Abstract:     Summarizing China′s development experience, the establishment of a systematic and complete industrial structure system under the government′s planning and the continuous innovation, supplementation and improvement of modernization under the influence of the market have made China the only country in the world with all industrial categories. Taking the technological innovation of central cities as the driving force to promote the development of the urban agglomeration industry toward the advanced and diversified model is an important practice path to realize the development of a modern industrial system and promote the optimization and upgrading of the economic system in the new era. However, due to the endogenous and external effects of technological innovation, whether the central city technological innovation agglomeration effect under government guidance and policy empowerment can effectively promote the advancement of the urban agglomeration′s industrial foundation and the development of industrial diversification, and form a reasonable industrial division system. There is still uncertainty. The research attempts to carry out a systematic analysis of this problem.
    The research takes urban agglomerations as the research object, analyzes the relationship between technological innovation in central cities and the advanced and diversified industries of urban agglomerations, and uses historical-geographic materialism time-space restoration theory and evolutionary economic geography theory to compare the endogenous and external technological innovations. The role of endogenous and externality are incorporated into a unified framework, and the theoretical construction and analysis of the relationship between technological innovation in central cities and the advanced and diversified industries of urban agglomerations are carried out from the perspectives of time restoration and space restoration from the three dimensions of macro, medium and micro.
    On this basis, the study examines the relationship between technological innovation in central cities on the advancement and diversification of urban agglomeration industries through a combination of two-way fixed effect nonlinear estimation, endogenous testing, threshold effect model, and moderating effect model. The use of historical dimensional instrumental variables (quantified data from Chinese historical officials, data on ancient Chinese city walls) to carry out endogeneity testing and identification of technological innovation in central cities has enhanced the accuracy and credibility of the research conclusions. The threshold system effect model is used to more accurately identify and estimate the U-shaped structural change points of the central city′s scientific and technological innovation, and the effect and influence mechanism of the moderating effect model on the central city′s scientific and technological innovation are estimated and analyzed, which enhances the scientificity and application of the research conclusions value.
    The research found that: First, the technological innovation of central cities presents a U-shaped effect on the development of urban agglomeration′s industrial advancement and diversification, indicating that the technological innovation of central cities inhibits and then promotes the development of urban agglomeration′s industrial upgrading and advancement. The role relationship: when the number of patent applications for technological innovation and development in central cities exceeds 11,442, it will promote the development of advanced and diversified urban agglomeration industries. Second, the impact of technological innovation in central cities on the advancement and diversification of urban agglomeration industries is restricted by the level of scientific expenditure. The increase in the level of scientific expenditure can further expand the marginal effect of technological innovation in central cities on the advancement and diversification of urban agglomeration industries.

Key words:  central city, urban agglomeration industry development, technological innovation, space-time restoration, evolutionary economic geography