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   2593279篇
  免费   185332篇
  国内免费   7596篇
耳鼻咽喉   34309篇
儿科学   85301篇
妇产科学   71631篇
基础医学   364283篇
口腔科学   69764篇
临床医学   234890篇
内科学   516952篇
皮肤病学   62564篇
神经病学   213732篇
特种医学   100174篇
外国民族医学   736篇
外科学   387713篇
综合类   50420篇
现状与发展   5篇
一般理论   968篇
预防医学   196412篇
眼科学   56744篇
药学   188316篇
  8篇
中国医学   5345篇
肿瘤学   145940篇
  2021年   20107篇
  2019年   20704篇
  2018年   29386篇
  2017年   22696篇
  2016年   26335篇
  2015年   29634篇
  2014年   40597篇
  2013年   60580篇
  2012年   80503篇
  2011年   84813篇
  2010年   51202篇
  2009年   49294篇
  2008年   79310篇
  2007年   84185篇
  2006年   85887篇
  2005年   82058篇
  2004年   79057篇
  2003年   76345篇
  2002年   73624篇
  2001年   128564篇
  2000年   131483篇
  1999年   110663篇
  1998年   31348篇
  1997年   27983篇
  1996年   28284篇
  1995年   27434篇
  1994年   25099篇
  1993年   23477篇
  1992年   85267篇
  1991年   81647篇
  1990年   78859篇
  1989年   76137篇
  1988年   69529篇
  1987年   68059篇
  1986年   63611篇
  1985年   60571篇
  1984年   44989篇
  1983年   37983篇
  1982年   22481篇
  1981年   20002篇
  1979年   38982篇
  1978年   27464篇
  1977年   23275篇
  1976年   21508篇
  1975年   22838篇
  1974年   26810篇
  1973年   25391篇
  1972年   23764篇
  1971年   21976篇
  1970年   20199篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
BACKGROUND: The MR and pathologic features of hippocampal sclerosis (HS) are well described and include volume decrease and T2-weighted signal increase for MRI, and neuron cell loss and gliosis for pathology. OBJECTIVE: To confirm the established correlation between hippocampal volumes and neuron cell counts, and to study the still controversial association between signal change and gliosis. METHODS: The authors studied 44 patients (22 men and 22 women; mean age at surgery, 37 years) with refractory temporal lobe epilepsy. Quantitative assessment of hippocampal volumes and T2 relaxometry, and neuron and glial cell count in the region CA1 and molecular layer of the dentate gyrus was performed. The proportion of glial fibrillary acidic protein (GFAP)-positive glial cells (reactive astrocytes) was indicated. RESULTS: In a stepwise regression, the ipsilateral hippocampal volume was predicted best by the neuron cell count in the dentate gyrus (p = 0.005, r = 0.4). Hippocampal T2 time, however, was predicted best by the glial cell count in the dentate gyrus (p = 0.01, r = 0.4). None of the other cell counts contributed to either model. In the dentate, 31% of the glial cells were reactive astrocytes, whereas in CA1, 5% were reactive. CONCLUSION: The results confirmed the correlation between hippocampal volumes and neuron cell counts. T2-weighted signal increase in the hippocampus was mainly influenced by gliosis in the dentate gyrus, where a high proportion of glial cells show abnormal activity. This activity may reflect changes important in the development of hippocampal epileptogenicity.  相似文献   
993.
INTRODUCTION: Intravascular brachytherapy (IVBT) utilises the percutaneous insertion of a radioactive source to inhibit myointimal hyperplasia in arteries treated by balloon angioplasty or stenting. A systematic review was performed of trials of IVBT in patients with Peripheral Arterial Disease (PAD). METHODS: Search strategy - the reviewers searched Medline, Embase, the Cochrane Peripheral Vascular Diseases Group trials register, DARE, CCT and NHS EED for clinical studies and trials of adjuvant IVBT in PAD. Two reviewers assessed trial quality independently. RESULTS: Fourteen clinical trials were identified by the search, representing five clinical studies (all allocated D for not randomised) and one randomised controlled trial (allocated A). The randomised trial showed a benefit for IVBT compared with placebo (OR 0.35, 95% CI 0.24-0.53). In the non-randomised studies, 12 month cumulative patency rates ranged from 60-87%. There were few technical complications. In the only report involving IVBT and routine concurrent stent insertion acute thrombosis occurred in 7 (21%) of patients. CONCLUSION: Early reports have confirmed the safety and technical feasibility of IVBT. However, follow-up is too short at present to assess the durability and long-term complications of this new therapeutic option.  相似文献   
994.
995.
Oxidative stress is an important factor in many pathological conditions such as inflammation, cancer, ageing and organ response to ischemia-reperfusion. Humans have developed a complex antioxidant system to eliminate or attenuate oxidative stress. Liver ischemia-reperfusion injury occurs in a number of clinical settings, including liver surgery, transplantation, and hemorrhagic shock with subsequent fluid resuscitation, leading to significant morbidity and mortality. It is characterized by significant oxidative stress but accompanied with depletion of endogenous antioxidants. This review has 2 aims: firstly, to highlight the clinical significance of liver ischemia-reperfusion injury, the underlying mechanisms and the main pathways by which the antioxidants function, and secondly, to describe the new developments that are ongoing in antioxidant therapy and to present the experimental and clinical evidence about the role of antioxidants in modulating hepatic ischemia-reperfusion injury.  相似文献   
996.
Background: Tight perioperative control of blood glucose improves the outcome of diabetic patients undergoing cardiac surgery. Because stress response and cardiopulmonary bypass can induce profound hyperglycemia, intraoperative glycemic control may become difficult. The authors undertook a prospective cohort study to determine whether poor intraoperative glycemic control is associated with increased intrahospital morbidity.

