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恢复演替中草地斑块动态及尺度转换分析 被引量:34
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作者 辛晓平 徐斌 +2 位作者 单保庆 李建东 杨允菲 《生态学报》 CAS CSCD 北大核心 2000年第4期587-593,共7页
研究了 9a草地恢复演替系列中斑块边界形状和斑块面积分布动态 ,并进行了尺度转换分析。獐茅斑块的边界分维数和斑块化指数最高 ,羊草斑块的较低 ,碱蓬斑块的斑块化指数略小于羊草斑块 ,边界分维数大于羊草斑块。其他类型斑块的两种指... 研究了 9a草地恢复演替系列中斑块边界形状和斑块面积分布动态 ,并进行了尺度转换分析。獐茅斑块的边界分维数和斑块化指数最高 ,羊草斑块的较低 ,碱蓬斑块的斑块化指数略小于羊草斑块 ,边界分维数大于羊草斑块。其他类型斑块的两种指数基本上介于獐茅斑块和羊草斑块之间。斑块化指数的年际变动滞后于斑块边界分维数。斑块边界分维数在整个试验的尺度范围内符合同一自相似规律 。 展开更多
关键词 斑块边界 斑块面积分布 分形指数 尺度转换 草地
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口腔粘膜赤斑严重癌前病变4例报告
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作者 霍绍彤 张世珍 杨志强 《广州医学院学报》 1998年第1期64-65,共2页
关键词 癌前病变 口腔粘膜炎症 均质型 手术切除 白色念珠菌感染 细胞间变 不良修复体 原位癌 斑块边界 浸润癌
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Intravascular Ultrasound Image Hard Plaque Recognition and Media-adventitia Border Detection
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作者 XING Dong YANG Feng +3 位作者 GAO Jing QIU Xuan TU Sheng-xian Jouke Dijkstra 《Chinese Journal of Biomedical Engineering(English Edition)》 2012年第3期110-116,共7页
Intravascular ultrasound (IVUS) is a new technology for the diagnosis of coronary artery disease, and for the support of coronary intervention. IVUS image segmentation often encounters difficulties when plaque and aco... Intravascular ultrasound (IVUS) is a new technology for the diagnosis of coronary artery disease, and for the support of coronary intervention. IVUS image segmentation often encounters difficulties when plaque and acoustic shadow are present A novel approach for hard plaque recognition and media-adventitia border detection of IVUS images is presented in this paper. The IVUS images were first enhanced by a spatial-frequency domain filter that was constructed by the directional filter and histogram equalization. Then, the hard plaque was recognized based on the intensity variation within different regions that were obtained using the k-means algorithm. In the next step, a cost matrix representing the probability of the media-adventitia border was generated by combining image gradient, plaque location and image intensity. A heuristic graph-searching was applied to find the media-adventitia border from the cost matrix.Experiment results showed that the accuracy of hard plaque recognition and media-adventitia border detection was 89.94% and 95.57%, respectively. In conclusion,using hard plaques recognition could improve media-adventitia border detection in IVUS images. 展开更多
关键词 intravascular ultrasound enhancement media adventitia border hard plaque heuristic graph-searching
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