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   267683篇
  免费   16094篇
  国内免费   1045篇
耳鼻咽喉   3090篇
儿科学   8727篇
妇产科学   5887篇
基础医学   37323篇
口腔科学   10316篇
临床医学   21444篇
内科学   60420篇
皮肤病学   6811篇
神经病学   24187篇
特种医学   7678篇
外国民族医学   27篇
外科学   29953篇
综合类   1785篇
现状与发展   1篇
一般理论   109篇
预防医学   26730篇
眼科学   4828篇
药学   17230篇
中国医学   980篇
肿瘤学   17296篇
  2023年   1799篇
  2022年   3893篇
  2021年   6873篇
  2020年   4446篇
  2019年   6167篇
  2018年   7961篇
  2017年   6036篇
  2016年   6186篇
  2015年   7001篇
  2014年   9320篇
  2013年   12077篇
  2012年   18605篇
  2011年   19253篇
  2010年   10145篇
  2009年   9005篇
  2008年   15239篇
  2007年   15892篇
  2006年   14712篇
  2005年   14699篇
  2004年   13564篇
  2003年   12384篇
  2002年   9960篇
  2001年   5543篇
  2000年   5368篇
  1999年   5000篇
  1998年   2317篇
  1997年   1920篇
  1996年   1806篇
  1995年   1527篇
  1994年   1494篇
  1993年   1307篇
  1992年   2949篇
  1991年   2788篇
  1990年   2551篇
  1989年   2535篇
  1988年   2305篇
  1987年   2119篇
  1986年   1997篇
  1985年   1877篇
  1984年   1404篇
  1983年   1151篇
  1982年   731篇
  1981年   628篇
  1980年   613篇
  1979年   1005篇
  1978年   691篇
  1977年   552篇
  1975年   602篇
  1974年   620篇
  1973年   611篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
55.
56.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic.  相似文献   
57.
58.
Objective:The present study evaluates a training program for fitting different hearing protection devices (HPDs) based on personal attenuation rating (PAR) before, immediately after, and six months after training.Methods:A total of 67 workers from a public university in the city of São Paulo, Brazil, were invited to participate in the measurement of PARs for foam and silicone protectors through the 3M™ E-A-Rfit Validation System. Two evaluations were performed for each protector at each sampling date: one after reading printed material (the package instructions) and another after being trained by an audiologist. The same procedures were repeated after six months. The final sample consisted of 30 individuals. ANOVA was used for statistical analysis.Results:Larger PAR values were observed after training by the audiologist, and smaller values were observed after six months. Then, after re-training, the values increased again. There were no statistically significant differences in PAR among the HPDs tested. Even after the two training sessions, 23 to 27% of the subjects did not obtain adequate PAR values.Conclusion:These findings emphasize the need for continual worker training in the correct fit of earplug HPDs and the importance of longitudinal PAR monitoring. In addition, some workers, despite the training provided, did not adapt to the HPDs used. Therefore, it is essential that other protection methods and/or other HPD types are made available to these individuals.Key words: Hearing, noise-induced hearing loss, occupational health, personal protective equipment, hearing protection devices  相似文献   
59.
60.

Introduction

Little is known about dementia incidence in diverse populations of oldest-old, the age group with highest dementia incidence.

Methods

Incident dementia diagnoses from 1/1/2010 to 9/30/2015 were abstracted from medical records for 2350 members of an integrated health care system in California (n = 1702 whites, n = 375 blacks, n = 105 Latinos, n = 168 Asians) aged ≥90 in 2010. We estimated race/ethnicity-specific age-adjusted dementia incidence rates and implemented Cox proportional hazards models and Fine and Gray competing risk of death models adjusted for demographics and comorbidities in midlife and late-life.

Results

Dementia incidence rates (n = 771 cases) were lowest among Asians (89.9/1000 person-years), followed by whites (96.9/1000 person-years), Latinos (105.8/1000 person-years), and blacks (121.5/1000 person-years). Cox regression and competing risk models estimated 28% and 36% higher dementia risk for blacks versus whites adjusting for demographics and comorbidities.

Discussion

Patterns of racial/ethnic disparities in dementia seen in younger older adults continue after the age of 90 years, though smaller in magnitude.  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