Social networks and agricultural technology extension Research on the reform of grass-root agricultural technology extension systems Innovative practice and theory of "1+1+N mode"of agricultural technology extension Exploration on motivation for local agricultural technology extension talents Ancient agricultural technology social network and economic action Research on construction of diversified agricultural technology extension system social networks and mental health 并列题名：Research on the reform of grass-root agricultural technology extension systems Innovative practice and theory of "1+1+N mode"of agricultal technology extension