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   1408043篇
  免费   115731篇
  国内免费   3331篇
耳鼻咽喉   18371篇
儿科学   46566篇
妇产科学   41048篇
基础医学   200707篇
口腔科学   37690篇
临床医学   125949篇
内科学   284187篇
皮肤病学   33352篇
神经病学   116834篇
特种医学   53836篇
外国民族医学   464篇
外科学   210514篇
综合类   32753篇
现状与发展   3篇
一般理论   487篇
预防医学   109896篇
眼科学   31471篇
药学   98536篇
  1篇
中国医学   3348篇
肿瘤学   81092篇
  2021年   10852篇
  2019年   11669篇
  2018年   16573篇
  2017年   12669篇
  2016年   14264篇
  2015年   16011篇
  2014年   22565篇
  2013年   33394篇
  2012年   45403篇
  2011年   47938篇
  2010年   28162篇
  2009年   27058篇
  2008年   44337篇
  2007年   46834篇
  2006年   47393篇
  2005年   45881篇
  2004年   43763篇
  2003年   41706篇
  2002年   40196篇
  2001年   73005篇
  2000年   74534篇
  1999年   61568篇
  1998年   16992篇
  1997年   15435篇
  1996年   15585篇
  1995年   14795篇
  1994年   13399篇
  1993年   12584篇
  1992年   45847篇
  1991年   43482篇
  1990年   41501篇
  1989年   39565篇
  1988年   36186篇
  1987年   35364篇
  1986年   32868篇
  1985年   31284篇
  1984年   23831篇
  1983年   20032篇
  1982年   12215篇
  1981年   10790篇
  1979年   20718篇
  1978年   14585篇
  1977年   12087篇
  1976年   11366篇
  1975年   11624篇
  1974年   13990篇
  1973年   13534篇
  1972年   12633篇
  1971年   11469篇
  1970年   10913篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
961.
Sixty drinking water samples collected from various sources in different areas of Delhi during epidemic of cholera and gastroenteritis were analysed for bacteriological standards. Only 27 (45 per cent) samples were found to be satisfactory for human consumption. Remaining thirty-three (55 per cent) samples showed presence of coliform organisms with MPN value ranging from 10 to 1800+ per 100 ml. Among these positive samples, 31 (93.9 per cent) samples contained faecal coli. Twenty out of thirty (66.6 per cent) Hand pump, 9 out of 21 (42.8 per cent) Taps 2 out of 4 (50 per cent) Tube well and 2 out of 5 (40 per cent) of miscellaneous sources showed contamination with coliform organisms.  相似文献   
962.
963.
964.
965.
966.
We carried out a nonrandomized, unblinded study to compare the efficacy of rifampin alone with that of rifampin in combination with trimethoprim in the eradication of the Haemophilus influenzae type b (HIB) carrier state among contacts of patients with invasive HIB infection. The study population comprised 17 index patients admitted to hospital with severe HIB infections and 233 contacts, 43 of whom had nasopharyngeal colonization with HIB of the same biotype as that of the index patient. Rifampin in a daily dose of 20 mg/kg (maximum 600 mg) for 4 days eradicated the carrier state in 86% of cases, as did the combination of rifampin at the same dosage and trimethoprim in a daily dose of 5 mg/kg (maximum 160 mg) for 4 days.  相似文献   
967.
968.
Intravenous administration of human bone marrow stromal cells (hMSCs) after middle cerebral artery occlusion (MCAo) in rats provides functional benefit. We tested the hypothesis that these functional benefits are derived in part from hMSC production of growth and trophic factors. Quantitative sandwich enzyme‐linked immunosorbent assay (ELISA) of hMSCs cultured with normal and MCAo brain extracts were performed. hMSCs cultured in supernatant derived from ischemic brain extracts increased production of brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These neurotrophins and angiogenic growth factors increased in a post‐ischemia time‐dependent manner. The hMSC capacity to increase expression of growth and trophic factors may be the key to the benefit provided by transplanted hMSCs in the ischemic brain.  相似文献   
969.
Background: Mitochondrial adenosine triphosphate-sensitive potassium (mitoKATP) channels play a pivotal role in mediating cardiac preconditioning. The effects of intravenous anesthetics on this protective channel have not been investigated so far, but would be of importance with respect to experimental as well as clinical medicine.

Methods: Live cell microscopy was used to visualize and measure autofluorescence of flavoproteins, a direct reporter of mitoKATP channel activity, in response to the direct and highly selective mitoKATP channel opener diazoxide, or to diazoxide following exposure to various anesthetics commonly used in experimental and clinical medicine. A cellular model of ischemia with subsequent hypoosmolar trypan blue staining served to substantiate the effects of the anesthetics on mitoKATP channels with respect to myocyte viability.

Results: Diazoxide-induced mitoKATP channel opening was significantly inhibited by the anesthetics R-ketamine, and the barbiturates thiopental and pentobarbital. Conversely, urethane, 2,2,2-trichloroethanol (main metabolite of [alpha]-chloralose and chloral hydrate), and the opioid fentanyl potentiated the channel-opening effect of diazoxide, which was abrogated by coadministration of chelerythrine, a specific protein kinase C inhibitor. S-ketamine, propofol, xylazine, midazolam, and etomidate did not affect mitoKATP channel activity. The significance of these modulatory effects of the anesthetics on mitoKATP channel activity was substantiated in a cellular model of simulated ischemia, where diazoxide-induced cell protection was mitigated by R-ketamine and the barbiturates, while urethane, 2,2,2-trichloroethanol, and fentanyl potentiated myocyte protection.  相似文献   

970.
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