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   84540篇
  免费   7984篇
  国内免费   370篇
耳鼻咽喉   1431篇
儿科学   3227篇
妇产科学   2236篇
基础医学   9960篇
口腔科学   1206篇
临床医学   12338篇
内科学   15561篇
皮肤病学   1478篇
神经病学   7913篇
特种医学   2224篇
外国民族医学   3篇
外科学   10014篇
综合类   1127篇
现状与发展   2篇
一般理论   134篇
预防医学   10516篇
眼科学   1360篇
药学   5242篇
  1篇
中国医学   67篇
肿瘤学   6854篇
  2023年   847篇
  2022年   660篇
  2021年   1557篇
  2020年   1539篇
  2019年   1512篇
  2018年   2109篇
  2017年   1780篇
  2016年   2049篇
  2015年   2191篇
  2014年   3030篇
  2013年   4327篇
  2012年   5052篇
  2011年   5380篇
  2010年   3408篇
  2009年   3338篇
  2008年   4866篇
  2007年   5014篇
  2006年   4969篇
  2005年   4999篇
  2004年   4675篇
  2003年   4375篇
  2002年   4091篇
  2001年   1234篇
  2000年   1083篇
  1999年   1159篇
  1998年   1165篇
  1997年   1061篇
  1996年   1005篇
  1995年   969篇
  1994年   780篇
  1993年   633篇
  1992年   857篇
  1991年   821篇
  1990年   703篇
  1989年   725篇
  1988年   670篇
  1987年   649篇
  1986年   654篇
  1985年   658篇
  1984年   577篇
  1983年   500篇
  1982年   489篇
  1981年   418篇
  1980年   357篇
  1979年   425篇
  1978年   379篇
  1977年   295篇
  1976年   251篇
  1975年   261篇
  1974年   269篇
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
71.
We examined determinants of nonvertebral fracture in elderly men from six U.S. communities followed an average of 4.1 years. Six clinical risk factors predicted fracture risk independent of hip BMD: tricyclic antidepressant use, previous fracture, inability to complete a narrow walk trial, falls in previous year, age > or =80 years, and depressed mood. INTRODUCTION: There are few prospective studies of fracture determinants in men. We examined the associations between a comprehensive set of clinical risk factors and risk of nonspine fracture in older men and whether determinants of fracture risk were independent of total hip BMD. MATERIALS AND METHODS: A total of 5995 men > or =65 years of age were recruited from six communities in the Unites States and followed prospectively for an average of 4.1 years. Baseline assessments of demographic, lifestyle, medical history, functional status, anthropometry, and cognitive, visual, and neuromuscular function were assessed by questionnaire or examination. Triannual mailed questionnaires ascertained incident fracture; reported fractures were adjudicated by physicians using medical records and X-ray reports. Proportional hazards models were used to develop multivariable models, selecting variables and controlling for BMD. RESULTS: Of 5876 men, 4.7% (N = 275) reported an incident nonspine fracture during follow-up (11.46/1000 person-years). Tricyclic antidepressant use (hazard ratio [HR], 2.36; 95% CI, 1.25-4.46), history of fracture at or after age 50 (HR, 2.07; 95% CI, 1.62-2.65), inability to complete a narrow walk trial (HR, 1.70; 95% CI, 1.23-2.34), falls in previous year (HR, 1.59; 95% CI, 1.23-2.05), age > or =80 years (HR, 1.33; 95% CI, 1.01-1.76), depressed mood (HR, 1.72; 95% CI, 1.00-2.95), and decreased total hip BMD (HR, 1.53; 95% CI, 1.34-1.74) were independently related to increased risk. Compared with having none (48.0% of men), having three or more of the clinical risk factors (4.9% of men) increased fracture risk 5-fold, independent of BMD. Having three or more risk factors and being in the lowest tertile of BMD was associated with a 15-fold greater risk than having no risk factors and being in the highest BMD tertile. CONCLUSIONS: Several clinical risk factors were independently associated with nonspine fractures in elderly men. The combination of multiple risk factors and low BMD was a very powerful indicator of fracture risk.  相似文献   
72.
73.
74.
75.
Background. The National Heart, Lung, and Blood Institute (NHLBI) guidelines recommend that patients receive a follow-up outpatient asthma visit after being discharged from an emergency department (ED) for asthma. Objective. To measure the frequency of follow-up outpatient asthma visits and its association with repeat ED asthma visit. Design. We conducted a retrospective cohort study of children with asthma using claims data from a university-based managed care organization from 01 1998 to 10 2000. We performed a multivariate survival analysis using Cox proportional hazards model to determine the effect of follow-up outpatient asthma visits on the likelihood of a repeat ED asthma visit, after controlling for severity of illness, patient age, gender, insurance, and the specialty of the primary care provider. Results: A total of 561 children had 780 ED asthma visits. Of these, 103 (17%) had a repeat ED asthma visit within 1 year. Almost two-thirds of children (66%) did not receive outpatient follow-up for asthma within 30 days of an ED asthma visit. Outpatient asthma visits within 30 days of an ED asthma visit are associated with an increased likelihood (relative risk = 1.80; 95% confidence interval 1.19, 2.72) for repeat ED asthma visits within 1 year. Conclusions. Most patients do not have outpatient follow-up after an ED asthma visit. However, those patients that present for outpatient follow-up have an increased likelihood for repeat ED asthma visits. For the primary care provider, these outpatient follow-up visits signal an increased risk that a patient will return to the ED for asthma and are a key opportunity to prevent future ED asthma visits.  相似文献   
76.
77.
78.
Deb Miller  RN  BS  CNOR 《AORN journal》2002,76(5):898
  相似文献   
79.
80.
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