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   1592774篇
  免费   133590篇
  国内免费   4446篇
耳鼻咽喉   22802篇
儿科学   50767篇
妇产科学   40891篇
基础医学   216975篇
口腔科学   39957篇
临床医学   161509篇
内科学   328925篇
皮肤病学   37021篇
神经病学   134680篇
特种医学   60984篇
外国民族医学   278篇
外科学   245197篇
综合类   28154篇
现状与发展   75篇
一般理论   735篇
预防医学   124703篇
眼科学   35688篇
药学   106681篇
  8篇
中国医学   2313篇
肿瘤学   92467篇
  2021年   16354篇
  2020年   13621篇
  2019年   16007篇
  2018年   24974篇
  2017年   20373篇
  2016年   22558篇
  2015年   24947篇
  2014年   38385篇
  2013年   50461篇
  2012年   56737篇
  2011年   59888篇
  2010年   40622篇
  2009年   42406篇
  2008年   56292篇
  2007年   57962篇
  2006年   59366篇
  2005年   55984篇
  2004年   52964篇
  2003年   49432篇
  2002年   47906篇
  2001年   60988篇
  2000年   60878篇
  1999年   52574篇
  1998年   18857篇
  1997年   17049篇
  1996年   17141篇
  1995年   16130篇
  1994年   14023篇
  1993年   13007篇
  1992年   40198篇
  1991年   39653篇
  1990年   38016篇
  1989年   36896篇
  1988年   34127篇
  1987年   33305篇
  1986年   31823篇
  1985年   29965篇
  1984年   23192篇
  1983年   20303篇
  1982年   12677篇
  1979年   21596篇
  1978年   16115篇
  1977年   13523篇
  1976年   12407篇
  1975年   13324篇
  1974年   16051篇
  1973年   15808篇
  1972年   14934篇
  1971年   13863篇
  1970年   13098篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
BACKGROUND/PURPOSE: Tattoos have become increasingly popular followed by a growing demand for tattoo removal, and yet there is little knowledge and monitoring of tattoo pigment deposition in skin layers. The purpose of this pilot study is to describe optical coherence tomography image characteristics of intradermal tattoos. METHODS: We included five black tattoos in 3 female volunteers, 39, 35 and 30 years old. In vivo imaging of tattoo pigments in the skin is possible with optical coherence tomography (OCT), a novel non-invasive, in vivo optical imaging technology with a resolution and a penetration in skin high enough for visualization of tattoo pigment in the dermis. RESULTS: In optical coherence tomography images tattoo pigments clusters appear as dark, homogenous vertical columns and structures in the papillary dermis. OCT-scanned normal skin (without tattoos) appeared to be free of this dark structure. CONCLUSION: We have demonstrated that OCT can be used to visualize clusters of light absorbing pigments in a predictable manner.  相似文献   
995.
背景:Nissen胃底折叠术(Nissen fundoplication,NF)已不是治疗胃食管返流性疾病(gastroesophageal reflux disease,GERD)的唯一、有效的方法。对于能降低胃酸的手术方式来讲,如高选择性迷走神经切断术(highly selective vagotomy,HSV),也不仅仅是一种辅助治疗方法。对高选择性迷走神经切断术联合Nissen胃底折叠术(Nissen fundoplication with highly selective vagotomy,NFHSV)治疗GERD的作用目前尚无完整的评价。方法:2003年6月~2005年6月8例女性病人接受NFHSV,8例均有6个月GERD病史,经药物治疗症状无缓解,有餐前痛、消化性溃疡或严重的胃炎。平均随访时间12个月,术前、术后进行烧心严重程度评分测定(heart burn severity score,HSS)。结果:平均手术时间110min,无手术并发症。1例术后须用质子泵抑制剂,术后经戒烟5个月后停药。8例术后症状和烧心严重程度评分测定有明显改善。结论:NFHSV是有效的联合手术方式,尚需要进一步的研究证实这一联合术式的完全有效性和安全性。  相似文献   
996.
997.
Pulmonary arterial hypertension (PAH) is a disease of the small vessels in which there is a substantial increase in pulmonary vascular resistance leading to right ventricle failure and death. Invasive haemodynamic evaluation is mandatory not only for diagnosis confirmation but also to address prognosis and eligibility for the use of calcium-channel blockers through an acute vasodilator challenge. Noninvasive surrogate response markers to the acute vasodilator test have been sought. In the present study, the relationship between pulmonary artery distensibility, assessed using magnetic resonance imaging (MRI), and response to acute vasodilator tests was investigated. In total, 19 patients diagnosed with idiopathic PAH without any specific treatment were evaluated. Within a 48-h window after pulmonary artery catheterisation, patients underwent cardiac MRI. Cardiac index, calculated after the determination (invasively and noninvasively) of cardiac output, showed excellent correlation, as did right atrial pressure and right ventricle ejection fraction. Pulmonary artery distensibility was significantly higher in responders. A receiver operating characteristic curve analysis has shown that 10% distensibility was able to differentiate responders from nonresponders with 100% sensitivity and 56% specificity. The present findings suggest that magnetic resonance imaging and pulmonary artery distensibility may be useful noninvasive tools for the evaluation of patients with pulmonary hypertension.  相似文献   
998.
The present study was designed to evaluate the hypothesis that nebulised budesonide (NB) might be an alternative to systemic corticosteroids (SC) in the treatment of patients with exacerbations of chronic obstructive pulmonary disease (ECOPD). Patients hospitalised with ECOPD (n = 159) were randomised into three groups. Group 1 received only standard bronchodilator treatment (SBDT), group 2 received SC (40 mg prednisolone) plus SBDT, and group 3 received NB (1,500 microg q.i.d.) plus SBDT. Improvement during 10-day hospitalisation was compared with exacerbation and rehospitalisation rates after discharge. While mean+/-sd age was 64.1+/-8.9 yrs (female/male = 0.1), mean forced expiratory volume in one second (FEV(1)) at admission was found to be 37.2+/-12.2% predicted. Arterial blood gases and spirograms recovered faster in groups 2 and 3. While improvements in arterial oxygen tension (P(a,O(2))) and forced vital capacity (FVC) in group 2, and improvements in P(a,O(2)), FVC and FEV(1) in group 3, became significant at 24-h control, the first significant improvement in group 1 appeared in arterial oxygen saturation at 72-h control. The mean improvement of P(a,O(2)) after 10 days was 1.20 and 1.06 kPa (9 and 8 mmHg) higher in group 2 and 3, respectively, than in group 1. Blood glucose exhibited an upward trend only in group 2. The study demonstrates that nebulised budesonide may be an effective and safe alternative to systemic corticosteroids in the treatment of exacerbations of chronic obstructive pulmonary disease.  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