Lexical functions (LF) model relations between terms in the lexicon. These relations can be knowledge about the world (Napoleon was an emperor) or knowledge about the language (,destiny- is synonym of ,fate-). In this article, we show that LF instanciation in texts is useful both for semantic analysis (for example, resolution of lexical ambiguities or prepositional attachment and synthesis, i.e. natural language generation. We describe the architecture of a Semantic Lexical Base and the way how LFs are modeled, detected and used. More precisely, we show how each LF is modelled using thematic (conceptual vectors) and lexical (materialised relations between database objects) information and how we exploit the results in the base. We also describe how these functions allow the database to be explored continuously rather than in a discrete way.