6LIEFNER I,HENNEMANN S.Structural holes and new dimensions of distance:the spatial configuration of the scientific knowledge network of China's optical technology sector [ J ].Environment and Planning A 2011,43:810-829.
7BOSCHMA R A.Proximity and innovation:a critical assessment [ J].Regional Studio:s,2005,39:61-74.
8SORENSON O,RIVKIN J W,FLEMING L.Complexity,networks and knowledge flow [J].Research Policy,2006,35:994-1017.
9POWELL W W,WHITE D R,KOPUT K W.Network dynamics and field evolution:the growth of inter-organizational collaboration in the life scien'es [ J 7-American Jottrnal of Sociology,2005,110:1132-1205.
10BALLAND P A.Proximity and the evolution of collaboration networks:evidence from research and development projects within !he global navigation satellite system(GNSS)industry [ J].R'gional Studies,2012,46:741-756.