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   4297269篇
  免费   362277篇
  国内免费   15426篇
耳鼻咽喉   61168篇
儿科学   133700篇
妇产科学   112637篇
基础医学   658278篇
口腔科学   119603篇
临床医学   390709篇
内科学   781546篇
皮肤病学   103608篇
神经病学   368254篇
特种医学   171450篇
外国民族医学   914篇
外科学   655827篇
综合类   126598篇
现状与发展   24篇
一般理论   2613篇
预防医学   364702篇
眼科学   101305篇
药学   303956篇
  24篇
中国医学   11436篇
肿瘤学   206620篇
  2021年   55964篇
  2020年   35654篇
  2019年   58798篇
  2018年   73545篇
  2017年   56122篇
  2016年   62493篇
  2015年   75779篇
  2014年   110689篇
  2013年   176236篇
  2012年   119573篇
  2011年   122976篇
  2010年   123651篇
  2009年   126736篇
  2008年   110182篇
  2007年   116947篇
  2006年   126283篇
  2005年   121484篇
  2004年   122269篇
  2003年   112662篇
  2002年   103329篇
  2001年   154505篇
  2000年   150641篇
  1999年   139726篇
  1998年   71430篇
  1997年   67850篇
  1996年   65698篇
  1995年   61559篇
  1994年   55649篇
  1993年   51668篇
  1992年   103693篇
  1991年   99075篇
  1990年   94151篇
  1989年   91789篇
  1988年   85407篇
  1987年   83879篇
  1986年   79541篇
  1985年   78003篇
  1984年   66025篇
  1983年   58910篇
  1982年   48215篇
  1981年   44941篇
  1980年   42237篇
  1979年   57899篇
  1978年   47088篇
  1977年   41648篇
  1976年   38688篇
  1975年   37911篇
  1974年   42465篇
  1973年   40608篇
  1972年   38054篇
排序方式: 共有10000条查询结果,搜索用时 28 毫秒
991.
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   
992.
993.
994.
995.
996.
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   
997.
998.
999.
1000.
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