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   21765篇
  免费   1723篇
  国内免费   55篇
耳鼻咽喉   205篇
儿科学   697篇
妇产科学   639篇
基础医学   3068篇
口腔科学   279篇
临床医学   3102篇
内科学   4053篇
皮肤病学   369篇
神经病学   2432篇
特种医学   459篇
外科学   1944篇
综合类   181篇
一般理论   28篇
预防医学   2840篇
眼科学   243篇
药学   1416篇
中国医学   42篇
肿瘤学   1546篇
  2024年   31篇
  2023年   253篇
  2022年   401篇
  2021年   931篇
  2020年   576篇
  2019年   874篇
  2018年   923篇
  2017年   642篇
  2016年   689篇
  2015年   799篇
  2014年   1009篇
  2013年   1273篇
  2012年   1923篇
  2011年   1828篇
  2010年   1007篇
  2009年   826篇
  2008年   1362篇
  2007年   1322篇
  2006年   1123篇
  2005年   1114篇
  2004年   1003篇
  2003年   857篇
  2002年   711篇
  2001年   151篇
  2000年   121篇
  1999年   149篇
  1998年   138篇
  1997年   107篇
  1996年   96篇
  1995年   99篇
  1994年   67篇
  1993年   80篇
  1992年   60篇
  1991年   56篇
  1990年   66篇
  1989年   47篇
  1988年   54篇
  1987年   46篇
  1986年   45篇
  1985年   52篇
  1984年   50篇
  1983年   43篇
  1982年   42篇
  1981年   26篇
  1980年   34篇
  1978年   24篇
  1976年   35篇
  1974年   26篇
  1973年   23篇
  1971年   23篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
21.
22.

Introduction

In the United States there has been a large increase in participation in lacrosse for both males and females. The purpose of this study was to analyze the number of head injuries, injury rates (calculated using the reported number of participants) and types of head injuries that are seen in emergency departments in the United States.

Methods

We compared injuries between male and female lacrosse participants. This was a retrospective study using a publicly available database produced by the US Consumer Product Safety Commission and information about lacrosse participation from US Lacrosse.

Results

A linear regression was performed and showed a positive correlation between number of head injuries to males and time from 2002 to 2010 (R2?=?0.823; p?=?0.001). While the number of injuries to the head in female lacrosse participants was not significant. There was a negative correlation between the number of head injuries to males from 2010 to 2016 (R2?=?0.800; p?=?0.007), but again, there was no significance for female injury count (R2?=?0.417; p?=?0.117). Other significant differences between head injuries in males and females included the mechanism of injury and the type of injury recorded.

Conclusion

The most recent data from 2010 to 2016, suggest that both males and females have had a decrease in injury rate. However the total number of female head injuries is not significantly decreasing and as the sport continues to grow there will likely be more total head injuries and visits to the emergency department.  相似文献   
23.
24.
For patients who receive a liver transplant (LTX) for alcoholic liver disease (ALD), investigators are focusing beyond survival to determine specific alcohol use outcomes. Studies suggest the use of alcohol ranges from 8 to 22% for the first post-transplant year with cumulative rates reaching 30 to 40% by 5 years following transplantation. Yet while investigators are interested in determining specific rates of alcohol use and predictors of use, only three studies since 1990 have been prospective. In 1998, we began a prospective study of post-LTX alcohol consumption in ALD recipients using multiple repeated measures of alcohol use. After 5 years of follow-up, we found that 22% had used any alcohol by the first year and 42% had a drink by 5 years. By 5 years, 26% drank at a heavier use (binge) pattern and 20% drank in a frequent pattern. In a univariate model, predictors of alcohol use included pre-transplant length of sobriety, a diagnosis of alcohol dependence, a history of other substance use, and prior alcohol rehabilitation.  相似文献   
25.
Computed tomography of the brain in the Smith-Lemli-Opitz syndrome   总被引:1,自引:0,他引:1  
Computed tomographic (CT) scans of the brain in a child with Smith-Lemli-Opitz syndrome revealed enlargement of the ventricular system, hypoplasia of the cerebellum, and abnormal thickening of the gray matter, consistent with pachygyria. These findings have been previously noted in autopsies performed on patients with this disorder. We conclude that CT scanning is a valuable tool in the evaluation of children suspected of having the Smith-Lemli-Opitz syndrome.  相似文献   
26.
The action of papain and bromelain, prepared over a pH range from 4.6 to 8.6, was evaluated for the ability to render red cells agglutinable by five incomplete antibodies of differing blood group specificities using a two-stage technique. The optimal pH for treatment of red cells by activated papain or bromelain was between 5.4 and 5.8. Above this pH range, a fall in serological sensitivity was apparent which was much more pronounced with papain than with bromelain. The optimal pH for enzyme treatment of red cells can be achieved in two-stage techniques, but not in one-stage techniques due to the buffering effect of serum proteins.  相似文献   
27.
28.
BACKGROUND: The impact of exercise programmes for heart failure on those close to the patient is largely unknown. We examined the effect of a hospital and home-based exercise intervention on burden, anxiety and depression of informal caregivers. DESIGN: The study was a randomized, controlled trial. Heart failure patients were randomized to a seated 12-week hospital-based exercise programme. Caregiver measures were gathered at baseline, 3 months later and 6 months following baseline. METHODS: Sixty caregivers (mean age 63.4 years, 65% female) of heart failure patients (n = 82, mean age 80.5 years, 44% female) participating in a trial of an exercise intervention were recruited. Caregiver burden, anxiety and depression were assessed. RESULTS: There were no differences in caregiver burden, depression or anxiety between the two groups of caregivers at baseline (caregiver burden, patient control 33.1 versus patient exercise 34.1; anxiety 4.1 versus 5.5; depression 2.8 versus 3.8). At 3 months there were no differences between caregivers in the two groups on outcomes. At 6-month follow-up caregivers of heart failure patients in the exercise group had burden scores that were significantly worse than the control group. There were no differences between the carers of exercise and control groups in anxiety and depression. Levels of anxiety and depression in the entire carer sample were marginally higher than reference values in a healthy non-clinical sample. CONCLUSION: The present exercise interventions for frail older patients did not benefit caregivers and was associated with an increase in caregiver burden. We suggest that future exercise interventions for heart failure patients should actively incorporate informal caregivers into research designs.  相似文献   
29.
30.
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