This is Thrilling Wonder Stories for February 1940, cover by Howard V. Brown. The ISFDB entry for this issue is here. I found this version of the cover at Pulp Art. And yes, I know I’ve featured it before as a Tumblr favorite, but really, how could I not feature it again? Just look at it: there’s a blonde-tootsie tube girl, a spaceman (with a ray gun, of course), a white-coated scientist (who also has a ray gun, which he’s firing), some laboratory stuff, and freakin’ dragon. I think this must be the most trope-a-riffic pulp sci-fi cover ever to have graced America’s newsstands.
Fitting the cover, there is some entertainingly insane interior art in this issue, such as this by Alex Schomburg, illustrating John Coleman and Hubert Burroughs’s story “The Lightening men.”
As well another Alex Schomburg piece illustrating Jackson Gregory, Jr.’s “The Secret of the Cyclotron.
You can read and download the entire issue at The Internet Archive.