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   4937篇
  免费   165篇
  国内免费   15篇
耳鼻咽喉   14篇
儿科学   53篇
妇产科学   66篇
基础医学   518篇
口腔科学   85篇
临床医学   594篇
内科学   1472篇
皮肤病学   53篇
神经病学   587篇
特种医学   91篇
外科学   424篇
综合类   13篇
预防医学   463篇
眼科学   33篇
药学   360篇
中国医学   3篇
肿瘤学   288篇
  2024年   20篇
  2023年   28篇
  2022年   85篇
  2021年   184篇
  2020年   99篇
  2019年   166篇
  2018年   198篇
  2017年   118篇
  2016年   118篇
  2015年   126篇
  2014年   217篇
  2013年   262篇
  2012年   413篇
  2011年   431篇
  2010年   264篇
  2009年   212篇
  2008年   322篇
  2007年   303篇
  2006年   311篇
  2005年   284篇
  2004年   258篇
  2003年   225篇
  2002年   201篇
  2001年   24篇
  2000年   16篇
  1999年   29篇
  1998年   38篇
  1997年   32篇
  1996年   22篇
  1995年   27篇
  1994年   18篇
  1993年   7篇
  1992年   4篇
  1991年   8篇
  1990年   8篇
  1989年   5篇
  1988年   4篇
  1987年   3篇
  1986年   4篇
  1985年   4篇
  1981年   4篇
  1979年   1篇
  1976年   1篇
  1971年   1篇
  1964年   1篇
  1962年   2篇
  1961年   1篇
  1960年   3篇
  1933年   1篇
  1929年   1篇
排序方式: 共有5117条查询结果,搜索用时 15 毫秒
71.
BACKGROUND: Lung damage progression is the most frequent condition in patients with common variable immunodeficiency (CVID). Appropriate immunoglobulin dose adjustments and follow-up guidelines to evaluate this have not been well established. Objective: To assess the evolution of lung damage once stable residual serum levels of IgG over 600 mg/dl had been achieved. METHODS: A prospective study was conducted in 24 adult patients consecutively diagnosed with CVID, with no previous intravenous immunoglobulin (IVIG) treatment. IVIG dose, total serum IgG level, bacterial infection rate, pulmonary function tests (PFTs) and high resolution computed tomography (HRCT) of the thorax were monitored over 2 years. Moreover, outcome data were determined by measurement of chronic pulmonary disease (CPD). RESULTS: IVIG dose variability (205-372 mg/kg/21 days) to obtain the required serum IgG levels was determined. Patients with CPD needed higher doses than those without CPD (p=0.045). A significant reduction in severe and mild infections/patient-year was observed during treatment. Overall, there were no changes in PFTs and HRCT scores in patients without CPD, but both improved in patients with CPD. An increase of over 15% in overall HRCT score was detected in two patients without evidence of impairment in either clinical status or PFT values. CONCLUSIONS: Residual levels of total IgG over 600 mg/dl may help prevent progression of lung damage in patients with CVID. Levels of IgG, clinical manifestations and PFTs seem sufficient for routine follow-up. HRCT examination of the thorax, at least biennially, may help to identify patients in whom lung injury is progressing even though they may remain symptom-free and with stable PFTs.  相似文献   
72.
73.
74.
75.
Endomyocardial disease is a restrictive cardiomyopathy that includes L?ffler endocarditis, which is characterized by hypereosinophilia, and endomyocardial fibrosis, which is not. Echocardiography enables cardiac function and anatomy to be assessed and the differential diagnosis of other causes of restrictive disease, but magnetic resonance imaging provides information about the tissue itself. Furthermore, paramagnetic contrast agents are useful in detecting myocardial abnormalities. We report three cases of endomyocardial disease and the typical findings of magnetic resonance imaging.  相似文献   
76.
77.
78.
The effects of the South American psychotropic beverage ayahuasca on subjective and cardiovascular variables and urine monoamine metabolite excretion were evaluated, together with the drug's pharmacokinetic profile, in a double-blind placebo-controlled clinical trial. This pharmacologically complex tea, commonly obtained from Banisteriopsis caapi and Psychotria viridis, combines N,N-dimethyltryptamine (DMT), an orally labile psychedelic agent showing 5-hydroxytryptamine2A agonist activity, with monoamine oxidase (MAO)-inhibiting beta-carboline alkaloids (harmine, harmaline, and tetrahydroharmine). Eighteen volunteers with prior experience in the use of psychedelics received single oral doses of encapsulated freeze-dried ayahuasca (0.6 and 0.85 mg of DMT/kg of body weight) and placebo. Ayahuasca produced significant subjective effects, peaking between 1.5 and 2 h, involving perceptual modifications and increases in ratings of positive mood and activation. Diastolic blood pressure showed a significant increase at the high dose (9 mm Hg at 75 min), whereas systolic blood pressure and heart rate were moderately and nonsignificantly increased. Cmax values for DMT after the low and high ayahuasca doses were 12.14 ng/ml and 17.44 ng/ml, respectively. Tmax (median) was observed at 1.5 h after both doses. The Tmax for DMT coincided with the peak of subjective effects. Drug administration increased urinary normetanephrine excretion, but, contrary to the typical MAO-inhibitor effect profile, deaminated monoamine metabolite levels were not decreased. This and the negligible harmine plasma levels found suggest a predominantly peripheral (gastrointestinal and liver) site of action for harmine. MAO inhibition at this level would suffice to prevent first-pass metabolism of DMT and allow its access to systemic circulation and the central nervous system.  相似文献   
79.
80.
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