Abstract:    Due to the tension between the need for innovation and the liability of newness and smallness, innovative SMEs often rely on external cooperation to acquire necessary resources for survival and growth. Such cooperation meets the needs of innovative SMEs but also puts them into a situation that powerful partners may "covet" and "exploit" the innovative technology or innovative knowledge of innovative SMEs, and even realize the technology or market monopoly through controlling or merging the latter ones. From innovation and entrepreneurship perspective, this phenomenon is named as "Sharks Dilemma", which refers to the dilemma of "maintaining resource acceptance relationship with partners and preventing potential opportunistic behaviors" when innovative SMEs establish external cooperation. Confronting the opportunistic behavior of strong partners, most innovative SMEs are often passive and lack of countermeasures. How to make full use of all kinds of resources embedded in the social environment to implement social defense actions has become the key to tackle "Sharks Dilemma".Talking about innovative SMEs, social defense can be understood as a series of measures against opportunistic behavior risk of strong partners. Measures such as patent protection, secrecy, timing, third-party supervision have been proved to be effective to prevent opportunistic behaviors of strong partners in some degree. However, it is worth noticing that the relationship and action among enterprises often exist in a wider environment, and existing literatures show inadequate attention on the relationship between social defense actions and their environment. Institutional theory emphasizes that corporate behaviors are reflections of embedded institutional environment, while institutional logics further reflects the behavior mode of enterprises. From institutional logics perspective, "Sharks Dilemma" can be examined from the perspective of "rules" and "norms", and the internal construct and external relationship of social defense of innovative SMEs can be explained in a more comprehensive way. Therefore, this paper analyzes the connotation and mechanism of social defense from institutional logics perspective and puts forward the theoretical model of social defense mechanism, which contributes to the construction of balanced sustainable ecological practice in enterprise-wide cooperation.This paper conducts exploratory multi-case study combining grounded technique. Based on theoretical sampling, 7 innovative SMEs are selected and analyzed as cases. This paper collects first-hand and second-hand data, and takes sentences or segments closely related to research subject, which have relatively complete and contain non-repetition information as coding unit. By conducting word by word, sentence by sentence and segment coding as the comprehensive strategy, this paper encodes the data via open coding, axial coding and selective coding, and 186 original statements or segments are reserved with 32 concepts and 28 primary categories being extracted. According to the "Condition-Action-Result" paradigm, 28 primary categories based on open coding are grouped into 3 main categories. This paper further extracts the connotation of social defense and analyzes the core category of "social defense mechanism" of innovative SMEs to get the theoretical framework of social defense mechanism. This paper conducts literal replication, theoretical replication and rival analysis as well for testing the preliminary findings, and after within-case and cross-case analysis, this paper summarizes the comprehensive theoretical model of social defense mechanism.The findings are summarized as follows. (1)Social defense is a series of measures to protect key members, corporate control rights and intellectual property by using rules and norms embedded in the institutional context; (2)Social defense mechanism consists of social defense context, social defense measures and social defense targets, which is the unity of behavior, system, relationship and time; (3)Social defense mechanism has the essence of institutional logics, and its measures and actions are unified in the institutional logics framework of rules and norms; (4)Social defense mechanism contains multi-level storyline and there are multiple closed-loop logic structures among the specific measures, the subset of measures and the basic contents; (5) The key members′ protection are the most fundamental part of all the social defense mechanism measures, and only the key members′ protection, corporate control rights′ protection, intellectual property′s protection, taking advantage of the key relationship and timing selection and control are functioning simultaneously and collaboratively can make it possible to protect and preserve the key members, corporate control rights and intellectual property in all directions and time.This research makes some important theoretical contributions in clarifying the connotation of social defense of innovative SMEs, refining the multiple logic of social defense mechanism, revealing the institutional logics essence of social defense mechanism, and structuring a comprehensive theoretical model of social defense mechanism. From the perspective of concept construction and mechanism analysis, this paper clarifies the theoretical connotation and framework of social defense mechanism, expands the application of institutional theory in innovation and entrepreneurial context, promotes the exploration of "Sharks Dilemma", and lays the foundation of concept and analysis framework for subsequent research.This research has some important enlightenments to practice: as founders of a company, ones should learn and grow up fast, which is the key breaking point to deal with the potential threat of the strong partners, and the most basic premise for all defensive measures to be effective; the founders and the managers of innovative SMEs should fully understand and make good use of the policies, laws, regulations and other rules in the environment, as well as the industry customs, examples, orientation and other norms, especially with the help of the existing social ties to form a balanced and enduring cooperative relationship, so as to create good conditions for their own sustainable development.

Key words: innovative SME, institutional logics, social defense mechanism, Sharks Dilemma, multi-case study