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   1659篇
  免费   81篇
  国内免费   18篇
耳鼻咽喉   7篇
儿科学   61篇
妇产科学   14篇
基础医学   228篇
口腔科学   24篇
临床医学   197篇
内科学   486篇
皮肤病学   40篇
神经病学   76篇
特种医学   84篇
外科学   141篇
综合类   90篇
预防医学   96篇
眼科学   13篇
药学   103篇
中国医学   3篇
肿瘤学   95篇
  2023年   9篇
  2022年   10篇
  2021年   32篇
  2020年   12篇
  2019年   33篇
  2018年   31篇
  2017年   23篇
  2016年   28篇
  2015年   26篇
  2014年   43篇
  2013年   49篇
  2012年   59篇
  2011年   78篇
  2010年   50篇
  2009年   52篇
  2008年   86篇
  2007年   137篇
  2006年   87篇
  2005年   63篇
  2004年   49篇
  2003年   60篇
  2002年   48篇
  2001年   42篇
  2000年   52篇
  1999年   46篇
  1998年   23篇
  1997年   22篇
  1996年   33篇
  1995年   19篇
  1994年   23篇
  1993年   12篇
  1992年   24篇
  1991年   30篇
  1990年   34篇
  1989年   46篇
  1988年   23篇
  1987年   20篇
  1986年   27篇
  1985年   18篇
  1984年   21篇
  1983年   14篇
  1981年   13篇
  1980年   8篇
  1979年   12篇
  1978年   8篇
  1976年   9篇
  1975年   8篇
  1974年   14篇
  1972年   8篇
  1966年   10篇
排序方式: 共有1758条查询结果,搜索用时 62 毫秒
31.
Clinical Oral Investigations - The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic has created hitherto unknown challenges for healthcare systems and patient care. This study...  相似文献   
32.
33.
34.
PURPOSE: To report the outcome of a prospective randomized safety and performance trial of 2 access site closure devices versus a wound dressing. METHODS: Between October 2005 and July 2006, 852 consecutive patients (605 men; mean age 67 years) undergoing diagnostic or interventional catheterization procedures thru a 5- or 6-F femoral sheath were randomized to one of the 3 closure methods: a collagen plug device (Angio-Seal), a clip (StarClose), or a wound dressing (D-Stat Dry). The efficacy of the devices was assessed, as well as the complications occurring at the puncture site during the hospital stay. The primary endpoint of the study was the cumulative incidence of access site pseudoaneurysm, major access site bleeding requiring transfusion, access site vascular surgery, or death from all causes. RESULTS: There were no significant differences in baseline characteristics between the 3 treatment groups. The primary endpoint was reached in 20 (7.1%) of 281 patients treated with D-Stat Dry and in 11 (1.9%) of 571 patients treated with the mechanical closure devices (p<0.0001). There was no significant difference among the mechanical closure devices concerning the incidence of the primary endpoint (Angio-Seal 1.1% versus StarClose 2.8%; p = 0.13). CONCLUSION: The collagen plug device had the lowest rates of major and minor access site-related complications after removal of 5- or 6-F femoral sheaths. The difference between the mechanical closure devices concerning the incidence of the primary endpoint did not reach statistical significance. The wound dressing showed significantly higher major and minor complication rates.  相似文献   
35.

Background

Red blood cell transfusion benefit during acute myocardial infarction remains unclear in the elderly. We aimed to assess the transfusion impact on 1-year mortality in acute myocardial infarction patients aged ≥65 years, according to their age and hemoglobin nadir.

Methods

We included 3316 consecutive patients with acute myocardial infarction aged ≥65 years from the “obseRvatoire des Infarctus de Côte d'Or” (RICO) survey. They were categorized according to their hemoglobin nadir (≤8, >8 to ≤10, and >10 g/dL) and age (<80 or ≥80 years).

Results

A total of 1906 patients (57%) were 65-79 years old, and 1410 (43%) were aged ≥80 years, of whom 103 (5%) and 145 (10%) patients received red blood cell transfusion, respectively (P < .001). In Cox regression analysis, transfusion was associated with increased 1-year mortality for hemoglobin nadir >10 g/dL but no significant effect for hemoglobin nadir between 8 and 10 g/dL. When hemoglobin nadir was ≤8 g/dL, transfusion did not influence 1-year mortality for younger patients (65-79 years). However, for older patients (≥80 years), transfusion was associated with lower mortality (hazard ratio 0.43 [95% confidence interval, 0.22-0.86], P = .016).

