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   281431篇
  免费   15745篇
  国内免费   1721篇
耳鼻咽喉   4174篇
儿科学   8358篇
妇产科学   7805篇
基础医学   43844篇
口腔科学   8533篇
临床医学   22730篇
内科学   51221篇
皮肤病学   7039篇
神经病学   25122篇
特种医学   11004篇
外国民族医学   5篇
外科学   41690篇
综合类   5909篇
一般理论   79篇
预防医学   17394篇
眼科学   6249篇
药学   21435篇
中国医学   1059篇
肿瘤学   15247篇
  2021年   2524篇
  2020年   1982篇
  2019年   2756篇
  2018年   4837篇
  2017年   3964篇
  2016年   4847篇
  2015年   4712篇
  2014年   5595篇
  2013年   8650篇
  2012年   11592篇
  2011年   12723篇
  2010年   7382篇
  2009年   5724篇
  2008年   12332篇
  2007年   12935篇
  2006年   12659篇
  2005年   12157篇
  2004年   11500篇
  2003年   11437篇
  2002年   11197篇
  2001年   12867篇
  2000年   14456篇
  1999年   10284篇
  1998年   3700篇
  1997年   2886篇
  1996年   2145篇
  1995年   1869篇
  1994年   1773篇
  1993年   1703篇
  1992年   5003篇
  1991年   4977篇
  1990年   4725篇
  1989年   4708篇
  1988年   4417篇
  1987年   4336篇
  1986年   4015篇
  1985年   4099篇
  1984年   3046篇
  1983年   2645篇
  1982年   1760篇
  1981年   1560篇
  1979年   2699篇
  1978年   1855篇
  1977年   1650篇
  1975年   1797篇
  1974年   1927篇
  1973年   1928篇
  1972年   1823篇
  1971年   1709篇
  1970年   1568篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.

Background

Hyperglycaemia is common in patients with acute brain injury admitted to an intensive care unit (ICU). Many studies have found associations between development of hyperglycaemia and increased mortality in hospitalised patients. However, the optimal target for blood glucose control is unknown. We want to conduct a systematic review with meta-analysis and trial sequential analysis to explore the beneficial and harmful effects of restrictive versus liberal glucose control on patient outcomes in adults with severe acute brain injury.

Methods

We will systematically search medical databases including CENTRAL, Embase, MEDLINE and trial registries. We will search the following websites for ongoing or unpublished trials: http://www.controlled-trials.com/ , http://www.clinicaltrials.gov/ , www.eudraCT.com , http://centerwatch.com/ , The Cochrane Library's CENTRAL, PubMed, EMBASE, Science Citation Index Expanded and CINAHL. Two authors will independently review and select trials and extract data. We will include randomised trials comparing levels of glucose control in our analyses and observational studies will be included to address potential harms. The primary outcomes are defined as all-cause mortality, functional outcome and health-related quality of life. Secondary outcomes include serious adverse events including hypoglycaemia, length of ICU stay and duration of mechanical ventilation, and explorative outcomes including intracranial pressure and infection. Trial Sequential Analysis will be used to investigate the risk of type I error due to repetitive testing and to further explore imprecision. Quality of trials will be evaluated using the Cochrane Risk of Bias tool, and quality of evidence will be assessed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach.

Discussion

The results of the systematic review will be disseminated through peer-reviewed publication. With the review, we hope to inform future randomised clinical trials and improve clinical practice.  相似文献   
4.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
5.
Troppmair  Teresa  Egger  J.  Krösbacher  A.  Zanvettor  A.  Schinnerl  A.  Neumayr  A.  Baubin  M. 《Der Anaesthesist》2022,71(4):272-280
Die Anaesthesiologie - Die Qualität eines Rettungssystems zeichnet sich auch durch den effizienten Einsatz seiner personellen und Fahrzeugressourcen aus. So können im berechtigten Fall...  相似文献   
6.
7.
8.
9.
10.
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