Abstract:  With the increasing complexity of technology and the profound changes in the pattern of innovation resource allocation, it is difficult for enterprises to rely solely on internal resources for R&D innovation. The traditional closed innovation has gradually turned to open innovation, and enterprises have begun to seek external knowledge sources for R&D innovation and gain innovation benefits. Although the external technology acquisition can integrate market resources and improve efficiency of the new product in a short period of time, it may also encroach on the benefits brought by external technology acquisition due to the increase of search cost, information cost and supervision cost. Excessive reliance on external technology is likely to cause the lack of core competitiveness. Therefore, enterprises need to rationally allocate R&D boundaries when formulating technology acquisition strategies, and grasp the balance between internal R&D and external technology acquisition to ensure that external technology acquisition achieves optimal innovation performance.
Numerous studies have focused on exploring complementary and alternative relationships between internal R&D and external technology acquisition, but have reached conflicting conclusions. Based on the current relevant research, there still remains research gaps. Firstly, the existing research explores the relationship between the two technology acquisition activities from a static perspective, without consideration of time factors. Actually, the two types of innovation activities have essential differences. It takes a long time to obtain results through internal R&D, while the external technology acquisition cycle is much shorter. Therefore, the time when the two types of innovation activities have the best impact on the innovation performance of the enterprise may be different.
Secondly, from the perspective of classification, the existing research only makes a simple dichotomy for internal R&D and external technology acquisition, and lacks further classification of technology acquisition mode. According to the nature difference of the partners, the technology acquisition targets are different, so the impact mechanism on the innovation performance is different. It is necessary to further explore the impact of different types of external technology acquisition models on the innovation performance. Based on the associations between enterprises and organizations of different natures, external technology acquisition can be divided into science-based external technology acquisition and market-based technology acquisition. Science-based external technology acquisition refers to the joint with universities and research institutions, and conducts basic science. Market-based external technology acquisition refers to acquiring technology in the market through R&D cooperation with upstream and downstream enterprises, consumers, and competitors, or through technology introduction and purchase. Based on the above research gaps, this paper explores the impact of internal R&D and external technology acquisition from a dynamic perspective, and analyzes the influence mechanism of different technology acquisition modes on innovation performance and the relationship with internal R&D.
We use the data of high-tech private enterprises in Guangdong Province to conduct empirical research on the above problems.The data in this paper comes from the statistical data of the enterprise R&D activities approved by the Guangdong Provincial Department of Science and Technology for the subsidy after the enterprise′s R&D investment. The specific data comes from the financial audit report of the declared enterprise and the table of large and medium-sized industrial enterprises′ scientific and technological projects (B107- 1) and table of science and technology activities of large and medium-sized industrial enterprises (B107-2) that have been reviewed by the relevant management departments. As the empirical data of this paper selects the financial data and R&D data of the enterprise reviewed by relevant departments, the authenticity of the empirical data is guaranteed. After eliminating the invalid data, the sample data in the paper was finally established as: 499 high-tech private enterprises, each sample collected data from 2010 to 2013, and a total of 1996 observations in four years, which constitute the parallel panel data. The fixed effect model was used for analysis and the following conclusions were drawn.
The impact of internal R&D and external technology acquisition on the dynamic impact of corporate patent applications and new product output values is different. Internal R&D has a role in patent applications in the current period and is sustainable. External technology acquisition has a positive impact on the lag phase and a negative impact over time. Further decomposition, science-based external technology acquisition has a significant positive impact and persistence in the current period, while market-based external technology acquisition has no significant impact. For the output value of new products, internal R&D has a significant negative impact in the current period. As time goes from negative to positive, it is the best in one year. External technology acquisitions have a role in the current period and gradually diminish over time. The science-based external technology acquisition lags the best effect in the first phase, and the market-based external technology acquisition plays a role in the current period and changes to a negative influence with time.
There is no simple complement or substitute relationship between internal R&D and external technology acquisition, and different time for patent application and new product output value to be optimal. The market-based external technology acquisition rate has an inverted U-shaped relationship with the patent application, indicating that the market-based external technology has the optimal value for the enterprise patent application. The non-symmetric external technology acquisition rate and the new product output value shows an inverted U-shaped relationship. The current external technology acquisition and the internal R&D on the lag phase have the best impact on the new product output value. The interaction between internal R&D expenditures and different modes of external technology acquisition does not significantly affect the company′s patent applications and new product output.

Key words: internal R&D, external technology acquisition, science-based, market-based