全文获取类型
收费全文 | 47568篇 |
免费 | 4622篇 |
国内免费 | 1516篇 |
专业分类
耳鼻咽喉 | 614篇 |
儿科学 | 592篇 |
妇产科学 | 750篇 |
基础医学 | 5120篇 |
口腔科学 | 539篇 |
临床医学 | 7085篇 |
内科学 | 5383篇 |
皮肤病学 | 186篇 |
神经病学 | 12951篇 |
特种医学 | 6144篇 |
外国民族医学 | 12篇 |
外科学 | 3842篇 |
综合类 | 4762篇 |
现状与发展 | 1篇 |
预防医学 | 1041篇 |
眼科学 | 500篇 |
药学 | 2082篇 |
11篇 | |
中国医学 | 711篇 |
肿瘤学 | 1380篇 |
出版年
2024年 | 160篇 |
2023年 | 1011篇 |
2022年 | 1542篇 |
2021年 | 2586篇 |
2020年 | 2438篇 |
2019年 | 2282篇 |
2018年 | 1967篇 |
2017年 | 1994篇 |
2016年 | 1816篇 |
2015年 | 1790篇 |
2014年 | 3050篇 |
2013年 | 2989篇 |
2012年 | 2363篇 |
2011年 | 2662篇 |
2010年 | 2170篇 |
2009年 | 2182篇 |
2008年 | 2213篇 |
2007年 | 2113篇 |
2006年 | 2037篇 |
2005年 | 1777篇 |
2004年 | 1431篇 |
2003年 | 1368篇 |
2002年 | 1248篇 |
2001年 | 960篇 |
2000年 | 722篇 |
1999年 | 648篇 |
1998年 | 587篇 |
1997年 | 540篇 |
1996年 | 545篇 |
1995年 | 483篇 |
1994年 | 464篇 |
1993年 | 345篇 |
1992年 | 328篇 |
1991年 | 269篇 |
1990年 | 234篇 |
1989年 | 225篇 |
1988年 | 180篇 |
1987年 | 167篇 |
1986年 | 156篇 |
1985年 | 237篇 |
1984年 | 209篇 |
1983年 | 165篇 |
1982年 | 164篇 |
1981年 | 145篇 |
1980年 | 147篇 |
1979年 | 127篇 |
1978年 | 101篇 |
1977年 | 78篇 |
1976年 | 83篇 |
1974年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Subacute sclerosing panencephalitis (SSPE) is a rare, slowly progressing but invariably fatal disease that is related to a prior measles virus infection and most commonly affects paediatric patients. Magnetic resonance (MR) imaging is the modality of choice for determining such changes in white matter. SSPE typically demonstrates bilateral but asymmetric periventricular and subcortical white matter involvement. We herein report a rare case of unilateral white matter involvement in a 13-year-old boy with SSPE that closely simulated Rasmussen’s encephalitis. To the best of our knowledge, this is the first report of an atypical presentation on MR imaging in which SSPE was a rare cause of unilateral brain parenchymal involvement in a patient with intractable seizures. 相似文献
55.
《Biomaterials》2015
Mesoporous silica nanoparticles (MSNs) can provide a structural foundation for a new generation of nanocarriers with a broad range of functionalities. Multifunctional MSNs can serve as all-in-one diagnostic and therapeutic tools that can be used to simultaneously visualize and treat various diseases, such as cancer. This research study is the first time that two lanthanide-based imaging systems have been combined to incorporate controlled drug release and targeted tracing into a single MSN-based nano-platform for a novel theranostic drug delivery system. Doping lanthanide ions, i.e., europium (Eu) and gadolinium (Gd) ions, into an MSN structure (EuGd-MSNs) imparts fluorescence and magnetism to the nanostructure that can be used to develop magnetic resonance imaging (MRI) and biological fluorescence tools. Current cancer research has revealed that most human cancer cells express a large number of folate receptors on their surface. Grafting folic acid (FA) onto the EuGd-MSN surface (EuGd-FA-MSNs) imparts a targeting function to the MSN because of the specificity of the binding of FA to cell surface receptors. Furthermore, grafting anticancer drugs, such as camptothecin (CPT), onto the surface of these MSNs by forming disulfide bonds (EuGd-SS-CPT-FA-MSNs) enables intracellular controlled drug release. A high concentration of intracellular glutathione cleaves the disulfide bond to release the drug and treat the disease. The results of in vitro and in vivo studies show that the functionalized MSNs can be successfully used as a platform to integrate dual-imaging, targeting, and therapeutic treatment in multifunctional diagnosis drug delivery systems. 相似文献
56.
