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   177580篇
  免费   1078篇
  国内免费   17篇
耳鼻咽喉   1155篇
儿科学   6647篇
妇产科学   3028篇
基础医学   16808篇
口腔科学   1563篇
临床医学   12500篇
内科学   31232篇
皮肤病学   704篇
神经病学   16858篇
特种医学   9039篇
外科学   29169篇
综合类   2334篇
预防医学   18162篇
眼科学   2819篇
药学   9603篇
中国医学   636篇
肿瘤学   16418篇
  2022年   72篇
  2021年   103篇
  2020年   65篇
  2019年   85篇
  2018年   21979篇
  2017年   17404篇
  2016年   19570篇
  2015年   971篇
  2014年   904篇
  2013年   904篇
  2012年   7102篇
  2011年   21137篇
  2010年   18903篇
  2009年   11602篇
  2008年   19609篇
  2007年   21841篇
  2006年   663篇
  2005年   2301篇
  2004年   3471篇
  2003年   4433篇
  2002年   2585篇
  2001年   287篇
  2000年   423篇
  1999年   173篇
  1998年   233篇
  1997年   231篇
  1996年   111篇
  1995年   118篇
  1994年   114篇
  1993年   70篇
  1992年   43篇
  1991年   90篇
  1990年   126篇
  1989年   81篇
  1988年   62篇
  1987年   47篇
  1986年   26篇
  1985年   35篇
  1984年   26篇
  1983年   28篇
  1982年   33篇
  1980年   43篇
  1970年   22篇
  1939年   22篇
  1938年   64篇
  1937年   25篇
  1935年   23篇
  1934年   32篇
  1932年   56篇
  1930年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
Though a high frequency of postoperative complications after an original Bentall procedure has been reported, several procedures that reduce the incidence of complications have been developed. Complications relating to anastomoses of the interposed graft are infrequent but life-threatening. This report describes a case of a 61-year-old man who presented with heart failure secondary to bilateral detachment of coronary ostial anastomoses and graft stenosis 21 years after undergoing a modified Bentall procedure. These complications were successfully repaired by reconstructing the conduit and coronary arteries.  相似文献   
963.
964.
965.
The protective potential of dandelion on acute hepatitis, lung injury and colorectal cancer has recently been revealed. Importantly, ulcerative colitis (UC), a clinically defined inflammatory bowel disease, accelerates the risk of colorectal cancer. However, studies focusing on the activity of dandelion on UC are extremely limited. In the present study, we found that an aqueous extract of dandelion root increases cell viability and decreases apoptosis in dextran sodium sulfate (DSS)-incubated NCM460 human colonic epithelial cells, probably through removing the production of reaction oxygen species and blocking nuclear factor-kappaB signaling. We then examined the anti-colitis efficacy of this extract in an in vivo study. We detected that dandelion root extract efficiently ameliorates progressive acute injury as demonstrated by a reduction in body weight loss, severity scores of disease index and shortened colon length during DSS treatment, as well as reducing the inflammatory conditions and oxidative stress in the colon of DSS-induced mice. Our study clearly demonstrates that dandelion has a strong cytoprotective effect on NCM460 colonocytes and shows powerful defense on an established experimental mouse model of DSS-induced UC. Therefore, dandelion root extract can be an effective anti-colitis complex mixture and can provide a complementary alternative to currently available therapeutic intervention in UC.  相似文献   
966.
967.
Primary clear cell adenocarcinoma (CCA) of the colorectum is a rare tumor. We report on a 48-year-old man with early stage CCA in the descending colon who underwent detailed examination with image-enhanced endoscopy, such as magnifying endoscopy with narrow-band imaging and crystal violet staining. The tumor was treated successfully with endoscopic mucosal resection at our hospital.  相似文献   
968.
With hereditary colorectal cancer prevention studies it is difficult to demonstrate reduced mortality. Large populations are needed with well characterized genetics followed over a long period of time. Those studies do exist for standard white light colonoscopy surveillance in Lynch syndrome, but not for newer technologies including chromoscopy. For these newer technologies adenoma detection rate becomes the stand-in for mortality, and the assumption is made that surveillance efficacy impacts cancer occurrence. Though well-designed and important work exists in this area, the data do not support firm conclusions regarding the use of chromoscopy in Lynch syndrome.  相似文献   
969.
970.
P-glycoprotein (P-gp) is one of the major obstacles to efficiency of cancer chemotherapy. Here, we investigated whether combination of metformin and 2-deoxyglucose reverses the multidrug resistance (MDR) of K562/Dox cells and tried to elucidate the possible mechanisms. The combination of metformin and 2-deoxyglucose selectively enhanced the cytotoxicity of doxorubicin against K562/Dox cells. Metformin was not a substrate of P-gp but suppressed the elevated level of P-gp in K562/Dox cells. The downregulation of P-gp may be partly attributed to the inhibition of extracellular signal-regulated kinase pathway. The addition of 2-deoxyglucose to metformin initiated a strong metabolic stress in both K562 and K562/Dox cells. Combination of metformin and 2-deoxyglucose inhibited glucose uptake and lactate production in K562 and K562/Dox cells leading to a severe depletion in ATP and a enhanced autophagy. Above all, P-gp substrate selectively aggravated this ATP depletion effect and increased cell apoptosis in K562/Dox cells. In conclusion, metformin decreases P-gp expression in K562/Dox cells via blocking phosphorylation of extracellular signal-regulated kinase. P-gp substrate increases K562/Dox cell apoptosis via aggravating ATP depletion induced by combination of metformin and 2-deoxyglucose. Our observations highlight the importance of combination of metformin and 2-deoxyglucose in reversing multidrug resistance.  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