Scientific relatedness in solar energy: a comparative study between the USA and China

In this paper, we make use of keywords in scientific articles in null null during the period 2000---2013 to investigate scientific relatedness at the topic level (i.e. relatedness between topic and topic) and the country level (i.e. relatedness between topic and country). The bibliometric analyses show that both publications and knowledge topics exhibit significant rise, and China has exceeded the USA and developed into the largest scientific...