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   1993篇
  免费   587篇
  国内免费   137篇
耳鼻咽喉   4篇
儿科学   11篇
妇产科学   7篇
基础医学   206篇
口腔科学   21篇
临床医学   247篇
内科学   150篇
皮肤病学   10篇
神经病学   166篇
特种医学   592篇
外科学   142篇
综合类   329篇
预防医学   422篇
眼科学   22篇
药学   184篇
  3篇
中国医学   97篇
肿瘤学   104篇
  2024年   3篇
  2023年   38篇
  2022年   121篇
  2021年   160篇
  2020年   132篇
  2019年   94篇
  2018年   75篇
  2017年   70篇
  2016年   57篇
  2015年   72篇
  2014年   224篇
  2013年   176篇
  2012年   249篇
  2011年   289篇
  2010年   177篇
  2009年   135篇
  2008年   95篇
  2007年   127篇
  2006年   97篇
  2005年   55篇
  2004年   44篇
  2003年   52篇
  2002年   32篇
  2001年   21篇
  2000年   26篇
  1999年   23篇
  1998年   13篇
  1997年   12篇
  1996年   8篇
  1995年   4篇
  1994年   6篇
  1993年   14篇
  1992年   7篇
  1991年   6篇
  1990年   1篇
  1989年   2篇
排序方式: 共有2717条查询结果,搜索用时 15 毫秒
1.
分析和探讨放射卫生机构在核辐射卫生应急体系中发挥的作用。通过对比发现,核辐射紧急医学救援基地多由取得放射卫生技术服务(甲级)资质或放射性疾病诊断机构资质的单位承担建设任务。放射卫生机构在平时工作中积累的辐射监测、污染检测、剂量估算、健康效应评价等技术能力可在核辐射卫生应急处置中发挥重要作用,实现能力建设的“平急结合”。建议各级放射卫生机构继续发挥自身所长,通过参加放射卫生监测项目的机会提高自身能力,并积极参与放射卫生技术机构检测能力考核,为核辐射卫生应急工作做好人才和技术储备。  相似文献   
2.
王萍  范莉  田梅 《中国辐射卫生》2022,31(4):524-529
皮肤是人体受到电离辐射时最先接触的器官,因其基底细胞层及毛细血管对射线很敏感,所以放射性皮肤损伤十分常见,急性放射性皮肤损伤常与表皮和真皮中的细胞改变和炎症有关,而皮肤的晚期损伤主要与辐射对血管影响有关。放射性皮肤损伤的临床表现为皮肤黏膜出现红斑、干性脱屑、湿性脱屑、溃疡,严重程度与射线种类、剂量等相关。目前,放射性皮肤损伤的潜在发生机制在很大程度上是未知的,辐射损伤后还未建立治疗的金标准,已知的放射性皮肤损伤的发生机制大致可分为3个途径:活性氧大量增加引发的氧化应激损伤、细胞因子被转录激活后引发的炎症、骨髓源性细胞引起的免疫反应。本文综述了放射性皮肤损伤发生机制的3大途径,为进一步研究放射性皮肤损伤的机制以及预防治疗提供参考。  相似文献   
3.
PurposeCerebral microbleeds (CMBs) are considered essential indicators for the diagnosis of cerebrovascular disease and cognitive disorders. Traditionally, CMBs are manually interpreted based on criteria including the shape, diameter, and signal characteristics after an MR examination, such as susceptibility-weighted imaging or gradient echo imaging (GRE). In this paper, an efficient method for CMB detection in GRE scans is presented.Materials and methodsThe proposed framework consists of the following phases: (1) pre-processing (skull extraction), (2) the first training with the ground truth labeled using CMB, (3) the second training with the ground truth labeled with CMB mimicking the same subjects, and (4) post-processing (cerebrospinal fluid (CSF) filtering). The proposed technique was validated on a dataset of 1133 CBMs that consisted of 5284 images for training and 1737 images for testing. We applied a two-stage approach using a region-based CNN method based on You Only Look Once (YOLO) to investigate a novel CMB detection technique.ResultsThe sensitivity, precision, F1-score and false positive per person (FPavg) were evaluated as 80.96, 60.98, 69.57 and 6.57, 59.69, 62.70, 61.16 and 4.5, 66.90, 79.75, 72.76 and 2.15 for YOLO with a single label, YOLO with double labels, and YOLO + CSF filtering, respectively, and YOLO + CSF filtering showed the highest precision performance, F1-score and lowest FPavg.ConclusionsUsing proposed framework, we developed an optimized CMB learning model with low false positives and a balanced performance in clinical practice.  相似文献   
4.
