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   109篇
  免费   8篇
  117篇
  2023年   2篇
  2022年   10篇
  2021年   8篇
  2020年   6篇
  2016年   8篇
  2015年   6篇
  2014年   4篇
  2013年   6篇
  2012年   5篇
  2011年   12篇
  2010年   4篇
  2009年   5篇
  2008年   3篇
  2007年   5篇
  2006年   4篇
  2005年   3篇
  2004年   1篇
  2003年   4篇
  2002年   1篇
  2001年   1篇
  2000年   1篇
  1998年   2篇
  1996年   1篇
  1989年   5篇
  1988年   1篇
  1985年   1篇
  1980年   2篇
  1969年   3篇
  1964年   1篇
  1961年   1篇
  1950年   1篇
排序方式: 共有117条查询结果,搜索用时 15 毫秒
91.
92.
Background and aimHepatocellular carcinoma (HCC) is a major health burden globally. Dysregulation of miRNA 148a-3p is engaged in carcinogenesis. TGF-β is a profibrogenic cytokine. This study assesses the expression level of miRNA 148a-3p and its relationship with serum TGF-β1 and fibrosis index based on four factors (FIB-4) in Egyptian patients with HCV-associated HCC.Subjectsand Methods: The study included 72 HCC patients with HCV, 48 HCV cirrhotic patients, and 47 healthy controls. Serum TGF-β1 was assessed by ELISA and the expression of miRNA 148a-3p was measured by RT-PCR.ResultsPatients with HCC had lower plasma miRNA 148a-3p, higher serum TGF-β1, and higher FIB-4 levels than patients with cirrhosis and controls. miRNA 148a-3p discriminated HCC either from control (AUC: 0.997, 95.83% sensitivity, 85.11% specificity) or from cirrhosis (AUC: 0.943, 91.67% sensitivity, 81.25% specificity). Moreover, it distinguished metastatic from nonmetastatic patients (AUC: 0.800, 88.89% sensitivity, 60.0% specificity). The decreased miRNA 148a-3p and the increased TGF-β1 levels were related to distant metastasis, multinodular lesions, advanced TNM stage, and BCLC score (C). A negative correlation between miRNA 148a-3p and each of FIB-4 and TGF-β1 was detected. The decreased miRNA 148a-3p was associated with poor overall survival and poor progression-free survival.ConclusionAn inverse relationship between miRNA 148a-3p and both TGF-β1 and FIB-4 was observed, which could be involved in HCC pathogenesis. Moreover, this miRNA is a potential diagnostic and prognostic biomarker for HCC.  相似文献   
93.
Biological Trace Element Research - The present study was conducted to investigate the effects of nano-selenium (Nano Se) or/and vitamin E (VE) on growth performance, blood health, intestinal...  相似文献   
94.
Allelochemicals are secondary metabolites which are not edible and can be used as growth regulators and bio-herbicides. The goal of current study was to assess allelopathic ability of Lantana camara (Sage-plant) flowers against weeds viz. Avena fatua (Wild oat), Euphorbia helioscopia (Sun-spurge), Chenopodium album (Goosefoot), Phalaris minor (Canary-grass), and Rumex dentatus (Knotweed). Bioassay analysis of three methanolic fractions of the Combiflash from L. camara was performed at 50%, 75% and 100% concentration using germination percentage parameters, inhibition of plumule and radicle size. The fraction II of Combiflash strongly suppressed all weeds with negligible effect on T. aestivum. Gas chromatography-mass spectroscopy was conducted for the fraction, and isolated compounds were used to perform bioassays. From fraction II GC–MS detected four methyl esters of allelopathic fatty acid viz. Methyl oleate, methyl palmitate, methyl stearate and methyl linoleate. The evaluation of physiological effects of the bioassay revealed substantial suppression of chlorophyll, antioxidant enzymes (superoxide, dismutase peroxidase) and protein material in all weeds by methyl palmitate. Bioassay activity and study of physiological parameters revealed that the effective bio-herbicidal compound in Lantana camara flowers is methyl palmitate. This is the first time that methyl palmitate (a fatty acid methyl ester) has been related to herbicidal activity in L. camara flowers. It is proposed that field studies based on hormesis research and the mechanism of action of this compound be carried out.  相似文献   
95.
