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   2222篇
  免费   145篇
  国内免费   4篇
耳鼻咽喉   19篇
儿科学   50篇
妇产科学   40篇
基础医学   295篇
口腔科学   248篇
临床医学   209篇
内科学   392篇
皮肤病学   41篇
神经病学   189篇
特种医学   34篇
外科学   181篇
综合类   8篇
一般理论   2篇
预防医学   297篇
眼科学   19篇
药学   116篇
中国医学   11篇
肿瘤学   220篇
  2024年   3篇
  2023年   30篇
  2022年   53篇
  2021年   68篇
  2020年   69篇
  2019年   64篇
  2018年   81篇
  2017年   66篇
  2016年   69篇
  2015年   82篇
  2014年   83篇
  2013年   108篇
  2012年   194篇
  2011年   181篇
  2010年   108篇
  2009年   97篇
  2008年   133篇
  2007年   154篇
  2006年   124篇
  2005年   118篇
  2004年   105篇
  2003年   73篇
  2002年   67篇
  2001年   36篇
  2000年   34篇
  1999年   28篇
  1998年   10篇
  1997年   3篇
  1996年   6篇
  1995年   9篇
  1994年   4篇
  1993年   10篇
  1992年   11篇
  1991年   7篇
  1990年   11篇
  1989年   5篇
  1988年   5篇
  1987年   8篇
  1986年   8篇
  1985年   5篇
  1984年   9篇
  1983年   3篇
  1981年   2篇
  1979年   2篇
  1978年   3篇
  1977年   4篇
  1976年   2篇
  1973年   2篇
  1970年   4篇
  1969年   4篇
排序方式: 共有2371条查询结果,搜索用时 15 毫秒
31.
Objectives To estimate, by neonatal screening, the birth prevalence of congenital toxoplasmosis among live‐born infants in Sergipe state, Brazil, and to investigate the clinical features of affected infants. Methods Dried blood spot specimens obtained from 15 204 neonates were assayed for the presence of anti‐T. gondii IgM antibodies. Duplicate retesting was done in infants with positive and borderline results. Confirmatory testing in peripheral blood samples consisted of testing for anti‐T. gondii IgG and IgM in infants and mothers. Those with possible congenital toxoplasmosis were evaluated and followed up to a median age of 20 months. Congenital infection was confirmed in the presence of persisting anti‐T. gondii IgG antibodies beyond 12 months of age. All infants with confirmed infection were treated with pyrimethamine, sulfadiazine and folinic acid for 1 year. Results Fifty‐three infants had detectable IgM in dried blood spot specimens. Confirmatory testing was reactive in 39/50, of which, 38 completed follow‐up. Six of 15 204 newborns were diagnosed with congenital toxoplasmosis, resulting in an estimated birth prevalence of four per 10 000 [CI 95% 1.4–8.0]. Four infants (67%) showed signs of congenital toxoplasmosis in their first year of life; three (75%) had retinochoroidal scars, and one had cerebral calcifications. Two infants remained asymptomatic until 20 months of age. Conclusions The birth prevalence of congenital toxoplasmosis is high in the Brazilian state of Sergipe, with most of the infants showing ocular lesions. Preventive measures are strongly warranted.  相似文献   
32.
An approximately 3,000 finishing swine operation in the United States experienced an outbreak of an atypical neurologic disease in 11‐weeks‐old pigs with an overall morbidity of 20% and case fatality rate of 30%. The clinical onset and progression of signs in affected pigs varied but included inappetence, compromised ambulation, ataxia, incoordination, mental dullness, paresis, paralysis and decreased response to environmental stimuli. Tissues from affected pigs were submitted for diagnostic investigation. Histopathologic examination of the cerebrum, cerebellum and spinal cord revealed severe lymphoplasmacytic and necrotizing polioencephalomyelitis with multifocal areas of gliosis and neuron satellitosis, suggestive of a neurotropic viral infection. Bacterial pathogens were not isolated by culture of neurologic tissue from affected pigs. Samples tested by polymerase chain reaction (PCR) were negative for pseudorabies virus and atypical porcine pestivirus. Immunohistochemistry for porcine reproductive and respiratory syndrome virus, porcine circovirus and Listeria was negative. Porcine sapelovirus (PSV) was identified in spinal cord by a nested PCR used to detect porcine enterovirus, porcine teschovirus and PSV. Next‐generation sequencing of brainstem and spinal cord samples identified PSV and the absence of other or novel pathogens. In addition, Sapelovirus A mRNA was detected in neurons and nerve roots of the spinal cord by in situ hybridization. The PSV is genetically novel with an overall 94% amino acid identity and 86% nucleotide identity to a recently reported sapelovirus from Korea. This is the first case report in the United States associating sapelovirus with severe polioencephalomyelitis in pigs.  相似文献   
33.
34.
35.

