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   371篇
  免费   30篇
  国内免费   5篇
耳鼻咽喉   4篇
儿科学   9篇
妇产科学   5篇
基础医学   40篇
口腔科学   1篇
临床医学   36篇
内科学   120篇
皮肤病学   6篇
神经病学   51篇
特种医学   12篇
外科学   39篇
综合类   1篇
预防医学   15篇
眼科学   4篇
药学   19篇
肿瘤学   44篇
  2024年   1篇
  2023年   4篇
  2022年   2篇
  2021年   15篇
  2020年   10篇
  2019年   13篇
  2018年   8篇
  2017年   6篇
  2016年   13篇
  2015年   13篇
  2014年   6篇
  2013年   13篇
  2012年   37篇
  2011年   36篇
  2010年   11篇
  2009年   30篇
  2008年   36篇
  2007年   23篇
  2006年   16篇
  2005年   13篇
  2004年   23篇
  2003年   21篇
  2002年   22篇
  2001年   2篇
  2000年   3篇
  1999年   5篇
  1998年   9篇
  1997年   5篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1993年   3篇
  1990年   1篇
  1984年   1篇
  1969年   1篇
排序方式: 共有406条查询结果,搜索用时 171 毫秒
1.
2.
3.
PURPOSE: Fenretinide (4-HPR) is a synthetic retinoid that has shown a preventive activity in prostate cancer animal models. EXPERIMENTAL DESIGN: We measured the changes in total and free prostate-specific antigen (PSA) and its association with insulin-like growth factor I (IGF-I) and IGFBP-3 levels after 1 year of treatment in 24 subjects given 4-HPR and 24 control subjects enrolled in a randomized bladder cancer prevention trial. RESULTS: No significant effect of 4-HPR was observed on total and free fraction of PSA levels. The median percentage [95 confidence interval (95% CI)] change for % free PSA and total PSA in the 4-HPR and the control group were, respectively, 7.6 (95% CI, -4.0 to 69.3) versus 5.1 (95% CI, -21.4 to 59.8) and -7.8 (95% CI, -18.2 to 52.5) versus -12.3 (95% CI, -44.6 to 9.6). However, in patients ages <60 years, there was a trend to an increase of total free PSA and % free PSA after treatment with 4-HPR that was different from a trend to a decrease in the control group (P = 0.002 and 0.052, respectively). The interaction between age and treatment was statistically significant on free PSA (P = 0.001). A similar pattern was noted with smoking status (P = 0.011 for the interaction on free PSA). No association was observed between PSA levels and IGF-I or IGFBP-3 levels. CONCLUSIONS: We conclude that 4-HPR has no significant effect on circulating PSA, but it increases significantly free PSA levels in subjects younger than 60 years and in nonsmokers. These effects might support an activity in prostate cancer prevention but further studies are required.  相似文献   
4.
5.
ABSTRACT: INTRODUCTION: Manual hyperinflation (MH), a frequently applied maneuver in critically ill intubated and mechanically ventilated patients, is suggested to mimic a cough so that airway secretions are mobilized towards the larger airways where they can easily be removed. As such, MH could prevent plugging of the airways. METHOD: We performed a search in the databases of Medline, Embase and the Cochrane Library from January 1990 to April 2012. We systematically reviewed the literature on evidence for postulated benefits and risks of MH in critically ill intubated and mechanically ventilated patients. RESULTS: The search identified 50 articles, of which 19 were considered relevant. We included 13 interventional studies and 6 observational studies. The number of studies evaluating physiological effects of MH is limited. Trials differed too much to permit meta-analysis. It is uncertain whether MH was applied similarly in the retrieved studies. Finally, most studies are underpowered to show clinical benefit of MH. Use of MH is associated with short-term improvements in lung compliance, oxygenation and secretion clearance, without changes in outcomes. MH has been reported to be associated with short-term and probably clinically insignificant side-effects, including decreases in cardiac output, alterations of heart rates and increased central venous pressures. CONCLUSIONS: Studies have failed to show MH benefits critically ill intubated and mechanically ventilated patients. MH is infrequently associated with short-term side-effects.  相似文献   
6.
