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   4822776篇
  免费   387142篇
  国内免费   15881篇
耳鼻咽喉   68725篇
儿科学   150191篇
妇产科学   126507篇
基础医学   724487篇
口腔科学   136243篇
临床医学   439806篇
内科学   877696篇
皮肤病学   115038篇
神经病学   404529篇
特种医学   191704篇
外国民族医学   1106篇
外科学   731216篇
综合类   139658篇
现状与发展   23篇
一般理论   2729篇
预防医学   403064篇
眼科学   115249篇
药学   347284篇
  29篇
中国医学   12887篇
肿瘤学   237628篇
  2021年   56401篇
  2019年   59013篇
  2018年   74855篇
  2017年   57331篇
  2016年   63901篇
  2015年   76698篇
  2014年   111628篇
  2013年   177135篇
  2012年   132615篇
  2011年   138521篇
  2010年   127916篇
  2009年   129264篇
  2008年   124787篇
  2007年   133763篇
  2006年   142213篇
  2005年   136786篇
  2004年   137300篇
  2003年   127598篇
  2002年   117852篇
  2001年   187395篇
  2000年   185112篇
  1999年   167526篇
  1998年   75033篇
  1997年   70263篇
  1996年   68154篇
  1995年   63973篇
  1994年   57875篇
  1993年   53643篇
  1992年   125351篇
  1991年   120088篇
  1990年   115057篇
  1989年   112119篇
  1988年   103834篇
  1987年   101816篇
  1986年   96716篇
  1985年   94200篇
  1984年   77051篇
  1983年   67947篇
  1982年   51663篇
  1981年   47688篇
  1980年   45000篇
  1979年   68367篇
  1978年   53374篇
  1977年   47407篇
  1976年   43665篇
  1975年   44096篇
  1974年   49914篇
  1973年   47844篇
  1972年   44954篇
  1971年   41446篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
A 3‐year‐old Arab boy with a history of hypoplastic left heart syndrome was referred to the pediatric dermatology clinic at Sheba Medical Center for evaluation of hypomelanosis, manifested by fair skin pigmentation and silvery‐grey hair, eyebrows, and eyelashes. The child had one older brother with similar hypopigmentation and another older brother who had died of congenital heart disease. The child had no history of neurologic deficits or immunodeficiency and no additional findings on clinical evaluation.  相似文献   
972.
973.
974.
975.
976.
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   
977.
978.
979.
980.
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   
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