In+this = em+este = neste. We also have masc/fem, sing/plu. Neste, nesta, nestes, nestas. You'll also see nesse,nessa, nesses, nesses, nisso, nisto.
great! do you know maybe an article on wikipedia for this sort of adjectives and prepositions?
Ive found some links for you: http://www.sonia-portuguese.com/text/pronouns.htm#Demonstrative Pronouns ---- http://www.easyportuguese.com/Portuguese-Lessons/Demonstrative-Pronouns.html --- http://www.nativlang.com/po/qg_pronouns_demonstratives.htm --- http://www.saunalahti.fi/huuhilo/portuguese/gb_demonstrative.htm (to be true, we dont differenciate when the objet is near the speaker - este, esta, isto -or when it's near the person we'e talking to)