Patients with acute myocardial infarction (AMI) who do not receive early reperfusion therapy are at high risk of reinfarction or death, and the efficacy and safety of antithrombotic therapy in this group of patients has not been evaluated. Enoxaparin is a low-molecular-weight heparin (LMWH) that has previously been shown to reduce the incidence of ischemic events in patients with unstable angina or non–Q-wave MI. The principal aims of the TETAMI study are to investigate the efficacy and safety of treatment with enoxaparin or tirofiban (a glycoprotein IIb/IIIa receptor antagonist) alone or in combination for 2 to 8 days in patients with AMI who are not eligible for early reperfusion therapy. In this 2 by 2 factorial design study approximately 900 patients will be randomly assigned, in a blinded manner, to one of four treatments: enoxaparin alone, enoxaparin plus tirofiban, unfractionated heparin (UFH), or UFH plus tirofiban, with appropriate matched placebos. The primary end point is the composite of death, recurrent AMI, and recurrent angina, analyzed at 30 days after AMI. The design and methods of the TETAMI study are described in this article.  相似文献   
7.
The objective of this study was to evaluate the pharmacokinetic response to intravenous (IV) enoxaparin given 8-12 hr after subcutaneous (SC) dosing in patients undergoing percutaneous coronary intervention (PCI). Fifty-five patients received SC enoxaparin (1 mg/kg every 12 hr) followed by an IV bolus (0.3 mg/kg) 8-12 hr after the last SC dose, at the start of PCI or during catheterization. Anti-Xa levels were within the target range in 98% of patients 2-8 hr after the last SC dose, in 96% of patients following the IV bolus, and in 91% of patients for a further 2 hr. Subcutaneous enoxaparin (1 mg/kg every 12 hr) provides sufficient anti-Xa levels for PCI 2-8 hr after the last dose. An additional 0.3 mg/kg enoxaparin dose given IV 8-12 hr after the last SC dose reliably maintains anti-Xa levels within the target for at least 2 additional hr.  相似文献   
8.
Notch signaling is involved in numerous cell fate decisions in invertebrates and vertebrates. The Notch receptor is a type I transmembrane (TM) protein that undergoes two proteolytic steps after ligand binding, first by an ADAM (a distintegrin and metalloprotease) in the extracellular region, followed by gamma-secretase-mediated cleavage inside the TM domain. We demonstrate here that the murine ligand Delta1 (Dll1) undergoes the same sequence of cleavages, in an apparently signal-independent manner. Identification of the ADAM-mediated shedding site localized 10 aa N-terminal to the TM domain has enabled us to generate a noncleavable mutant. Kuzbanian/ADAM10 is involved in this processing event, but other proteases can probably substitute for it. We then show that Dll1 is part of a high-molecular-weight complex containing presenilin1 and undergoes further cleavage by a gamma-secretase-like activity, therefore releasing the intracellular domain that localizes in part to the nucleus. Using the shedding-resistant mutant, we demonstrate that this gamma-secretase cleavage depends on prior ectodomain shedding. Therefore Dll1 is a substrate for regulated intramembrane proteolysis, and its intracellular region possibly fulfills a specific function in the nucleus.  相似文献   
9.
A 32-year-old asymptomatic female was diagnosed with an isolated thyroid nodule of 2.5 cm diameter. Fine needle aspiration suggested a medullary thyroid carcinoma. Consequently, a total thyroidectomy was performed. The nodule stained positive for chromogranin A, neurone-specific enolase and synaptophysin, but not for calcitonin. Finally, pathological analysis showed a thyroid paraganglioma. Although the tumour appeared to be sporadic in a patient with no personal or familial history of paraganglioma and/or pheochromocytoma, we have identified a new mutation (392delC) of the succinate dehydrogenase-B (SDHB) gene in the genomic DNA extracted from the leukocytes of the patient. That mutation induced a shift in the reading frame of the gene creating a premature stop codon (P131fsX135) which was predicted to result in a truncated SDHB protein of 135 amino acids.This report highlights the difficulties of this unexpected diagnosis of hereditary thyroid paraganglioma. It also discusses the clinical involvements in terms of familial screening and the necessary follow-up of the patient.  相似文献   
10.
The spread of extended-spectrum-β-lactamase-producing Enterobacteriaceae (ESBL-PE) in low-income countries, where the burden of neonatal sepsis is high, may have a serious impact on neonatal mortality rates. Given the potential for mother-to-child transmission of multiresistant bacteria, this study investigated the ESBL-PE rectal colonization among pregnant women at delivery in the community in Madagascar and estimated a prevalence of 18.5% (95% confidence interval, 14.5% to 22.6%). One strain of Klebsiella pneumoniae isolated was also a New Delhi metallo-β-lactamase-1 (NDM-1) producer.  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