图传不上，就是 反-1，4-二甲基环己烷，在chemdaw上的命名问什么是(1r,4r)-1,4-dimethylcyclohexane？1和4位都不是手性碳呀
小写的，s,s就表示cis, r,r表示trans.
"P-91.2.1.1 Cahn-Ingold-Prelog (CIP) stereodescriptors
Some stereodescriptors described in the Cahn-Ingold-Prelog (CIP) priority system, called 'CIP stereodescriptors', are recommended to specify the configuration of organic compounds, (…), and in the nomenclature of natural products (…). The following stereodescriptors are used as preferred stereodescriptors (…):
(a) 'R' and 'S', to designate the absolute configuration of tetracoordinate (quadriligant) chirality centers;
(b) 'r' and 's', to designate the absolute configuration of pseudoasymmetric centers;"
