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   4272913篇
  免费   362212篇
  国内免费   15281篇
耳鼻咽喉   61019篇
儿科学   133087篇
妇产科学   111996篇
基础医学   654886篇
口腔科学   119501篇
临床医学   388889篇
内科学   775878篇
皮肤病学   103458篇
神经病学   366630篇
特种医学   170923篇
外国民族医学   912篇
外科学   652816篇
综合类   126165篇
现状与发展   34篇
一般理论   2581篇
预防医学   362664篇
眼科学   100626篇
药学   301906篇
  25篇
中国医学   11366篇
肿瘤学   205044篇
  2021年   55769篇
  2020年   35762篇
  2019年   58656篇
  2018年   73520篇
  2017年   56231篇
  2016年   62594篇
  2015年   75894篇
  2014年   110680篇
  2013年   176067篇
  2012年   117562篇
  2011年   120620篇
  2010年   123167篇
  2009年   126529篇
  2008年   107716篇
  2007年   114175篇
  2006年   123683篇
  2005年   118784篇
  2004年   119698篇
  2003年   110420篇
  2002年   101019篇
  2001年   154404篇
  2000年   150514篇
  1999年   139648篇
  1998年   71433篇
  1997年   67871篇
  1996年   65772篇
  1995年   61593篇
  1994年   55639篇
  1993年   51672篇
  1992年   103631篇
  1991年   98999篇
  1990年   94107篇
  1989年   91748篇
  1988年   85343篇
  1987年   83821篇
  1986年   79509篇
  1985年   77935篇
  1984年   65968篇
  1983年   58883篇
  1982年   48159篇
  1981年   44897篇
  1980年   42189篇
  1979年   57839篇
  1978年   47044篇
  1977年   41617篇
  1976年   38667篇
  1975年   37860篇
  1974年   42432篇
  1973年   40562篇
  1972年   38025篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
992.
993.
994.
Fluid is usually restricted during thoracic surgery, and vasoactive agents are often administered to maintain blood pressure. One-lung ventilation (OLV) decreases arterial oxygenation; thus oxygen delivery to the brain can be decreased. In this study, we compared phenylephrine and dopamine with respect to maintaining cerebral oxygenation during OLV in major thoracic surgery.Sixty-three patients undergoing lobectomies were randomly assigned to the dopamine (D) or phenylephrine (P) group. The patients’ mean arterial pressure was maintained within 20% of baseline by a continuous infusion of dopamine or phenylephrine. Maintenance fluid was kept at 5 mL/kg/h. The depth of anesthesia was maintained with desflurane 1MAC and remifentanil infusion under bispectral index guidance. Regional cerebral oxygen saturation (rScO2) and hemodynamic variables were recorded using near-infrared spectroscopy and esophageal cardiac Doppler.The rScO2 was higher in the D group than the P group during OLV (OLV 60 min: 71 ± 6% vs 63 ± 12%; P = 0.03). The number of patients whose rScO2 dropped more than 20% from baseline was 0 and 6 in the D and P groups, respectively (P = 0.02). The D group showed higher cardiac output, but lower mean arterial pressure than the P group (4.7 ± 1.0 vs 3.9 ± 1.2 L/min; 76.7 ± 8.1 vs 84.5 ± 7.5 mm Hg; P = 0.02, P = 0.02). Among the variables, age, hemoglobin concentration, and cardiac output were associated with rScO2 by correlation analysis.Dopamine was superior to phenylephrine in maintaining cerebral oxygenation during OLV in thoracic surgery.  相似文献   
995.
996.
997.
998.
Liver-related death in human immunodeficiency virus (HIV)-infected individuals is about 10 times higher compared with the general population, and the prevalence of significant liver fibrosis in those with HIV approaches 15%. The present study aimed to assess risk factors for development of hepatic fibrosis in HIV patients receiving a modern combination anti-retroviral therapy (cART).This cross-sectional prospective study included 432 HIV patients, of which 68 (16%) patients were anti-hepatitis C virus (HCV) positive and 23 (5%) were HBsAg positive.Health trajectory including clinical characteristics and liver fibrosis stage assessed by transient elastography were collected at inclusion. Liver stiffness values >7.1 kPa were considered as significant fibrosis, while values >12.5 kPa were defined as severe fibrosis. Logistic regression and Cox regression uni- and multivariate analyses were performed to identify independent factors associated with liver fibrosis.Significant liver fibrosis was detected in 10% of HIV mono-infected, in 37% of HCV co-infected patients, and in 18% of hepatitis B virus co-infected patients. The presence of diabetes mellitus (odds ratio [OR] = 4.6) and FIB4 score (OR = 2.4) were independently associated with presence of significant fibrosis in the whole cohort. Similarly, diabetes mellitus (OR = 5.4), adiposity (OR = 4.6), and the FIB4 score (OR = 3.3) were independently associated with significant fibrosis in HIV mono-infected patients. Importantly, cumulative cART duration protected, whereas persistent HIV viral replication promoted the development of significant liver fibrosis along the duration of HIV infection.Our findings strongly indicate that besides known risk factors like metabolic disorders, HIV may also have a direct effect on fibrogenesis. Successful cART leading to complete suppression of HIV replication might protect from development of liver fibrosis.  相似文献   
999.
1000.
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