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   41751篇
  免费   3094篇
  国内免费   1558篇
耳鼻咽喉   77篇
儿科学   565篇
妇产科学   225篇
基础医学   2654篇
口腔科学   155篇
临床医学   5135篇
内科学   12836篇
皮肤病学   229篇
神经病学   1240篇
特种医学   2087篇
外国民族医学   1篇
外科学   2013篇
综合类   8433篇
预防医学   2239篇
眼科学   309篇
药学   5022篇
  34篇
中国医学   2196篇
肿瘤学   953篇
  2024年   17篇
  2023年   518篇
  2022年   776篇
  2021年   1379篇
  2020年   1398篇
  2019年   1129篇
  2018年   1096篇
  2017年   1146篇
  2016年   1251篇
  2015年   1285篇
  2014年   2599篇
  2013年   3047篇
  2012年   2264篇
  2011年   2641篇
  2010年   2148篇
  2009年   1998篇
  2008年   2099篇
  2007年   2175篇
  2006年   2130篇
  2005年   1813篇
  2004年   1569篇
  2003年   1387篇
  2002年   1161篇
  2001年   1202篇
  2000年   988篇
  1999年   814篇
  1998年   712篇
  1997年   666篇
  1996年   540篇
  1995年   510篇
  1994年   503篇
  1993年   403篇
  1992年   362篇
  1991年   330篇
  1990年   281篇
  1989年   239篇
  1988年   251篇
  1987年   219篇
  1986年   185篇
  1985年   223篇
  1984年   197篇
  1983年   137篇
  1982年   130篇
  1981年   122篇
  1980年   89篇
  1979年   76篇
  1978年   51篇
  1977年   44篇
  1976年   31篇
  1974年   22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.
ObjectivesThe aim of this study was to test whether optical coherence tomographic (OCT) guidance would provide additional useful information beyond that obtained by angiography and lead to a shift in reperfusion strategy and improved clinical outcomes in patients with ST-segment elevation myocardial infarction (STEMI) with early infarct artery patency.BackgroundAngiography is limited in assessing the underlying pathophysiological mechanisms of the culprit lesion.MethodsEROSION III (Optical Coherence Tomography–Guided Reperfusion in ST-Segment Elevation Myocardial Infarction With Early Infarct Artery Patency) is an open-label, prospective, multicenter, randomized, controlled study approved by the ethics committees of participating centers. Patients with STEMI who had angiographic diameter stenosis ≤ 70% and TIMI (Thrombolysis In Myocardial Infarction) flow grade 3 at presentation or after antegrade blood flow restoration were recruited and randomized to either OCT guidance or angiographic guidance. The primary efficacy endpoint was the rate of stent implantation.ResultsAmong 246 randomized patients, 226 (91.9%) constituted the per protocol set (112 with OCT guidance and 114 with angiographic guidance). The median diameter stenosis was 54.0% (IQR: 48.0%-61.0%) in the OCT guidance group and 53.5% (IQR: 43.8%-64.0%) in the angiographic guidance group (P = 0.57) before randomization. Stent implantation was performed in 49 of 112 patients (43.8%) in the OCT group and 67 of 114 patients (58.8%) in the angiographic group (P = 0.024), demonstrating a 15% reduction in stent implantation with OCT guidance. In patients treated with stent implantation, OCT guidance was associated with a favorable result with lower residual angiographic diameter stenosis (8.7% ± 3.7% vs 11.8% ± 4.6% in the angiographic guidance group; P < 0.001). Two patients (1 cardiac death, 1 stable angina) met the primary safety endpoint in the OCT guidance group, as did 3 patients (3 cardiac deaths) in the angiographic guidance group (1.8% vs 2.6%; P = 0.67). Reinfarction was not observed in either group. At 1 year, the rates of predefined cardiocerebrovascular events were comparable between the groups (11.6% after OCT guidance vs 9.6% after angiographic guidance; P = 0.66).ConclusionsIn patients with STEMI with early infarct artery patency, OCT guidance compared with angiographic guidance of reperfusion was associated with less stent implantation during primary percutaneous coronary intervention. These favorable results indicate the value of OCT imaging in optimizing the reperfusion strategy of patients with STEMI. (EROSION III: OCT- vs Angio-Based Reperfusion Strategy for STEMI; NCT03571269)  相似文献   
3.
杨军 《当代医学》2022,28(7):4-6
目的观察分析急性心肌梗死患者早期嚼服氯吡格雷与阿司匹林联合静脉溶栓治疗的临床效果。方法选取2019年11月至2020年11月本院收治的100例急性心肌梗死患者作为研究对象,随机分为常规组(嚼服阿司匹林治疗)和研究组(嚼服氯吡格雷及阿司匹林治疗),各50例。比较两组临床疗效、左室射血分数、急性生理与慢性健康评分(APACHEⅡ)及出血不良反应情况。结果研究组治疗总有效率高于常规组(P<0.05);研究组左室射血分数高于常规组,APACHEⅡ评分低于常规组(P<0.05);两组出血不良反应发生率比较差异无统计学意义。结论急性心肌梗死患者静脉溶栓治疗后嚼服氯吡格雷与阿司匹林,可进一步提高临床疗效,改善患者心功能,且安全性较高,出血不良反应少,值得临床推广应用。  相似文献   
4.
