中文摘要：

过滤是住房的生命周期与家庭的生命周期之间相互作用的产物，包括两大支流：以建立经济理论和模型为代表的关注住房的过滤研究、有关居民迁居的强调家庭的过滤研究。过滤理论的地理学视角可以追溯到霍伊特（Hoyt）的扇形模型，提供了关于居民迁居和城市社会空间结构之关系的解释。过滤理论意义主要有：为低收入群体提供合适住房、解释城市微观和宏观空间变化、分析和解释与住房市场有关的社会问题。过滤理论是中国城市转型研究的新视角。

英文摘要：

The filtering theory indicates that when high income groups move out to new houses, the houses left behind by them filter down to lower income groups. In this constant dynamic shifting progress, residents filter up according to their social classes, as houses filter down. The core of the theory is housing units and house- holds. Filtering results from the interaction of life-cycle trajectories of housing units and those of households. The progress is complex because it is the intersection of economic and social forces related to housing and households over time. There are active filtering and positive filtering in act. The mechanism of filtering con- tains three dimensions including ＂qualities of households and housing units＂, ＂command over resources＂ and ＂location in social and geographic space＂. These dimensions influence the function of active and positive fil- tering, and reflect the process and results of filtering. Filtering theory relates to economic, social, geographic and other different fields. The origin and development of the theory is a mutually reinforcing process of aca- demic researches and practice in housing market. The concept of filtering first appeared in Britain in the mid-19th century, but the study and applications of the theory are carried out mainly in the USA. Researches on filtering are divided into two major streams. One began in the late 1940s, focusing on housing units based on economic theory and models. The other began in 1980s emphasizing on households concerning residential mobility. In this kind of researches, the demographic model of filtering process contributes to elaborate a per- spective on social stratification, and combines filtering with social problems. The geographic perspective of filtering theory can be traced back to the sector model developed by Homer Hoyt in 1930s. From this point of view, the concept of filtering is of crucial significance, as it provides an explanation of the relationship be- tween residential mobility and urban social spatial struc