中文摘要：

以长江三角洲城市群16个核心城市为样本,运用社会网络分析方法从网络密度、中心性和凝聚子群角度,分析高铁时代前后长三角城市群空间结构特征演变。结果表明：长三角城市群整体网络密度迅速提高;各个城市的点出度和点入度都在不断上升,中心城市对外辐射增强;网络中心势有缓慢下降趋势,城市群存在不对称和不均衡的现象;城市群城市的接近中心度在逐年提高,城市间联系更加紧密;城市群中间中心度呈现逐年下降的趋势,网络结构逐渐趋向均衡;长三角城市群划分成4个子群,大部分子群之间联系强度要大于整体网络密度;高铁建成后长三角城市群空间结构得到优化。为了促进长三角城市群内资源有效配置,既要发挥“一区两点”对外辐射作用,也要改善边缘城市对外交通设施。

英文摘要：

Taking the 16 core cities in the Yangtze River Delta city group as a sample, from the network density,centrality and condensing subgroup, analysis the characteristic evolution of the spatial structure in the Yangtze River Delta city group before and after the high-speed rail Era. The results of the social network analysis： The network density is rapidly increasing in the Yangtze River Delta city group; the outdegree and indegree in each city are on the rise, the external radiation of center cities enhance; network centralization has a slow downward trend, city group exist asymmetric and unbalanced phenomenon; The close centrality of city increased year by year in the city group, the contact among cities become more closely; The betweenness centrality showed a downward trend year by year in the city group,network structure gradually tend to the equilibrium; The Yangtze River Delta city group is divided into 4 sub-groups, the association strength between subgroups is greater than the density of the whole network. Since the completion of highspeed railway, the spatial structure of the Yangtze River Delta city group has been optimized.To promote effective allocation of resources in the Yangtze River Delta city group, the＂one zone two point＂external radiation is played to their role and the edge cities＇ transportation facilities is improved.