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   3074852篇
  免费   241328篇
  国内免费   31264篇
耳鼻咽喉   38838篇
儿科学   94985篇
妇产科学   79420篇
基础医学   424217篇
口腔科学   83318篇
临床医学   297858篇
内科学   580038篇
皮肤病学   66488篇
神经病学   233877篇
特种医学   115962篇
外国民族医学   920篇
外科学   440997篇
综合类   132569篇
现状与发展   93篇
一般理论   975篇
预防医学   234649篇
眼科学   74009篇
药学   235481篇
  436篇
中国医学   30649篇
肿瘤学   181665篇
  2021年   38270篇
  2020年   26807篇
  2019年   33064篇
  2018年   42939篇
  2017年   35029篇
  2016年   36698篇
  2015年   46012篇
  2014年   61983篇
  2013年   80406篇
  2012年   112223篇
  2011年   120785篇
  2010年   73945篇
  2009年   66955篇
  2008年   103771篇
  2007年   108728篇
  2006年   108640篇
  2005年   104502篇
  2004年   94861篇
  2003年   90591篇
  2002年   85620篇
  2001年   145738篇
  2000年   149011篇
  1999年   124807篇
  1998年   37179篇
  1997年   33255篇
  1996年   32339篇
  1995年   30899篇
  1994年   27940篇
  1993年   25125篇
  1992年   91609篇
  1991年   87793篇
  1990年   84286篇
  1989年   80751篇
  1988年   73794篇
  1987年   71997篇
  1986年   67322篇
  1985年   63951篇
  1984年   47641篇
  1983年   40270篇
  1982年   23461篇
  1979年   41883篇
  1978年   29133篇
  1977年   24502篇
  1976年   23056篇
  1975年   23976篇
  1974年   29028篇
  1973年   27997篇
  1972年   26075篇
  1971年   23916篇
  1970年   22548篇
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
71.
There is a sharp difference in how one views TCR structure–function–behaviour dependent on whether its recognition of major histocompatibility complex‐encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele‐specific. The establishing of allele‐specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele‐specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable.  相似文献   
72.
73.
Krishna S. Iyer 《Platelets》2020,31(4):474-482
Abstract

Platelets are small, anucleated effector cells that play an important role in linking the hemostatic and inflammatory processes in the body. Platelet function is known to be altered under various inflammatory conditions including aging. A gain in platelet function during aging can increase the risk of thrombotic events, such as stroke and acute myocardial infarction. Anti-platelet therapy is designed to reduce risk of serious cerebrovascular and cardiovascular events, but the adverse consequences of therapy, such as risk for bleeding increases with aging as well. Age-associated comorbidities such as obesity, diabetes, and hyperlipidemia also contribute to increased platelet activity and thus can enhance the risk of thrombosis. Therefore, identification of unique mechanisms of platelet dysfunction in aging and in age-associated comorbidities is warranted to design novel antiplatelet drugs. This review outlines some of the current areas of research on aging-related mechanisms of platelet hyperactivity and addresses the clinical urgency for designing anti-platelet therapies toward novel molecular targets in the aging population.  相似文献   
74.
通过病案举例,介绍大承气汤在中医脑病治疗中的使用技巧,说明大承气汤可以运用于出血性中风头痛、癫痫、失眠等多种脑病的治疗,疗效显著。大承气汤具有通腑泄热、祛邪外出的作用。对于六经辨证属阳明腑实证者,无论病种,皆可用大承气汤加味化裁。  相似文献   
75.
76.
77.
78.
肿瘤免疫检查点抑制剂治疗为肿瘤患者带来生存获益的同时,也面临了许多挑战,例如免疫介导的肝毒性的发生。深入了解免疫检查点抑制剂治疗肿瘤过程中导致肝损伤的发生情况、可能机制、危险因素等,有助于更好地临床管理。  相似文献   
79.
BACKGROUND Approximately 20% of patients with neuroendocrine tumours(NETs) develop carcinoid syndrome(CS),characterised by flushing and diarrhoea.Somatostatin analogues or telotristat can be used to control symptoms of CS through inhibition of serotonin secretion.Although CS is often the cause of diarrhoea among patients with gastroenteropancreatic NETs(GEP-NETs),other causes to consider include pancreatic enzyme insufficiency(PEI),bile acid malabsorption and small intestinal bacterial overgrowth.If other causes of diarrhoea unrelated to serotonin secretion are mistaken for CS diarrhoea,these treatments may be ineffective against the diarrhoea,risking detrimental effects to patient quality of life.AIM To identify and synthesise qualitative and quantitative evidence relating to the differential diagnosis of diarrhoea in patients with GEP-NETs.METHODS Electronic databases(MEDLINE,Embase and the Cochrane Library) were searched from inception to September 12,2018 using terms for NETs and diarrhoea.Congresses,systematic literature review bibliographies and included articles were also hand-searched.Any study designs and publication types were eligible for inclusion if relevant data on a cause(s) of diarrhoea in patients with GEP-NETs were reported.Studies were screened by two independent reviewers at abstract and full-text stages.Framework synthesis was adapted to synthesise quantitative and qualitative data.The definition of qualitative data was expanded to include all textual data in any section of relevant publications.RESULTS Forty-seven publications(44 studies) were included,comprising a variety of publication types,including observational studies,reviews,guidelines,case reports,interventional studies,and opinion pieces.Most reported on PEI on/after treatment with somatostatin analogs;9.5%-84% of patients with GEP-NETs had experienced steatorrhoea or confirmed PEI.Where reported,14.3%–50.7% of patients received pancreatic enzyme replacement therapy.Other causes of diarrhoea reported in patients with GEP-NETs included bile acid malabsorption(80%),small intestinal bacterial overgrowth(23.6%-62%),colitis(20%) and infection(7.1%).Diagnostic approaches included faecal elastase,breath tests,tauroselcholic(selenium-75) acid(Se HCAT) scan and stool culture,although evidence on the effectiveness or diagnostic accuracy of these approaches was limited.Assessment of patient history or diarrhoea characteristics was also reported as initial approaches for investigation.From the identified evidence,if diarrhoea is assumed to be CS diarrhoea,consequences include uncontrolled diarrhoea,malnutrition,and perceived ineffectiveness of CS treatment.Approaches for facilitating differential diagnosis of diarrhoea include improving patient and clinician awareness of non-CS causes and involvement of a multidisciplinary clinical team,including gastroenterologists.CONCLUSION Diarrhoea in GEP-NETs can be multifactorial with misdiagnosis leading to delayed patient recovery and inefficient resource use.This systematic literature review highlights gaps for further research on prevalence of non-CS diarrhoea and suitability of diagnostic approaches,to determine an effective algorithm for differential diagnosis of GEP-NET diarrhoea.  相似文献   
80.
Pharmaceutical Chemistry Journal - An HPLC-MS method for simultaneous quantitative determination of a novel gestagenic pharmaceutical and two of its metabolites in rat and rabbit blood sera was...  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