What kind of Science Fiction Did They Have in the Mid-Forties?

DC comics were around for most of the Thirties and all of the Forties. You can be sure that Superman was around. There weren't a lot of science fiction films until the 50's. There were a handful of horror films during the 40's, and a few Sci-fi, but otherwise it's mostly romance, drama, and noir. But nothing really remembered. Your best bet is to look through 40's sci-fi written fiction and old archived DC comics if you can find them, or at least scans of.

Some of the rare examples of 40's Sci-fi film.
The Ape Man, 1943 starring Bela Lugosi
Boom in the Moon, 1946, starring Buster Keaton
Mighty Joe Young, 1949, starring Terry Moore

It was really the space race that inspired science fiction the most.

However, a good alternative would be to research UFO incidents from the time period. Roswell occurred in 1947, so might be a good source of info.

"Bearing ourselves humbly before God ... we await undismayed the impending assault ... be the ordeal sharp or long, or both, we shall seek no terms, we shall tolerate no parlay; we may show mercy – we shall ask for none." ~ Winston Churchill, July 1940

Amazing, Astounding and Wierd Tales published most of the big names of the day- editors were Hugo Gernsback and John Campbell