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   101991篇
  免费   8429篇
  国内免费   3052篇
耳鼻咽喉   448篇
儿科学   3041篇
妇产科学   1018篇
基础医学   7182篇
口腔科学   1719篇
临床医学   13481篇
内科学   26249篇
皮肤病学   1234篇
神经病学   3753篇
特种医学   3656篇
外科学   7677篇
综合类   19459篇
现状与发展   14篇
一般理论   7篇
预防医学   7931篇
眼科学   990篇
药学   8855篇
  104篇
中国医学   5966篇
肿瘤学   688篇
  2024年   96篇
  2023年   1636篇
  2022年   2513篇
  2021年   4148篇
  2020年   4543篇
  2019年   3655篇
  2018年   3497篇
  2017年   3422篇
  2016年   3510篇
  2015年   3411篇
  2014年   7054篇
  2013年   7341篇
  2012年   6188篇
  2011年   6584篇
  2010年   5296篇
  2009年   5031篇
  2008年   4885篇
  2007年   5060篇
  2006年   4351篇
  2005年   4038篇
  2004年   3252篇
  2003年   2980篇
  2002年   2546篇
  2001年   2344篇
  2000年   1921篇
  1999年   1690篇
  1998年   1473篇
  1997年   1305篇
  1996年   995篇
  1995年   1065篇
  1994年   1000篇
  1993年   739篇
  1992年   738篇
  1991年   665篇
  1990年   527篇
  1989年   516篇
  1988年   452篇
  1987年   423篇
  1986年   369篇
  1985年   385篇
  1984年   338篇
  1983年   196篇
  1982年   227篇
  1981年   192篇
  1980年   166篇
  1979年   149篇
  1978年   130篇
  1977年   107篇
  1976年   99篇
  1975年   72篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
DNA损伤是衰老相关疾病领域的研究热点, 可引起细胞周期停滞、凋亡, 加快个体衰老速度、增加衰老相关疾病的患病风险。本文将从细胞衰老和个体衰老两个层面阐述其与衰老之间的研究进展, 并综述其与衰老常见相关疾病(肿瘤、心血管疾病、阿尔茨海默病)及早衰综合征的关系, 为抗衰老研究和临床干预衰老相关疾病提供理论依据。  相似文献   
2.
3.
BackgroundIschemia reperfusion (I/R) play an imperative role in the expansion of cardiovascular disease. Sinomenine (SM) has been exhibited to possess antioxidant, anticancer, anti-inflammatory, antiviral and anticarcinogenic properties. The aim of the study was scrutinized the cardioprotective effect of SM against I/R injury in rat.MethodsRat were randomly divided into normal control (NC), I/R control and I/R + SM (5, 10 and 20 mg/kg), respectively. Ventricular arrhythmias, body weight and heart weight were estimated. Antioxidant, inflammatory cytokines, inflammatory mediators and plasmin system indicator were accessed.ResultsPre-treated SM group rats exhibited the reduction in the duration and incidence of ventricular fibrillation, ventricular ectopic beat (VEB) and ventricular tachycardia along with suppression of arrhythmia score during the ischemia (30 and 120 min). SM treated rats significantly (P < 0.001) altered the level of antioxidant parameters. SM treatment significantly (P < 0.001) repressed the level of creatine kinase MB (CK-MB), creatine kinase (CK) and troponin I (Tnl). SM treated rats significantly (P < 0.001) repressed the tissue factor (TF), thromboxane B2 (TXB2), plasminogen activator inhibitor 1 (PAI-1) and plasma fibrinogen (Fbg) and inflammatory cytokines and inflammatory mediators.ConclusionOur result clearly indicated that SM plays anti-arrhythmia effect in I/R injury in the rats via alteration of oxidative stress and inflammatory reaction.  相似文献   
4.
5.
BackgroundSelection of the transcatheter heart valve size for a mitral valve-in-valve procedure is based on the type and manufacturer’s labelled size. However, accurate information of surgical heart valve (SHV) size may not be available in the patient’s medical record. The purpose of this study is to establish reference data for computed tomography (CT) dimensions of commonly used mitral SHV in order to determine the manufacturer’s labelled size from a cardiac CT data set.MethodsCT datasets of 105 patients with surgical mitral bioprosthesis and available manufacturer labeled datasets were included in the analysis. CT derived valve dimensions were assessed by two observers using multiplanar reformats aligned with the basal sewing ring. A circular region of interest was used in a standardized fashion to minimize influence of image acquisition and reconstruction parameters. Interobserver variability was assessed by Bland-Altman analysis.ResultsThe CT-derived dimensions were stratified by valve size and type, and SHV properties were demonstrated for 5 common valve types. Variability of measurements was small and inter-observer limits of agreement were narrow. Stratified by SHV type, no overlap was noted for CT-derived dimensions among different SHV sizes . A reference table of CT characteristics of surgical mitral bioprosthesis types was created.ConclusionThe study provides reference CT data for determining the manufacturers’ labeled SHV size across a range of commonly used mitral SHVs. The findings will be important to help identify types of surgical mitral bioprosthesis utilizing CT characteristics for patients without SHV size documentation.  相似文献   
6.
