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   11066篇
  免费   805篇
  国内免费   403篇
耳鼻咽喉   27篇
儿科学   160篇
妇产科学   82篇
基础医学   692篇
口腔科学   27篇
临床医学   1468篇
内科学   1732篇
皮肤病学   27篇
神经病学   1416篇
特种医学   420篇
外科学   1048篇
综合类   2414篇
预防医学   392篇
眼科学   84篇
药学   860篇
  12篇
中国医学   1367篇
肿瘤学   46篇
  2024年   13篇
  2023年   135篇
  2022年   220篇
  2021年   350篇
  2020年   385篇
  2019年   257篇
  2018年   316篇
  2017年   313篇
  2016年   331篇
  2015年   360篇
  2014年   686篇
  2013年   713篇
  2012年   619篇
  2011年   654篇
  2010年   573篇
  2009年   463篇
  2008年   557篇
  2007年   559篇
  2006年   525篇
  2005年   480篇
  2004年   378篇
  2003年   392篇
  2002年   329篇
  2001年   295篇
  2000年   281篇
  1999年   233篇
  1998年   158篇
  1997年   193篇
  1996年   141篇
  1995年   170篇
  1994年   152篇
  1993年   91篇
  1992年   119篇
  1991年   98篇
  1990年   83篇
  1989年   70篇
  1988年   72篇
  1987年   59篇
  1986年   48篇
  1985年   64篇
  1984年   50篇
  1983年   30篇
  1982年   44篇
  1981年   44篇
  1980年   34篇
  1979年   40篇
  1978年   30篇
  1977年   19篇
  1976年   14篇
  1974年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
BackgroundWhen patients with Fontan circulation require a computed tomographic pulmonary angiogram (CTPA), there are significant challenges in achieving adequate contrast opacification due to the altered anatomical connections. This study used Time Resolved Angiography with Interleaved Stochastic Trajectories (TWIST) Magnetic Resonance Angiography (MRA) to examine contrast circulation in a cohort of patients with Fontan circulation who were having routine MRI follow up to inform the contrast timing of any subsequent CT.MethodsThis is a single centre, cross-sectional, observational, retrospective study. The time to peak (TTP) signal intensity from the MRA was recorded using regions of interest on the aorta, pulmonary arteries, cavae and Fontan conduit. Patients were grouped by ejection fraction, global longitudinal strain, indexed stroke volume and cardiac index to examine if these cardiac performance parameters affected the mean TTP. Statistical analysis was performed to find the mean TTP for each of the vessels, which was consequently compared between the different cardiac performance parameters.Results35 patients were included in the study. Mean TTP contrast enhancement was 31s in the thoracic aorta, 46s in the right pulmonary artery, 41s in the left pulmonary artery and 55s in the Fontan conduit. Cardiac performance shows no statistically significant relationship to the peak contrast enhancement whether measured by ejection fraction, global longitudinal strain, stroke volume index or cardiac index.ConclusionThe mean optimal timing for a single-phase examination of the Fontan circulation, following an upper limb injection, was 55 s following start of contrast injection irrespective of cardiac performance. In TWIST MRA, the IV bolus is 4–5 s duration. A longer bolus is required for CTA, around 20s, suggesting an additional delay will be required. We propose that an optimal single phase CTPA to be protocolled at 70 s following the start of contrast injection, assuming adequate iodinated contrast dose.  相似文献   
52.
53.
54.
Background and aimsIn-hospital cardiac arrest (CA) is a clinical entity with high morbidity and mortality that occurs in up to 2% of hospitalized patients. It is a public health problem with important economic, social, and medical repercussions, and as such its incidence needs to be reviewed and improved. The aim of this study was to determine the incidence of in-hospital CA, return of spontaneous circulation (ROSC), and survival rates at Hospital de la Princesa, and to define the clinical and demographic characteristics of patients with in-hospital CA.Material and methodsRetrospective observational chart review of patients presenting in-hospital CA and treated by anaesthesiologists from the hospital's rapid intervention team. Data were collected over 1 year.ResultsForty-four patients were included in the study, of which 22 (50%) were women. Mean age was 75.70 years (± 15.78 years), and incidence of in-hospital CA was 2.88 per 100,000 hospital admissions. Twenty-two patients (50%) achieved ROSC and 11 patients (25%) survived until discharge home. The most prevalent comorbidity was arterial hypertension (63.64%); 66.7% of cases were not witnessed, and only 15.9% presented a shockable rhythm.ConclusionsThese results are similar to those reported in other larger studies. We recommend introducing immediate intervention teams and devoting time to training hospital staff in in-hospital CA.  相似文献   
55.
