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   1983746篇
  免费   145787篇
  国内免费   3659篇
耳鼻咽喉   26937篇
儿科学   64116篇
妇产科学   56166篇
基础医学   289943篇
口腔科学   55479篇
临床医学   178334篇
内科学   390527篇
皮肤病学   42606篇
神经病学   158853篇
特种医学   76391篇
外国民族医学   584篇
外科学   293756篇
综合类   41908篇
现状与发展   3篇
一般理论   790篇
预防医学   157028篇
眼科学   45213篇
药学   144086篇
  6篇
中国医学   3565篇
肿瘤学   106901篇
  2018年   20583篇
  2016年   17350篇
  2015年   19936篇
  2014年   27884篇
  2013年   42884篇
  2012年   57980篇
  2011年   61810篇
  2010年   36523篇
  2009年   34842篇
  2008年   58595篇
  2007年   62434篇
  2006年   62199篇
  2005年   61101篇
  2004年   58687篇
  2003年   56424篇
  2002年   54973篇
  2001年   87591篇
  2000年   89600篇
  1999年   76045篇
  1998年   21406篇
  1997年   19490篇
  1996年   19866篇
  1995年   18588篇
  1994年   17529篇
  1993年   16457篇
  1992年   60327篇
  1991年   58829篇
  1990年   57428篇
  1989年   55385篇
  1988年   51466篇
  1987年   50413篇
  1986年   48260篇
  1985年   45779篇
  1984年   34645篇
  1983年   29908篇
  1982年   17953篇
  1981年   16095篇
  1979年   32893篇
  1978年   23710篇
  1977年   19959篇
  1976年   18590篇
  1975年   20279篇
  1974年   24471篇
  1973年   23847篇
  1972年   22542篇
  1971年   20932篇
  1970年   19921篇
  1969年   18802篇
  1968年   17678篇
  1967年   16015篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
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   
63.
64.
65.
66.
67.
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   
68.
69.
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   
70.
Behçet disease is a complex, multisystem disease characterized by recurrent oral and genital ulcerations. It rarely occurs in infants or children. Neonatal Behçet disease has been reported in infants whose ulcers resolve at or before 9 weeks of age. Few cases of neonatal Behçet disease persisting into childhood have previously been reported. We report the case of a 1‐month‐old infant who presented with severe recurrent genital ulcerations and at 6 months developed recurrent oral ulcerations. Her orogenital ulcerations continue to recur. Human leukocyte antigen testing revealed HLA‐B51 and B44 positivity. This is a case of pediatric Behçet disease in the neonatal period. Behçet disease should be considered in the differential diagnosis of recurrent genital and oral ulcerations in infants and children.  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