全文获取类型
收费全文 | 706篇 |
免费 | 96篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 9篇 |
妇产科学 | 3篇 |
基础医学 | 79篇 |
口腔科学 | 8篇 |
临床医学 | 25篇 |
内科学 | 89篇 |
皮肤病学 | 16篇 |
神经病学 | 89篇 |
特种医学 | 13篇 |
外科学 | 35篇 |
综合类 | 78篇 |
预防医学 | 250篇 |
眼科学 | 5篇 |
药学 | 51篇 |
中国医学 | 9篇 |
肿瘤学 | 56篇 |
出版年
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 26篇 |
2020年 | 31篇 |
2019年 | 41篇 |
2018年 | 34篇 |
2017年 | 32篇 |
2016年 | 33篇 |
2015年 | 37篇 |
2014年 | 41篇 |
2013年 | 53篇 |
2012年 | 43篇 |
2011年 | 57篇 |
2010年 | 42篇 |
2009年 | 34篇 |
2008年 | 41篇 |
2007年 | 31篇 |
2006年 | 29篇 |
2005年 | 26篇 |
2004年 | 24篇 |
2003年 | 23篇 |
2002年 | 19篇 |
2001年 | 21篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有818条查询结果,搜索用时 18 毫秒
1.
【目的】探究大气污染与脑卒中急性期死亡的关联性,以及大气污染环境中脑卒中急性期死亡的易感人群情况。【方法】汇总上海市松江区2012—2014年大气污染数据,并收集户籍人口脑卒中急性期死亡的全部病例,采用时间分层-病例交叉设计方法分析两者间关系,并确立易感人群。【结果】共纳入了514例脑卒中急性期死亡病例。研究期间内,PM2.5、SO2、NO2等污染物质量浓度分别为77.45、21.22、57.59μg·m-3。NO2显著增加了<65岁人群的脑卒中急性期死亡的发病风险。在Lag2和Lag03的时间点上,NO2的质量浓度上升1个四分位数间距导致脑卒中急性期死亡的OR值分别为3.86(1.53~9.75)和5.83(1.40~24.34)。65岁以上人群则对PM2.5质量浓度增加更加敏感。在Lag03的时间点上其导致脑卒中急性期死亡的OR值为1.28(1.00~1.64)。NO2质量浓度的增加还显著增大了超重及肥胖人群的致死性脑卒中的发病风险。【结论】PM2.5、NO2等污染物质量浓度的上升可以显著增加敏感人群的脑卒中急性期死亡的发病风险。65岁以下及超重肥胖人群是NO2导致的脑卒中急性期死亡的易感人群,65岁以上人群是SO2导致的脑卒中急性期死亡的易感人群。 相似文献
2.
目的:应用条件性重编程细胞(conditionally reprogrammed cells,CRCs)技术建立人肺癌细胞体外长期培养体系,研究扁塑藤素对人肺癌CRCs增殖和迁移能力的影响,并探讨相关作用机制。方法:免疫组化法检测Notch 1、HES1和Cyclin D3在肿瘤组织和癌旁组织中的表达水平;使用CRCs技术分离培养非小细胞肺癌原代细胞;使用2,4,8,16 μmol·L-1的扁塑藤素处理人肺癌CRCs,MTS法检测细胞活力,Annexin V/PI流式细胞术检测细胞凋亡,Transwell法检测细胞迁移能力,Western Blot检测细胞中Notch信号通路相关蛋白Notch 1、HES1和Cyclin D3的表达水平。结果:在非小细胞肺癌患者肿瘤组织中Notch 1、HES1和Cyclin D3的表达水平高于癌旁组织;扁塑藤素能够诱导人肺癌CRCs死亡,并在一定范围内呈现时间和浓度依赖性(P<0.05);随着扁塑藤素作用浓度的增高,人肺癌CRCs凋亡率明显增高(P<0.05),细胞迁移能力下降(P<0.05);扁塑藤素能够下调人肺癌CRCs中Notch 1、HES1和Cyclin D3的蛋白表达水平。结论:扁塑藤素可能通过调控Notch信号通路相关蛋白的表达水平,抑制人肺癌CRCs的增殖和迁移,并诱导其凋亡,为肺癌的治疗提供新的实验数据和理论依据。 相似文献
3.
