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   2653篇
  免费   114篇
  国内免费   18篇
耳鼻咽喉   9篇
儿科学   69篇
妇产科学   133篇
基础医学   265篇
口腔科学   80篇
临床医学   166篇
内科学   658篇
皮肤病学   74篇
神经病学   264篇
特种医学   102篇
外科学   383篇
综合类   9篇
预防医学   110篇
眼科学   42篇
药学   145篇
中国医学   9篇
肿瘤学   267篇
  2023年   22篇
  2022年   52篇
  2021年   61篇
  2020年   33篇
  2019年   53篇
  2018年   63篇
  2017年   53篇
  2016年   64篇
  2015年   61篇
  2014年   114篇
  2013年   119篇
  2012年   195篇
  2011年   170篇
  2010年   99篇
  2009年   83篇
  2008年   178篇
  2007年   166篇
  2006年   185篇
  2005年   173篇
  2004年   181篇
  2003年   147篇
  2002年   108篇
  2001年   33篇
  2000年   28篇
  1999年   44篇
  1998年   50篇
  1997年   25篇
  1996年   20篇
  1995年   15篇
  1994年   24篇
  1993年   6篇
  1992年   16篇
  1991年   16篇
  1990年   13篇
  1989年   14篇
  1988年   19篇
  1987年   8篇
  1986年   8篇
  1985年   14篇
  1984年   12篇
  1983年   7篇
  1982年   4篇
  1980年   3篇
  1979年   5篇
  1977年   3篇
  1976年   3篇
  1975年   2篇
  1973年   2篇
  1970年   2篇
  1969年   2篇
排序方式: 共有2785条查询结果,搜索用时 46 毫秒
31.
BACKGROUND AND PURPOSE: We studied the relationship of heart rate-corrected QT interval with subclinical atherosclerosis, as determined by ultrasonographic measurement of carotid intima-media thickness (IMT) in nondiabetic subjects in the Insulin Resistance Atherosclerosis Study (IRAS). Prolonged heart rate-corrected QT interval is an unfavorable prognostic factor of cardiovascular morbidity and mortality, and QT interval prolongation may be the result of atherosclerosis. METHODS: B-mode ultrasound imaging of the carotid artery IMT was performed in a large, triethnic, nondiabetic population free of clinical coronary artery disease (n=912). QT interval was measured on resting electrocardiograms with use of a computer program and corrected for heart rate with standard equations. RESULTS: IMT of the common carotid artery correlated significantly with heart rate-corrected QT interval duration (r=0.15 for QT(60) and r=0.14 for QTc), whereas no relationship between IMT of the internal carotid artery and QT interval was found (r=-0.01). The association was somewhat stronger in women than in men. In a multiple regression analysis adjusting for demographic variables, the association of common carotid artery IMT to heart rate-corrected QT interval remained highly significant, but adjustment for cardiovascular risk factors weakened the relationship. CONCLUSIONS: We found a significant relation of heart rate-corrected QT interval to carotid atherosclerosis in nondiabetic subjects that was stronger in women and partly mediated by cardiovascular risk factors, including hypertension. QT interval may therefore serve as a marker for clinically undetected ("subclinical") atherosclerotic disease.  相似文献   
32.
33.
Objectives: The etiology of male breast cancer is obscure, although an excess risk has been associated with Klinefelter syndrome, testicular disorders, benign breast disease including gynecomastia, use of exogenous estrogens, radiation, and a family history of male or female breast cancer. We conducted a case-control study to investigate risk factors further for breast cancer in men.Methods: Based on data from the 1986 National (United States) Mortality Followback Survey (NMFS) of almost 20,000 deceased adults (age 25 years or over), we compared information obtained from next-of-kin interviews of 178 men who died of breast cancer with that of 512 male controls who died of other causes. Information was obtained on selected demographic and other factors, including diet, exercise, occupation, height and weight, and use of tobacco and alcohol.Results: Increased risks were found for men who were described by their next-of-kin as very overweight (odds ratio [OR] = 2.3, 95 percent confidence interval [CI] = 1.1-5.0). The risks associated with the three upper quartiles of body mass index (BMI) (wt/ht2) were 1.3, 1.6, and 2.3, respectively, with a significant dose-response relationship (P < 0.01). An excess risk was also associated with limited exercise (OR = 1.3, CI = 0.8-2.0). Consumption of red meat was associated with an increased risk, and consumption of fruits and vegetables with a decreased risk, although the trends were not significant. No association was found for tobacco or alcohol use, but an excess risk was associated with higher levels of socioeconomic status (SES) (OR = 1.8, CI = 1.1-3.0).Conclusions: Our study suggests that obesity increases the risk of male breast cancer, possibly through hormonal mechanisms, while dietary factors, physical activity, and SES indicators also deserve further investigation. Cancer Causes andd Control 1998, 269-275  相似文献   
34.
OBJECTIVE: To investigate the effect of different delivery room strategies on survival, short term morbidity, and outcomes in extremely premature infants. METHODS: This retrospective cohort study included all preterm infants with a gestational age between 24 and 28 weeks who were born in 1992-1997 (period A; n = 161) and in 1998-2003 (period B; n = 163). In period A, elective intubation was performed. In period B, if spontaneous breathing was present, nasal continuous positive airway pressure (nCPAP) was applied. RESULTS: Survival rate and the number of never-intubated infants significantly increased in period B. No differences were found concerning short-term morbidity. Among major outcomes, the need for retinopathy of prematurity (ROP) surgery and the length of stay were significantly lower in period B. Subgroup analysis showed no significant differences from period A to period B in infants with gestational age 24-26 weeks. In the 27-28 weeks subgroup, the never-intubated infants rate increased from 2.8% to 21.3% and survival rate increased from 63% to 79%. A reduced need for ROP surgery and a shorter hospital stay were also observed. CONCLUSIONS: Changes in delivery room strategy tending to reduce mechanical ventilation in extremely premature infants are likely to benefit essentially infants of 27-28 weeks of gestation. Extension of such benefits to premature infants at the limit of viability requires further research.  相似文献   
35.
36.
37.
38.
39.
40.
Peripillous sheaths, or hair casts, are asymptomatic, white, cylindrical concretions that encircle the hair without adhering to it. They are infrequently documented in the literature, are often misdiagnosed, and generate avoidable apprehension and expense for parents and caregivers. Dermoscopy is the standard for a rapid, noninvasive, cost‐effective diagnosis. We describe a case of peripillous sheaths presenting in a boy.  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