There are various research oriented companies where I'd like to do an internship and possibly come back for a full-time position later when I finished my academic education. However, most of those companies explicitly state that they don't offer internships.
On one hand, I'm very interested in gaining experience in the fields of those companies. On the other hand, it seems wrong to apply with having in mind to quit after 6 months or a year. Also, when I want to come back later for a real full-time employment, my chances might be smaller.
Is it acceptable practice to apply for full-time positions and quit after a year or earlier? What would be the implications?