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   1074691篇
  免费   73165篇
  国内免费   1368篇
耳鼻咽喉   15023篇
儿科学   34632篇
妇产科学   28652篇
基础医学   153591篇
口腔科学   29575篇
临床医学   95087篇
内科学   203888篇
皮肤病学   24424篇
神经病学   81563篇
特种医学   43052篇
外国民族医学   201篇
外科学   163165篇
综合类   21704篇
现状与发展   1篇
一般理论   263篇
预防医学   74729篇
眼科学   24554篇
药学   86175篇
  7篇
中国医学   2805篇
肿瘤学   66133篇
  2019年   7797篇
  2018年   11332篇
  2017年   8938篇
  2016年   10126篇
  2015年   11288篇
  2014年   15315篇
  2013年   22255篇
  2012年   30621篇
  2011年   32364篇
  2010年   18999篇
  2009年   17863篇
  2008年   30032篇
  2007年   32143篇
  2006年   32779篇
  2005年   31107篇
  2004年   29786篇
  2003年   28598篇
  2002年   27572篇
  2001年   60028篇
  2000年   61481篇
  1999年   50934篇
  1998年   12459篇
  1997年   11013篇
  1996年   11020篇
  1995年   10332篇
  1994年   9345篇
  1993年   8865篇
  1992年   37791篇
  1991年   36276篇
  1990年   35748篇
  1989年   34286篇
  1988年   30870篇
  1987年   29992篇
  1986年   28220篇
  1985年   26452篇
  1984年   19188篇
  1983年   16115篇
  1982年   8830篇
  1979年   17034篇
  1978年   11407篇
  1977年   10232篇
  1976年   8839篇
  1975年   10069篇
  1974年   11652篇
  1973年   11274篇
  1972年   10754篇
  1971年   10094篇
  1970年   9253篇
  1969年   8939篇
  1968年   7919篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
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   
23.
24.
25.
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   
26.
27.
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   
28.
29.
As millions of people turn to social media for health information, better understanding the factors that guide health-related judgments and perceptions in this context is imperative. We report on two Web experiments (n > 400 total) examining the power of society’s widespread weight bias and related stereotypes to influence nutrition judgments in social media spaces. In Experiment 1, meals were judged as lower in nutritional quality when the person who recommended them (the source) was depicted as obese rather than of normal weight, an effect mediated by stereotypic beliefs about the source as a generally unhealthy person. Experiment 2 replicated this effect, which—notably—remained significant when controlling for objective nutritional information (calories and fat content). Results highlight spillover effects of weight bias that extend beyond person perception to color impressions of objects (here, food) that are associated with stigmatized attributes. Implications for everyday nutrition judgments and public health are considered.  相似文献   
30.
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