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   2097篇
  免费   165篇
  国内免费   5篇
耳鼻咽喉   19篇
儿科学   56篇
妇产科学   86篇
基础医学   324篇
口腔科学   14篇
临床医学   162篇
内科学   383篇
皮肤病学   9篇
神经病学   362篇
特种医学   77篇
外科学   253篇
综合类   14篇
预防医学   168篇
眼科学   21篇
药学   153篇
肿瘤学   166篇
  2023年   17篇
  2022年   11篇
  2021年   67篇
  2020年   37篇
  2019年   45篇
  2018年   63篇
  2017年   59篇
  2016年   48篇
  2015年   51篇
  2014年   60篇
  2013年   97篇
  2012年   140篇
  2011年   165篇
  2010年   96篇
  2009年   72篇
  2008年   103篇
  2007年   135篇
  2006年   107篇
  2005年   104篇
  2004年   112篇
  2003年   73篇
  2002年   93篇
  2001年   34篇
  2000年   26篇
  1999年   32篇
  1998年   12篇
  1997年   15篇
  1996年   9篇
  1995年   8篇
  1994年   9篇
  1992年   18篇
  1991年   30篇
  1990年   22篇
  1989年   22篇
  1988年   16篇
  1987年   21篇
  1986年   25篇
  1985年   31篇
  1984年   20篇
  1983年   13篇
  1981年   10篇
  1979年   18篇
  1978年   13篇
  1976年   13篇
  1975年   8篇
  1974年   13篇
  1973年   8篇
  1972年   7篇
  1970年   9篇
  1969年   8篇
排序方式: 共有2267条查询结果,搜索用时 15 毫秒
1.
2.
3.
In 1998, a cholera epidemic in east Africa reached the Comoros Islands, an archipelago in the Mozambique Channel that had not reported a cholera case for more than 20 years. In just a little over 1 year (between January 1998 and March 1999), Grande Comore, the largest island in the Union of the Comoros, reported 7,851 cases of cholera, about 3% of the population. Using case reports and field observations during the medical response, we describe the epidemiology of the 1998–1999 cholera epidemic in Grande Comore. Outbreaks of infectious diseases on islands provide a unique opportunity to study transmission dynamics in a nearly closed population, and they may serve as stepping-stones for human pathogens to cross unpopulated expanses of ocean.  相似文献   
4.
5.
6.
7.
8.
We hypothesized that tobacco smoke induces alterations to the 3-OH fatty acids present in lipid A in a manner consistent with a microflora of reduced inflammatory potential. Whole saliva samples and full-mouth clinical periodontal recordings were obtained from persons with (22 smokers; 15 non-smokers) and without (14 smokers; 15 non-smokers) chronic periodontitis. Clear differences in the contributions of multiple saturated 3-OH fatty acid species were noted in the group with disease compared with healthy individuals. Increases in the long-chain fatty acids associated with anaerobic bacterial periodontopathogens, particularly 3-OH-C(i17.0) (146.7%, relative to controls), were apparent. Significant reductions in the 3-OH fatty acids associated with the consensus (high potency) enteric LPS structure (3-OH-C(12.0) and 3-OH-C(14.0); 33.3% and 15.8% reduction, respectively) were noted in smokers compared with non-smokers with chronic periodontitis. Thus, smoking is associated with specific structural alterations to the lipid-A-derived 3-OH fatty acid profile in saliva that are consistent with an oral microflora of reduced inflammatory potential. These findings provide much-needed mechanistic insight into the established clinical conundrum of increased infection with periodontal pathogens but reduced clinical inflammation in smokers.  相似文献   
9.
10.
Bone strength is predominantly determined by bone density, but bone microarchitecture also plays an important role. We examined whether trabecular bone score (TBS) predicts the risk of vertebral fractures in a Japanese female cohort. Of 1950 randomly selected women aged 15 to 79 years, we analyzed data from 665 women aged 50 years and older, who completed the baseline study and at least one follow‐up survey over 10 years, and who had no conditions affecting bone metabolism. Each survey included spinal imaging by dual‐energy X‐ray absorptiometry (DXA) for vertebral fracture assessment and spine areal bone mineral density (aBMD) measurement. TBS was obtained from spine DXA scans archived in the baseline study. Incident vertebral fracture was determined when vertebral height was reduced by 20% or more and satisfied McCloskey‐Kanis criteria or Genant's grade 2 fracture at follow‐up. Among eligible women (mean age 64.1 ± 8.1 years), 92 suffered incident vertebral fractures (16.7/103 person‐years). These women were older with lower aBMD and TBS values relative to those without fractures. The unadjusted odds ratio of vertebral fractures for one standard deviation decrease in TBS was 1.98 (95% confidence interval [CI] 1.56, 2.51) and remained significant (1.64, 95% CI 1.25, 2.15) after adjusting for aBMD. The area under the receiver operating characteristic curve of TBS and aBMD combined was 0.700 for vertebral fracture prediction and was not significantly greater than that of aBMD alone (0.673). However, reclassification improvement measures indicated that TBS and aBMD combined significantly improved risk prediction accuracy compared with aBMD alone. Further inclusion of age and prevalent vertebral deformity in the model improved vertebral fracture prediction, and TBS remained significant in the model. Thus, lower TBS was associated with higher risk of vertebral fracture over 10 years independently of aBMD and clinical risk factors including prevalent vertebral deformity. TBS could effectively improve fracture risk assessment in clinical settings. © 2014 American Society for Bone and Mineral Research.  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