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   139947篇
  免费   11183篇
  国内免费   2851篇
耳鼻咽喉   1751篇
儿科学   2999篇
妇产科学   2134篇
基础医学   18636篇
口腔科学   1869篇
临床医学   14898篇
内科学   28596篇
皮肤病学   2105篇
神经病学   11296篇
特种医学   5942篇
外国民族医学   12篇
外科学   20424篇
综合类   6207篇
现状与发展   6篇
一般理论   110篇
预防医学   9092篇
眼科学   3561篇
药学   11247篇
  27篇
中国医学   2007篇
肿瘤学   11062篇
  2024年   131篇
  2023年   1161篇
  2022年   2265篇
  2021年   4760篇
  2020年   2868篇
  2019年   3964篇
  2018年   4439篇
  2017年   3398篇
  2016年   3746篇
  2015年   4783篇
  2014年   6277篇
  2013年   7192篇
  2012年   10925篇
  2011年   11595篇
  2010年   6706篇
  2009年   5698篇
  2008年   8771篇
  2007年   8952篇
  2006年   8313篇
  2005年   8163篇
  2004年   7061篇
  2003年   6647篇
  2002年   6018篇
  2001年   2223篇
  2000年   1870篇
  1999年   1950篇
  1998年   1473篇
  1997年   1316篇
  1996年   1012篇
  1995年   894篇
  1994年   783篇
  1993年   682篇
  1992年   782篇
  1991年   636篇
  1990年   624篇
  1989年   583篇
  1988年   536篇
  1987年   461篇
  1986年   426篇
  1985年   380篇
  1984年   373篇
  1983年   291篇
  1982年   331篇
  1981年   322篇
  1980年   260篇
  1979年   262篇
  1978年   218篇
  1977年   173篇
  1976年   126篇
  1975年   137篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Barrett's esophagus (BE) is the precursor to esophageal adenocarcinoma (EAC). Progression to cancer typically occurs in a stepwise fashion through worsening dysplasia and ultimately, invasive neoplasia. Established EAC with deep involvement of the esophageal wall and/or metastatic disease is invariably associated with poor long-term survival rates. This guides the rationale of surveillance of Barrett’s in an attempt to treat lesions at an earlier, and potentially curative stage. The last two decades have seen a paradigm shift in management of Barrett’s with rapid expansion in the role of endoscopic eradication therapy (EET) for management of dysplastic and early neoplastic BE, and there have been substantial changes to international consensus guidelines for management of early BE based on evolving evidence. This review aims to assist the physician in the therapeutic decision-making process with patients by comprehensive review and summary of literature surrounding natural history of Barrett’s by histological stage, and the effectiveness of interventions in attenuating the risk posed by its natural history. Key findings were as follows. Non-dysplastic Barrett’s is associated with extremely low risk of progression, and interventions cannot be justified. The annual risk of cancer progression in low grade dysplasia is between 1%-3%; EET can be offered though evidence for its benefit remains confined to highly select settings. High-grade dysplasia progresses to cancer in 5%-10% per year; EET is similarly effective to and less morbid than surgery and should be routinely performed for this indication. Risk of nodal metastases in intramucosal cancer is 2%-4%, which is comparable to operative mortality rate, so EET is usually preferred. Submucosal cancer is associated with nodal metastases in 14%-41% hence surgery remains standard of care, except for select situations.  相似文献   
6.
Heart Failure Reviews - The nitric oxide (NO)–guanylate cyclase (GC)–cyclic guanosine monophosphate (cGMP) pathway plays an important role in cardiovascular, pulmonary and renal...  相似文献   
7.
8.
Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100?nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.  相似文献   
9.
10.
Direct peroral cholangioscopy (POC) using an ultra‐slim upper endoscope is one modality of POC for intraductal endoscopic evaluation and treatment of the bile duct. Choledochoduodenostomy (CDS) is one modality of biliary bypass surgery that provides a new route to the bile duct. We carried out direct POC using an ultra‐slim upper endoscope without the use of accessories in 10 patients (four sump syndromes, three bile duct strictures and three intrahepatic duct stones) previously undergoing surgical CDS. Direct POC was successful in all patients. The use of an intraductal balloon catheter was required in one patient for advancement of the endoscope into the bile duct. Distal bile ducts with sump syndromes were cleared using baskets and water irrigation under direct POC. Cholangiocarcinoma was diagnosed in one patient with hilar bile duct stricture after cholangioscopic evaluation and a targeting forceps biopsy under direct POC. Intrahepatic duct stones were successfully extracted after intraductal fragmentation under direct POC. Oozing bleeding occurred during intraductal lithotripsy but stopped spontaneously. Direct POC using an ultra‐slim upper endoscope without the assistance of accessories can easily be carried out in patients undergoing CDS.  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