Sudden focal neurological symptoms or ‘brain attacks’ in children are a common scenario for acute paediatric care givers. A small proportion will have had a vascular stroke. Suspected stroke in adults, signalled by FAST (Face, Arms, Speech, Time) test positivity, is an accepted medical emergency. Children are rarely dealt with urgently unless there is coma. Barriers to stroke recognition and response in children are multifactorial. Childhood stroke is rare and may be ‘FAST negative’. Overall, there is low awareness, low clinical suspicion and many logistic obstacles to timely detection and aspired treatment delivery. Yet stroke continues to affect hundreds of children in the UK each year, causing life-changing disability and, in some, death. This article highlights current key recommendations for the diagnosis and management of acute stroke set out in the 2017 Royal College of Paediatrics and Child Health (RCPCH) Stroke in childhood guideline. Evidence and rationale are discussed, and important practice points offered. There is focus on arterial ischaemic stroke in light of the proposed hyperacute management pathway, which includes thrombolysis. Ongoing challenges on the ground and how these may be overcome are considered.  相似文献   
56.
57.
一、目的中国生物医学工程学会体外循环分会(以下称体外循环分会)、中华医学会胸心血管外科学分会和中国医师协会心血管外科医师分会基于当前临床研究证据和业内广泛接受的体外循环技术及我国体外循环专家共识,制定中国体外循环专业技术标准(以下简称标准),旨在为开展体外循环手术的单位或团队建立临床体外循环工作规程提供一个框架性参考文件,以保障体外循环技术实施的可靠性、安全性和有效性。  相似文献   
58.
《中国体外循环杂志》2021,(2):118-122,128
本文对婴幼儿心脏术后急性肾损伤(AKI)的高危因素与致病机制、AKI分级及常用诊断标准、防治措施以及相关研究进展进行综述,旨在通过对婴幼儿心脏术后AKI的合理认识,为临床诊疗提供依据,改善心脏手术患儿的近期及远期预后。  相似文献   
59.
BackgroundMild cognitive impairment (MCI) is a neurocognitive state between normal cognitive aging and dementia, with evidence of neuropsychological changes but insufficient functional decline to warrant a diagnosis of dementia. Individuals with MCI are at increased risk for progression to dementia; and an appreciable proportion display neuropsychiatric symptoms (NPS), also a known risk factor for dementia. Cerebrovascular disease (CVD) is thought to be an underdiagnosed contributor to MCI/dementia. The Ginkgo biloba extract, EGb 761®, is increasingly being used for the symptomatic treatment of cognitive disorders with/without CVD, due to its known neuroprotective effects and cerebrovascular benefits.AimsTo present consensus opinion from the ASian Clinical Expert group on Neurocognitive Disorders (ASCEND) regarding the role of EGb 761® in MCI.Materials & MethodsThe ASCEND Group reconvened in September 2019 to present and critically assess the current evidence on the general management of MCI, including the efficacy and safety of EGb 761® as a treatment option.ResultsEGb 761® has demonstrated symptomatic improvement in at least four randomized trials, in terms of cognitive performance, memory, recall and recognition, attention and concentration, anxiety, and NPS. There is also evidence that EGb 761® may help delay progression from MCI to dementia in some individuals.DiscussionEGb 761® is currently recommended in multiple guidelines for the symptomatic treatment of MCI. Due to its beneficial effects on cerebrovascular blood flow, it is reasonable to expect that EGb 761® may benefit MCI patients with underlying CVD.ConclusionAs an expert group, we suggest it is clinically appropriate to incorporate EGb 761® as part of the multidomain intervention for MCI.  相似文献   
60.
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