维甲酸(RA)是导致多种颅面部发育畸形的致畸剂，其导致的畸形包括鳃弓畸形和腭裂。

Retinoic acid (ra) is a teratogen that induces a variety of craniofacial abnormalities, including branchial arch deformities and cleft palate.

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维甲酸异构体的微柱固相萃取过程包括柱老化、上样、 洗涤、 洗脱以及柱再生等步骤。

The sensitivity was improved more than 100-fold. The extraction procedure included conditioning, loading, washing, eluting and regenerating.

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