内消旋体（mesomer）分子内含有不对称性的原子，但具有对称因素而使分子内总旋光度为零，即无旋光性。通常以meso或i表示。
n. mesomer
misc. mesomeride
指出了内消旋体消旋原因传统解释的不合理性。
For the reason why optical activity of mesomer is counteracted classical answer was not convincing.
从螺旋理论看，芳香轮烯和非芳香轮烯都是内消旋体和外消旋体的混合物，故都不呈现旋光性。
In the light of the helix theory, aromatic annulenes and non-aromatic annulcncs are all the mixture of the mesomer and raceme, so they haven't opticity activeity.
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