介绍了近年来Seyfert领域中关于分子环(torus)研究情况和现状。分子环 模型的提出源于2型Seyfert 星系核的光学偏振观测的结果与传统的1型Seyfert 核的观测特征的相似性。在torus结构 存在的假设下，讨论其对观测的作用，阐述了torus可能的结构和演化及其 在Seyfert统一模型中的重要地位。还讨论了torus的遮挡、束流效应和由此造成的多波 段观测特性，着重介绍了散射效应及其造成的偏振。
The study of the molecular torus in seyfert galaxies is introduced. This structure
is suggested from the similarity between the polarization measarements
of Seyfert 2 and the observational data of Seyfert 1. With torus structure hypothesis, we discuss
its effects on observational results, describe
the possible structure and evolution of torus as well as its
importance in the unified model.
The effects of obscuring and beaming, and
multi-waveband properties caused by these effects are described.
The scattering effect and the observed polarization induced by this
effect are emphasized.
Key words active galactic nuclei(AGN)---galaxies: Seyfert---torus---polarization