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   1450篇
  免费   123篇
  国内免费   1篇
耳鼻咽喉   5篇
儿科学   18篇
妇产科学   50篇
基础医学   233篇
口腔科学   3篇
临床医学   131篇
内科学   358篇
皮肤病学   30篇
神经病学   211篇
特种医学   26篇
外科学   228篇
综合类   3篇
预防医学   70篇
眼科学   9篇
药学   58篇
肿瘤学   141篇
  2023年   12篇
  2022年   8篇
  2021年   47篇
  2020年   24篇
  2019年   26篇
  2018年   38篇
  2017年   26篇
  2016年   39篇
  2015年   44篇
  2014年   49篇
  2013年   61篇
  2012年   104篇
  2011年   106篇
  2010年   73篇
  2009年   59篇
  2008年   115篇
  2007年   108篇
  2006年   96篇
  2005年   85篇
  2004年   76篇
  2003年   77篇
  2002年   79篇
  2001年   17篇
  2000年   17篇
  1999年   11篇
  1998年   16篇
  1997年   10篇
  1996年   7篇
  1995年   7篇
  1994年   3篇
  1992年   9篇
  1991年   13篇
  1990年   5篇
  1989年   4篇
  1988年   7篇
  1987年   7篇
  1986年   17篇
  1985年   8篇
  1984年   6篇
  1983年   5篇
  1982年   4篇
  1979年   4篇
  1978年   3篇
  1974年   3篇
  1972年   4篇
  1971年   5篇
  1970年   5篇
  1969年   4篇
  1968年   3篇
  1966年   3篇
排序方式: 共有1574条查询结果,搜索用时 15 毫秒
31.
We report 3 new cases of Mitochondrial-Neuro-Gastro-Intestinal Encephalomyopathy (MNGIE) (or Pseudo-Obstruction-Leukoencephalopathy-Intestinal-Pseudoobstruction Syndrome [POLIP]), a rare disease that associates chronic intestinal pseudo-obstruction (CIPO) and neurological symptoms. A review of the 72 reported cases together with these 3 cases revealed that this condition was associated with (a) a specific cluster of neurological symptoms including leukoencephalopathy (96%), polyneuropathy (96%), ophthalmoplegia (91%) and hearing loss (55%); (b) a CIPO syndrome with the presence of small bowel diverticulae (53%); and (c) mitochondrial cytopathy in 36 of the 37 tested patients (2 of our 3 cases), and thymidine phosphorylase gene mutations in all the 37 tested patients (2 of our cases). The etiology of POLIP/MNGIE syndrome appears therefore to be due to a mitochondrial cytopathy secondary to thymidine phosphorylase gene mutation(s). In 3 cases, including 2 of our 3 patients, mitochondrial abnormalities were evidenced at the ultrastructural level in digestive smooth muscle demonstrating that the pathogenesis of gastrointestinal involvement was directly related to mitochondrial alterations in digestive smooth muscle cells.  相似文献   
32.
Lymphatic endothelial cells (LECs) present peripheral tissue antigens to induce T cell tolerance. In addition, LECs are the main source of sphingosine-1-phosphate (S1P), promoting naive T cell survival and effector T cell exit from lymph nodes (LNs). Autophagy is a physiological process essential for cellular homeostasis. We investigated whether autophagy in LECs modulates T cell activation in experimental arthritis. Whereas genetic abrogation of autophagy in LECs does not alter immune homeostasis, it induces alterations of the regulatory T cell (T reg cell) population in LNs from arthritic mice, which might be linked to MHCII-mediated antigen presentation by LECs. Furthermore, inflammation-induced autophagy in LECs promotes the degradation of Sphingosine kinase 1 (SphK1), resulting in decreased S1P production. Consequently, in arthritic mice lacking autophagy in LECs, pathogenic Th17 cell migration toward LEC-derived S1P gradients and egress from LNs are enhanced, as well as infiltration of inflamed joints, resulting in exacerbated arthritis. Our results highlight the autophagy pathway as an important regulator of LEC immunomodulatory functions in inflammatory conditions.  相似文献   
33.
