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   26974篇
  免费   2516篇
  国内免费   53篇
耳鼻咽喉   501篇
儿科学   710篇
妇产科学   523篇
基础医学   3777篇
口腔科学   635篇
临床医学   2592篇
内科学   4967篇
皮肤病学   427篇
神经病学   1979篇
特种医学   903篇
外国民族医学   1篇
外科学   4297篇
综合类   576篇
一般理论   27篇
预防医学   2784篇
眼科学   690篇
药学   1745篇
中国医学   21篇
肿瘤学   2388篇
  2021年   371篇
  2020年   229篇
  2019年   338篇
  2018年   431篇
  2017年   334篇
  2016年   386篇
  2015年   419篇
  2014年   603篇
  2013年   909篇
  2012年   1313篇
  2011年   1290篇
  2010年   761篇
  2009年   662篇
  2008年   1195篇
  2007年   1352篇
  2006年   1291篇
  2005年   1287篇
  2004年   1171篇
  2003年   1168篇
  2002年   1102篇
  2001年   801篇
  2000年   795篇
  1999年   700篇
  1998年   329篇
  1997年   311篇
  1996年   300篇
  1995年   266篇
  1994年   267篇
  1993年   238篇
  1992年   625篇
  1991年   530篇
  1990年   511篇
  1989年   518篇
  1988年   458篇
  1987年   436篇
  1986年   414篇
  1985年   426篇
  1984年   354篇
  1983年   289篇
  1982年   238篇
  1981年   245篇
  1980年   192篇
  1979年   312篇
  1978年   279篇
  1977年   200篇
  1976年   179篇
  1975年   198篇
  1974年   266篇
  1973年   204篇
  1972年   216篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
41.
OBJECTIVE: To determine whether the experience of the specialist team was associated with adverse events following endovascular treatment of abdominal aortic aneurysms. METHODS: The EUROSTAR database is a voluntary registry of 2863 patients admitted to 93 hospitals in Europe with an abdominal aortic aneurysm treated with endovascular stenting. Mortality, rupture and the need for secondary interventions were the main outcomes. RESULTS: In patients who underwent endovascular stenting by the most experienced specialist teams the mortality rate was 40% lower than in those treated by the least experienced teams (adjusted hazard ratio 0.60, 95% confidence interval: 0.4-1.0; p = 0.05). Also patients treated by the most experienced specialist teams were 68% less likely to have adverse events necessitating a secondary intervention than those treated by the least experienced teams (adjusted hazard ratio 0.32, 95% confidence interval: 0.2-0.5; p < 0.001). The crude rupture rate was 0.1% among patients treated by the most experienced specialist teams and 0.8% among those treated by the least experienced teams (p = 0.74). CONCLUSIONS: Specialist teams with a high level of experience of endovascular abdominal aortic aneurysm stenting encounter lower mortality rates and fewer adverse events leading to secondary interventions.  相似文献   
42.
43.
44.
Pseudomembranous tracheobronchitis caused by Aspergillus   总被引:1,自引:0,他引:1  
Four immunosuppressed patients with a rapidly evolving, febrile, respiratory distress syndrome were found at autopsy to have Aspergillus pseudomembranes of their lower tracheobronchial tree. Steroids, neutropenia, broad spectrum antibiotic use, and alcoholism appear to be predisposing risk factors. Bronchoscopy may reveal the pathology but antemortem diagnosis is difficult because of the low yield of sputum cultures and fulminant nature of the disease.  相似文献   
45.
We have previously shown that neuregulin-1 (NRG-1) protects neurons from ischemic brain injury if administered before focal stroke. Here, we examined the therapeutic window and functional recovery after NRG-1 treatment in rats subjected to 90 mins of middle cerebral artery occlusion (MCAO) and 24 h of reperfusion. Neuregulin-1 (2.5 ng/kg bolus, 1.25 ng/kg/min infusion) reduced infarct volume by 89.2%+/-41.9% (mean+/-s.d.; n=8; P<0.01) if administered immediately after the onset of reperfusion. Neuroprotection was also evident if NRG-1 was administered 4 h (66.4%+/-52.6%; n=7; P<0.01) and 12 h (57.0%+/-20.8%; n=8; P<0.01) after reperfusion. Neuregulin-1 administration also resulted in a significant improvement of functional neurologic outcome compared with vehicle-treated animals (32.1%+/-5.7%; n=9; P<0.01). The neuroprotective effect of the single administration of NRG-1 was seen as long as 2 weeks after treatment. Neurons labeled with the neurodegeneration marker dye Fluoro-JadeB were observed after MCAO in the cortex, but the numbers were significantly reduced after NRG-1 treatment. These results indicate that NRG-1 is a potent neuroprotective compound with an extended therapeutic window that has practical therapeutic potential in treating individuals after ischemic brain injury.  相似文献   
46.
