首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3096篇
  免费   188篇
  国内免费   71篇
耳鼻咽喉   97篇
儿科学   80篇
妇产科学   32篇
基础医学   516篇
口腔科学   49篇
临床医学   218篇
内科学   327篇
皮肤病学   31篇
神经病学   745篇
特种医学   140篇
外科学   194篇
综合类   294篇
预防医学   134篇
眼科学   153篇
药学   225篇
  1篇
中国医学   70篇
肿瘤学   49篇
  2023年   29篇
  2022年   63篇
  2021年   76篇
  2020年   97篇
  2019年   80篇
  2018年   85篇
  2017年   74篇
  2016年   71篇
  2015年   87篇
  2014年   135篇
  2013年   174篇
  2012年   163篇
  2011年   142篇
  2010年   112篇
  2009年   146篇
  2008年   141篇
  2007年   160篇
  2006年   131篇
  2005年   98篇
  2004年   116篇
  2003年   106篇
  2002年   72篇
  2001年   61篇
  2000年   73篇
  1999年   37篇
  1998年   56篇
  1997年   55篇
  1996年   45篇
  1995年   39篇
  1994年   40篇
  1993年   37篇
  1992年   46篇
  1991年   43篇
  1990年   42篇
  1989年   34篇
  1988年   28篇
  1987年   35篇
  1986年   27篇
  1985年   35篇
  1984年   40篇
  1983年   24篇
  1982年   33篇
  1981年   28篇
  1980年   31篇
  1979年   17篇
  1978年   25篇
  1977年   15篇
  1976年   11篇
  1975年   9篇
  1973年   8篇
排序方式: 共有3355条查询结果,搜索用时 15 毫秒
61.
报道1例62岁女性患者,将`枚可摘局部义齿误吞入消化道。当日急诊未能在胃镜下成功将义齿取出;2d后义齿经过肠道时,在回盲部发生嵌顿,并引发肠穿孔及急性弥漫性腹膜炎。最后,通过剖腹手术取出义齿,并对肠穿孔进行了修补。1周后,腹膜炎治愈后出院。  相似文献   
62.
Objectives: Visual hallucinations (VH) are common in Lewy body disease (LBD), and have been associated with cognitive and structural brain alterations. Evidence so far concerns mainly Parkinson’s disease (PD), but little is known about symptom-specific pathophysiological mechanisms across the LBD spectrum, especially related to the presence of dementia. The aim of the present pilot study was to investigate the neuroanatomical, and neuropsychological characteristics related to VH in two forms of LBD, namely dementia with Lewy bodies (DLB) and PD without dementia.

Methods: Whole brain voxel-based morphometry (VBM) analyses on 3D MRI acquired structural brain scans, and neuropsychological testing were performed on 28 clinically diagnosed DLB (11 with VH, 17 NVH), and 24 PD (9 with VH, and 15 NVH) patients. In order to assess differences in gray matter (GM) regional volumes, and cognitive performance, hallucinating patients for each group were compared with corresponding non-hallucinating ones.

Results: DLB patients with VH presented significantly worse visual attention deficits compared to those without, which persisted even when controlling for visual perception. Whole brain VBM analysis revealed decreased GM volume in DLB with VH in the right superior and medial frontal gyri, putamen, caudate nucleus and insula. Subcortical regional volumes were also significantly associated with visual attention performance. Hallucinating PD patients, instead, presented more severe executive dysfunction, but VBM showed no volumetric differences between the two PD subgroups. Post hoc region of interest analyses revealed striatal GM loss in PD with VH.

