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   2239篇
  免费   280篇
  国内免费   5篇
耳鼻咽喉   45篇
儿科学   68篇
妇产科学   21篇
基础医学   235篇
口腔科学   175篇
临床医学   329篇
内科学   489篇
皮肤病学   45篇
神经病学   180篇
特种医学   34篇
外科学   284篇
综合类   25篇
一般理论   1篇
预防医学   278篇
眼科学   22篇
药学   137篇
肿瘤学   156篇
  2024年   3篇
  2023年   49篇
  2022年   22篇
  2021年   43篇
  2020年   44篇
  2019年   45篇
  2018年   77篇
  2017年   70篇
  2016年   64篇
  2015年   74篇
  2014年   115篇
  2013年   131篇
  2012年   152篇
  2011年   164篇
  2010年   109篇
  2009年   107篇
  2008年   116篇
  2007年   171篇
  2006年   121篇
  2005年   130篇
  2004年   148篇
  2003年   137篇
  2002年   123篇
  2001年   17篇
  2000年   15篇
  1999年   24篇
  1998年   35篇
  1997年   34篇
  1996年   24篇
  1995年   23篇
  1994年   16篇
  1993年   16篇
  1992年   12篇
  1991年   6篇
  1990年   7篇
  1989年   6篇
  1988年   5篇
  1987年   8篇
  1985年   6篇
  1984年   7篇
  1983年   4篇
  1982年   8篇
  1981年   3篇
  1980年   7篇
  1979年   3篇
  1977年   2篇
  1976年   6篇
  1966年   3篇
  1960年   2篇
  1936年   2篇
排序方式: 共有2524条查询结果,搜索用时 875 毫秒
101.
102.
103.
104.
Although thallium-201 is known to redistribute slowly into regions of ischemic myocardium after restoration of blood flow, it is not clear to what extent normalization of flow is an essential requirement for the redistribution process. In a search for a flow-independent component of thallium redistribution, 12 dogs with stenosis of the circumflex coronary artery underwent atrial pacing for either 20 minutes (group I, 6 dogs) or 2 hours (group II, 6 dogs). Radioactive thallium and radioactive microspheres, 7 to 10 μ, were injected after 10 minutes of atrial pacing in both groups. Pacing resulted in a 40 percent reduction in subendocardial blood flow to the circumflex-perfused myocardium in both groups I and II. This relative reduction in flow was maintained at a stable level over the 2 hour pacing period in group II. Thallium activity in the relatively ischemic zone was significantly greater in dogs with 2 hours of pacing (group II) than in those with 10 minutes of pacing (group I). Redistribution of thallium occurred despite the continued presence of reduced flow in circumflex-perfused endocardial tissue. These data suggest that a significant component of thallium redistribution may be flow-independent.  相似文献   
105.
The first part of this report, which looked at centre policy, showed that there was no consensus on the best way to manage a patient in the rest period between PD catheter insertion and the first use of the catheter for dialysis. This paper intends to investigate if the differences in policy had any effect on complication rate and individual patient outcomes. Data were included from 298 patients of 49 participating centres. The results revealed a high rate of catheter related complications, with half of the patients having been treated for complications including leakage (29%), malfunction (23%) or infection (10%), and a quarter of patients having been hospitalised for catheter problems. Leakage was more frequently observed in lean and obese patients and if the catheter was only immobilized for a short time period. Diabetes, having constipation at first use and having rested for less than 6 hours after catheter insertion were significant risk factors for malfunction. Infection seemed to be related to the type of catheter used and hygienic precautions (not significant) and showed a significant relationship with the frequency of dressing changes. There is still an important lack of evidence on which to develop an optimal protocol for PD catheter insertion and care before first use.  相似文献   
106.
107.
OBJECTIVES: To evaluate risk factors for ventilator-associated pneumonia (VAP), as well as its influence on in-hospital mortality, resource utilization, and hospital charges. DESIGN: Retrospective matched cohort study using data from a large US inpatient database. PATIENTS: Patients admitted to an ICU between January 1998 and June 1999 who received mechanical ventilation for > 24 h. MEASUREMENTS: Risk factors for VAP were examined using crude and adjusted odds ratios (AORs). Cases of VAP were matched on duration of mechanical ventilation, severity of illness on admission (predicted mortality), type of admission (medical, surgical, trauma), and age with up to three control subjects. Mortality, resource utilization, and billed hospital charges were then compared between cases and control subjects. RESULTS: Of the 9,080 patients meeting study entry criteria, VAP developed in 842 patients (9.3%). The mean interval between intubation, admission to the ICU, hospital admission, and the identification of VAP was 3.3 days, 4.5 days, and 5.4 days, respectively. Identified independent risk factors for the development of VAP were male gender, trauma admission, and intermediate deciles of underlying illness severity (on admission) [AOR, 1.58, 1.75, and 1.47 to 1.70, respectively]. Patients with VAP were matched with 2,243 control subjects without VAP. Hospital mortality did not differ significantly between cases and matched control subjects (30.5% vs 30.4%, p = 0.713). Nevertheless, patients with VAP had a significantly longer duration of mechanical ventilation (14.3 +/- 15.5 days vs 4.7 +/- 7.0 days, p < 0.001), ICU stay (11.7 +/- 11.0 days vs 5.6 +/- 6.1 days, p < 0.001), and hospital stay (25.5 +/- 22.8 days vs 14.0 +/- 14.6 days, p < 0.001). Development of VAP was also associated with an increase of > $40,000 USD in mean hospital charges per patient ($104,983 USD +/- $91,080 USD vs $63,689 USD+/- $75,030 USD, p < 0.001). CONCLUSIONS: This retrospective matched cohort study, the largest of its kind, demonstrates that VAP is a common nosocomial infection that is associated with poor clinical and economic outcomes. While strategies to prevent the occurrence of VAP may not reduce mortality, they may yield other important benefits to patients, their families, and hospital systems.  相似文献   
108.
We describe a case report of a 49-year-old man admitted to a cardiology unit with a series of arrhythmias with no initially obvious aetiology. Further assessment and the use of cardiac magnetic resonance imaging and histology allowed a diagnosis of cardiac sarcoidosis to be made. Cardiac sarcoidosis is a major cause of death in patients with systemic sarcoidosis. Cardiac magnetic resonance imaging is an additional diagnostic tool for this condition without ionizing radiation exposure.  相似文献   
109.
110.
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