全文获取类型
收费全文 | 177522篇 |
免费 | 13219篇 |
国内免费 | 3430篇 |
专业分类
耳鼻咽喉 | 949篇 |
儿科学 | 2356篇 |
妇产科学 | 3157篇 |
基础医学 | 11723篇 |
口腔科学 | 2807篇 |
临床医学 | 47676篇 |
内科学 | 17012篇 |
皮肤病学 | 1408篇 |
神经病学 | 9124篇 |
特种医学 | 3438篇 |
外国民族医学 | 20篇 |
外科学 | 13247篇 |
综合类 | 26720篇 |
现状与发展 | 4篇 |
一般理论 | 16篇 |
预防医学 | 17791篇 |
眼科学 | 2654篇 |
药学 | 14812篇 |
528篇 | |
中国医学 | 13655篇 |
肿瘤学 | 5074篇 |
出版年
2024年 | 346篇 |
2023年 | 3231篇 |
2022年 | 4113篇 |
2021年 | 6974篇 |
2020年 | 7525篇 |
2019年 | 6456篇 |
2018年 | 5783篇 |
2017年 | 6481篇 |
2016年 | 6713篇 |
2015年 | 6129篇 |
2014年 | 12559篇 |
2013年 | 12731篇 |
2012年 | 11234篇 |
2011年 | 12268篇 |
2010年 | 10313篇 |
2009年 | 8870篇 |
2008年 | 8291篇 |
2007年 | 8456篇 |
2006年 | 7548篇 |
2005年 | 6613篇 |
2004年 | 5230篇 |
2003年 | 4482篇 |
2002年 | 3455篇 |
2001年 | 3198篇 |
2000年 | 2559篇 |
1999年 | 2256篇 |
1998年 | 1943篇 |
1997年 | 1772篇 |
1996年 | 1487篇 |
1995年 | 1407篇 |
1994年 | 1221篇 |
1993年 | 1033篇 |
1992年 | 958篇 |
1991年 | 851篇 |
1990年 | 777篇 |
1989年 | 678篇 |
1988年 | 574篇 |
1987年 | 503篇 |
1986年 | 528篇 |
1985年 | 848篇 |
1984年 | 795篇 |
1983年 | 567篇 |
1982年 | 665篇 |
1981年 | 588篇 |
1980年 | 602篇 |
1979年 | 496篇 |
1978年 | 427篇 |
1977年 | 398篇 |
1976年 | 323篇 |
1975年 | 220篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
Objectives:To reassess the long-term camouflage effects of resin infiltration (Icon, DMG, Hamburg, Germany) of white spot lesions (WSL) and sound adjacent enamel (SAE) achieved in a previous trial. The null hypothesis was tested that there were no significantly different CIE-L*a*b*-ΔE-values between WSL and SAE areas of assessment after at least 24 months (T24) compared to those at baseline (T0).Materials and Methods:Of twenty subjects who received previous resin infiltration treatment of nteeth = 111 nonrestored, noncavitated postorthodontic WSL after multibracket treatment during a randomized controlled trial and were contacted 20 months after baseline, eight subjects (trial teeth nteeth = 40; m/f ratio 1/7; age range (mean; SD) 12–17 [15.25; 2.12] years); response rate: 40%) were available for follow-up after at least 24 months (T24). CIE-L*a*b* differences between summarized color and lightness values (ΔEWSL/SAE) of WSL and SAE were assessed using a spectrophotometer and compared to baseline data assessed prior to infiltration (T0), and those after 6 (T6), and 12 (T12) months using paired t tests at a significance level of α = 5%.Results:T24 assessments were performed after a mean 33.86 (SD: 8.64; Min: 24; Max: 45) months following T0. Mean (SD) ΔEWSL/SAE units of available teeth were 8.76 (5.33) at baseline; 5.5 (2.75) at T6; 5.2 (2.41) at T12; and 5.57 (2.6) at T24. Comparisons of T6, T12, and T24 with T0 yielded highly significant differences, whereas T6–T24 and T12–T24 differences were found to be not significant.Conclusions:Assimilation of infiltrated WSL to the color of adjacent enamel by resin infiltration is considered to be suitable for the long-term improvement in the esthetic appearance of postorthodontic WSL. 相似文献
122.
【摘要】 目的 了解社区中老年人群的血脂、血糖现状水平,探讨其与性别和年龄的关系,为本地区心脑血管疾病、糖尿病等疾病的防治提供诊疗依据。方法 对我市38078名社区居民采集清晨空腹血清标本,检测血糖(GLU)、甘油三酯(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL C)和低密度脂蛋白胆固醇(LDL C)的结果,并对其进行年龄、性别分组统计分析。结果 不同性别和年龄组间的血脂、血糖水平差异有统计学意义(P<005),74~89岁年龄组血脂、血糖总体水平高于其他各年龄组(P<005);女性血脂水平普遍高于男性(P<005)。结论 中老年人群血脂、血糖异常率高,应定期对中老年人进行血脂、血糖监测,开展宣传教育活动,提高自我保健意识,预防高血脂、高血糖的发生和发展。 相似文献
123.
