首页 | 官方网站   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   1256967篇
  免费   96483篇
  国内免费   1558篇
医药卫生   1355008篇
  2018年   13536篇
  2017年   10396篇
  2016年   11325篇
  2015年   13084篇
  2014年   18004篇
  2013年   27488篇
  2012年   37597篇
  2011年   39982篇
  2010年   23065篇
  2009年   22264篇
  2008年   37774篇
  2007年   40408篇
  2006年   39977篇
  2005年   39110篇
  2004年   37556篇
  2003年   35966篇
  2002年   34875篇
  2001年   56038篇
  2000年   57047篇
  1999年   48097篇
  1998年   13395篇
  1997年   12159篇
  1996年   11706篇
  1995年   11813篇
  1994年   11023篇
  1993年   10313篇
  1992年   38128篇
  1991年   37658篇
  1990年   36424篇
  1989年   35244篇
  1988年   32651篇
  1987年   32006篇
  1986年   30503篇
  1985年   28765篇
  1984年   21901篇
  1983年   19129篇
  1982年   11304篇
  1981年   10257篇
  1979年   20879篇
  1978年   15360篇
  1977年   12722篇
  1976年   11782篇
  1975年   12780篇
  1974年   15553篇
  1973年   15325篇
  1972年   14498篇
  1971年   13539篇
  1970年   12760篇
  1969年   12049篇
  1968年   11213篇
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
41.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
42.
43.
44.
Introduction: To increase students’ understanding of what it means to be a physician and engage in the everyday practice of medicine, a humanities program was implemented into the preclinical curriculum of the medical school curriculum. The purpose of our study was to determine how medical students’ views of being a doctor evolved after participating in a required humanities course.

Methods: Medical students completing a 16-clock hour humanities course from 10 courses were asked to respond to an open-ended reflection question regarding changes, if any, of their views of being a doctor. The constant comparative method was used for coding; triangulation and a variety of techniques were used to provide evidence of validity of the analysis.

Results: A majority of first- and second-year medical students (rr?=?70%) replied, resulting in 100 pages of text. A meta-theme of Contextualizing the Purpose of Medicine and three subthemes: the importance of Treating Patients Rather than a Disease, Understanding Observation Skills are Important, and Recognizing that Doctors are Fallible emerged from the data.

Conclusions: Results suggest that requiring humanities as part of the required preclinical curriculum can have a positive influence on medical students and act as a bridge to contextualize the purpose of medicine.  相似文献   
45.
46.
47.
48.
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   
49.
50.
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-23

京公网安备 11010802026262号