Global warming caused by greenhouse gas emissions seriously threatens a region's sustainable environmental and socioeconomic development. Promoting industrial restructuring and strengthening technological innovation have become an important path to achieving pollution and carbon reduction as well as the green transformation of economic structure. This paper explored the mechanism of the mediating effect of technological innovation on industrial restructuring and carbon reduction while accounting for the direct effect of industrial restructuring on carbon emissions. Then, based on China's provincial panel data from 2001 to 2019, we estimated the carbon emission intensity using the Intergovernmental Panel on Climate Change (IPCC)'s methods and analyzed its spatiotemporal evolution characteristics. Finally, we constructed a fixed-effect model and a mediating effect model to empirically analyze how industrial restructuring and technological innovation affect carbon emission intensity. The results are as follows: (1) From 2001 to 2019, China's carbon emission intensity showed a continuous downward trend, with a pronounced convergence trend; there were obvious differences in carbon emission intensity between eastern, central, and western regions (western region > central region > eastern region) due to the unbalanced industrial structure. (2) In terms of direct effects, industrial restructuring can significantly reduce carbon emission intensity. The intensity of the effect is inversely proportional to the level of industrial restructuring, and the results of sub-regional tests are similar. Nevertheless, there is an obvious regional difference in the size of the carbon emission reduction effect of industrial restructuring in the east, central, and western regions. (3) In terms of indirect effects, industrial restructuring can reduce carbon emission intensity by enhancing technological innovation, and it acts as a mediating variable in the process of industrial restructuring to reduce carbon emission. Finally, we put forward recommendations for promoting industrial restructuring, strengthening green technological innovation, and properly formulating carbon reduction measures to provide a reference for countries and regions to achieve the goals of carbon neutrality, carbon peaking, and high-quality economic development.

Industrial structure upgrading is an important prerequisite for achieving regional ecological environment protection and high-quality development, and environmental regulation can improve the capacity of scientific and technological innovation and promote industrial structure transformation and upgrading. Based on the panel data of 78 cities in the Yellow River Basin, the relationships among environmental regulation, scientific and technological innovation, and industrial structure upgrading in the Yellow River Basin were analyzed using the mediating effect model and the panel threshold model. The results showed the following findings: (1) Although both formal and informal environmental regulations can promote industrial structure upgrading in the Yellow River Basin, regional heterogeneity and temporal stage characteristics are observed. (2) Transmission mechanism test results show that formal and informal environmental regulations directly affect industrial structure upgrading and indirectly act on it through the level of scientific and technological innovation, showing a significant mediating effect. (3) Taking scientific and technological innovation as the threshold variable, formal environmental regulations have a corresponding relationship with industrial structure upgrading in the form of a broken line, and informal environmental regulations significantly promote industrial structure upgrading after scientific and technological innovation crosses a certain threshold. Finally, we discuss the article and make corresponding suggestions in terms of environmental regulation and technological innovation.