96.
97.
Feline immunodeficiency virus (FIV) is a lentivirus that causes immune suppression and neurological disease in cats. Among animal viruses, individual viral strains have been shown to be neurovirulent, but the role of viral strain specificity among lentiviruses and its relationship to systemic immune suppression in the development of neurological disease remains uncertain. To determine the extent to which different FIV strains caused neurological disease, FIV V1CSF and Petaluma were compared in ex vivo assays and in vivo. Both viruses infected and replicated in macrophage and mixed glial cell cultures at similar levels, but V1CSF induced significantly greater neuronal death than Petaluma in a neurotoxicity assay. V1CSF-infected animals showed significant neurodevelopmental delay compared to the Petaluma-infected and uninfected animals. Magnetic resonance spectroscopy studies of frontal cortex revealed significantly reduced N-acetyl aspartate/creatine ratios in the V1CSF group compared to the other groups. Cyclosporin A treatment of Petaluma-infected animals caused neurodevelopmental delay and reduced N-acetyl aspartate/creatine ratios in the brain. Reduced CD4+ and CD8+ cell counts were observed in the V1CSF-infected group compared to the uninfected and Petaluma-infected groups. These findings suggest that neurodevelopmental delay and neuronal injury is FIV strain specific but that systemic immune suppression is also an important determinant of FIV-induced neurovirulence.  相似文献   
98.
99.
J. Hill  K. Hamer  J. Tangah  M. Dawood 《Oecologia》2001,128(2):294-302
Tropical forest gaps are ephemeral and patchily distributed within forest areas and have very different light environments compared with closed-canopy forest. We used fruit-baited traps to investigate if gaps are exploited by more opportunistic butterfly species compared with closed-canopy forest. Gaps supported a higher diversity of butterflies in terms of species evenness but closed-canopy sites contained species with more restricted geographical distributions. There was little similarity between the assemblages of butterflies trapped in the canopy and those in either gap or closed-canopy sites, but the greater similarity was with gaps, and increased diversity in gaps was partly due to canopy species turning up in gaps. Dispersal rates (as measured by recapture rates) were higher in gaps and there was evidence that butterflies in gaps had relatively larger and broader thoraxes, indicating a flight morphology adapted for faster flight. These results support the notion of a distinctive gap fauna comprising more widespread, mobile species. Habitat modification that opens up the canopy is likely to result in an increase in these widespread species and a decline in understorey species with restricted distributions.  相似文献   
100.
Robotic assistance has enabled coronary artery bypass surgery to be performed safely in a completely endoscopic fashion, but diffusely diseased target vessels may pose a technical challenge. We present a case in which coronary endarterectomy was performed on the left anterior descending coronary artery during a two-vessel totally endoscopic coronary artery bypass procedure. A 52-year-old woman presented with intermittent substernal pain. Preoperative studies showed diffuse disease in the left coronary artery system. Bilateral internal mammary arteries were harvested robotically using a skeletonized technique in a completely endoscopic fashion. Cardiopulmonary bypass was achieved via peripheral cannulation, and the heart was arrested with intermittent cold antegrade hyperkalemic blood cardioplegia delivered via an ascending aortic occlusion balloon catheter. The first obtuse marginal anastomosis was performed. The left anterior descending coronary artery was diffusely diseased and heavily calcified. An end-to-side anastomosis was attempted to the right internal mammary artery with unsatisfactory results. A localized coronary endarterectomy was performed, and an extended anastomosis was completed using the right internal mammary artery. The patient recovered uneventfully and was discharged home on postoperative day 6. Diffuse coronary artery disease was once thought to be a prohibitive challenge for minimally invasive coronary bypass procedures. This case demonstrates that local coronary endarterectomy is feasible and safe in robotic totally endoscopic coronary artery bypass surgery.  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