Growth in the number of studies published in major peer-reviewed journals by U.S. scientists has flattened since the 1990s, according to a new report from the National Science Foundation (NSF).

Emerging Asian nations had large increases in publication numbers, reflecting their growing expertise in science and technology, the report finds. European Union totals also went up.

The report examined articles published in science and engineering journals.

In a statement released today, NSF officials said that despite the leveling of articles published, other evidence that indicates U.S. science and technology capability remains strong. In raw numbers, the United States continues to publish far more articles than any other country.

"In addition to numbers published, one should look at another very important indicator—article quality," said Derek Hill, senior analyst and a coauthor of the report. "The more often an article is cited by other publications, the higher quality it's believed to have. While citation is not a perfect indicator, U.S. publications are more highly cited than those from other countries."

China, Singapore, South Korea, and Taiwan led other countries with a combined average 15.9 percent growth in publications from 1992 to 2003.

Japan's article output rose at an average annual rate of 3.1 percent, five times faster than the United States.

The European Union, which passed the U.S. several years ago in total numbers of articles published, posted an average annual growth rate of 2.8 percent during the same period, more than four times faster than the United States.