Theoretical and empirical study of the tariffs protection and dynamic comparative advantage 并列题名：Theoretical and empirical study of the tariffs protection and dynamic comparative advantage Theoretical and empirical study on relation of physical and environmental reproduction Theoretical and empirical study on the operation of urban public service in China theoretical and empirical study of the Pearl River Delta region Theoretical and empirical study on the evolution and optimization of the human-earth system Theoretical and empirical study on cyclical company valuation