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   1271385篇
  免费   97422篇
  国内免费   1589篇
耳鼻咽喉   16462篇
儿科学   41188篇
妇产科学   35126篇
基础医学   190744篇
口腔科学   34958篇
临床医学   118580篇
内科学   249395篇
皮肤病学   27422篇
神经病学   102716篇
特种医学   47065篇
外国民族医学   265篇
外科学   180077篇
综合类   26058篇
现状与发展   3篇
一般理论   576篇
预防医学   105582篇
眼科学   28388篇
药学   93317篇
  7篇
中国医学   2026篇
肿瘤学   70441篇
  2018年   13735篇
  2017年   10537篇
  2016年   11461篇
  2015年   13260篇
  2014年   18278篇
  2013年   27902篇
  2012年   38190篇
  2011年   40582篇
  2010年   23412篇
  2009年   22622篇
  2008年   38462篇
  2007年   41121篇
  2006年   40679篇
  2005年   39757篇
  2004年   38249篇
  2003年   36547篇
  2002年   35445篇
  2001年   56154篇
  2000年   57125篇
  1999年   48237篇
  1998年   13530篇
  1997年   12352篇
  1996年   12766篇
  1995年   12019篇
  1994年   11196篇
  1993年   10474篇
  1992年   38279篇
  1991年   37746篇
  1990年   36506篇
  1989年   35346篇
  1988年   32768篇
  1987年   32099篇
  1986年   30605篇
  1985年   28872篇
  1984年   22025篇
  1983年   19270篇
  1982年   11445篇
  1981年   10396篇
  1979年   20997篇
  1978年   15452篇
  1977年   12828篇
  1976年   11901篇
  1975年   12848篇
  1974年   15617篇
  1973年   15391篇
  1972年   14549篇
  1971年   13574篇
  1970年   12809篇
  1969年   12086篇
  1968年   11254篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
44.
45.
Prevalence of osteoporosis is more than 50% in older adults, yet current clinical methods for diagnosis that rely on areal bone mineral density (aBMD) fail to detect most individuals who have a fragility fracture. Bone fragility can manifest in different forms, and a “one-size-fits-all” approach to diagnosis and management of osteoporosis may not be suitable. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides additive information by capturing information about volumetric density and microarchitecture, but interpretation is challenging because of the complex interactions between the numerous properties measured. In this study, we propose that there are common combinations of bone properties, referred to as phenotypes, that are predisposed to different levels of fracture risk. Using HR-pQCT data from a multinational cohort (n = 5873, 71% female) between 40 and 96 years of age, we employed fuzzy c-means clustering, an unsupervised machine-learning method, to identify phenotypes of bone microarchitecture. Three clusters were identified, and using partial correlation analysis of HR-pQCT parameters, we characterized the clusters as low density, low volume, and healthy bone phenotypes. Most males were associated with the healthy bone phenotype, whereas females were more often associated with the low volume or low density bone phenotypes. Each phenotype had a significantly different cumulative hazard of major osteoporotic fracture (MOF) and of any incident osteoporotic fracture (p < 0.05). After adjustment for covariates (cohort, sex, and age), the low density followed by the low volume phenotype had the highest association with MOF (hazard ratio = 2.96 and 2.35, respectively), and significant associations were maintained when additionally adjusted for femoral neck aBMD (hazard ratio = 1.69 and 1.90, respectively). Further, within each phenotype, different imaging biomarkers of fracture were identified. These findings suggest that osteoporotic fracture risk is associated with bone phenotypes that capture key features of bone deterioration that are not distinguishable by aBMD. © 2021 American Society for Bone and Mineral Research (ASBMR).  相似文献   
46.
47.
48.
49.
ContextIt is especially important that patients are well informed when making high-stakes, preference-sensitive decisions like those on the Physician Orders for Life-Sustaining Treatment (POLST) form. However, there is currently no way to easily evaluate whether patients understand key concepts when making these important decisions.ObjectivesTo develop a POLST knowledge survey.MethodsExpert (n = 62) ratings of key POLST facts were used to select items for a POLST knowledge survey. The survey was administered to nursing facility residents (n = 97) and surrogate decision-makers (n = 112). A subset (n = 135) were re-administered the survey after a standardized advance care planning discussion to assess the scale's responsiveness to change.ResultsThe 19-item survey demonstrated adequate reliability (α = 0.72.). Residents' scores (x = 11.4, standard deviation 3.3) were significantly lower than surrogate scores (x = 14.7, standard deviation 2.5) (P < 0.001). Scores for both groups increased significantly after administration of a standardized advance care planning discussion (P < 0.001). Although being a surrogate, age, race, education, cognitive functioning, and health literacy were significantly associated with higher POLST Knowledge Survey scores in univariate analyses, only being a surrogate (P < 0.001) and being white (P = 0.028) remained significantly associated with higher scores in multivariate analyses.ConclusionThe 19-item POLST Knowledge Survey demonstrated adequate reliability and responsiveness to change. Findings suggest the survey could be used to identify knowledge deficits and provide targeted education to ensure adequate understanding of key clinical decisions when completing POLST.  相似文献   
50.
Pharmaceutical Chemistry Journal - Three extracts were produced from the above-ground part of the meadowsweet Filipendula ulmaria (L.) Maxim. using water, 40% ethanol, and 70% ethanol. Comparative...  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