目的探讨前瞻性护理干预在急性心力衰竭患者中的应用效果。方法选取2018年4月—2020年5月河南省某医院收治的122例急性心力衰竭患者为研究对象,采用随机数字表法分为观察组与对照组,每组61例。对照组患者采用常规护理,观察组患者采用前瞻性护理,比较2组患者的干预效果、并发症发生情况,干预前后焦虑自评量表(SAS)、抑郁自评量表(SDS)评分及护理满意度。结果观察组患者干预总有效率为95.08%,高于对照组的75.41%,差异有统计学意义(χ2=9.385,P=0.002)。观察组患者并发症发生率为3.28%,低于对照组的18.03%,差异有统计学意义(χ2=6.974,P=0.008)。2组患者干预后SAS及SDS评分均低于干预前,且观察组低于对照组,差异均有统计学意义(P<0.05)。观察组患者护理满意度为98.36%,高于对照组的86.89%,差异有统计学意义(χ2=4.319,P=0.038)。结论前瞻性护理干预用于急性心力衰竭患者,有助于改善患者负性情绪及减少并发症的发生。  相似文献   
7.
BackgroundInflammation surrounding the coronary arteries can be non-invasively assessed using pericoronary adipose tissue attenuation (PCAT). While PCAT holds promise for further risk stratification of patients with low coronary artery disease (CAD) prevalence, its value in higher risk populations remains unknown.MethodsCORE320 enrolled patients referred for invasive coronary angiography with known or suspected CAD. Coronary computed tomography angiography (CCTA) images were collected for 381 patients for whom clinical outcomes were assessed 5 years after enrollment. Using semi-automated image analysis software, PCAT was obtained and normalized for the right coronary (RCA), left anterior descending (LAD), and left circumflex arteries (LCx). The association between PCAT and major adverse cardiovascular events (MACE) during follow up was assessed using Cox regression models.ResultsThirty-seven patients were excluded due to technical failure. For the remaining 344 patients, median age was 62 (interquartile range, 55–68) with 59% having ≥1 coronary artery stenosis of ≥50% by quantitative coronary angiography. Mean attenuation values for PCAT in RCA, LAD, and LCx were ?74.9, ?74.2, and ?71.2, respectively. Hazard ratios and 95% confidence intervals (CI) for normalized PCAT in the RCA, LAD, and LCx for MACE were 0.96 (CI: 0.75–1.22, p ?= ?0.71), 1.31 (95% CI: 0.96–1.78, p ?= ?0.09), and 0.98 (95% CI: 0.78–1.22, p ?= ?0.84), respectively. For death, stroke, or myocardial infarction only, hazard ratios were 0.68 (0.44–1.07), 0.85 (0.56–1.29), and 0.57 (0.41–0.80), respectively.ConclusionsIn patients referred for invasive coronary angiography with suspected CAD, PCAT did not predict MACE during long term follow up. Further studies are needed to understand the relationship of PCAT with CAD risk.  相似文献   
8.
9.
BackgroundInvasive Fungal Diseases (IFD), account for high morbidity and mortality in immunocompromised and seriously ill patients worldwide. Early, faster and accurate diagnosis with timely and appropriate patient management is critical for improved patient outcome and antifungal stewardship. Clinical/radiological presentations in IFD are non-specific and microscopy/culture based tests have low sensitivity and long turnaround time. Biomarkers have clinical utility for diagnosing IFD but their interpretation is not straight forward.ObjectivesThis review discusses the salient characteristics, clinical usefulness and limitations of common biomarkers such as Galactomannan (GM), 1–3, β D glucan (βDG), mannan, anti-mannan antibody (Mn/antiMn), Cryptococcal antigen test (CrAg), Nucleic Acid Amplification (NAA) tests and next generation sequencing for diagnosing IFD.ContentsFungal biomarkers are useful adjuncts as screening and diagnostic tools for IFD and are much more suited for ‘ruling out’ rather than ‘ruling in’ disease. GM, NAA tests are promising biomarkers for screening of invasive Aspergillosis in high risk asymptomatic patients who are not on antifungal therapy and for diagnosis of breakthrough infections in symptomatic patients. 1–3, β D glucan has limitations both as a ‘rule in’ and ‘rule out’ test and is useful in only specific clinical settings. Two consecutive positive 1-3-βDG tests or combined positivity with GM increases its specificity. Mn/antiMn, T2Candida nano diagnostic panel are promising candidates for diagnosing invasive candidiasis. Combining two or more biomarkers improves the sensitivity for prompt initiation of antifungal therapy and the negative predictive value for suspension of empirical treatment.Serum CrAg test is a good ‘rule in’ rather than a ‘rule out’ test in immunocompetent patients but has good diagnostic accuracy in immunocompromised patients. Detection of single nucleotide polymorphisms by next generation sequencing is useful for fungal characterization and identification of host determinants responsible for increased susceptibility to fungal infections but is still in experimental stages.  相似文献   
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