A clinical impact of cognitive reserve (CR) has been demonstrated in Alzheimer's disease, whereas its role in vascular cognitive impairment (VCI) is largely unknown. In this study, we investigated the impact of CR in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a genetic variant of pure VCI. A total of 247 NOTCH3 mutation carriers from a two-center study were investigated using detailed neuropsychological and neuroimaging protocols. CR was operationalized as years of formal education. Brain pathology was assessed by MRI using normalized brain volume and lacunar lesion volume as proxies. Multivariate analyses were done for each structural measure with scores of processing speed, executive function, and memory as dependent variables. Additional linear regression models were conducted with interaction terms for education × brain volume and education × lacunar lesion volume. Education had an independent impact on cognitive performance in subjects with mild and moderate degrees of brain pathology, whereas there was no significant influence of education on cognition in patients with severe MRI changes. This interaction was found for processing speed, the cognitive domain most impaired in our patients. Our findings demonstrate an interaction of education and brain pathology in regard to cognitive impairment: the effect of education seems most pronounced in early disease stages but may ultimately be overwhelmed by the pathological changes. The results extend the concept of CR to VCI.  相似文献   
34.
35.
OBJECTIVES: We sought to assess the electromechanical parameters, using tissue Doppler echocardiography, as potential independent predictors of heart failure (HF) worsening. BACKGROUND: Ventricular conduction disorders worsen the prognosis for HF patients. However, the relationships between the QRS width and morphology, hemodynamic parameters, and presence and magnitude of intra-left ventricular (LV) and inter-ventricular (V) asynchrony have not been well clarified. METHOD: A total of 104 patients with an LV ejection fraction (EF) 相似文献   
36.
37.
In implant dentistry, plaque control and oral hygiene practices are essential to limit the risk of complication and failure in the long term. All conditions around an implant in function that influence the load and pathogenicity of the microbiota are considered local risk indicators. They concern the prosthetic suprastructure design and the possibility for the patient to easily access each implant for plaque removal. Use of cemented prostheses should be limited to avoid excess cement acting as a foreign body and leading to peri‐implant disease. The crown margins should be supramucosal, and the connection should be precise to avoid a gap between the implant and the suprastructure. Every implant system is characterised by a specific design, surface texture and connection type. These features may influence peri‐implantitis development and progression, and the clinician should consider the risk of infection when selecting an implant. The soft‐tissue conditions around the implant, the width of keratinised mucosa, and the phenotype and thickness of the mucosa are also considered major risk indicators, as the presence of any mucosal defect around an implant can increase plaque accumulation and result in tissue inflammation. The pathogenicity of the microbiota around an implant is primarily dependent on pocket depth. Deep pockets around implants should be avoided and, if present, closely monitored and/or reduced. Proximity to natural teeth presenting endodontic and/or periodontal lesions may result in implant contamination, but the influence of the type of edentulism on perio‐pathogen presence is still unclear. These local conditions around an implant have a clear influence on peri‐implant diseases development and progression, but there is still only limited evidence regarding their role as true risk indicators.  相似文献   
38.
39.
Nerium oleander is potentially lethal plants after ingestion. We report a case of poisoning by these plants. Our patient complained of nausea, vomiting, and diarrhoea. He had bradycardia during first twelve hours. He was discharge after 3 days. All parts of these plants are toxic and contain a variety of cardiac glycosides including oleandrin. In most cases, clinical management of poisoning by N. oleander involves administration of activated charcoal and supportive care. Digoxin specific Fab fragments are an effective treatment.  相似文献   
40.
The present study analyzed the relationship between the genetic diversity of Plasmodium falciparum and parasitologic/entomologic indices in the Mount Cameroon region by using merozoite surface protein 1 as a genetic marker. Blood samples were collected from asymptomatic children from three altitude zones (high, intermediate, and low). Parasitologic and entomologic indices were determined by microscopy and landing catch mosquito collection/circumsporozoite protein-enzyme-linked immunosorbent assay, respectively. A total of 142 randomly selected P. falciparum-positive blood samples were genotyped by using a nested polymerase chain reaction-based technique. K-1 polymerase chain reaction products were also sequenced. As opposed to high altitude, the highest malaria prevalence (70.65%) and entomologic inoculation rate (2.43 infective/bites/night) were recorded at a low altitude site. Seven (18.91%), 22 (36.66%), and 19 (42.22%) samples from high, intermediate, and low altitudes, respectively, contained multiclonal infections. A new K-1 polymorphism was identified. This study shows a positive non-linear association between low/intermediate altitude (high malaria transmission) and an increase in P. falciparum merozoite surface protein 1 block 2 polymorphisms.  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