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   222338篇
  免费   16478篇
  国内免费   774篇
耳鼻咽喉   2538篇
儿科学   5828篇
妇产科学   4587篇
基础医学   28705篇
口腔科学   4829篇
临床医学   21468篇
内科学   47455篇
皮肤病学   2943篇
神经病学   21302篇
特种医学   7307篇
外国民族医学   13篇
外科学   34578篇
综合类   3749篇
现状与发展   2篇
一般理论   298篇
预防医学   20317篇
眼科学   4572篇
药学   15274篇
  1篇
中国医学   380篇
肿瘤学   13444篇
  2023年   909篇
  2022年   1506篇
  2021年   3623篇
  2020年   2237篇
  2019年   3577篇
  2018年   4158篇
  2017年   3378篇
  2016年   3561篇
  2015年   4285篇
  2014年   6335篇
  2013年   9184篇
  2012年   13653篇
  2011年   14848篇
  2010年   8370篇
  2009年   7549篇
  2008年   14040篇
  2007年   14927篇
  2006年   14393篇
  2005年   14859篇
  2004年   14262篇
  2003年   13368篇
  2002年   12842篇
  2001年   2272篇
  2000年   1936篇
  1999年   2403篇
  1998年   2973篇
  1997年   2553篇
  1996年   2333篇
  1995年   2064篇
  1994年   1856篇
  1993年   1749篇
  1992年   1518篇
  1991年   1448篇
  1990年   1325篇
  1989年   1233篇
  1988年   1237篇
  1987年   1237篇
  1986年   1252篇
  1985年   1303篇
  1984年   1657篇
  1983年   1603篇
  1982年   1935篇
  1981年   1717篇
  1980年   1641篇
  1979年   992篇
  1978年   1069篇
  1977年   1040篇
  1976年   927篇
  1975年   798篇
  1974年   806篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
OBJECTIVE: To illustrate the safety and efficacy of the endoscopic laser approach for cricopharyngeal myotomy (CPM) compared to the traditional transcervical approach. STUDY DESIGN AND SETTING: Retrospective chart review of 22 patients undergoing CPM from 1996 to 2003 at the Mayo Clinic, Jacksonville. RESULTS: The laser CPM technique was used in 14 patients, and an open approach in 8. The mean hospital stay and operative times were shorter for the laser group. Functional outcome analyses showed improvement in both groups. There were no major complications in the laser group, while 1 patient in the transcervical group had a pharyngocutaneous fistula. CONCLUSIONS: The laser technique is at least as effective as the transcervical approach for CPM to improve dysphagia symptoms in the properly selected patient, with a low risk of major complications. SIGNIFICANCE: In this report, we provide the reader with data to support the safety and efficacy of laser CPM. EBM rating: B-3b.  相似文献   
12.
13.
14.
BACKGROUND: Previous research has demonstrated that academic and neuropsychological functions are compromised in pediatric bipolar disorder (PBD). Investigation of the degree to which neuropsychological deficits might contribute to those academic problems is needed to aid in the recognition and intervention for school achievement difficulties in PBD. METHODS: A sample of 55 children and adolescents with PBD with and without attention-deficit/hyperactivity disorder (ADHD) (PBD group, n = 28; PBD+ADHD group, n = 27) were tested with a computerized neurocognitive battery and standardized neuropsychological tests. Age range of subjects was 7-17 years, with the mean age of 11.97 (3.18) years. Parents completed a structured questionnaire on school and academic functioning. RESULTS: Logistic regression analyses indicated that executive function, attention, working memory, and verbal memory scores were poorer in those with a history of reading/writing difficulties. A separate logistic regression analysis found that attentional dysfunction predicted math difficulties. These relationships between neuropsychological function and academic difficulties were not different in those with PBD+ADHD than in those with PBD alone. CONCLUSIONS: In PBD neuropsychological deficits in the areas of attention, working memory, and organization/problem solving skills all contribute to academic difficulties. Early identification and intervention for these difficulties might help prevent lower academic achievement in PBD.  相似文献   
15.
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   
16.
B.  Greg  Brown  John  Growley  宋善俊 《美国医学会杂志》2006,25(2):124-126
过去15年来,有关动脉粥样硬化的流行病学、基础生物学和实验研究均支持下述假设:抗氧化剂可通过抑制动脉壁低密度脂蛋白的氧化而抑制动脉粥样硬化的发生。这种作用机制可抑制胆固醇酯通过巨噬细胞清除受体在动脉斑块内发生病理性沉积。胆固醇酯病理沉积是一种可引起斑块破裂及心血管事件的过程。同样,生物机制亦已确定,癌基因可被抗氧化剂阻断。  相似文献   
17.
The purpose of this study was to investigate radiographic measurements in a cohort of patients with juvenile hallux valgus (with a hallux valgus angle > 15 degrees ) using standardized weightbearing x-rays compared with an age-matched control group. First metatarsal protrusion distance, metatarsus primus adductus angle, metatarsus adductus, first metatarsal cuneiform angle, calcaneal inclination angle, and talocalcaneal angles were assessed with discriminant functional analysis. A total of 37 sets of data were analyzed from patients with a mean age of 13.45 +/- 1.75 years. The study identified 2 significant components of juvenile hallux valgus: a positive first metatarsal protrusion distance (P <.001) and metatarsal primus adductus angle (P = .002). Discriminant functional analysis was then used to determine the best predictors of juvenile hallux valgus. This analysis allowed only 1 variable, metatarsal protrusion distance, as a predictor of whether juvenile hallux valgus was present (P < .001), with 94.3% accuracy. This study showed that a positive metatarsal protrusion distance is a significant component of juvenile hallux valgus.  相似文献   
18.
19.
20.
Over 100 mutations in the presenilin‐1 gene (PSEN1) have been shown to result in familial early onset Alzheimer disease (EOAD), but only a relatively few give rise to plaques with an appearance like cotton wool (CWP) and/or spastic paraparesis (SP). A family with EOAD, seizures and CWP was investigated by neuropathological study and DNA sequencing of the PSEN1 gene. Aβ was identified in leptomeningeal vessels and in cerebral plaques. A single point mutation, p.L420R (g.1508T > G) that gives rise to a missense mutation in the eighth transmembrane (TM8) domain of PS1 was identified in two affected members of the family. p.L420R (g.1508T > G) is the mutation responsible for EOAD, seizures and CWP without SP in this family.  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