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   2368876篇
  免费   173115篇
  国内免费   3370篇
耳鼻咽喉   32378篇
儿科学   76735篇
妇产科学   63342篇
基础医学   351373篇
口腔科学   64035篇
临床医学   212993篇
内科学   460913篇
皮肤病学   52137篇
神经病学   187344篇
特种医学   88805篇
外国民族医学   503篇
外科学   356610篇
综合类   47605篇
现状与发展   12篇
一般理论   850篇
预防医学   183784篇
眼科学   54749篇
药学   176158篇
  11篇
中国医学   4587篇
肿瘤学   130437篇
  2021年   19266篇
  2019年   19791篇
  2018年   27371篇
  2017年   20624篇
  2016年   23120篇
  2015年   25991篇
  2014年   36571篇
  2013年   54607篇
  2012年   75548篇
  2011年   80375篇
  2010年   47557篇
  2009年   45082篇
  2008年   75522篇
  2007年   80431篇
  2006年   81205篇
  2005年   78680篇
  2004年   75116篇
  2003年   72472篇
  2002年   70091篇
  2001年   109274篇
  2000年   111999篇
  1999年   93983篇
  1998年   27241篇
  1997年   23850篇
  1996年   24208篇
  1995年   22854篇
  1994年   21023篇
  1993年   19834篇
  1992年   72295篇
  1991年   70424篇
  1990年   68719篇
  1989年   65932篇
  1988年   60564篇
  1987年   59390篇
  1986年   55480篇
  1985年   53252篇
  1984年   39493篇
  1983年   33545篇
  1982年   19950篇
  1979年   36067篇
  1978年   25789篇
  1977年   21344篇
  1976年   20451篇
  1975年   21948篇
  1974年   26316篇
  1973年   24945篇
  1972年   23328篇
  1971年   22145篇
  1970年   20344篇
  1969年   19400篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
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   
52.
53.
54.
55.
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   
56.
57.
58.
59.
Nevo  N.  Goldstein  A. L.  Staierman  M.  Eran  N.  Carmeli  I.  Rayman  S.  mnouskin  Y. 《Hernia》2022,26(6):1491-1499
Hernia - The minimally invasive surgical repair of combined inguinal and ventral hernias often requires shifting from one approach or plane to another. The traditional enhanced-view totally...  相似文献   
60.
BackgroundSecond-hand smoking or environmental tobacco smoke is a critical health risk. Children are the most vulnerable to second-hand smoking because of their small bronchial ducts, less developed immunity, and low-physical activity.ObjectivesThe purpose of this study was to ascertain the effects of second-hand smoking on lung functions in athlete and non-athlete school-aged children.MethodsThis observational study included forty-six school-aged children, their age was 8–15 years, assigned to three groups; 2 study groups and 1 control group (n=15). The study groups comprised of 16 football players, and of 15 cyclists. Lung functions were evaluated recording forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow using digital spirometer.ResultsAll measures were recorded in definite values and the children were also classified into second-hand smoking (SH), or non-exposed to tobacco smoking (NE). The findings presented a significant increase (p<0.05) of the study groups in forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow solely for the non-exposed children. However, there were non-significant differences between the cyclists and football players or between the passive smoking children and non-exposed children in any of the two study groups (p>0.05).ConclusionThe outcomes of this study suggest beneficial influences of the sports activity on the lung functions, without different influences of the cyclists and football players on the lung functions.  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