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   2336025篇
  免费   186629篇
  国内免费   7497篇
耳鼻咽喉   31987篇
儿科学   78443篇
妇产科学   64278篇
基础医学   326150篇
口腔科学   63881篇
临床医学   209020篇
内科学   471834篇
皮肤病学   53365篇
神经病学   188589篇
特种医学   94707篇
外国民族医学   883篇
外科学   362439篇
综合类   53110篇
现状与发展   3篇
一般理论   747篇
预防医学   183473篇
眼科学   51061篇
药学   168817篇
  7篇
中国医学   4189篇
肿瘤学   123168篇
  2018年   23678篇
  2017年   18249篇
  2016年   21200篇
  2015年   23814篇
  2014年   33205篇
  2013年   50328篇
  2012年   64933篇
  2011年   69469篇
  2010年   42573篇
  2009年   41080篇
  2008年   65605篇
  2007年   70259篇
  2006年   71335篇
  2005年   69133篇
  2004年   66724篇
  2003年   64964篇
  2002年   62697篇
  2001年   112431篇
  2000年   116349篇
  1999年   97948篇
  1998年   28443篇
  1997年   25590篇
  1996年   26522篇
  1995年   26124篇
  1994年   24524篇
  1993年   22886篇
  1992年   79851篇
  1991年   78047篇
  1990年   75470篇
  1989年   72105篇
  1988年   66566篇
  1987年   65332篇
  1986年   61351篇
  1985年   59029篇
  1984年   44860篇
  1983年   37791篇
  1982年   22914篇
  1981年   20698篇
  1980年   19102篇
  1979年   40397篇
  1978年   28821篇
  1977年   24477篇
  1976年   22549篇
  1975年   23938篇
  1974年   28138篇
  1973年   27009篇
  1972年   24893篇
  1971年   22896篇
  1970年   21230篇
  1969年   19574篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
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   
62.
Lasers in Medical Science - Studies reported the harmful effects of 2,4-D on body tissues, provoking changes in the anatomy and physiology of the kidneys, liver, and testicles. Thus, the objective...  相似文献   
63.
64.
65.
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   
66.
67.
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   
68.
69.
Haemophilia is a common cause of genetically inherited bleeding disorders. Pseudotumours occur in 1–2 % of persons with severe forms of haemophilia. These are a result of repeated haemorrhage into soft tissues, subperiosteum or a site of bone fracture with inadequate resorption of the extravasated blood. There are a number of therapeutic alternatives for this dangerous condition: surgical removal, percutaneous management, irradiation, embolization etc. In this case report, we describe the natural history, clinical course and successful surgical management of a patient with haemophilia who presented with a massive pseudotumour. We also briefly review the relevant literature on the various therapeutic modalities that have been implemented in the management of this rare complication. Though surgeons may be averse to operate on haemophiliacs, primary surgical management as done in our case may prove to be the definitive treatment option for such patients.  相似文献   
70.
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