全文获取类型
收费全文 | 99837篇 |
免费 | 7260篇 |
国内免费 | 2414篇 |
专业分类
耳鼻咽喉 | 829篇 |
儿科学 | 1462篇 |
妇产科学 | 1124篇 |
基础医学 | 9014篇 |
口腔科学 | 1430篇 |
临床医学 | 11302篇 |
内科学 | 9964篇 |
皮肤病学 | 880篇 |
神经病学 | 10411篇 |
特种医学 | 2844篇 |
外国民族医学 | 2篇 |
外科学 | 7260篇 |
综合类 | 15254篇 |
现状与发展 | 6篇 |
一般理论 | 3篇 |
预防医学 | 15722篇 |
眼科学 | 1122篇 |
药学 | 12310篇 |
127篇 | |
中国医学 | 4737篇 |
肿瘤学 | 3708篇 |
出版年
2024年 | 246篇 |
2023年 | 1723篇 |
2022年 | 3052篇 |
2021年 | 4350篇 |
2020年 | 4244篇 |
2019年 | 3521篇 |
2018年 | 3348篇 |
2017年 | 3237篇 |
2016年 | 3328篇 |
2015年 | 3218篇 |
2014年 | 7374篇 |
2013年 | 7161篇 |
2012年 | 6594篇 |
2011年 | 7058篇 |
2010年 | 5332篇 |
2009年 | 5132篇 |
2008年 | 5175篇 |
2007年 | 4932篇 |
2006年 | 4253篇 |
2005年 | 3540篇 |
2004年 | 2882篇 |
2003年 | 2458篇 |
2002年 | 1880篇 |
2001年 | 1614篇 |
2000年 | 1389篇 |
1999年 | 1178篇 |
1998年 | 1075篇 |
1997年 | 1061篇 |
1996年 | 879篇 |
1995年 | 825篇 |
1994年 | 781篇 |
1993年 | 675篇 |
1992年 | 624篇 |
1991年 | 599篇 |
1990年 | 485篇 |
1989年 | 412篇 |
1988年 | 434篇 |
1987年 | 397篇 |
1986年 | 364篇 |
1985年 | 516篇 |
1984年 | 425篇 |
1983年 | 256篇 |
1982年 | 287篇 |
1981年 | 263篇 |
1980年 | 236篇 |
1979年 | 153篇 |
1978年 | 136篇 |
1977年 | 124篇 |
1976年 | 90篇 |
1974年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
《Diagnostic and interventional imaging》2020,101(12):821-830
PurposeTo compare morphological imaging features and CT texture histogram parameters between grade 3 pancreatic neuroendocrine tumors (G3-NET) and neuroendocrine carcinomas (NEC).Materials and methodsPatients with pathologically proven G3-NET and NEC, according to the 2017 World Health Organization classification who had CT and MRI examinations between 2006-2017 were retrospectively included. CT and MRI examinations were reviewed by two radiologists in consensus and analyzed with respect to tumor size, enhancement patterns, hemorrhagic content, liver metastases and lymphadenopathies. Texture histogram analysis of tumors was performed on arterial and portal phase CT images. images. Morphological imaging features and CT texture histogram parameters of G3-NETs and NECs were compared.ResultsThirty-seven patients (21 men, 16 women; mean age, 56 ± 13 [SD] years [range: 28-82 years]) with 37 tumors (mean diameter, 60 ± 46 [SD] mm) were included (CT available for all, MRI for 16/37, 43%). Twenty-three patients (23/37; 62%) had NEC and 14 patients (14/37; 38%) had G3-NET. NECs were larger than G3-NETs (mean, 70 ± 51 [SD] mm [range: 18 - 196 mm] vs. 42 ± 24 [SD] mm [range: 8 - 94 mm], respectively; P = 0.039), with more tumor necrosis (75% vs. 33%, respectively; P = 0.030) and lower attenuation on precontrast (30 ± 4 [SD] HU [range: 25-39 HU] vs. 37 ± 6 [SD] [range: 25-45 HU], respectively; P = 0.002) and on portal venous phase CT images (75 ± 18 [SD] HU [range: 43 - 108 HU] vs. 92 ± 19 [SD] HU [range: 46 - 117 HU], respectively; P = 0.014). Hemorrhagic content on MRI was only observed in NEC (P = 0.007). The mean ADC value was lower in NEC ([1.1 ± 0.1 (SD)] × 10−3 mm2/s [range: (0.91 - 1.3) × 10−3 mm2/s] vs. [1.4 ± 0.2 (SD)] × 10−3 mm2/s [range: (1.1 - 1.6) × 10−3 mm2/s]; P = 0.005). CT histogram analysis showed that NEC were more heterogeneous on portal venous phase images (Entropy-0: 4.7 ± 0.2 [SD] [range: 4.2-5.1] vs. 4.5 ± 0.4 [SD] [range: 3.7-4.9]; P = 0.023).ConclusionPancreatic NECs are larger, more frequently hypoattenuating and more heterogeneous with hemorrhagic content than G3-NET on CT and MRI. 相似文献
32.