Ignacio Ramos-Vidal Jorge Palacio Elsy Domínguez de la Ossa Ingrid Wehdking 《Journal of community psychology》2022,50(1):553-575
The Program for Psychosocial Care and Comprehensive Health for Victims serves, on a yearly basis, an average of 25,000 users in northern Colombia alone. The program is implemented by multidisciplinary teams comprised of psychologists, social workers, and community facilitators, who step in at the individual, family, and community levels. An attempt has been made to determine the effect generated by the timeframe through which professionals have been engaged with the program-filling positions of centrality and betweenness within the networks of information exchange and user referral, including the potential mediating effect from the structure of the egocentric network of implementers in the two aforementioned networks and the moderating effect of the sense of belonging to a team of professionals. Both centrality and betweenness are positional measures describing the location actors occupied within the network structure. Centrality reflects the nominations made and receipt by an actor in a network and is considered an individual indicator of prominence and power. Betweenness shows the times that an actor act as a bridge among two actors in a network and it is considered an indicator of strategic positioning in social networks. An egocentric network is the local structure of relationships that each implementer maintains with his or her direct contacts. In this study, 112 active implementers were included, mostly women (n = 97, 88.2%), who had been working on the program for 16.9 months on average (SD = 14.7). Through conditional process analysis, it has been shown that the time that the implementers have been working on the program and the sense of belonging to the task team are relevant factors that interact with each other toward explaining the level of centrality and betweenness of professionals in the information exchange and user referral networks. 相似文献
4.
肝脏计算机断层扫描成像(CT)的三维(3D)肝脏和肿瘤分割对于辅助医生的诊断及预后具有非常重要的临床价值。为了准确快速地分割肝脏及肿瘤区域,本文提出了一种基于条件生成对抗网络(cGAN)的肿瘤3D条件生成对抗分割网络(T3scGAN),同时采用了一个由粗到细的3D自动分割框架对肝脏及肿瘤区域实施精准分割。本文采用2017年肝脏和肿瘤分割挑战赛(LiTS)公开数据集中的130个病例进行训练、验证和测试T3scGAN模型。最终3D肝脏区域分割的验证集和测试集的平均戴斯(Dice)系数分别为0.963和0.961,而3D肿瘤区域分割的验证集和测试集的平均Dice系数分别为0.819和0.796。实验结果表明,提出的T3scGAN模型能够有效地分割3D肝脏及其肿瘤区域,因此能够更好地辅助医生进行肝脏肿瘤的精准诊断和治疗。 相似文献
5.
Comparing estimation approaches for the illness–death model under left truncation and right censoring 下载免费PDF全文
Left‐truncated data arise when lifetimes are observed only if they are larger than independent truncation times. For example, in a cross‐sectional sampling, only individuals who live long enough to be present on the sampling day are observed. There are several ways to perform statistical inference under this setting. One can do the following: (i) use an unconditional approach, (ii) condition on the value of the truncation variable, or (iii) condition on all the history up to the time of truncation. The latter two approaches are equivalent when analyzing univariate survival outcomes but differ under the multi‐state framework. In this paper, we consider the illness–death model and compare between the three estimation approaches in a parametric regression framework. We show that approach (ii) is more efficient than the standard approach (iii), although it requires more computational effort. Approach (i) is the most efficient approach, but it requires knowledge on the distribution of the truncation variable and hence is less robust. The methods are compared using a theoretical example and simulations and are applied to intensive care units data collected in a cross‐sectional design, where the illness state corresponds to a bloodstream infection. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
7.
8.
《Value in health》2020,23(2):191-199
BackgroundChanges in the regulatory context enable faster approval of transformative medicines. They also lead to health technology assessment (HTA) agencies having to make decisions with less evidence. In response, HTA agencies have also initiated forms of conditional approval. When the evidence base for a new oncology treatment leaves substantial uncertainty, the new Cancer Drugs Fund allows the National Institute for Heath and Care Excellence to give the manufacturer two options: (1) offer a low price based on conservative assumptions and obtain immediate approval (“stick”) or (2) wait until the evidence base has further matured before finalizing a potentially higher agreed price (“twist”).ObjectivesThe purpose of this article is to explain how, using the theoretical framework of the expected value of sample information, simulation methods can help inform a manufacturer’s decisions when faced with the option to stick or twist.MethodsWe first summarize a general model to help frame the manufacturer’s negotiating strategy. We then use a motivating case study, based on a hypothetical immunotherapy, to illustrate how manufacturers can use simulation methods to robustly characterize the uncertainty inherent to further data collection and incorporate this uncertainty within their decision making.ResultsOur approach allows us to estimate the commercial value of generating additional data (the difference between the estimated net present value of stick and twist). We test the sensitivity of the results to different assumptions via scenario analyses.ConclusionsThis article shows that simulation methods can be used to help pharmaceutical managers make informed strategic decisions in contexts of uncertainty. 相似文献
9.
10.
Qiang Fu Yuan Chang Huimin An Hangcheng Fu Yu Zhu Le Xu Weijuan Zhang Jiejie Xu 《British journal of cancer》2015,113(11):1581-1589