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   25760篇
  免费   1673篇
  国内免费   84篇
耳鼻咽喉   286篇
儿科学   607篇
妇产科学   384篇
基础医学   3723篇
口腔科学   650篇
临床医学   2527篇
内科学   5133篇
皮肤病学   480篇
神经病学   2473篇
特种医学   1281篇
外国民族医学   25篇
外科学   3271篇
综合类   175篇
一般理论   20篇
预防医学   2516篇
眼科学   300篇
药学   2161篇
中国医学   88篇
肿瘤学   1417篇
  2022年   206篇
  2021年   457篇
  2020年   294篇
  2019年   410篇
  2018年   495篇
  2017年   374篇
  2016年   443篇
  2015年   542篇
  2014年   696篇
  2013年   953篇
  2012年   1417篇
  2011年   1464篇
  2010年   829篇
  2009年   805篇
  2008年   1360篇
  2007年   1349篇
  2006年   1308篇
  2005年   1244篇
  2004年   1116篇
  2003年   1045篇
  2002年   987篇
  2001年   605篇
  2000年   642篇
  1999年   541篇
  1998年   280篇
  1997年   214篇
  1996年   171篇
  1995年   199篇
  1994年   214篇
  1993年   293篇
  1992年   611篇
  1991年   560篇
  1990年   468篇
  1989年   319篇
  1988年   301篇
  1987年   304篇
  1986年   259篇
  1985年   291篇
  1984年   217篇
  1983年   159篇
  1982年   145篇
  1981年   143篇
  1979年   174篇
  1978年   150篇
  1977年   137篇
  1976年   148篇
  1975年   151篇
  1974年   189篇
  1973年   168篇
  1971年   145篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Abstract

Gaining a better grasp on factors related to changes in alcohol use is of particular interest for clinicians. Past research has highlighted a negative link between future time perspective (i.e. a disposition guiding how individuals consider and act regarding their future) and alcohol misuse. However, much remains at stake in the understanding of this association. The objective of this research was to explore bidirectional relationships between future time perspective and severity of alcohol-related problems, in a clinical setting. The sample includes 79 patients followed up in an outpatient alcohol treatment centre. Two measurement times were planned: at entry into care and 6 months later. Multiple linear regression analyses were carried out, controlling for sociodemographic variables. We found that baseline future time perspective predicted level of alcohol-related problems after 6 months in treatment, even when effects of baseline alcohol-related problems and sociodemographic variables were controlled. This study shows that the way patients see and position themselves regarding their future can affect level of alcohol-related problems. It may be useful for clinicians to identify patients with low future time perspective to offer tailored interventions and consider this dimension as a resource for change.  相似文献   
4.
5.
Delayed contrast enhancement after injection of a gadolinium-chelate (Gd-chelate) is a reference imaging method to detect myocardial tissue changes. Its localization within the thickness of the myocardial wall allows differentiating various pathological processes such as myocardial infarction (MI), inflammatory myocarditis, and cardiomyopathies. The aim of the study was first to characterize benign myocarditis using quantitative delayed-enhancement imaging and then to investigate whether the measure of the extracellular volume fraction (ECV) can be used to discriminate between MI and myocarditis.In 6 patients with acute benign myocarditis (32.2 ± 13.8 year-old, subepicardial late gadolinium enhancement [LGE]) and 18 patients with MI (52.3 ± 10.9 year-old, subendocardial/transmural LGE), myocardial T1 was determined using the Modified Look-Locker Imaging (MOLLI) sequence at 3 Tesla before and after Gd-chelate injection. T1 values were compared in LGE and normal regions of the myocardium. The myocardial T1 values were normalized to the T1 of blood, and the ECV was calculated from T1 values of myocardium and blood pre- and post-Gd injection.In both myocarditis and MI, the T1 was lower in LGE regions than in normal regions of the left ventricle. T1 of LGE areas was significantly higher in myocarditis than in MI (446.8 ± 45.8 vs 360.5 ± 66.9 ms, P = 0.003) and ECV was lower in myocarditis than in MI (34.5 ± 3.3 vs 53.8 ± 13.0 %, P = 0.004).Both inflammatory process and chronic fibrosis induce LGE (subepicardial in myocarditis and subendocardial in MI). The present study demonstrates that the determination of T1 and ECV is able to differentiate the 2 histological patterns.Further investigation will indicate whether the severity of ECV changes might help refine the predictive risk of LGE in myocarditis.  相似文献   
6.

Objective

Low psoas muscle area is shown to be an indicator for worse postoperative outcome in patients undergoing vascular surgical. Additionally, it has been associated with longer durations of hospital stay in patients with cancer who undergo surgery and subsequently greater health care costs in Europe and the United States. We sought to evaluate this effect on hospital expenditure for patients undergoing vascular repair in a health care system with universal access.

Methods

Skeletal muscle mass was assessed on preoperative abdominal computed tomography scans of patients undergoing open aortic aneurysm repair in a retrospective fashion. The skeletal muscle index (SMI) was used to define low muscle mass. Health care costs were obtained for all patients and the relationship between a low SMI and higher costs was explored using linear regression and cross-sectional analysis.

Results

We included 156 patients (81.5% male) with a median age of 72 years undergoing elective surgery for infrarenal abdominal aortic aneurysm in this analysis. The median SMI for patients with low skeletal muscle mass was 53.21 cm2/kg and for patients without, 70.07 cm2/kg. Hospital duration of stay was 2 days longer in patients with low skeletal muscle mass as compared with patients with normal (14 days vs 11 days; P = .001), as was duration of intensive care stay (3 days vs 1 day; P = .01). The median overall hospital costs were €10,460 higher for patients with a low SMI as compared with patients with a normal physical constitution (€53,739 [interquartile range, €45,007-€62,471] vs €43,279 [interquartile range, €39,509-€47,049]; P = .001). After confounder adjustment, a low SMI was associated with a 14.68% cost increase in overall hospital costs, for a cost increase of €6521.

Conclusions

Low skeletal muscle mass is independently associated with higher hospital as well as intensive care costs in patients undergoing elective aortic aneurysm repair. Strategies to reduce this risk factor are warranted for these patients.  相似文献   
7.
8.
9.
10.
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