China's Beijing and Shanghai have been named by the Nature Index as China's most scientifically productive cities, which also enjoy the highest city-to-city collaboration in the country.

In an article posted on its website on Wednesday, Nature Index says China's economic rise dramatically boosted research activity across the country, including the two leading cities.

Between 2012 and 2016, researchers in Beijing increased their contribution to papers in the Nature Index by 43 percent, and Shanghai's contribution increased by 22 percent. These trends supported a national growth of 45 percent for the same period, says the article.

The Nature Index is a database of author affiliation information collated from research articles published in an independently selected group of 68 high-quality science journals. The database is compiled by Nature Research.

Last year, Beijing's contribution to journals included in the Nature Index, measured as weighted fractional count (WFC), was 1,693, and Shanghai's was 762. Together, the two cities contributed to more papers than the next dozen cities combined in China, according to the Nature Index.

Beijing and Shanghai both attract the best researchers from across the country and overseas, and incentives for cooperation remain strong.

The number of partnerships between an institution in Beijing and an institution in Shanghai has increased since 2012. The two cities have formed 382 institutional partnerships in 2016, the highest city-pair in the country, figures provided by the Nature Index show.