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   3284405篇
  免费   289311篇
  国内免费   20330篇
耳鼻咽喉   45084篇
儿科学   99267篇
妇产科学   84333篇
基础医学   522711篇
口腔科学   89617篇
临床医学   298581篇
内科学   568928篇
皮肤病学   86993篇
神经病学   281694篇
特种医学   130515篇
外国民族医学   236篇
外科学   511565篇
综合类   119865篇
现状与发展   44篇
一般理论   2348篇
预防医学   274171篇
眼科学   75385篇
药学   231374篇
  133篇
中国医学   15548篇
肿瘤学   155654篇
  2021年   60280篇
  2020年   38928篇
  2019年   61463篇
  2018年   74352篇
  2017年   56942篇
  2016年   62185篇
  2015年   78156篇
  2014年   113743篇
  2013年   179092篇
  2012年   97878篇
  2011年   96874篇
  2010年   121728篇
  2009年   125442篇
  2008年   80364篇
  2007年   82413篇
  2006年   92959篇
  2005年   87954篇
  2004年   88054篇
  2003年   78628篇
  2002年   67288篇
  2001年   86420篇
  2000年   78386篇
  1999年   82114篇
  1998年   64152篇
  1997年   62505篇
  1996年   60075篇
  1995年   55599篇
  1994年   49889篇
  1993年   46445篇
  1992年   58085篇
  1991年   55298篇
  1990年   52396篇
  1989年   51900篇
  1988年   48649篇
  1987年   47490篇
  1986年   45252篇
  1985年   45785篇
  1984年   43748篇
  1983年   40406篇
  1982年   40371篇
  1981年   38201篇
  1980年   36094篇
  1979年   37017篇
  1978年   33617篇
  1977年   30916篇
  1976年   28110篇
  1975年   26632篇
  1974年   27789篇
  1973年   26684篇
  1972年   25131篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
31.
32.
Coronavirus disease-19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is now a pandemic threat. This virus is supposed to be spread by human to human transmission. Cellular angiotensin-converting enzyme 2 (ACE2) is the receptor of SARS-CoV-2 which is identical or similar in different species of animals such as pigs, ferrets, cats, orangutans, monkeys, and humans. Moreover, a recent study predicted that dogs might be secondary hosts during the evolution of SARS-CoV-2 from bat to human. Therefore, there is a possibility of spreading SARS-CoV-2 through domestic pets. There are now many reports of SARS-CoV-2 positive cases in dogs, cats, tigers, lion, and minks. Experimental data showed ferrets and cats are highly susceptible to SARS-CoV-2 as infected by virus inoculation and can transmit the virus directly or indirectly by droplets or airborne routes. Based on these natural infection reports and experimental data, whether the pets are responsible for SARS-CoV-2 spread to humans; needs to be deeply investigated. Humans showing clinical symptoms of respiratory infections have been undergoing for the COVID-19 diagnostic test but many infected people and few pets confirmed with SARS-CoV-2 remained asymptomatic. In this review, we summarize the natural cases of SARS-CoV-2 in animals with the latest researches conducted in this field. This review will be helpful to think insights of SARS-CoV-2 transmissions, spread, and demand for seroprevalence studies, especially in companion animals.  相似文献   
33.
34.
Anaplastic thyroid carcinoma (ATC) is an aggressive thyroid malignancy with high mortality rate. This malignancy arises in thyroid follicular cells either denovo or with an associated differentiated thyroid carcinoma component. Clinically, it usually presents as a rapidly enlarging mass, pain and locally compressive symptoms. Histopathologic variability and heterogeneity often pose diagnostic challenges, especially in scant and paucicellular specimens. This article describes the clinical, histopathologic and molecular features of ATC and also addresses the associated diagnostic limitations and challenges.  相似文献   
35.
36.
Bone mineral density (BMD) is a highly heritable predictor of osteoporotic fracture. GWAS have identified hundreds of loci influencing BMD, but few have been functionally analyzed. In this study, we show that SNPs within a BMD locus on chromosome 14q32.32 alter splicing and expression of PAR-1a/microtubule affinity regulating kinase 3 (MARK3), a conserved serine/threonine kinase known to regulate bioenergetics, cell division, and polarity. Mice lacking Mark3 either globally or selectively in osteoblasts have increased bone mass at maturity. RNA profiling from Mark3-deficient osteoblasts suggested changes in the expression of components of the Notch signaling pathway. Mark3-deficient osteoblasts exhibited greater matrix mineralization compared with controls that was accompanied by reduced Jag1/Hes1 expression and diminished downstream JNK signaling. Overexpression of Jag1 in Mark3-deficient osteoblasts both in vitro and in vivo normalized mineralization capacity and bone mass, respectively. Together, these findings reveal a mechanism whereby genetically regulated alterations in Mark3 expression perturb cell signaling in osteoblasts to influence bone mass.  相似文献   
37.
38.
The coronavirus disease 2019 (COVID-19) pandemic has rapidly created widespread impacts on global health and the economy. Data suggest that women are less susceptible to severe illness. However, sex-disaggregated data are incomplete, leaving room for misinterpretation, and focusing only on biologic sex underestimates the gendered impact of the pandemic on women. This narrative review summarizes what is known about gender disparities during the COVID-19 pandemic and the economic, domestic, and health burdens along with overlapping vulnerabilities related to the pandemic. In addition, this review outlines recommended strategies that advocacy groups, community leaders, and policymakers should implement to mitigate the widening gender disparities related to COVID-19.  相似文献   
39.
40.
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