Keywords DNA sequences,characteristic sequences,protein,RNA secondary structure,distance matrix,L/L matrix,normalized leading eigvalue,sequence invariant,structure invariant,minimum free energy.;

• DNA序列;特征序列;蛋白质;RNA二级结构;距离矩阵;L/L矩阵;正规化最大特征值;序列不变量;结构不变量;最小自由能;