年   7136篇
  1970年   6886篇
  1969年   6312篇
  1968年   5788篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.

Aims

To obtain an overview of the management and outcomes of children aged 18 years or younger diagnosed with differentiated thyroid carcinoma of follicular cell origin across the UK, by collecting and analysing data from the limited number of centres treating these patients. This multicentre data might provide a more realistic perspective than single-institution series.

Materials and methods

Six centres submitted data extracted from historical records on patients aged 18 years or younger, diagnosed between 1964 and 2017. The univariate and multivariable Cox proportional hazard model was used to identify potential predictors of progression-free survival, using national data as a control.

Results

Data on 166 patients were available for analysis. Females (74%) were predominant, and the age ranged from 3 to 19 years at diagnosis, mean 14.1 years. Nodal metastases were present in 51%; 12% had distant metastases. After surgery, 95% received radioactive iodine (39% on more than one occasion) and 4% received external beam radiotherapy. With a median follow-up duration of 5 years, 69% are alive with no evidence of disease; 20% are alive with a raised thyroglobulin level as the only evidence of residual disease; 6% have residual structural disease detectable on imaging; 2% have died, from cerebral metastases.

Conclusion

Despite most patients having advanced disease at presentation, outcomes are very good. A national prospective registry should allow systematic collection of good-quality data and may facilitate research to further improve outcomes.  相似文献   
22.

Cellular arachidonic acid (AA), an unsaturated fatty acid found ubiquitously in plasma membranes, is metabolized to different prostanoids, such as prostacyclin (PGI2) and prostaglandin E2 (PGE2), by the three-step reactions coupling the upstream cyclooxygenase (COX) isoforms (COX-1 and COX-2) with the corresponding individual downstream synthases. While the vascular actions of these prostanoids are well-characterized, their specific roles in the hippocampus, a major brain area for memory, are poorly understood. The major obstacle for its understanding in the brain was to mimic the biosynthesis of each prostanoid. To solve the problem, we utilized Single-Chain Hybrid Enzyme Complexes (SCHECs), which could successfully control cellular AA metabolites to the desired PGI2 or PGE2. Our in vitro studies suggested that neurons with higher PGI2 content and lower PGE2 content exhibited survival protection and resistance to Amyloid-β-induced neurotoxicity. Further extending to an in vivo model, the hybrid of PGI2-producing transgenic mice and Alzheimer’s disease (AD) mice showed restored long-term memory. These findings suggested that the vascular prostanoids, PGI2 and PGE2, exerted significant regulatory influences on neuronal protection (by PGI2), or damage (by PGE2) in the hippocampus, and raised a concern that the wide uses of aspirin in cardiovascular diseases may exert negative impacts on neurodegenerative protection.

Our study intended to understand the crosstalk of prostanoids in the hippocampus, a major brain area impacted in AD, by using hybrid enzymes to redirect the synthesis of prostanoids to PGE2 and PGI2, respectively. Our data indicated that during inflammation, the vascular mediators, PGI2 and PGE2, exerted significant regulatory influences on neuronal protection (by PGI2), or damage (by PGE2) in the hippocampus. These findings also raised a concern that the widely uses of non-steroidal anti-inflammatory drugs in cardiovascular diseases may exert negative impacts on neurodegenerative protection.

  相似文献   
23.
24.
25.
26.
27.
28.
29.
30.
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