《Health Policy and Technology》2022,11(3):100647
BackgroundUnequal housing access resulted in more than 150 million homeless people worldwide, with millions more expected to be added every year due to the ongoing climate-related crises. Homeless population has a counterproductive effect on the social, psychological integration efforts by the community and exposure to other severe health-related issues. Geographic Information Systems (GIS) have long been applied in urban planning and policy, housing and homelessness, and health-related research.MethodsWe used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method to systematically review 24 articles collected from multiple databases (n = 10) that focused on health-related issues among homeless people and used geospatial analysis techniques in their research.ResultsOur findings indicated a geographic clustering of case study locations– 26 out of the 31 case study sites are from the USA and Canada. Studies used spatial analysis techniques to identify hotspots, clusters and patterns of patient location and population distribution. Studies also reported relationships among the location of homeless shelters and substance use, discarded needles, different infectious and non-infectious disease clusters.ConclusionMost studies were restricted in analyzing and visualizing the patterns and disease clusters; however, geospatial analyses techniques are useful and offer diverse techniques for a more sophisticated understanding of the spatial characteristics of the health issues among homeless people. Better integration of GIS in health research among the homeless would help formulate sensible policies to counter health inequities among this vulnerable population group. 相似文献
124.
《Gait & posture》2022
BackgroundParkinson’s disease (PD) is a chronic and progressive neurodegenerative disease with no cure, presenting a challenging diagnosis and management. However, despite a significant number of criteria and guidelines have been proposed to improve the diagnosis of PD and to determine the PD stage, the gold standard for diagnosis and symptoms monitoring of PD is still mainly based on clinical evaluation, which includes several subjective factors. The use of machine learning (ML) algorithms in spatial-temporal gait parameters is an interesting advance with easy interpretation and objective factors that may assist in PD diagnostic and follow up.Research questionThis article studies ML algorithms for: i) distinguish people with PD vs. matched-healthy individuals; and ii) to discriminate PD stages, based on selected spatial-temporal parameters, including variability and asymmetry.MethodsGait data acquired from 63 people with PD with different levels of PD motor symptoms severity, and 63 matched-control group individuals, during self-selected walking speed, was study in the experiments.ResultsIn the PD diagnosis, a classification accuracy of 84.6 %, with a precision of 0.923 and a recall of 0.800, was achieved by the Naïve Bayes algorithm. We found four significant gait features in PD diagnosis: step length, velocity and width, and step width variability. As to the PD stage identification, the Random Forest outperformed the other studied ML algorithms, by reaching an Area Under the ROC curve of 0.786. We found two relevant gait features in identifying the PD stage: stride width variability and step double support time variability.SignificanceThe results showed that the studied ML algorithms have potential both to PD diagnosis and stage identification by analysing gait parameters. 相似文献
125.
126.
127.
128.
目的探讨不同剂量骨水泥PKP联合雌激素对绝经后女性骨质疏松性腰椎体压缩性骨折患者的影响。方法选取2015年1月至2018年6月我院收治的120例老年女性骨质疏松性腰椎体压缩性骨折患者为研究对象,按行PKP手术治疗时骨水泥注入的剂量不同分为三组(A组2-4 mL、B组4-5 mL、C组5-6 mL),所有患者均随访1年,比较术后三组患者VAS评分、ODI评分、伤椎椎体前缘高度、椎体中部高度及并发症的发生率。结果三组患者相比,治疗前VAS评分、ODI评分组间比较差异无显著性(P0.05);术后3天及1年后随访时,三组患者各项指标均较治疗前显著改善,组内比较差异具有显著性(P0.05),组间比较差异无显著性(P0.05);治疗前伤椎椎体前缘高度及椎体中部高度组间比较差异无显著性(P0.05);术后3天及1年后随访时,三组患者治疗后椎体前缘、中间高度均较术前明显增加(P0.05),组间比较椎体前缘高度:C组B组A组,椎体中间高度:C组B组A组,且组间比较有统计学差异(P0.05); A组患者并发症的发生率(12.5%)明显低于B组(30.0%)、C组(41.0%),有统计学差异(P0.05)。结论 PKP术中注入小剂量骨水泥(2-4 mL)对于治疗老年女性OVCFs具有良好的治疗效果及较高的安全性。 相似文献
129.
130.
《The Journal of thoracic and cardiovascular surgery》2023,165(1):149-158.e4
BackgroundCoronary artery bypass grafting (CABG) improves survival in patients with heart failure and severely reduced left ventricular systolic function (LVEF). Limited data exist regarding adverse cardiovascular event rates after CABG in patients with heart failure with midrange ejection fraction (HFmrEF; LVEF > 40% and < 55%).MethodsWe analyzed data on isolated CABG patients from the Veterans Affairs national database (2010-2019). We stratified patients into control (normal LVEF and no heart failure), HFmrEF, and heart failure with reduced LVEF (HFrEF) groups. We compared all-cause mortality and heart failure hospitalization rates between groups with a Cox model and recurrent events analysis, respectively.ResultsIn 6533 veterans, HFmrEF and HFrEF was present in 1715 (26.3%) and 566 (8.6%) respectively; the control group had 4252 (65.1%) patients. HFrEF patients were more likely to have diabetes mellitus (59%), insulin therapy (36%), and previous myocardial infarction (31%). Anemia was more prevalent in patients with HFrEF (49%) as was a lower serum albumin (mean, 3.6 mg/dL). Compared with the control group, a higher risk of death was observed in the HFmrEF (hazard ratio [HR], 1.3 [1.2-1.5)] and HFrEF (HR, 1.5 [1.2-1.7]) groups. HFmrEF patients had the higher risk of myocardial infarction (subdistribution HR, 1.2 [1-1.6]; P = .04). Risk of heart failure hospitalization was higher in patients with HFmrEF (HR, 4.1 [3.5-4.7]) and patients with HFrEF (HR, 7.2 [6.2-8.5]).ConclusionsHeart failure with midrange ejection fraction negatively affects survival after CABG. These patients also experience higher rates myocardial infarction and heart failure hospitalization. 相似文献