全文获取类型
收费全文 | 54628篇 |
免费 | 4092篇 |
国内免费 | 1175篇 |
专业分类
耳鼻咽喉 | 392篇 |
儿科学 | 991篇 |
妇产科学 | 1434篇 |
基础医学 | 5903篇 |
口腔科学 | 975篇 |
临床医学 | 6164篇 |
内科学 | 7657篇 |
皮肤病学 | 385篇 |
神经病学 | 2411篇 |
特种医学 | 2141篇 |
外国民族医学 | 11篇 |
外科学 | 3965篇 |
综合类 | 8257篇 |
预防医学 | 8070篇 |
眼科学 | 486篇 |
药学 | 6206篇 |
112篇 | |
中国医学 | 1985篇 |
肿瘤学 | 2350篇 |
出版年
2023年 | 784篇 |
2022年 | 1150篇 |
2021年 | 2098篇 |
2020年 | 2208篇 |
2019年 | 1707篇 |
2018年 | 1666篇 |
2017年 | 1786篇 |
2016年 | 1825篇 |
2015年 | 1810篇 |
2014年 | 3715篇 |
2013年 | 3798篇 |
2012年 | 3457篇 |
2011年 | 3745篇 |
2010年 | 2805篇 |
2009年 | 2622篇 |
2008年 | 2594篇 |
2007年 | 2646篇 |
2006年 | 2165篇 |
2005年 | 1957篇 |
2004年 | 1684篇 |
2003年 | 1420篇 |
2002年 | 1266篇 |
2001年 | 1093篇 |
2000年 | 920篇 |
1999年 | 841篇 |
1998年 | 670篇 |
1997年 | 668篇 |
1996年 | 624篇 |
1995年 | 590篇 |
1994年 | 588篇 |
1993年 | 430篇 |
1992年 | 470篇 |
1991年 | 423篇 |
1990年 | 357篇 |
1989年 | 334篇 |
1988年 | 309篇 |
1987年 | 264篇 |
1986年 | 221篇 |
1985年 | 316篇 |
1984年 | 272篇 |
1983年 | 181篇 |
1982年 | 218篇 |
1981年 | 189篇 |
1980年 | 173篇 |
1979年 | 143篇 |
1978年 | 103篇 |
1977年 | 94篇 |
1976年 | 93篇 |
1975年 | 93篇 |
1974年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
1.
Mathew Vithayathil Scott Smith Mingyang Song 《International journal of cancer. Journal international du cancer》2023,152(6):1085-1094
Serrated polyps (SPs) are precursors to one-third of colorectal cancers (CRCs), with histological subtypes: hyperplastic polyps (HPs), sessile serrated lesions (SSLs) and traditional serrated adenomas (TSAs). The incidence of early-onset CRC before the age of 50 is increasing, with limited understanding of SPs in younger cohorts. Using a large colonoscopy-based cohort, we characterized epidemiologic profiles of SP subtypes, compared to conventional adenomas, with secondary analysis on early-onset polyps. Ninety-four thousand four hundred and twenty-seven patients underwent screening colonoscopies between 2010 and 2018. Demographic, endoscopic and histopathologic characteristics of each polyp subtype were described. High-risk polyps included SSLs ≥10 mm/with dysplasia and conventional adenomas ≥10 mm/with tubulovillous/villous histology/high-grade dysplasia. We examined polyp prevalence with age and compared early- (age < 50) and late-onset polyps (age ≥ 50). Eighteen thousand one hundred and twenty-five patients had SPs (4357 SSLs, 15 415 HPs, 120 TSAs) and 26 699 had conventional adenomas. High-risk SSLs were enriched in the ascending colon (44.1% vs 2.6-35.8% for other locations; P < .003). Early- and late-onset SPs had similar subsite distribution. Early-onset conventional adenomas were more enriched in the distal colon/rectum (51.8% vs 43.4%, P < .001). Multiple conventional adenomas were more represented in late-onset groups (40.8% vs 33.8%, P < .001), with no difference in SSLs. The prevalence of conventional adenomas/high-risk conventional adenomas increased continuously with age, whereas the prevalence of SSLs/high-risk SSLs was stable from age 40 years onwards. A higher proportion of women were diagnosed with early-onset than late-onset SSLs (62.9% vs 57.6%, P = .03). Conventional adenomas, SSLs, early- and late-onset polyps have distinct epidemiology. The findings have implications for improved colonoscopy screening and surveillance and understanding the etiologic heterogeneity of CRC. 相似文献
2.
《Archivos de bronconeumología》2022,58(5):406-411
IntroductionLung cancer (LC) is usually diagnosed at advanced stages with only a 12% 5-year survival. Trials as NLST and NELSON show a mortality decrease, which justifies implementation of lung cancer screening in risk population. Our objective was to show survival results of the largest LC screening program in Spain with low dosage computed tomography (LDCT).MethodsClinical records from International Early Lung Cancer Detection Program (IELCAP) at Valencia, Spain were analysed. This program recruited volunteers, ever-smokers aged 40-80 years, since 2008. Results are compared to those from other similar sizeable programs.ResultsA total of 8278 participants were screened with at least two-rounds until November 2020. A mean of 6 annual screening rounds were performed. We detected 239 tumours along 12-year follow-up. Adenocarcinoma was the most common histology, being 61.3% at stage I. The lung cancer prevalence and incidence proportion was 1.5% and 1.4%, respectively with an annual detection rate of 0.17. One-year survival and 10-year survival were 90% and 80.1%, respectively. Adherence was 96.84%.ConclusionLargest lung cancer screening in Spain shows that survival is improved when is performed in multidisciplinary team experienced in management of LC, and is comparable to similar screening programs. 相似文献
3.
