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   2355篇
  免费   315篇
  国内免费   51篇
耳鼻咽喉   30篇
儿科学   51篇
妇产科学   12篇
基础医学   225篇
口腔科学   10篇
临床医学   167篇
内科学   733篇
皮肤病学   14篇
神经病学   149篇
特种医学   430篇
外科学   110篇
综合类   115篇
预防医学   48篇
眼科学   22篇
药学   371篇
  1篇
中国医学   17篇
肿瘤学   216篇
  2024年   6篇
  2023年   76篇
  2022年   111篇
  2021年   159篇
  2020年   139篇
  2019年   150篇
  2018年   130篇
  2017年   131篇
  2016年   99篇
  2015年   89篇
  2014年   155篇
  2013年   214篇
  2012年   136篇
  2011年   121篇
  2010年   102篇
  2009年   87篇
  2008年   110篇
  2007年   85篇
  2006年   85篇
  2005年   94篇
  2004年   50篇
  2003年   53篇
  2002年   56篇
  2001年   43篇
  2000年   28篇
  1999年   18篇
  1998年   27篇
  1997年   18篇
  1996年   20篇
  1995年   25篇
  1994年   19篇
  1993年   14篇
  1992年   4篇
  1991年   6篇
  1990年   7篇
  1989年   4篇
  1988年   4篇
  1987年   3篇
  1986年   7篇
  1985年   3篇
  1984年   8篇
  1983年   6篇
  1982年   8篇
  1981年   5篇
  1980年   4篇
  1979年   1篇
  1976年   1篇
排序方式: 共有2721条查询结果,搜索用时 24 毫秒
1.
2.
3.
Recent epidemiological studies suggested that proton pump inhibitor (PPI) use was associated with an increased risk of biliary tract cancer (BTC), however, confounders were not adequately controlled. Our study aimed to evaluate PPI use and subsequent risk of BTC and its subtypes in three well-established cohorts. We conducted a pooled analysis of the subjects free of cancers in UK Biobank (n = 463 643), Nurses' Health Study (NHS, n = 80 235) and NHS II (n = 95 869). Propensity score weighted Cox models were used to estimate marginal HRs of PPIs use on BTC risk, accounting for potential confounders. We documented 284 BTC cases in UK Biobank (median follow-up: 7.6 years), and 91 cases in NHS and NHS II cohorts (median follow-up: 15.8 years). In UK biobank, PPI users had a 96% higher risk of BTC compared to nonusers in crude model (HR 1.96, 95% CI 1.44-2.66), but the effect was attenuated to null after adjusting for potential confounders (HR 0.95, 95% CI 0.60-1.49). PPI use was not associated with risk of BTC in the pooled analysis of three cohorts (HR 0.93, 95% CI 0.60-1.43). We also observed no associations between PPI use with risk of intrahepatic (HR 1.00, 95% CI 0.49-2.04), extrahepatic bile duct (HR 1.09, 95% CI 0.52-2.27) and gallbladder cancers (HR 0.66, 95% CI 0.26-1.66) in UK Biobank. In summary, regular use of PPIs was not associated with the risk of BTC and its subtypes.  相似文献   
4.
5.
6.
7.
Prescribing of proton pump inhibitors (PPIs) has markedly increased since their inception more than 30 years ago. The increase is related to inappropriate and long-term prescribing of PPIs, associated with a lack of education and unclear prescribing and deprescribing guidelines. The implementation of prescribing stewardship programs influences the reduction and inappropriate use of this medication. The purpose of this review is to address the gaps that exist regarding the use of PPIs along with determining methods for deprescribing. Guidelines and stewardship programs, along with education, are needed to reduce the adverse health effects of long-term PPI therapy.  相似文献   
8.
A new strategy to yield information from the maximum number of voxels, each at the optimum signal-to-noise ratio (SNR) per unit time, in MR spectroscopic imaging (MRSI) is introduced. In the past, maximum acquisition duty-cycle was obtained by multiplexing in time several single slices each repetition time (TR), while optimal SNR was achieved by encoding the entire volume of interest (VOI) each TR. We show that optimal SNR and acquisition efficiency can both be achieved simultaneously by multiplexing in space and time several slabs of several slices, each. Since coverage of common VOIs in 3D proton MRSI in the human brain typically requires eight or more slices, at 3 T or higher magnetic fields, two or more slabs can fit into the optimum TR (approximately 1.6 s). Since typically four or less slices would then fit into each slab, Hadamard encoding is favored in that direction for slice profile reasons. It is demonstrated that per fixed examination length, the new method gives, at 3 T, twice as many voxels, each of the same SNR and size, compared with current 3D chemical shift imaging techniques. It is shown that this gain will increase for more extensive spatial coverage or higher fields.  相似文献   
9.
10.
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