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   285106篇
  免费   45890篇
  国内免费   10557篇
耳鼻咽喉   6163篇
儿科学   7111篇
妇产科学   3918篇
基础医学   24091篇
口腔科学   3944篇
临床医学   42715篇
内科学   64948篇
皮肤病学   8741篇
神经病学   21199篇
特种医学   11112篇
外国民族医学   65篇
外科学   53599篇
综合类   23477篇
现状与发展   99篇
一般理论   12篇
预防医学   16382篇
眼科学   6686篇
药学   17175篇
  121篇
中国医学   7754篇
肿瘤学   22241篇
  2023年   6569篇
  2022年   4639篇
  2021年   9412篇
  2020年   11146篇
  2019年   6796篇
  2018年   12080篇
  2017年   11674篇
  2016年   12510篇
  2015年   14511篇
  2014年   23009篇
  2013年   22915篇
  2012年   15874篇
  2011年   16550篇
  2010年   18030篇
  2009年   20409篇
  2008年   13324篇
  2007年   11569篇
  2006年   13352篇
  2005年   9971篇
  2004年   7863篇
  2003年   6720篇
  2002年   6085篇
  2001年   7151篇
  2000年   5908篇
  1999年   5763篇
  1998年   5219篇
  1997年   5112篇
  1996年   4542篇
  1995年   4378篇
  1994年   3011篇
  1993年   2315篇
  1992年   2307篇
  1991年   2281篇
  1990年   1837篇
  1989年   1895篇
  1988年   1657篇
  1987年   1382篇
  1986年   1404篇
  1985年   1133篇
  1984年   909篇
  1983年   816篇
  1982年   775篇
  1981年   620篇
  1980年   550篇
  1979年   504篇
  1978年   520篇
  1977年   604篇
  1976年   425篇
  1975年   395篇
  1972年   386篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Post-induction hypotension is common and associated with postoperative complications. We hypothesised that pneumatic leg compression reduces post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy. In this double-blind randomised study, patients were allocated randomly to the pneumatic leg compression group (n = 50) or control (n = 50). In the intervention group, pneumatic leg compression was initiated before induction of anaesthesia. In the control group, pneumatic leg compression was initiated 20 min after anaesthesia induction. The primary outcome was the incidence of post-induction hypotension in these groups. Post-induction hypotension was defined as systolic blood pressure < 90 mmHg during the first 20 min after induction. Haemodynamic variables and area under the curve of post-induction systolic blood pressure over time were assessed. Complications associated with pneumatic leg compression were recorded, including: peripheral neuropathy; compartment syndrome; extensive bullae beneath the leg sleeves; and pulmonary thromboembolism. The incidence of post-induction hypotension decreased in the pneumatic leg compression group compared with that in the control group; 5 (10%) vs. 29 (58%), respectively, p < 0.001. In the pneumatic leg compression group, the lowest systolic, diastolic and mean blood pressures 20 min after induction of anaesthesia were significantly greater than the control group. Pneumatic leg compression resulted in an increased area under the curve of systolic blood pressure in the first 20 min after induction, p = 0.001. There were no pneumatic leg compression-related complications. Pneumatic leg compression reduced post-induction hypotension in elderly patients undergoing robot-assisted laparoscopic prostatectomy, suggesting that it is an effective and safe intervention to prevent post-induction hypotension among elderly patients undergoing general anaesthesia.  相似文献   
4.
5.
6.
7.
8.
9.
Pancreatic cancer (PC) is a cancer of the digestive system, and pancreatic ductal adenocarcinoma (PDAC) accounts for approximately 90% of all PC cases. Exosomes derived from PDAC (PDAC-exosomes) promote PDAC development and metastasis. Exosomes are nanoscale vesicles secreted by most cells, which can carry biologically active molecules and mediate communication and cargo transportation among cells. Recent studies have focused on transforming exosomes into good drug delivery systems (DDSs) to improve the clinical treatment of PDAC. This review considers PDAC as the main research object to introduce the role of PDAC-exosomes in PDAC development and metastasis. This review focuses on the following two themes: (a) the great potential of PDAC-exosomes as new diagnostic markers for PDAC, and (b) the transformation of exosomes into potential DDSs.  相似文献   
10.
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   
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