A novel kind of alkaloid was isolated from the aerial of Epimedium koreanum Naki. The molecular weight and molecular formula were achieved by FT-ICRMS as 370 128 5012 and C 20H 20O 6N. The molecular structure of the compound C 20H 20O 6N was determined on the basis of spectral analyses as 6-hydroxy-11,12-dimethoxy-2,2-dimethyl-1,8-dioxo-1,3,4,8-tetrahydro-2H-7-oxa-2-azonia-benzo phenanthene. Using electrospray ionization multi-stage mass spectrometry, the structure was confirmed further. The compound was first reported from this kind of plant.
在局部图像特征的研究中,提出了一种用于实时图像匹配的仿射不变快速局部特征(Affine invariant fast local feature,AIFLF)描述方法。在兴趣点的局部邻域内利用归一化的梯度值建立基于仿射不变矩的描述子。模拟实验中,将利用Harris-Laplacian检测子的本文算法与经典SIFT算法进行了对比。结果表明:在识别率相当的条件下,本文算法运行时间明显小于SIFT描述子。在标准评估图片和移动机器人平台拍摄的定位图片构成的数据集下,本文算法在尺度、视角和旋转变换中的匹配效果好于经典的SIFT算子和SURF算子。
