From Springer Nature:
The Nature Index 2018 Science Cities supplement published in Nature today includes the first Nature Index global science city ranking. The ranking confirms dominance of China and the United States in research output. Beijing is the top science city globally, followed by New York, Boston, San Francisco and Baltimore.
Besides Beijing, nine other cities in China rank amongst the top 50 cities globally, as measured by the Nature Index, which tracks the authorship of articles in 82 high-quality research journals.* The US accounts for 19 of the top 50 cities. Tokyo (6th) and Paris (8th) are the only cities in the global top 10 that are outside the US and China.