活动星系核(AGN)的宽线区(BLR)(Ⅰ)

The Broad-line Region in Active Galactic Nuclei (Ⅰ)

AGN天体（不包括BLLac天体）的主要特征之一，就是它们的光谱中有宽而强的发射线，因此，这些宽发射线的产生区域BLR为人们提供了一个了解AGN天体物理本质的独特而重要的场所。在文中围绕讨论BLR的基本物理特征，评述近年来有关的理论和观测研究进展及其现状。在文（Ⅰ）中将重点介绍和讨论BLR研究的基本理论框架，即气体云团的光致电离模型以及发射线云团的起源和约束问题。

One of typical characteristics of active galactic nuclei (AGNs, except BL Lac objects) is that strong and broad emission lines apear in their spectra. It is therefore that the broad-line region (BLR), from which broad emission lines come, affords us a unique and important probe of the physics of AGNs. This paper will discuss the various physical conditions of the BLR, review the recent progress and situation in the observations and theoretical studies of the BLR. In paper (Ⅱ), our interests will centre on the size,geometrical structure and kinematics of the BLR.