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   1261498篇
  免费   96516篇
  国内免费   1572篇
耳鼻咽喉   16310篇
儿科学   40980篇
妇产科学   34947篇
基础医学   189352篇
口腔科学   34739篇
临床医学   117691篇
内科学   247491篇
皮肤病学   27285篇
神经病学   101825篇
特种医学   46777篇
外国民族医学   265篇
外科学   178612篇
综合类   25742篇
现状与发展   3篇
一般理论   568篇
预防医学   104531篇
眼科学   28033篇
药学   92531篇
  6篇
中国医学   2019篇
肿瘤学   69879篇
  2018年   13541篇
  2017年   10392篇
  2016年   11326篇
  2015年   13082篇
  2014年   18006篇
  2013年   27487篇
  2012年   37578篇
  2011年   39979篇
  2010年   23063篇
  2009年   22261篇
  2008年   37764篇
  2007年   40400篇
  2006年   39970篇
  2005年   39108篇
  2004年   37547篇
  2003年   35957篇
  2002年   34872篇
  2001年   56037篇
  2000年   57055篇
  1999年   48103篇
  1998年   13395篇
  1997年   12223篇
  1996年   12644篇
  1995年   11915篇
  1994年   11110篇
  1993年   10399篇
  1992年   38199篇
  1991年   37678篇
  1990年   36450篇
  1989年   35259篇
  1988年   32690篇
  1987年   32033篇
  1986年   30528篇
  1985年   28788篇
  1984年   21941篇
  1983年   19193篇
  1982年   11367篇
  1981年   10321篇
  1979年   20946篇
  1978年   15394篇
  1977年   12792篇
  1976年   11847篇
  1975年   12812篇
  1974年   15591篇
  1973年   15367篇
  1972年   14513篇
  1971年   13553篇
  1970年   12791篇
  1969年   12066篇
  1968年   11232篇
排序方式: 共有10000条查询结果,搜索用时 703 毫秒
41.
42.
43.
44.
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   
45.
46.
47.
48.
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   
49.
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   
50.
Caring for patients with end-stage kidney disease (ESKD) in the United States is challenging, due in part to the complex epidemiology of the disease's progression as well as the ways in which care is delivered. As CKD progresses toward ESKD, the number of comorbidities increases and care involves multiple healthcare providers from multiple subspecialties. This occurs in the context of a fragmented US healthcare delivery system that is traditionally siloed by provider specialty, organization, as well as systems of payment and administration. This article describes the role of care fragmentation in the delivery of optimal ESKD care and identifies research gaps in the evidence across the continuum of care. We then consider the impact of care fragmentation on ESKD care from the patient and health system perspectives and explore opportunities for system-level interventions aimed at improving care for patients with ESKD.  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