《Vaccine》2022,40(18):2525-2527
4.
《The Journal of thoracic and cardiovascular surgery》2023,165(1):94-103.e24
ObjectiveNew-onset postoperative atrial fibrillation (POAF) after cardiac surgery is common, with rates up to 60%. POAF has been associated with early and late stroke, but its association with other cardiovascular outcomes is less known. The objective was to perform a meta-analysis of the studies reporting the association of POAF with perioperative and long-term outcomes in patients with cardiac surgery.MethodsWe performed a systematic review and a meta-analysis of studies that presented outcomes for cardiac surgery on the basis of the presence or absence of POAF. MEDLINE, EMBASE, and the Cochrane Library were assessed; 57 studies (246,340 patients) were selected. Perioperative mortality was the primary outcome. Inverse variance method and random model were performed. Leave-one-out analysis, subgroup analyses, and metaregression were conducted.ResultsPOAF was associated with perioperative mortality (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.58-2.33), perioperative stroke (OR, 2.17; 95% CI, 1.90-2.49), perioperative myocardial infarction (OR, 1.28; 95% CI, 1.06-1.54), perioperative acute renal failure (OR, 2.74; 95% CI, 2.42-3.11), hospital (standardized mean difference, 0.80; 95% CI, 0.53-1.07) and intensive care unit stay (standardized mean difference, 0.55; 95% CI, 0.24-0.86), long-term mortality (incidence rate ratio [IRR], 1.54; 95% CI, 1.40-1.69), long-term stroke (IRR, 1.33; 95% CI, 1.21-1.46), and longstanding persistent atrial fibrillation (IRR, 4.73; 95% CI, 3.36-6.66).ConclusionsThe results suggest that POAF after cardiac surgery is associated with an increased occurrence of most short- and long-term cardiovascular adverse events. However, the causality of this association remains to be established. 相似文献
5.
[摘要]?目的?结合环介导等温扩增技术(loop-mediated isothermal amplification, LAMP)和微流控芯片技术,建立一种适合现场快速检测登革病毒的方法。方法?利用RT-LAMP,针对登革病毒基因组中3’非编码区中特异性序列进行扩增,建立基于微流控芯片技术的LAMP检测方法,优化检测体系,并对该方法的灵敏性和特异性进行评估。结果?基于LAMP 和微流控芯片技术的登革病毒检测方法,通过对病毒模板进行扩增,发现与其他病毒无交叉反应,特异性良好;同时,结果显示该方法对登革病毒检测灵敏性可达61.2 pg/μl,与实时荧光定量PCR仪所达到的检测灵敏性一致。结论?基于LAMP和微流控芯片技术的登革病毒检测方法具有操作简单、快速、对设备要求低等优势,并且灵敏性、特异性均较好,是一种便于开展现场快速检测的方法。 相似文献
6.
《Vaccine》2022,40(19):2679-2695
Vaccinations are essential for preventing infectious diseases in children with chronic diseases as they have increased risk of infection from frequent use of biologics. Response to immunizations in this group is not well known.ObjectiveA systematic review was performed to evaluate three primary outcomes: efficacy; immunogenicity; and safety of vaccines in children with chronic conditions treated with biologics.MethodsThe protocol for our systematic review and meta-analysis was registered and published with PROSPERO. We searched electronic bibliographic databases for studies published from 2009 to 2019, focusing on vaccinations in children with chronic conditions treated with biologics.ResultsWe retrieved 532 records. Thirty-one full-text articles were selected, and 14 were included in the meta-analysis. No significant publication bias was found. Efficacy: limited data are available regarding the efficacy of vaccination, as most studies have focused on immunogenicity as surrogate outcome for efficacy. Immunogenicity: patients receiving anti-TNF-alpha therapy had a statistically significant risk of poor seroconversion (p = 0.028) and seroprotection by the serotype B influenza vaccine [inflammatory bowel disease (IBD) p = 0.013; juvenile idiopathic arthritis (JIA) p = 0.004]. We found adequate responses with H1N1 and H3N2 serotypes. Few studies existed for pneumococcal, hepatitis A virus, hepatitis B virus, varicella-zoster virus, Measles Mumps Rubella virus, and multiple vaccine administration. Safety: vaccine administration was not associated with serious side effects, but JIA patients on anti-TNF alpha therapy had a statistically significant risk of presenting with myalgia or arthralgia postinfluenza vaccine (p = 0.014).ConclusionsMore evidence concerning efficacy, immunogenicity, and safety of vaccinations is needed to guide physicians in the vaccine decision process for this pediatric population. 相似文献
7.
8.
9.
目的 分析南京市某国际高中学生艾滋病知识知晓率及其影响因素,为制定高中生艾滋病健康教育策略提供依据。方法 对南京市某国际高中所有学生开展纸质问卷调查,统计分析艾滋病知识知晓率及其影响因素。 共纳入171名高中生为调查对象,艾滋病和梅毒的知识知晓率分别为56.1%和46.8%;有过性行为的占14.6%,其艾滋病知识知晓率最高为32.0%,(χ2=10.799,P=0.005);有吸毒史的学生占9.3%,其艾滋病知识知晓率最高为31.2%,(χ2=21.062,P<0.001);梅毒知识知晓者与不知晓者的艾滋病知识知晓率差异具有统计学意义(χ2=21.716,P<0.001)。 该国际高中学生性病和艾滋病知识知晓率较低,对高中生开展毒品危害教育和性病艾滋病防治应作为健康教育工作重点。 相似文献