《Diagnostic and interventional imaging》2020,101(9):555-564
PurposeThe purpose of this study was to determine whether computed tomography (CT)-based machine learning of radiomics features could help distinguish autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC).Materials and MethodsEighty-nine patients with AIP (65 men, 24 women; mean age, 59.7 ± 13.9 [SD] years; range: 21–83 years) and 93 patients with PDAC (68 men, 25 women; mean age, 60.1 ± 12.3 [SD] years; range: 36–86 years) were retrospectively included. All patients had dedicated dual-phase pancreatic protocol CT between 2004 and 2018. Thin-slice images (0.75/0.5 mm thickness/increment) were compared with thick-slices images (3 or 5 mm thickness/increment). Pancreatic regions involved by PDAC or AIP (areas of enlargement, altered enhancement, effacement of pancreatic duct) as well as uninvolved parenchyma were segmented as three-dimensional volumes. Four hundred and thirty-one radiomics features were extracted and a random forest was used to distinguish AIP from PDAC. CT data of 60 AIP and 60 PDAC patients were used for training and those of 29 AIP and 33 PDAC independent patients were used for testing.ResultsThe pancreas was diffusely involved in 37 (37/89; 41.6%) patients with AIP and not diffusely in 52 (52/89; 58.4%) patients. Using machine learning, 95.2% (59/62; 95% confidence interval [CI]: 89.8–100%), 83.9% (52:67; 95% CI: 74.7–93.0%) and 77.4% (48/62; 95% CI: 67.0–87.8%) of the 62 test patients were correctly classified as either having PDAC or AIP with thin-slice venous phase, thin-slice arterial phase, and thick-slice venous phase CT, respectively. Three of the 29 patients with AIP (3/29; 10.3%) were incorrectly classified as having PDAC but all 33 patients with PDAC (33/33; 100%) were correctly classified with thin-slice venous phase with 89.7% sensitivity (26/29; 95% CI: 78.6–100%) and 100% specificity (33/33; 95% CI: 93–100%) for the diagnosis of AIP, 95.2% accuracy (59/62; 95% CI: 89.8–100%) and area under the curve of 0.975 (95% CI: 0.936–1.0).ConclusionsRadiomic features help differentiate AIP from PDAC with an overall accuracy of 95.2%. 相似文献
33.
目的研究和开发支持中医和现代生物医学本体和术语集的语义标注系统。方法以MedPortal本体库和中医临床术语集等为术语资源库,设计语义标注系统工作流程和功能框架,并开发Web应用系统。结果构建了一个基于Web的中医药文献语义标注系统,支持语料库管理与维护、术语词典管理、语义标注和语义检索等功能,既可以为基于机器学习的信息抽取算法研究提供训练集,又能实现语义层面的多来源数据集成与知识融合。结论该中医药文献语义标注系统设计方案已经过实际项目验证,可为其他同类系统研发提供参考。 相似文献
34.