Background and PurposeAcute strokes due to large vessel occlusion in hospitalized patients is not uncommon. We performed a systematic review and meta-analysis to investigate the timing and outcome of endovascular thrombectomy (EVT) for in-hospital stroke.MethodsWe conducted a meta-analysis of clinical studies published in English until September 2020 in the MEDLINE and Cochrane databases. Studies reporting original data on the characteristics and outcomes of in-hospital stroke patients treated with EVT were included. We extracted data on the time-metrics from last known well (LKW) until reperfusion was achieved. We also collected data on procedural and functional outcomes.ResultsOut of 5093 retrieved studies, 8 were included (2,622 patients). The median age was 71.4 years and median NIHSS score on admission was 16. Patients were mostly admitted to the cardiology service (27.3%). The pooled time from LKW to recognition by staff was 72.9 min (95% CI: 40.7 to 105 min). 25.6% received IV tPA. The mean time from stroke recognition to arterial puncture was 134.5 min (95% CI: 94.9 to 174.1). Successful reperfusion occurred in 82.8.% with a pooled mean time from detection to reperfusion of 193.1 min (95% CI: 139.5 to 246.7). The 90-day independent functional outcome was reported in 42% of patients (95% CI 29 to 55%).ConclusionEVT can be performed safely and successfully for in-hospital strokes. Noticeable delays from LKW to detection and then to puncture are noted. This calls for better stroke pathways to identify and treat these patients.BackgroundStroke in hospitalized patients, referred to as in-hospital stroke (IHS), accounts for 2.2–17% of all strokes.1 The majority of these are ischemic while intracranial hemorrhage represents 2–11% of all IHS.1 These patients are expected to have a rapid diagnosis and treatment given the ongoing medical supervision, and therefore favorable outcomes.1–3 However, existing studies report poor outcomes in patients with IHS with a mortality risk that exceeds that of community-onset stroke (COS): 24.7% vs 9.6%.4 Surviving IHS patients are also less likely to be discharged home compared to COS (27.7% vs 49.9%) and to be functionally independent at 3 months (31.0% vs 50.4%).1–4  相似文献   
5.
In this study, we examine the potential for using face imaging sensing technology in place of a human forensic practitioner to estimate the age of cadavers. We used the age estimation software FieldAnalyst for Signage Ver. 6.0 AW32. To validate the usefulness of its age estimation for living subjects, images of 28 subjects were taken at three angles (+30°, 0°, and −30°) with respect to the horizontal plane, with their eyes open and closed. The highest positive correlation between mean the estimated age and the actual age (y = 1.02x − 0.35, and Spearman’s rank correlation coefficient of 0.78, P < 0.001) was obtained when the subjects had their eyes closed and the image was captured at an angle of 0°. The ages of 93% of the subjects were estimated within ±10 years of their actual ages. We then applied this procedure to 61 cadavers with their eyes closed. Facial images were taken at an angle of 0° with respect to the horizontal plane and used to estimate the ages of the cadavers. Although a positive correlation between the actual and mean estimated ages was obtained (y = 1.28x + 0.43, Pearson’s correlation coefficient of 0.69, P < 0.001), the mean estimated ages of only 39.3% of the subjects were within ±10 years of their actual ages. It appears that this technology is not accurate enough to use to determine the age of a cadaver. Therefore, medical inspectors with adequate knowledge and experience are still required for postmortem examination.  相似文献   
6.
