Analog is the magazine of "science fiction and fact." They publish stories in which some "aspect of future science or technology is so integral to the plot that, if that aspect were removed, the story would collapse. " They pay 8-10 cents a word, up to 7,500 words. That means payment up to $750. They also publish serials and novellas, up to 80,000 words, at 6 cents per word. To learn more, read their submission guidelines.