Rishad R. Jivani Gaurang J. Lakhtaria Dhaval D. Patadiya Laxman D. Patel Nurrudin P. Jivani Bhagyesh P. Jhala 《Saudi Pharmaceutical Journal》2016,24(1):1-20
Advancement in microelectromechanical system has facilitated the microfabrication of polymeric substrates and the development of the novel class of controlled drug delivery devices. These vehicles have specifically tailored three dimensional physical and chemical features which together, provide the capacity to target cell, stimulate unidirectional controlled release of therapeutics and augment permeation across the barriers. Apart from drug delivery devices microfabrication technology’s offer exciting prospects to generate biomimetic gastrointestinal tract models. BioMEMS are capable of analysing biochemical liquid sample like solution of metabolites, macromolecules, proteins, nucleic acid, cells and viruses. This review summarized multidisciplinary application of biomedical microelectromechanical systems in drug delivery and its potential in analytical procedures. 相似文献
35.
目的 分析社区"5+1"糖尿病分阶段达标管理对2型糖尿病患者生存质量的干预效果及其影响因素,为提高患者生存质量提供依据。方法 采用分层整群抽样的方法在山西省、江苏省和宁夏回族自治区选择12个社区卫生服务中心,分别作为干预组(管理方式:社区"5+1"糖尿病分阶段达标管理)、对照组[管理方式:依据《国家基本公共卫生服务规范(2011年版)》的相关要求],进行为期2年的随访观察。采用面对面问卷调查的方式,收集患者的人口学信息等基本信息;采用健康调查简表(SF-36)对患者在干预前后测量生存质量。采用SAS 9.4软件进行双重差分法以及多重线性回归模型分析。结果 基线时共纳入2 467名研究对象,终末时共1 924人接受了为期2年完整的随访管理。干预后,干预组、对照组患者生理健康维度(PCS)、心理健康维度(MCS)评分变化净差值分别为13.6分、29.8分。多重线性回归分析结果显示,影响患者PCS得分的主要因素有年龄、医保类型、基线PCS得分以及所在地区,影响患者MCS得分的主要因素有年龄、医保类型、基线MCS得分、是否合并高血压以及所在地区。结论 社区"5+1"糖尿病分阶段达标管理对2型糖尿病患者生存质量的干预效果较好。 相似文献
36.
[目的] 系统评价八段锦治疗神经根型颈椎病的临床疗效。[方法] 计算机检索中国知网数据库(CNKI)、维普资讯中文科技期刊数据库(VIP)、万方数据库(Wan-fang)、中国生物医学文献数据库(SinoMed)、Web of science、Clinical Trials gov、Pubmed、EMBASE、CENTRAL、Cochrane Library,查找出八段锦治疗神经根型颈椎病的随机对照试验(RCT),检索时限均从建库至2019年7月1日。两名研究者按照纳入与排除标准独立进行文献筛选、资料提取和偏倚风险评估,应用RevMan 5.3软件对最后纳入的研究进行Meta分析。[结果] 最终纳入10个RCT,共843例患者。Meta分析结果显示:八段锦+常规治疗与常规治疗比较,其临床疗效的总有效率差异具有统计学意义[OR=4.19,95% CI(2.42,7.26),P<0.000 01];八段锦+常规治疗与常规治疗+颈部“米”字操比较,其临床疗效的总有效率差异具有统计学意义[OR=3.41,95% CI(1.56,7.46),P=0.002];八段锦+常规治疗与常规治疗比较,其疼痛视觉模拟评分法(VAS)评分差异具有统计学意义[MD=-1.90,95% CI(-1.97,-1.83),P<0.000 01]。[结论] 基于现有的研究,该系统评价显示,与常规治疗相比,八段锦+常规治疗在临床疗效总有效率、VAS评分方面有一定的治疗优势。与常规治疗+颈部“米”字操比较,八段锦+常规治疗在临床疗效的总有效率方面有一定的治疗优势。但由于纳入研究的质量不高,仍需要大样本、多中心、随机、双盲试验及试验参照CONSORT标准和STRICTA声明进行RCT研究。 相似文献
37.