BackgroundCardiopulmonary resuscitation (CPR) sometime cause severe injuries and can affect quality of life, lead to long-term disabilities or death of the patient. The aim of this study is to identify the risk factors causing CPR-induced injuries and those of serious injuries.MethodsThis was a retrospective forensic autopsy study in a single institution. Among 885 forensic autopsies undertaken between 2011 and 2018, those in which the victim had undergone CPR immediately after cardiac arrest were recorded. ‘Serious injuries’ were defined as an Abbreviated Injury Scale (AIS) score ≥ 3. CPR-induced injuries were evaluated by three experienced forensic pathologists. With the background and history of the patient, the circumstances of cardiac arrest and risks of causing CPR-induced injuries were determined by multivariate analyses.ResultsSeventy-five victims comprised the study cohort. CPR-induced injuries were found in 52 victims (69.3%). Rib fracture was the most common (60.0%), followed by sternal fracture (37.3%), heart injury (21.3%) and liver injury (8.0%). Multivariate analysis revealed higher age to be an independent factor causing CPR-induced injuries (odds ratio [OR], 1.07, P < 0.001). Thirty-six victims had 39 serious injuries in the chest or abdomen: fracture of ≥ 3 ribs (35 cases), aortic dissection (two), lung contusion (one) and rupture of the heart (one). Multivariate analysis revealed higher age to be an independent factor causing CPR-induced serious injuries (OR, 1.09; P < 0.001).ConclusionAging was the significant factor causing CPR-induced injuries and serious injuries.  相似文献   
7.
目的:通过回顾性数据分析,探讨皮肤T细胞淋巴瘤在中国的发病情况。方法:通过检索公开发表的有关淋巴瘤和皮肤T细胞淋巴瘤的发病情况研究文献,应用聚类分析法对符合纳入标准的文献进行纳入并统计其中皮肤T细胞淋巴瘤的发病率。经过汇总整理与《中国淋巴瘤亚型分布国内多中心性病例10 002例分析》进行对比。结果:本研究共纳入17篇文献,涉及13个省市自治区,共计16 885例患者。分析结果显示,中国皮肤T细胞淋巴瘤从1993年到2017年发病率约为0.69/105,与《中国淋巴瘤亚型分布国内多中心性病例10 002例分析》中的结果一致,与国外文献报道中美国皮肤T细胞淋巴瘤发病率0.64/105也基本一致。结论:皮肤T细胞淋巴瘤在中国和有关国家都是发病率很低的一种恶性肿瘤,属于WHO定义的罕见病。  相似文献   
8.
电离辐射会对人体造成损伤,根据受照剂量、时间等因素的不同可诱发多种生物效应。目前对于低剂量辐射产生的健康效应仍有争议,筛选对低剂量敏感的辐射响应生物标志物,对于完善低剂量辐射生物效应机制、拓宽低剂量辐射在临床中的应用均具有重要理论意义。综述探讨各核糖核酸(RNA)在低剂量辐射反应中的变化及其对辐射敏感性的调节作用,同时评估各RNA作为低剂量辐射响应标志物的潜力。  相似文献   
9.
在辐射防护领域,运行实用量用于估算防护量,是场所剂量监测中的重要量值。随着电离辐射粒子类型和能量范围的扩展,现行运行实用量在估算防护量的过程中出现局限。ICRU第95号报告提出了新的运行实用量体系,在定义方式和模体上与防护量相统一,在更广泛的粒子类型和能量范围中实现了对防护量的更好估算。本文重点关注新运行实用量体系在模体应用、转换系数更新、监测仪器的设计和校准等方面对场所剂量监测的影响。  相似文献   
10.
This study evaluated the genetic variation of 17 autosomal short tandem repeat (STR) loci included in the PowerPlex® 18D Kit. Samples of 562 unrelated healthy Lahu individuals living in Yunnan Province in southwestern China were investigated. The data were analyzed to provide information on allele frequencies and other statistical parameters relevant to the forensic population. Of the 17 loci, 16 reached the Hardy–Weinberg equilibrium after Bonferroni correction. A total of 176 alleles were identified in 17 STR loci, and allele frequencies ranged from 0.000 890 to 0.578 292. The combined discrimination power (CPD) and probability of excluding paternity (CPE) of the 17 STR loci were 0.999 999 999 999 999 999 489 and 0.999 998 301 753 122. The genetic relationships among 28 populations were also estimated.  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