We propose a Deep learning-based weak label learning method for analyzing whole slide images (WSIs) of Hematoxylin and Eosin (H&E) stained tumor tissue not requiring pixel-level or tile-level annotations using Self-supervised pre-training and heterogeneity-aware deep Multiple Instance LEarning (DeepSMILE). We apply DeepSMILE to the task of Homologous recombination deficiency (HRD) and microsatellite instability (MSI) prediction. We utilize contrastive self-supervised learning to pre-train a feature extractor on histopathology tiles of cancer tissue. Additionally, we use variability-aware deep multiple instance learning to learn the tile feature aggregation function while modeling tumor heterogeneity. For MSI prediction in a tumor-annotated and color normalized subset of TCGA-CRC (n=360 patients), contrastive self-supervised learning improves the tile supervision baseline from 0.77 to 0.87 AUROC, on par with our proposed DeepSMILE method. On TCGA-BC (n=1041 patients) without any manual annotations, DeepSMILE improves HRD classification performance from 0.77 to 0.81 AUROC compared to tile supervision with either a self-supervised or ImageNet pre-trained feature extractor. Our proposed methods reach the baseline performance using only 40% of the labeled data on both datasets. These improvements suggest we can use standard self-supervised learning techniques combined with multiple instance learning in the histopathology domain to improve genomic label classification performance with fewer labeled data.  相似文献   
5.
6.
背景IgA血管炎(IgAV)的长期预后取决于肾脏损伤的程度,有关IgAV肾损害发病机制的研究发现细胞因子在介导、驱动肾脏的损伤过程中发挥了重要作用。目的通过研究IgAV及肾损害患儿血清细胞因子水平变化,探讨细胞因子在IgAV肾损害过程中的意义和价值。方法选取2018年1月至2020年6月于中国医科大学附属盛京医院小儿肾脏内科住院的IgAV患儿194例作为研究对象,根据有无肾脏损害分为IgAV肾损害组(n=97),IgAV组(n=97),选取同时期本院儿童保健科进行体检的健康儿童60例为对照组。收集受试儿童及患儿细胞因子〔白介素(IL)-2、IL-4、IL-6、IL-10、IL-17、干扰素γ(IFN-γ)及肿瘤坏死因子α(TNF-α)〕以及患儿淋巴细胞绝对计数、免疫球蛋白A、免疫球蛋白E。采用多因素Logistic回归分析探讨IgAV肾损害的影响因素,绘制细胞因子对IgAV肾损害诊断价值的受试者工作特征(ROC)曲线。结果lgAV组IL-2水平高于lgAV肾损害组、对照组,且lgAV肾损害组IL-2水平高于对照组(P<0.05);lgAV肾损害组IL-17水平高于lgAV组、对照组,lgAV组IL-17水平高于对照组(P<0.05);lgAV组IL-6、IL-10和TNF-α水平高于lgAV肾损害组和对照组(P<0.05);lgAV肾损害组和对照组IFN-γ水平高于lgAV组(P<0.05)。多因素Logistic回归分析结果显示,IL-2、IL-17、IFN-γ、TNF-α是IgAV肾损害发生的影响因素(P<0.05)。IL-2预测IgAV肾损害的ROC曲线下面积(AUC)为0.589,灵敏度为38.0%,特异度为47.0%;IL-17预测IgAV肾损害的AUC为0.621,灵敏度为47.4%,特异度为77.3%;IFN-γ预测IgAV肾损害的AUC为0.688,灵敏度为75.0%,特异度为55.7%;TNF-α预测IgAV肾损害的AUC为0.614,灵敏度为42.0%,特异度为37.0%;IL-17和IFN-γ联合预测IgAV肾损害的AUC为0.710,灵敏度为71.1%,特异度为66.0%。结论细胞因子IL-17、IFN-γ与IgAV肾损害的发生密切相关,早期检测两者水平并动态监测其变化,可对肾脏受累的早期发现及调整治疗方案起到预警作用。  相似文献   
7.
目的分析急性心肌梗死患者在经皮冠状动脉介入治疗(PCI)术中应用全剂量替罗非班的临床效果。方法84例接受PCI术治疗的急性心肌梗死患者,依据随机数字表法分为试验组与对照组,各42例。对照组患者PCI术中配合半剂量替罗非班治疗;试验组患者PCI术中配合全剂量替罗非班治疗。对比两组心功能改善情况、心血管不良事件发生率、心肌梗死溶栓试验(TIMI)血流分级。结果治疗后,试验组的左室舒张末期内径(LVEDD)(50.98±4.23)mm短于对照组的(58.01±4.88)mm,左室射血分数(LVEF)(58.41±3.28)%高于对照组的(53.00±3.19)%,差异有统计学意义(P<0.05)。两组心血管不良事件发生率比较,差异无统计学意义(P>0.05)。试验组TIMI血流分级3级占比高于对照组,差异有统计学意义(P<0.05);两组血流分级2级、1级、0级占比比较,差异无统计学意义(P>0.05)。结论急性心肌梗死患者PCI术治疗时配合应用全剂量替罗非班能够更好的促进患者术后心功能恢复,且并不会增加治疗期间的不良事件发生率,值得在临床上推广使用。  相似文献   
8.
Transient stress hyperglycemia in the setting of acute myocardial infarction is a frequent phenomenon. Its transient nature should not dissuade the clinician from management of elevated blood glucose in a patient after an ST-elevation myocardial infarction. This case presents an adult patient after an ST-elevation myocardial infarction with transient stress hyperglycemia and the evidence used to identify optimal pharmacologic management and secondary prevention.  相似文献   
9.
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   
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