The present invention relates to bicyclic heterocycles of general formula wherein Ra, Rb and Rc are defined as in claim 1, their tautomers, their stereoisomers, their mixtures and their salts, in particular their physiologically acceptable salts with inorganic or organic acids and bases, which have valuable pharmacological properties, in particular an inhibitory action on the signal transduction mediated by tyrosine kinases, their use for the treatment of illnesses, in particular of tumoral diseases and of benign prostatic hyperplasia (BPH), of diseases of the lung and of the airways, and the preparation thereof.