Abstract:    The strategic issue on how appropriation strategies influence forms of open innovation activities needs to be solved for open innovation firms. It especially matters for entrepreneurial firms with strong demands for external knowledge, technology and other resources. This dual need for openness and protection makes it difficult for firms to make comprehensive management decisions when reaching the optimal profit point, so firms must understand the direct relationship between exclusive strategies and open innovation, which also caused scholars to explore the paradox of openness. In fact, the paradox of openness is the conflict and game between core firms and other participants in open innovation activities. The discussion on the relationship between appropriation strategies and open innovation will help to solve the paradox of openness, and provide a decision-making support when firms to weigh "openness" and "protection". Thus, this issue has been the focus of the open innovation research and appropriability literature in the academia.Based on the signaling theory, this paper empirically explored the asymmetric influences of appropriation strategies on formal and informal open innovation, and the moderating role of entrepreneurial orientation. The rationale is that appropriation strategies can be interpreted as signals of quality and protection. Appropriation strategies will fit well with contractual situation, which positively affect potential partners′ willingness to collaborate in formal open innovation activities. However, appropriation strategies will be incompatible with loose and non-contractual exchanges and restrain potential actors′ willingness to engage in informal open innovation activities. Entrepreneurial orientation will thus exert a positive effect on their relationships. To test hypotheses, we use an innovation survey with a sample of 764 manufacturing firms and adopt the negative binomial regression analysis.The findings showed that appropriation strategies have positive influences on formal open innovation, whereas exhibit an inverted U-shaped influence on informal open innovation. These findings demonstrated that there is an asymmetric influences of appropriation strategies on formal and informal open innovation. Entrepreneurial orientation can significantly strengthen the positive influence between appropriation strategies and formal open innovation. It also positively moderates the inverted U-shaped relationship between appropriation strategies and informal open innovation.This paper will contribute to the existing research in two aspects. First, this research will deepen the theoretical explanation of appropriation strategies as signals, and reveal the influence mechanism how appropriability relate to open innovation. Second, this research will introduce entrepreneurial orientation and clarify the boundary condition under which firms are more likely to engage in formal or informal open innovation activities.This paper will also provide some implications for making innovation-related policies. On the one hand, government departments should do a good job in the top-level design of intellectual property protection policies, encourage firms to establish their own intellectual property protection systems, guide enterprises to choose appropriate open innovation forms, and help firms better obtain and utilize external resources. On the other hand, government departments should encourage firms in open innovation activities to build entrepreneurial orientation, and promote continuous open innovation by grasping valuable entrepreneurial opportunities.

Key words: appropriation strategy, formal open innovation, informal open innovation, entrepreneurial orientation