A.发汗; B.不发汗; C.两者间的标准差(图4，5同)。

    图3 续断发汗和未发汗样品的原始光谱的光谱图

    Fig.3 The crude spectrum of the crude and sweated Dipsaci Radix

    图4 续断发汗和未发汗样品的一阶求导的光谱图

    Fig.4 The first derivative spectrum of the crude and sweated Dipsaci Radix

    2.2.4 主成分数选择 选取主成分(principal components， PCs)的个数取决于主成分的累计方差贡献

    图5 续断发汗和未发汗样品的二阶求导的光谱图

    Fig.5 The second derivative spectrum of the crude and sweated Dipsaci Radix

    表1 不同光谱预处理方法对性能指数的影响

    Table 1 The effects of different spectrum pretreated methods on the performance index

    光谱预处理方法性能指数

    MSC+spectrum+Ns94.457

    MSC+spectrum+S-G94.466

    MSC+1st D+Ns91.926

    MSC+1st D+S-G91.986

    MSC+1st D+Nd92.308

    MSC+2nd D+Ns85.417

    MSC+2nd D+S-G85.654

    MSC+2nd D+Nd91.710

    SNV+spectrum+Ns94.572

    SNV+spectrum+S-G94.575

    SNV+1st D+Ns91.776

    SNV+1st D+S-G91.821

    SNV+1st D+Nd92.097

    SNV+2nd D+Ns85.270

    SNV+2nd D+S-G85.504

    SNV+2nd D+Nd91.626

    率(cumulative) ......