Probably Nature or Science, though they're journals, not magazines. If I recall correctly Scientific American used to be like what you're asking for in that it

Probably Nature or Science, though they're journals, not magazines. If I recall correctly Scientific American used to be like what you're asking for in that it published articles written by practicing scientists aimed at the educated general public, but I think it long ago abandoned that model. If the only reason you don't want to be online is to avoid distractions why not install some software that lets you block access to certain web sites ?