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   3515697篇
  免费   271745篇
  国内免费   6869篇
耳鼻咽喉   49733篇
儿科学   112114篇
妇产科学   94658篇
基础医学   495683篇
口腔科学   103113篇
临床医学   320707篇
内科学   681203篇
皮肤病学   74893篇
神经病学   286185篇
特种医学   136553篇
外国民族医学   1084篇
外科学   531052篇
综合类   83991篇
现状与发展   5篇
一般理论   1394篇
预防医学   278430篇
眼科学   84216篇
药学   262364篇
  11篇
中国医学   7484篇
肿瘤学   189438篇
  2018年   37569篇
  2017年   28714篇
  2016年   31766篇
  2015年   35996篇
  2014年   51157篇
  2013年   76919篇
  2012年   104751篇
  2011年   110733篇
  2010年   65581篇
  2009年   61939篇
  2008年   104119篇
  2007年   110911篇
  2006年   111864篇
  2005年   108518篇
  2004年   104542篇
  2003年   100304篇
  2002年   98094篇
  2001年   166754篇
  2000年   172007篇
  1999年   144795篇
  1998年   41123篇
  1997年   36679篇
  1996年   36345篇
  1995年   35162篇
  1994年   32823篇
  1993年   30424篇
  1992年   114834篇
  1991年   111169篇
  1990年   107272篇
  1989年   103617篇
  1988年   95684篇
  1987年   93982篇
  1986年   88846篇
  1985年   84752篇
  1984年   63812篇
  1983年   54376篇
  1982年   32215篇
  1981年   28770篇
  1979年   58790篇
  1978年   41064篇
  1977年   34890篇
  1976年   32650篇
  1975年   34467篇
  1974年   42421篇
  1973年   40474篇
  1972年   37889篇
  1971年   34987篇
  1970年   32871篇
  1969年   30587篇
  1968年   28086篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
High levels of tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, are present in the wound fluid of chronic nonhealing wounds. This leads to increased inflammation, cytokine expression, and ultimately results in impaired wound healing and tissue destruction. Etanercept is a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1. It is an effective inhibitor of TNF-alpha and has been shown to provide rapid and sustained improvement in rheumatoid arthritis by acting as a soluble receptor binding TNF-alpha and preventing its proinflammatory activities. Therefore, the aim of this study was to determine whether Etanercept could inhibit TNF-alpha activity in chronic wound fluid. Wound fluid was collected from the venous leg ulcers of 16 different patients. The effect of Etanercept on TNF-alpha activity was evaluated using both a TNF-alpha bioassay and an enzyme-linked immunoassay. Etanercept was found to reduce the cytotoxic effect of chronic wound fluid on L929 fibroblasts by approximately 30% and neutralized TNF-alpha binding in the enzyme-linked immunoassay by up to 80%. Direct application of Etanercept to chronic wounds may therefore reduce the inflammatory activity of TNF-alpha, which could reduce the chronicity of venous leg ulcers and thus aid in the healing of these wounds.  相似文献   
992.
993.
For many parents stopping life-sustaining medical treatment on their dying infant is psychologically impossible. Dostoevsky's insights into human behavior, particularly the fact that individuals do not want the anxiety and guilt associated with responsibility for making difficult decisions, might change the way physicians approach parents for permission to withdraw life-prolonging medical interventions on dying infants.  相似文献   
994.
A series of 1-alkyl-3,4-dihydroisoquinolines and the related 4-alkyl-1,2-dihydro-benzo[f]isoquinolines was synthesized using reactions of dialkylbenzylcarbinols and their naphthyl analogs with alkylcyanides. Experiments showed that 1-alkyl-6,7-dimethoxy-3,4-dihydroisoquinolines typically produce a hypotensive action, while the benzo-annelated structures usually exhibit a hypertensive effects. The most active compound decreases the arterial pressure in cats by 52 Torr and the effect lasts for about 4 hours. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 3, pp. 15–17, March, 2006.  相似文献   
995.
996.
The authors discuss techniques for Monte Carlo (MC) cohort simulations that reduce the number of simulation replications required to achieve a given degree of precision for various output measures. Known as variance reduction techniques, they are often used in industrial engineering and operations research models, but they are seldom used in medical models. However, most MC cohort simulations are well suited to the implementation of these techniques. The authors discuss the cost of implementation versus the benefit of reduced replications.  相似文献   
997.
998.
999.
Consecutive patients (n = 215) who were referred to optometric (55%) or multidisciplinary (45%) low-vision services and above 50 years of age were recruited from four hospitals in the Netherlands. They completed two vision-related quality of life questionnaires, the Vision Quality of Life Core Measure (VCM1) and the Low Vision Quality of Life Questionnaire (LVQOL), before their first visit with low-vision services and 1 year later. At follow-up, patients referred to multidisciplinary low-vision services had lower scores on the mobility subscale of the LVQOL than patients referred to optometric low-vision services [5.3 points; 95% confidence interval (CI): 0.2-10.5]. Paired sample t-tests for the two groups of patients taken together show improvement for the VCM1 (3.1 points; 95% CI: 0.6-5.6) and deterioration for the basic aspects of vision (3.5 points; 95% CI: 1.1-5.9) and the mobility (6.6 points; 95% CI: 3.7-9.5) subscales of the LVQOL. In conclusion, people referred to optometric services showed less deterioration in mobility than those referred to multidisciplinary services. No differences were observed for any of the other subscales of the LVQOL and the VCM1. Future research in this field should include randomized controlled designs comparing low-vision services with no treatment or placebo.  相似文献   
1000.
目的:直肠腺瘤和其他疑似为良性的病变应用经肛门内镜切除术并未普及。该项研究旨在评估经肛门内镜切除术的效能和安全性。方法:回顾性研究分析在1993-2004年之间3所斯德哥尔摩医院中经肛门内镜切除术的患,内容包括患自身及病变特性、并发症、随访时间和复发率。结果:180例中共131例行经肛门内镜切除术。160例经组织学诊断为腺瘤,12例为癌瘤,其余8例分别为增生、纤维化或正常黏膜。直肠腺瘤患中,77例仅行单次经肛门内镜切除术,16例因巨大腺瘤而多次行该手术,27例因复发而需另行经肛门内镜切除术或其他手术。中位复发时间为7个月,但未出现直肠癌。16例手术患出现并发症。2例患必须行Hartman手术,1例因肠穿孔,另1例因出血。手术期间无死亡。未复发的中位随访期为32个月(极差0—67)。[编按]  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