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   38152篇
  免费   1800篇
  国内免费   117篇
耳鼻咽喉   491篇
儿科学   980篇
妇产科学   769篇
基础医学   6241篇
口腔科学   804篇
临床医学   2916篇
内科学   6947篇
皮肤病学   1473篇
神经病学   3793篇
特种医学   2300篇
外国民族医学   23篇
外科学   5225篇
综合类   140篇
一般理论   14篇
预防医学   1839篇
眼科学   655篇
药学   3287篇
中国医学   39篇
肿瘤学   2133篇
  2022年   186篇
  2021年   323篇
  2020年   294篇
  2019年   377篇
  2018年   545篇
  2017年   493篇
  2016年   674篇
  2015年   819篇
  2014年   869篇
  2013年   1215篇
  2012年   1855篇
  2011年   2019篇
  2010年   1187篇
  2009年   1098篇
  2008年   1930篇
  2007年   2059篇
  2006年   2051篇
  2005年   1997篇
  2004年   1934篇
  2003年   1947篇
  2002年   1886篇
  2001年   1002篇
  2000年   1033篇
  1999年   947篇
  1998年   503篇
  1997年   396篇
  1996年   353篇
  1995年   294篇
  1994年   268篇
  1993年   260篇
  1992年   457篇
  1991年   469篇
  1990年   446篇
  1989年   409篇
  1988年   373篇
  1987年   357篇
  1986年   301篇
  1985年   308篇
  1984年   276篇
  1983年   204篇
  1982年   210篇
  1981年   177篇
  1980年   194篇
  1979年   250篇
  1978年   192篇
  1977年   199篇
  1975年   207篇
  1974年   197篇
  1973年   203篇
  1972年   182篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
Die Anaesthesiologie - Phantomschmerzen haben eine hohe Prävalenz nach Majoramputationen und sind mit einer zusätzlichen Einschränkung der Lebensqualität verbunden....  相似文献   
2.
3.
4.
5.
Melatonin receptors play important roles in the regulation of circadian and seasonal rhythms, sleep, retinal functions, the immune system, depression, and type 2 diabetes development. Melatonin receptors are approved drug targets for insomnia, non‐24‐hour sleep‐wake disorders, and major depressive disorders. In mammals, two melatonin receptors (MTRs) exist, MT1 and MT2, belonging to the G protein‐coupled receptor (GPCR) superfamily. Similar to most other GPCRs, reliable antibodies recognizing melatonin receptors proved to be difficult to obtain. Here, we describe the development of the first monoclonal antibodies (mABs) for mouse MT1 and MT2. Purified antibodies were extensively characterized for specific reactivity with mouse, rat, and human MT1 and MT2 by Western blot, immunoprecipitation, immunofluorescence, and proximity ligation assay. Several mABs were specific for either mouse MT1 or MT2. None of the mABs cross‐reacted with rat MTRs, and some were able to react with human MTRs. The specificity of the selected mABs was validated by immunofluorescence microscopy in three established locations (retina, suprachiasmatic nuclei, pituitary gland) for MTR expression in mice using MTR‐KO mice as control. MT2 expression was not detected in mouse insulinoma MIN6 cells or pancreatic beta‐cells. Collectively, we report the first monoclonal antibodies recognizing recombinant and native mouse melatonin receptors that will be valuable tools for future studies.  相似文献   
6.
7.
8.
9.
The ban of lead in many electronic products and the expectation that, sooner or later, this ban will include the currently exempt piezoelectric ceramics based on Lead-Zirconate-Titanate has motivated many research groups to look for lead-free substitutes. After a short overview on different classes of lead-free piezoelectric ceramics with large strain, this review will focus on Bismuth-Sodium-Titanate and its solid solutions. These compounds exhibit extraordinarily high strain, due to a field induced phase transition, which makes them attractive for actuator applications. The structural features of these materials and the origin of the field-induced strain will be revised. Technologies for texturing, which increases the useable strain, will be introduced. Finally, the features that are relevant for the application of these materials in a multilayer design will be summarized.  相似文献   
10.
Marie Warrer Petersen  Tine Sylvest Meyhoff  Marie Helleberg  Maj-Brit Nørregaard Kjær  Anders Granholm  Carl Johan Steensen Hjortsø  Thomas Steen Jensen  Morten Hylander Møller  Peter Buhl Hjortrup  Mik Wetterslev  Gitte Kingo Vesterlund  Lene Russell  Vibeke Lind Jørgensen  Klaus Tjelle  Thomas Benfield  Charlotte Suppli Ulrik  Anne Sofie Andreasen  Thomas Mohr  Morten H. Bestle  Lone Musaeus Poulsen  Mette Friberg Hitz  Thomas Hildebrandt  Lene Surland Knudsen  Anders Møller  Christoffer Grant Sølling  Anne Craveiro Brøchner  Bodil Steen Rasmussen  Henrik Nielsen  Steffen Christensen  Thomas Strøm  Maria Cronhjort  Rebecka Rubenson Wahlin  Stephan Jakob  Luca Cioccari  Balasubramanian Venkatesh  Naomi Hammond  Vivekanand Jha  Sheila Nainan Myatra  Christian Gluud  Theis Lange  Anders Perner 《Acta anaesthesiologica Scandinavica》2020,64(9):1365-1375

Introduction

Severe acute respiratory syndrome coronavirus-2 has caused a pandemic of coronavirus disease (COVID-19) with many patients developing hypoxic respiratory failure. Corticosteroids reduce the time on mechanical ventilation, length of stay in the intensive care unit and potentially also mortality in similar patient populations. However, corticosteroids have undesirable effects, including longer time to viral clearance. Clinical equipoise on the use of corticosteroids for COVID-19 exists.

Methods

The COVID STEROID trial is an international, randomised, stratified, blinded clinical trial. We will allocate 1000 adult patients with COVID-19 receiving ≥10 L/min of oxygen or on mechanical ventilation to intravenous hydrocortisone 200 mg daily vs placebo (0.9% saline) for 7 days. The primary outcome is days alive without life support (ie mechanical ventilation, circulatory support, and renal replacement therapy) at day 28. Secondary outcomes are serious adverse reactions at day 14; days alive without life support at day 90; days alive and out of hospital at day 90; all-cause mortality at day 28, day 90, and 1 year; and health-related quality of life at 1 year. We will conduct the statistical analyses according to this protocol, including interim analyses for every 250 patients followed for 28 days. The primary outcome will be compared using the Kryger Jensen and Lange test in the intention to treat population and reported as differences in means and medians with 95% confidence intervals.

Discussion

The COVID STEROID trial will provide important evidence to guide the use of corticosteroids in COVID-19 and severe hypoxia.
  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