TY - PROGRESS IN GEOGRAPHY A1 - LI Yuyang, GU Renxu, WANG Tengfei, BI Xuecheng T1 - Spatial evolution and mechanism of knowledge gatekeepers in the Yangtze River Delta region Y1 - 2021-08-28 00:00:00.0 JF - PROGRESS IN GEOGRAPHY JO - PROGRESS IN GEOGRAPHY SP - 925 EP - 936 VL - 40 IS - 6 UR - {https://www.progressingeography.com/EN/10.18306/dlkxjz.2021.06.003} N1 - 10.18306/dlkxjz.2021.06.003 ER -