This article discusses the results of an investigation on discourse representation in a corpus of 34 million words constituted by texts in Brazilian Portuguese from two different genres: the research article and the science popularization article. Drawing on a systemic functional grammar perspective of language and pursuing a probabilistic approach, it focuses on the realization of lexicogrammatical systems of direct discourse representation as enacting interpersonal and social relationships. It is argued that the citation practices employed by writers in the genres (...) studied negotiate discursive distance and are influenced by the status culturally and historically ascribed to scientific knowledge. (shrink)