Conclusion

Among older patients with acute myocardial infarction, the effect of transfusion was largely dependent on hemoglobin threshold and age. Transfusion was associated with increased 1-year mortality when hemoglobin nadir was >10 g/dL. However, in patients aged ≥80 years with hemoglobin nadir <8 g/dL, transfusion was associated with a 50% reduction in 1-year mortality.  相似文献   
36.
OBJECTIVE: To investigate the role of vitamin C tissue content as a protective agent during myocardial ischemia-reperfusion injury, we have evaluated the postischemic functional recovery and free radical release of osteogenic disorder Shionogi (ODS) inherently scorbutic rat hearts and compared them to healthy Wistar rat hearts. METHODS: Isolated perfused hearts of ODS or Wistar rats underwent 30 min of a global total normothermic ischemia followed by 30 min of reperfusion. The lipid-soluble spin trap alpha-phenyl N-tert-butylnitrone (3 mM) was perfused upstream of the coronary bed. Functional parameters were recorded and samples of coronary effluents were analysed using electron spin resonance spectroscopy to characterise and quantify the amount of radical species released. RESULTS: From the onset of reperfusion, a large and long-lasting release of alkyl/alkoxyl radicals was detected, with a peak value of 29.0+/-3.2 nM obtained after 13 min, which was associated with a persistent contractile dysfunction. However, ODS rat hearts showed a higher myocardial recovery with lower left ventricular end diastolic pressure (44.34+/-1.74 vs. 55.03+/-1.57 mmHg for Wistar), higher recovery of rate pressure product (12.3+/-1.4 vs. 1.9+/-1.7x10(3) mmHg beats/min for Wistar) and shorter duration of contractile abnormalities during reperfusion (3.7+/-1.0 vs. 20.8+/-5.3 min for Wistar). Moreover, free radical release was identical in ODS rat hearts as compared to control Wistar rats. Ascorbic acid tissue content was significantly altered in ODS rats (31.9+/-3.3 vs. 591.0+/-54.9 mmol/g of tissue for Wistar) but superoxide dismutases, glutathion peroxidases and inducible heat shock protein 70 genes were up-regulated. CONCLUSIONS: This study shows that ascorbic-acid-deficient ODS rat hearts are more resistant to an ischemic insult than control Wistar rats, probably through the development of alternative protective defences, like the induction of heat shock proteins. These paradoxical results raise the question of the relative importance of each endogenous antioxidant in the cardiac resistance to ischemia-reperfusion injury.  相似文献   
37.
Objective: This study was designed to assess the prognostic value of myocardial tomoscintigraphy perfusion imaging after percutaneous coronary intervention (PCI) in asymptomatic diabetic patients. Methods: One hundred and fourteen diabetic patients were followed up during 27±16 (mean±SD) months after the myocardial tomoscintigraphy. PCI-related events were studied after myocardial tomoscintigraphy stress testing and included major cardiac events (MACE) (cardiovascular death, myocardial infarction) and revascularization (bypass surgery or new PCI). Stress myocardial tomoscintigraphy imaging was performed 5±5 months after PCI and ischemia was considered as present if at least 2 contiguous segments were showing reversible defects. Results: Persistent silent ischemia was found in 49/114 (43%) patients. No difference was observed between the two groups for MACE: four among the 65 (6%) non ischemic patients versus 2 among the 49 (4%) ischemic patients (NS). In contrast, 15 (31%) among the ischemic patients and 4 (6%) among the non ischemic patients underwent iterative revascularization (p<0.01). The relative risk of revascularization for patients with significant ischemia was 5.5 versus non ischemic patients (p<0.001). Conclusion: After PCI, in asymptomatic diabetic patients followed by myocardial tomoscintigraphy a high frequency of persistent silent ischemia was found and associated with a high risk for repeat interventional procedure, although no increase in major cardiac events was observed.  相似文献   
38.
39.
40.
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