期刊文献+
共找到2篇文章
< 1 >
每页显示 20 50 100
Soft Image Segmentation Based on the Mixture of Gaussians and the Phase-Transition Theory
1
作者 Celia A. Z. Barcelos Yunmei chen fuhua chen 《Applied Mathematics》 2014年第18期2888-2898,共11页
In this paper, we propose a new soft multi-phase segmentation model where it is assumed that the pixel intensities are distributed as a Gaussian mixture. The model is formulated as a minimization problem through the u... In this paper, we propose a new soft multi-phase segmentation model where it is assumed that the pixel intensities are distributed as a Gaussian mixture. The model is formulated as a minimization problem through the use of the maximum likelihood estimator and phase-transition theory. The mixture coefficients, which are estimated using a spatially varying mean and variance procedure, are used for image segmentation. The experimental results indicate the effectiveness of the method. 展开更多
关键词 Image SEGMENTATION VARIATIONAL Model GAUSSIAN MIXTURE
下载PDF
Cadmium and copper uptake and accumulation by Sesbania rostrata seedling, a N-fixing annual plant: implications for the mechanism of heavy metal tolerance
2
作者 fuhua chen Wei FANG +1 位作者 Zhongyi YANG Jiangang YUAN 《Frontiers in Biology》 CSCD 2009年第2期200-206,共7页
Sesbania rostrata,an annual tropical legume,has been found to be tolerant to heavy metals,with an unknown mechanism.It is a promising candidate species for revegetation at mine tailings.In this study,sequential extrac... Sesbania rostrata,an annual tropical legume,has been found to be tolerant to heavy metals,with an unknown mechanism.It is a promising candidate species for revegetation at mine tailings.In this study,sequential extractions with five buffers and strong acids were used to extract various chemical forms of cadmium and copper in S.rostrata,with or without Cd or Cu treatments,so that the mechanisms of tolerance and detoxification could be inferred.Both metals had low transition rates from roots to the aboveground of S.rostrata.The transition ratio of Cd(4.00%)was higher than that of Cu(1.46%).The proportion of NaCl extracted Cd(mostly in proteinbinding forms)increased drastically in Cd treated plants from being undetectable in untreated plants.This suggests that Cd induced biochemical processes producing proteinlike phytochelatins that served as a major mechanism for the high Cd tolerance of S.rostrata.The case for Cu was quite different,indicating that the mechanism for metal tolerance in S.rostrata is metal-specific.The proportion of water-insoluble Cu(e.g.oxalate and phosphate)in roots increased significantly with Cu treatment,which partially explains the tolerance of S.rostrata to Cu.However,how S.rostrata copes with the high biotic activity of inorganic salts of Cu,which increased in all parts of the plant under Cu stress,is a question for future studies.Sesbania rostrata is among the very few N-fixing plants tolerant to heavy metals.This study provides evidence for the detoxification mechanism of metals in Sesbania rostrata. 展开更多
关键词 Sesbania rostrata PHYTOREMEDIATION heavy metal tolerance sequential extraction chemical forms
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部