Polycentric Progress of the Three Major City Regions in China,2001-2009
研究改进了城市群多中心网络的测算方法，分析了2001-2009年京津冀、长三角和珠三角三大城市群的企业网络演化，发现跨城企业数量增加、区域一体化提升，但核心城市集聚更突出。
Our research firstly review measurement method of polycentric network of city regions and then optimize calculation method combining with characteristics of the headquarter-branch enterprises, on the basis of which, we take evolution research in 2001 to 2009 of polycentric network of three empirical city regions(i.e.Beijing-Tianjin-Hebei city region, the Yangtze River Delta city region and the Pearl River Delta city region). As results, the number of cross- cityenterprises in three city regions increases obviously. The connection of headquarter- branch enterprises become increasingly enhanced among cities. The degree of regional integration improves deeply. Although the polycentric degree of three empirical city regions enhances, hierarchy in city system strengthens at the same time. The agglomeration of multi- location enterprises in core cities is much prominent. The increase of polycentric degree mainly originates from evolution of topology structures of the entire network.