目的探究卡马西平与左乙拉西坦治疗成人癫痫的效果及对认知功能、骨密度的影响。方法92例成人癫痫患者作为研究对象,随机分为左乙拉西坦组与卡马西平组,各46例。左乙拉西坦组采用左乙拉西坦治疗,卡马西平组采用卡马西平治疗。比较两组患者治疗前及治疗6个月后认知功能[语言智商(VIQ)、操作智商(PIQ)、总智商(FIQ)]评分、骨密度(腰椎、股骨大转子、股骨颈)变化情况。结果治疗6个月后,两组患者VIQ、PIQ、FIQ评分均较治疗前显著提升,且左乙拉西坦组患者VIQ评分(101.2±3.1)分、PIQ评分(108.1±2.3)分、FIQ评分(105.2±1.8)分均明显高于卡马西平组的(95.1±2.8)、(94.1±2.0)、(93.5±1.6)分,差异有统计学意义(P<0.05)。治疗6个月后,卡马西平组患者腰椎、股骨大转子、股骨颈骨密度均较治疗前显著下降,且明显低于卡马西平组,差异有统计学意义(P<0.05);左乙拉西坦组治疗6个月后腰椎、股骨大转子、股骨颈骨密度与治疗前比较差异无统计学意义(P>0.05)。结论左乙拉西坦与卡马西平治疗成人癫痫,左乙拉西坦更能明显提升患者认知功能,且对患者骨密度无影响。 相似文献
38.
Alexandra Katsimardou Konstantinos Imprialos Konstantinos Stavropoulos Alexandros Sachinidis Michalis Doumas 《Expert opinion on pharmacotherapy》2020,21(10):1241-1252
ABSTRACT
Introduction
Type 1 diabetes mellitus (T1DM) is a chronic, autoimmune disease that is characterized by total absence of insulin production. Hypertension is a common comorbidity in T1DM with complex pathophysiology, while it is also a well-recognized risk factor for the development of cardiovascular disease (CVD), as well as other microvascular diabetic complications. 相似文献39.
目的:分析临床检验不合格血液标本的原因为何,研究相应的质量改进方法。方法:本课题自我院检验血液标本样本中抽取140份,其中2018年2月~2019年3月的70份命名成对照组,2019年4月~2020年3月的70份命名成试验组,前一组未进行质量改进,后一组进行质量改进,比较检验结果有何不同。结果:试验组这组的检验标本不合格率要比对照组那组的检验标本不合格率低,数据上是P<0.05的情况,即表明有统计学意义。结论:凝血反应、溶血反应、样本问题、送检失误、抗凝不全等是导致临床检验不合格血液标本的原因所在,实施质量改进可将血液标本质量提高。 相似文献
40.
Glaucoma, an irreversible blinding condition affecting 3–4% adults aged above 40 years worldwide, is set to increase with a rapidly aging global population. Raised intraocular pressure (IOP) is a major risk factor for glaucoma where the treatment paradigm is focused on managing IOP using medications, laser, or surgery regimens. However, notwithstanding IOP and other clinical parameters, patient-reported outcomes, including daily functioning, emotional well-being, symptoms, mobility, and social life, remain the foremost concerns for people being treated for glaucoma. These outcomes are measured using objective patient-centered outcome measures (PCOMs) and subjective patient-reported outcome measures (PROMs). Studies using PCOMs have shown that people with glaucoma have several mobility, navigational and coordination challenges; reading and face recognition deficits; and are slower in adapting to multiple real-world situations when compared to healthy controls. Similarly, studies have consistently demonstrated, using PROMs, that glaucoma substantially and negatively impacts on peoples’ self-reported visual functioning, mobility, independence, emotional well-being, self-image, and confidence in healthcare, compared to healthy individuals, particularly in those with late-stage disease undergoing a heavy treatment regimen. The patient-centred effectiveness of current glaucoma treatment paradigms is equivocal due to a lack of well-designed randomized controlled trials; short post-treatment follow-up periods; an inappropriate selection or availability of PROMs; and/or an insensitivity of currently available PROMs to monitor changes especially in patients with newly diagnosed early-stage glaucoma. We provide a comprehensive, albeit non-systematic, critique of the psychometric properties, limitations, and recent advances of currently available glaucoma-specific PCOMs and PROMs. Finally, we propose that item banking and computerized adaptive testing methods can address the multiple limitations of paper-pencil PROMs; customize their administration; and have the potential to improve healthcare outcomes for people with glaucoma. 相似文献