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   3718708篇
  免费   306930篇
  国内免费   16183篇
耳鼻咽喉   52251篇
儿科学   115889篇
妇产科学   98071篇
基础医学   582429篇
口腔科学   102204篇
临床医学   328066篇
内科学   667283篇
皮肤病学   96386篇
神经病学   311723篇
特种医学   146788篇
外国民族医学   463篇
外科学   583008篇
综合类   110617篇
现状与发展   24篇
一般理论   2250篇
预防医学   298604篇
眼科学   86472篇
药学   263711篇
  23篇
中国医学   11743篇
肿瘤学   183816篇
  2021年   55720篇
  2020年   35488篇
  2019年   58614篇
  2018年   72311篇
  2017年   54759篇
  2016年   60602篇
  2015年   74883篇
  2014年   109390篇
  2013年   174790篇
  2012年   97610篇
  2011年   98432篇
  2010年   118810篇
  2009年   122807篇
  2008年   86088篇
  2007年   90712篇
  2006年   100679篇
  2005年   96141篇
  2004年   97453篇
  2003年   88727篇
  2002年   78952篇
  2001年   127446篇
  2000年   120734篇
  1999年   116559篇
  1998年   68030篇
  1997年   64819篇
  1996年   62297篇
  1995年   57610篇
  1994年   51820篇
  1993年   48198篇
  1992年   82860篇
  1991年   79132篇
  1990年   75993篇
  1989年   75157篇
  1988年   69852篇
  1987年   67985篇
  1986年   64547篇
  1985年   63839篇
  1984年   55353篇
  1983年   50275篇
  1982年   43940篇
  1981年   41065篇
  1980年   38639篇
  1979年   46446篇
  1978年   39148篇
  1977年   35847篇
  1976年   32581篇
  1975年   32287篇
  1974年   33858篇
  1973年   32510篇
  1972年   30683篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
We present the case of 7‐year‐old African American girl with loose anagen syndrome. Although this is a common cause of hair loss in Caucasian children, and there have been reports of cases occurring in dark‐skinned children of North African and Middle Eastern descent, to our knowledge there have been no cases reported in black children of sub‐Saharan African ancestry. We present this case to broaden the differential diagnosis of hair loss in African Americans.  相似文献   
962.
963.
964.
Synthetic amorphous silica (SAS) in its nanosized form is now used in food applications although the potential risks for human health have not been evaluated. In this study, genotoxicity and oxidative DNA damage of two pyrogenic (NM‐202 and 203) and two precipitated (NM‐200 and ‐201) nanosized SAS were investigated in vivo in rats following oral exposure. Male Sprague Dawley rats were exposed to 5, 10, or 20 mg/kg b.w./day for three days by gavage. DNA strand breaks and oxidative DNA damage were investigated in seven tissues (blood, bone marrow from femur, liver, spleen, kidney, duodenum, and colon) with the alkaline and the (Fpg)‐modified comet assays, respectively. Concomitantly, chromosomal damage was investigated in bone marrow and in colon with the micronucleus assay. Additionally, malondialdehyde (MDA), a lipid peroxidation marker, was measured in plasma. When required, a histopathological examination was also conducted. The results showed neither obvious DNA strand breaks nor oxidative damage with the comet assay, irrespective of the dose and the organ investigated. Similarly, no increases in chromosome damage in bone marrow or lipid peroxidation in plasma were detected. However, although the response was not dose‐dependent, a weak increase in the percentage of micronucleated cells was observed in the colon of rats treated with the two pyrogenic SAS at the lowest dose (5 mg/kg b.w./day). Additional data are required to confirm this result, considering in particular, the role of agglomeration/aggregation of SAS NMs in their uptake by intestinal cells. Environ. Mol. Mutagen. 56:218–227, 2015. © 2014 Wiley Periodicals, Inc.  相似文献   
965.
966.
967.
968.
969.
Background  Machine learning (ML) has captured the attention of many clinicians who may not have formal training in this area but are otherwise increasingly exposed to ML literature that may be relevant to their clinical specialties. ML papers that follow an outcomes-based research format can be assessed using clinical research appraisal frameworks such as PICO (Population, Intervention, Comparison, Outcome). However, the PICO frameworks strain when applied to ML papers that create new ML models, which are akin to diagnostic tests. There is a need for a new framework to help assess such papers. Objective  We propose a new framework to help clinicians systematically read and evaluate medical ML papers whose aim is to create a new ML model: ML-PICO (Machine Learning, Population, Identification, Crosscheck, Outcomes). We describe how the ML-PICO framework can be applied toward appraising literature describing ML models for health care. Conclusion  The relevance of ML to practitioners of clinical medicine is steadily increasing with a growing body of literature. Therefore, it is increasingly important for clinicians to be familiar with how to assess and best utilize these tools. In this paper we have described a practical framework on how to read ML papers that create a new ML model (or diagnostic test): ML-PICO. We hope that this can be used by clinicians to better evaluate the quality and utility of ML papers.  相似文献   
970.
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