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   2584篇
  免费   187篇
  国内免费   15篇
耳鼻咽喉   20篇
儿科学   108篇
妇产科学   52篇
基础医学   244篇
口腔科学   44篇
临床医学   268篇
内科学   674篇
皮肤病学   29篇
神经病学   102篇
特种医学   294篇
外科学   227篇
综合类   104篇
预防医学   162篇
眼科学   227篇
药学   128篇
中国医学   9篇
肿瘤学   94篇
  2021年   18篇
  2020年   15篇
  2019年   28篇
  2018年   27篇
  2017年   29篇
  2016年   30篇
  2015年   39篇
  2014年   75篇
  2013年   116篇
  2012年   103篇
  2011年   102篇
  2010年   76篇
  2009年   89篇
  2008年   109篇
  2007年   127篇
  2006年   108篇
  2005年   92篇
  2004年   87篇
  2003年   77篇
  2002年   75篇
  2001年   61篇
  2000年   70篇
  1999年   63篇
  1998年   90篇
  1997年   64篇
  1996年   82篇
  1995年   56篇
  1994年   68篇
  1993年   54篇
  1992年   52篇
  1991年   51篇
  1990年   46篇
  1989年   67篇
  1988年   73篇
  1987年   55篇
  1986年   36篇
  1985年   36篇
  1984年   35篇
  1983年   29篇
  1982年   26篇
  1981年   32篇
  1980年   21篇
  1979年   19篇
  1978年   19篇
  1977年   27篇
  1976年   15篇
  1975年   15篇
  1974年   13篇
  1973年   13篇
  1972年   10篇
排序方式: 共有2786条查询结果,搜索用时 15 毫秒
1.
S R Wise  M Quigley  A W Saxe  M J Zdon 《Surgery》1990,108(6):1058-63; discussion 1063-4
Patients with hyperparathyroidism appear to be a particular risk for peptic ulcer disease. To test the hypothesis that hypercalcemia or parathyroid hormone plays a role in promoting ulcer disease, we studied the effect of varying concentrations of extracellular calcium on acid secretion using in vitro isolated rabbit gastric glands. Acid secretion was assessed by the accumulation of carbon 14-labeled aminopyrine (14C-AP). Glands were incubated with varying calcium concentrations in the unstimulated state and with histamine or carbachol (10(-7) to 10(-4) mol/L) in 1 or 2 mmol/L calcium medium. The effect of parathyroid hormone was also examined under identical conditions. Compared to 1 mmol/L standard calcium medium, unstimulated 14C-AP accumulation was significantly inhibited (p less than 0.05) at both lower (0.33 mmol/L) and higher (2 and 2.5 mmol/L) calcium concentrations. Accumulation of 14C-AP in response to histamine stimulation was unaffected by alteration of extracellular calcium (p greater than 0.2). Carbachol-stimulated 14C-AP accumulation was significantly augmented (p less than 0.01) by an increase in calcium concentration from 1 to 2 mmol/L. The addition of parathyroid hormone (10(-7) to 10(-4) mmol/L) alone or in combination with carbachol or histamine (10(-6) mmol/L) incubation did not alter 14C-AP accumulation. These data suggest that elevations in extracellular calcium play an active role in the potentiation of cholinergic-mediated gastric gland acid secretion and may thereby play a role in hyperparathyroid-related ulcer disease.  相似文献   
2.
3.
Fear of falling, defined as a lack of self-confidence that one may avoid falls while doing everyday activities, may have serious consequences for elderly people. This article examines the prevalence, risk factors, and consequences of fear of falling in the elderly population; methods for assessing those fears; and suggests evidence-based interventions. Incorporating successful strategies into programs to reduce falling can result in improved patient outcomes as well as decreased healthcare utilization and costs.  相似文献   
4.
To determine if amplification of the C-erb-B2 proto-oncogene could be correlated with prognosis in carcinoid tumours, 49 pulmonary carcinoid tumours (26 typical, 23 atypical) were examined using a polyclonal antibody to the C-terminal peptide of the C-erb-B2 protein sequence. No C-erb-B2 gene product could be shown: the demonstration of C-erb-B2 does not seem to help, therefore, in determining diagnosis or prognosis in pulmonary carcinoid tumours.  相似文献   
5.
Retrorenal colon: implications for percutaneous diskectomy   总被引:1,自引:0,他引:1  
Helms  CA; Munk  PL; Witt  WS; Davis  GW; Morris  J; Onik  G 《Radiology》1989,171(3):864-865
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary.  相似文献   
6.
7.
Using the Ektachem-700 multilayer film analyzer, we defined age- and sex-specific reference intervals for 20 analytes in sera from a healthy population of neonates and children ages one to 19 years. Upper and lower normal reference intervals for each analyte were determined by nonparametric methods as the 0.975 and 0.025 fractiles, respectively. Newborns have lower concentrations of total protein and albumin, and higher concentrations of phosphate, bilirubin, and enzymes in serum than older children do. Concentrations of urea, glucose, calcium, phosphate, and bilirubin change rapidly postnatally. Outside the neonatal period, no significant age- or sex-related difference was found for plasma glucose, serum amylase, conjugated or unconjugated bilirubin, or lipase. There was no sex-related difference in reference intervals for albumin, total protein, calcium, phosphate, or urea. However, concentrations of uric acid and creatine kinase are much higher in postpubertal boys than in girls. Alkaline phosphatase values peak later in boys. Except for lactate dehydrogenase and gamma-glutamyltransferase, the reference intervals defined here do not differ strikingly from data derived with use of other analyzers. The age- and sex-related trends are independent of method. However, each laboratory should determine the degree to which these reference ranges can be directly applied to analyses performed with another analyzer.  相似文献   
8.
9.
Lower lumbar disc surgery is an extremely common operation from which vascular complications are reported rarely. However vascular injury can occur with perforation of the anterior longitudinal ligament. External haemorrhage is uncommon and the true cause of the patient's hypotension may be misdiagnosed. If the hypotension is severe or prolonged laparotomy is indicated, to prevent exsanguination and to effect a repair of the vascular injury. Alternatively, if the injury is missed, an arteriovenous fistula may develop; this diagnosis may be delayed for months or years. One case of severe haemorrhage following lower lumbar disc surgery is reported and a further 69 cases of similar arterial injury have been reviewed from the world literature.  相似文献   
10.
采用间接ELISA检测23名肾移植受者血清巨细胞病毒(CMV)抗体,共检出18名(78%)活动性CMV感染,其中10名(44%)为原发性感染。结果证实CMV-IgE和-IgA具有较好的血清学诊断价值,优于CMV-IgM。  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