QALYfying the value of life.   总被引:10,自引:0,他引:10  
This paper argues that the Quality Adjusted Life Year or QALY is fatally flawed as a way of priority setting in health care and of dealing with the problem of scarce resources. In addition to showing why this is so the paper sets out a view of the moral constraints that govern the allocation of health resources and suggests reasons for a new attitude to the health budget.  相似文献   
47.
The human lung tumor-derived cell lines A549, Calu-1, Calu-3, HuT292, and SW900 and the transformed human bronchial epithelial cell line TBE-1, that was transfected with the v-Harvey-ras oncogene, were inoculated into deepithelialized Fisher 344 rat tracheas (5 X 10(5) cells/trachea). After the ends of the tracheas were sealed, the tracheas were transplanted into s.c. tissues of nude mice. In a parallel experiment, 1 X 10(6) cells from each of these cell lines were injected s.c. Histological examination of the tracheal transplants 2, 4, 8, 12, and 16 weeks after cell inoculation proved to be of greater usefulness than either clinical or histological observation of the s.c. injection sites. A549, Calu-1, and TBE-1 produced intratracheal neoplastic nodules as early as 2 weeks after cell inoculation. Calu-3, HuT292, and SW900 grew relatively slowly in the tracheas, and simple or stratified epithelia with slight or moderate atypia (preneoplastic lesions) were seen at 2 weeks. After the 4th week, they produced tumor nodules in the tracheal transplants, whereas no tumor cells could be seen at the s.c. injection sites. The human derivation of the cells was confirmed by in situ hybridization using human-specific DNA probes. The intratracheal inoculation and xenotransplantation of human-derived cell lines offers a time-saving alternative to the s.c. inoculation assay for tumorigenicity and is at the same time a potentially valuable approach to studying preneoplastic and neoplastic progression with human cell subpopulations.  相似文献   
48.
1. The present study investigated the effect of prior administration of nifedipine on AVP-induced ACTH release in seven normal volunteers. Three protocols were used: 20 mg oral nifedipine; 0.14 pressor units intramuscular (i.m.) per kg bodyweight aqueous AVP; oral nifedipine plus i.m. AVP 90 min later. Plasma ACTH and cortisol were measured at intervals for 2.5 h during each test. 2. The mean peak plasma ACTH and cortisol levels and the mean peak changes from basal in these levels were significantly lower in the nifedipine/AVP test than in the AVP alone test. The integrated area under the cortisol time curve was significantly lower for the nifedipine/AVP test than that for the AVP test alone. Nifedipine alone caused no changes in ACTH or cortisol. 3. Acute administration of oral nifedipine caused an inhibition of AVP-stimulated ACTH and cortisol release in normal humans. This effect may be due to blockade of plasma membrane calcium channels normally activated during AVP stimulation of pituitary corticotrophs.  相似文献   
49.
A 71 year old white male is reported in whom ischaemic ulceration of the lesser curve of the stomach, a variant of lesser curve necrosis, occurred after the combined procedures of highly selective vagotomy (HSV) and abdominal aortic aneurysmectomy. Other operations, particularly fundoplication and incidental splenectomy, have been implicated in the aetiology of lesser curve ischaemia, an otherwise rare complication of HSV. This case suggests that concomitant aortic surgery may also increase the risk of lesser curve ischaemia after HSV. Careful endoscopic monitoring of patients undergoing these combined procedures is therefore recommended to better define the risk.  相似文献   
50.
Cardiac arrhythmias are a well known cause of mortality for patients with heart disease. However, sinus tachycardia is a more unusual arrhythmia which can lead to serious heart damage or death. Even young patients with structurally normal hearts may become gravely ill.

This case study outlines the condition of sinus tachycardia, and associated changes in heart function, altered cellular structure of the myocardium and compensatory mechanisms in the body. Treatment modalities, including electro-physiological studies and drug therapies to moderate the tachycardia and myocardial oxygen demand of the heart, are discussed. Fourteen year old ‘Ben’ was previously a well, active and outgoing youth who suddenly became critically ill. He endured weeks of hospitalisation, numerous serious complications including Torsade de pointes arrhythmia, Cheyne-Stokes respirations, nausea and dizziness during this acute phase. Despite challenges, Ben's severely compromised heart muscle recovered at a remarkable rate.  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