Methods: Two hundred consecutive diabetic patients undergoing on-pump heart surgery were enrolled. A standard insulin protocol based on subcutaneous intermediary insulin was given the morning of the surgery. Intravenous insulin therapy was initiated intraoperatively from blood glucose concentrations of 180 mg/dl or greater and titrated according to a predefined protocol. Poor intraoperative glycemic control was defined as four consecutive blood glucose concentrations greater than 200 mg/dl without any decrease in despite insulin therapy. Postoperative blood glucose concentrations were maintained below 140 mg/dl by using aggressive insulin therapy. The main endpoints were severe cardiovascular, respiratory, infectious, neurologic, and renal in-hospital morbidity.

Results: Insulin therapy was required intraoperatively in 36% of patients, and poor intraoperative glycemic control was observed in 18% of patients. Poor intraoperative glycemic control was significantly more frequent in patients with severe postoperative morbidity (37% vs. 10%; P < 0.001). The adjusted odds ratio for severe postoperative morbidity among patients with a poor intraoperative glycemic control as compared with patients without was 7.2 (95% confidence interval, 2.7-19.0).  相似文献   

997.
998.
999.
1000.
OBJECTIVE: To determine the safety and the long-term results of primary stent placement for localized distal aortic occlusive disease. DESIGN: Retrospective observational study. PATIENTS AND METHODS: From July 1998 to July 2005 17 patients (14 female and 3 men, mean age 57 years (39-80)) were treated for intermittent claudication. Five of these patients underwent additional endovascular treatment of focal iliac lesions. RESULTS: Technical success defined as residual stenosis of less than 50% or a trans-stenotic systolic pressure gradient <10% was achieved in 14 of 17 (82%) patients. Major complications included dissection at the puncture site in one patient and thrombosis of additional iliac stents in another patient. Both of these complications were successfully treated. During a mean follow-up of 27 months (range 1-86), four patients had recurrence of symptoms due to in-stent restenoses (n=2), femoral (n=1) or iliac occlusion (n=1), respectively. By Kaplan-Meier analysis, primary aortic hemodynamic patency was 83% at 3 years. Secondary aortic hemodynamic patency was 100%. The primary clinical patency was 68% at 3 years. CONCLUSION: Primary stent placement for distal aortic stenoses is an alternative to surgical treatment because of its high patency and relatively low complication rates.  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