Is the United States losing ground in science? A global perspective on the world science system

Based on the Science Citation IndexExpanded webversion, the USA is still by far the strongest nation in terms of scientific performance. Its relative decline in percentage share of publications is largely due to the emergence of China and other Asian nations. In 2006, China has become the second largest nation in terms of the number of publications within this database. In terms of citations, the competitive advantage of the American domestic market is diminished, while the European Union EU is profiting more from the enlargement of the database over time than the US. However, the USA is still outperforming all other countries in terms of highly cited papers and citationpublication ratios, and it is more successful than the EU in coordinating its research efforts in strategic priority areas like nanotechnology. In this field, the Peoples Republic of China PRC has become second largest nation in both numbers of papers published and citations behind the USA