57.
58.
Sanne J. H. van Rooij Ryan D. Smith Anaïs F. Stenson Timothy D. Ely Xinyi Yang Nim Tottenham Jennifer S. Stevens Tanja Jovanovic 《Depression and anxiety》2020,37(4):303-312
Most studies investigating the effect of childhood trauma on the brain are retrospective and mainly focus on maltreatment, whereas different types of trauma exposure such as growing up in a violent neighborhood, as well as developmental stage, could have differential effects on brain structure and function. The current magnetic resonance imaging study assessed the effect of trauma exposure broadly and violence exposure more specifically, as well as developmental stage on the fear neurocircuitry in 8‐ to 14‐year‐old children and adolescents (N = 69). We observed reduced hippocampal and increased amygdala volume with increasing levels of trauma exposure. Second, higher levels of violence exposure were associated with increased activation in the amygdala, hippocampus, and ventromedial prefrontal cortex during emotional response inhibition. This association was specifically observed in children younger than 10 years. Finally, increased functional connectivity between the amygdala and brainstem was associated with higher levels of violence exposure. Based on the current findings, it could be hypothesized that trauma exposure during childhood results in structural changes that are associated with later risk for psychiatric disorders. At the same time, it could be postulated that growing up in an unsafe environment leads the brain to functionally adapt to this situation in a way that promotes survival, where the long‐term costs or consequences of these adaptations are largely unknown and an area for future investigations. 相似文献
59.
《Brain stimulation》2020,13(5):1159-1167
BackgroundInhibitory control refers to a central cognitive capacity involved in the interruption and correction of actions. Dysfunctions in these cognitive control processes have been identified as major maintaining mechanisms in a range of mental disorders such as ADHD, binge eating disorder, obesity, and addiction. Improving inhibitory control by transcranial direct current stimulation (tDCS) could ameliorate symptoms in a broad range of mental disorders.ObjectiveThe primary aim of this pre-registered meta-analysis was to investigate whether inhibitory control can be improved by tDCS in healthy and clinical samples. Additionally, several moderator variables were investigated.MethodsA comprehensive literature search was performed on PubMed/MEDLINE database, Web of Science, and Scopus. To achieve a homogenous sample, only studies that assessed inhibitory control in the go-/no-go (GNG) or stop-signal task (SST) were included, yielding a total of 75 effect sizes from 45 studies.ResultsResults of the meta-analysis indicate a small but significant overall effect of tDCS on inhibitory control (g = 0.21) which was moderated by target and return electrode placement as well as by the task. The small effect size was further reduced after correction for publication bias.ConclusionBased on the studies included, our meta-analytic approach substantiates previously observed differences between brain regions, i.e., involvement of the right inferior frontal gyrus (rIFG) vs. the right dorsolateral prefrontal cortex (rDLPFC) in inhibitory control. Results indicate a small moderating effect of tDCS on inhibitory control in single-session studies and highlight the relevance of technical and behavioral parameters. 相似文献
60.
目的 探讨改良单图像法手工测量髌骨不稳患者胫骨结节-股骨滑车沟(tibial tuberosity-trochlear groove,TT-TG)间距的可行性。
方法 选取髌骨不稳患者30例。高年资手术医师A、B,使用改良单图像法手工测量髌骨不稳患者TT-TG间距,对比高资年影像学医师C,使用双图法测量髌骨不稳患者TT-TG间距。应用Cronbach′s alpha系数评价结果的可信度。应用组内相关系数(intraclass correlation coefficient,ICC)评价结果的可重复性。使用Bland-Altman分析图评价结果的一致性。
结果 高年资手术医师A、B使用改良单图像法手工测量髌骨不稳患者TT-TG间距分别和高年资影像学医师C使用双图法测量髌骨不稳患者TT-TG间距比较,Cronbach′s alpha系数分别为0.913和0.959,组内相关系数分别为0.913和0.958。Bland-Altman分析图显示,TT-TG间距差值(mm)的均值为-0.276(95%CI:-3.526~2.974)和0.143(95%CI:-3.110~3.397)。A、B医师之间使用改良单图像法手工测量髌骨不稳患者TT-TG间距比较,Cronbach′s alpha系数为0.891,组内相关系数为0.891。Bland-Altman分析图显示TT-TG间距差值(mm)的均值为-0.276(95%CI:-3.526~2.974)。
结论 改良单图像法手工测量髌骨不稳患者TT-TG间距操作简单,可以准确测量出髌骨不稳患者的TT-TG间距,该方法和双图法可以相互替换使用。 相似文献