Background

The oral lichen planus is a chronic inflammatory disease. Although its aetiology is not well understood, the role of T lymphocytes in its inflammatory events is recognised. Identifying the epigenetic mechanisms involved in the pathogenesis of this immune‐mediated condition is fundamental for understanding the inflammatory reaction that occurs in the disease. The purpose of this work was to evaluate the methylation pattern of 21 immune response‐related genes in the different clinical forms of oral lichen planus.

Methods

A cross‐sectional study was performed to analyse the DNA methylation patterns in three distinct groups of oral lichen planus: (i) reticular/plaque lesions; (ii) erosive lesions; (iii) normal oral mucosa (control group). After DNA extraction from biopsies, the samples were submitted to digestions by methylation‐sensitive and methylation‐dependent enzymes and double digestion. The relative percentage of methylated DNA for each gene was provided using real‐time polymerase chain reaction arrays.

Results

Hypermethylation of the STAT5A gene was observed only in the control group (59.0%). A higher hypermethylation of the ELANE gene was found in reticular/plaque lesions (72.1%) compared to the erosive lesions (50.0%).

Conclusion

Our results show variations in the methylation profile of immune response‐related genes, according to the clinical type of oral lichen planus after comparing with the normal oral mucosa. Further studies are necessary to validate these findings using gene expression analysis.  相似文献   
36.
37.
38.
39.
The aim of this study was to evaluate the clinical effectiveness of .12% chlorhexidine applied via spray and the acceptance. A total of 26 individuals with mental health issues, aged 7–14, were included into two groups: placebo (control, n = 13) and chlorhexidine (experimental, n = 13). Both groups received two daily applications of spray during 2 months. The periodontal conditions were evaluated by the simplified oral hygiene index (OHI‐S) and gingival index (GI). The evaluation of acceptance of the application method (spray) was assessed by questionnaire. Data were analyzed with nonparametric tests, with a significance level of 5%. Regarding the OHI‐S index, only the experimental group showed significant change during the evaluations (p < 0.001). Regarding the GI, both groups showed significant changes during the evaluations. The method of application was well accepted by patients and caregivers, and .12% chlorhexidine solution applied via spray significantly reduced the rates of dental and gingival biofilm.  相似文献   
40.
BackgroundChromoblastomycosis is a skin infection caused by dematiaceous fungi that take the form of muriform cells in the tissue. It mainly manifests as verrucous plaques on the lower limbs of rural workers in tropical countries.ObjectivesThe primary objective of this review is to evaluate the accuracy of diagnostic methods for the identification of chromoblastomycosis, considering the histopathological examination as the reference test.MethodsMEDLINE, LILACS and Scielo databases were consulted using the terms “chromoblastomycosis” AND “diagnosis”. The eligibility criteria were: studies that evaluated the accuracy of tests for the diagnosis of chromoblastomycosis. Eleven studies were selected. Statistical analysis included the calculation of sensitivity and specificity of the diagnostic methods.ResultsConsidering the histopathological examination as the reference test, the culture showed a sensitivity (S) of 37.5% - 90.9% and a specificity (Sp) of 100%; while direct mycological examination showed S = 50% - 91.6% and Sp of 100% . Considering the culture as the reference test, the serology (precipitation techniques) showed S of 36% - 99%; and Sp of 80% - 100%; while the intradermal test showed S of 83.3% - 100% and Sp of 99.4% - 100%.Study limitationsThe small number of studies and very discrepant sensitivity results among them do not allow the calculation of summary measures through a meta-analysis.ConclusionsDirect mycological examination, culture, intradermal test and serology show sensitivity and specificity values ??for the diagnosis of chromoblastomycosis with no significant difference between the studies.  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