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   19769篇
  免费   1269篇
  国内免费   85篇
耳鼻咽喉   193篇
儿科学   549篇
妇产科学   498篇
基础医学   2791篇
口腔科学   1369篇
临床医学   2255篇
内科学   3626篇
皮肤病学   363篇
神经病学   1511篇
特种医学   480篇
外科学   1878篇
综合类   167篇
一般理论   13篇
预防医学   2514篇
眼科学   430篇
药学   1338篇
  1篇
中国医学   126篇
肿瘤学   1021篇
  2023年   138篇
  2022年   234篇
  2021年   608篇
  2020年   393篇
  2019年   557篇
  2018年   682篇
  2017年   436篇
  2016年   544篇
  2015年   629篇
  2014年   841篇
  2013年   1055篇
  2012年   1647篇
  2011年   1684篇
  2010年   911篇
  2009年   815篇
  2008年   1323篇
  2007年   1334篇
  2006年   1214篇
  2005年   1080篇
  2004年   1059篇
  2003年   826篇
  2002年   775篇
  2001年   237篇
  2000年   184篇
  1999年   210篇
  1998年   174篇
  1997年   120篇
  1996年   101篇
  1995年   96篇
  1994年   74篇
  1993年   71篇
  1992年   80篇
  1991年   71篇
  1990年   76篇
  1989年   84篇
  1988年   88篇
  1987年   81篇
  1986年   60篇
  1985年   70篇
  1984年   41篇
  1983年   54篇
  1982年   31篇
  1981年   44篇
  1980年   44篇
  1979年   31篇
  1978年   23篇
  1977年   18篇
  1976年   19篇
  1974年   18篇
  1973年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
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   
7.

Background

Bone mineral density (BMD) has been found to improve after parathyroidectomy (PTX) in patients with primary hyperparathyroidism. There are few data on the effect of PTX on BMD in normocalcemic and normohormonal primary hyperparathyroidism.

Methods

A retrospective analysis of 92 primary hyperparathyroidism patients who underwent PTX between 2004 and 2012 with pre- and post-PTX dual-energy x-ray absorptiometry was performed. Within-person changes in BMD pre- and post-PTX were analyzed using log linear mixed models, stratified by biochemical status.

Results

Bone mineral density increased post-PTX in the whole cohort at the lumbar spine (+2.5%), femoral neck (+2.1%), and total hip (+1.9%) and decreased at the one-third radius (–0.9%). On comparison of BMD changes by profile, BMD increased in those with the typical profile at the lumbar spine (3.2%), femoral neck (2.9%), and total hip (2.9%) but declined at the one-third radius (–1.5%). In contrast, BMD improved only at the femoral neck (4.3%) in the normohormonal group and did not change at any site in the normocalcemic group. The typical group had a greater increase in BMD over time at the femoral neck and total hip compared with normocalcemic patients.

Conclusion

Our results indicate that the skeletal benefit of PTX was attenuated in normocalcemic and normohormonal patients, suggesting that skeletal changes after PTX may depend on biochemical profile.  相似文献   
8.
9.
10.
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