Conclusion: Frontal and striatal GM atrophy may contribute to the emergence of VH in DLB, which may be fostered by the more severe attention deficits. Striatal GM loss and executive dysfunction, instead, appeared to underlie VH in PD without dementia.  相似文献   
63.
Summary. In 1962, a rod‐shaped cytoplasmic organelle of endothelial cells, later called the Weibel–Palade body, was serendipitously discovered by electron microscopy. It contains a set of parallel tubules and is wrapped in a membrane. Subsequent studies in the following decades established the unique localization of this organelle in endothelial cells of all vertebrates studied, meaning that it could serve as a marker of endothelial cells in tissue cultures. However, these studies did not reveal its functional significance, except for an indication that it could be related to an undefined thromboplastic substance. Twenty years after its discovery as a structural entity, it was shown by others that it houses von Willebrand factor and is thus clearly related to the coagulation system. In this review, I provide a personal historical account of the discovery and the subsequent limited work that I carried out on the organelle, putting it in the perspective of the current state of knowledge after half a century of research by many scientists.  相似文献   
64.
Ultrasound models, commonly referred to as “phantoms,” are simulation tools for ultrasound education. Commercially produced phantoms are available, but there are “homemade” alternatives such as raw poultry and gelatin molds. Precooked, processed meat, better known as SPAM (Hormel Foods Corporation, Austin, MN), can be used as an ultrasound phantom to teach several ultrasound applications. It is a versatile, hygienic, and easily manipulated medium that does not require refrigeration or preparatory work and can be easily discarded at the end of use.  相似文献   
65.
66.
67.
ObjectiveTo synthesize the evidence across longitudinal studies comparing survival in dementia with Lewy bodies (DLB) and Alzheimer’s disease (AD).MethodsWe conducted a systematic review and meta-analysis of studies comparing survival in clinically diagnosed DLB to AD. Longitudinal cohort studies were identified through a systematic search of major electronic databases from inception to May 2018. A random effects meta-analysis was performed to calculate survival time and relative risk of death.ResultsOverall, 11 studies were identified including 22,952 patients with dementia: 2029 with DLB (mean diagnosis age 76.3; 47% female) compared with 20,923 with AD (mean diagnosis age 77.2; 65.1% female). Average survival time in DLB from diagnosis was 4.11 years (SD ± 4.10) and in AD 5.66 (SD ± 5.32) years, equating to a 1.60 (95% CI: -2.44 to -0.77) years shorter survival in DLB (p < 0.01). Relative risk of death was increased by 1.35 (95%CI: 1.17–1.55) in DLB compared to AD (p < 0.01). Differences in survival were not explained by follow-up time, age at diagnosis, gender, or cognitive score.ConclusionsThere is consistent evidence for higher and earlier mortality in DLB compared to AD. This is important for all stakeholders and underlines the importance of expanding research into DLB.  相似文献   
68.
The vast majority of patients with idiopathic rapid eye movement sleep behaviour disorder will develop a neurodegenerative α‐synuclein‐related condition, such as Parkinson’s disease or dementia with Lewy bodies. The pathology underlying dream enactment overlaps anatomically with the brainstem regions that regulate circadian core body temperature. Previously, nocturnal core body temperature regulation has been shown to be impaired in Parkinson’s disease. However, no study to date has investigated nocturnal core body temperature changes in patients with idiopathic rapid eye movement sleep behaviour disorder, which may prove to be an early objective biomarker for α‐synucleinopathies. Ten healthy controls, 15 patients with idiopathic rapid eye movement sleep behaviour disorder, 31 patients with Parkinson’s disease and six patients with dementia with Lewy bodies underwent clinical assessment and nocturnal polysomnography with core body temperature monitoring. A validated cosinor method was utilised for core body temperature analysis. No differences in mesor, nadir or time of nadir were observed between groups. However, when compared with healthy controls, the amplitude of the nocturnal core body temperature (mesor minus nadir) was significantly reduced in patients with idiopathic rapid eye movement sleep behaviour disorder, Parkinson’s disease with concurrent rapid eye movement sleep behaviour disorder and dementia with Lewy bodies (p < 0.001, p = 0.043 and p = 0.017, respectively). Importantly, this relationship was not seen in those patients with Parkinson’s disease without rapid eye movement sleep behaviour disorder. In addition, there was a significant negative correlation between amplitude of the core body temperature and self‐reported rapid eye movement sleep behaviour disorder symptoms. Changes in thermoregulatory circadian rhythm may be specifically associated with the pathology underlying rapid eye movement sleep behaviour disorder rather than simply that of α‐synucleinopathy. These findings implicate thermoregulatory dysfunction as a potential early biomarker for development of rapid eye movement sleep behaviour disorder‐associated neurodegeneration, and suggest that subpopulations with differing pathological underpinnings might exist in Parkinson’s disease.  相似文献   
69.
70.
Birds in the genus Pitohui and Ifrita carry potent neurotoxins that are most abundant in skin and feathers. It was unknown precisely how or where in the skin these chemicals are stored. Here, we report high‐resolution electron microscopy using OsO4 staining to visualize the location of alkaloids. Our images suggest that toxic alkaloids accumulate in multigranular bodies of epidermal cells and are likely secreted as part of the avian epidermal barrier, where they are made available for chemical defense.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号