When it comes to clinical trials, there is a lot negative data getting buried. Amgen famously was only able to reproduce a small fraction of cancer drug trials. Negative result in a drug trial means your drug doesnt work. But on the flip side, the CDC in the US conspired to destroy positive results showing a link between autism and the MMR vax. They actually had meetings to destroy data. You may have heard about that too.
Some journals have their own positive result bias, absolutely. There is at least one journal of negative results that I know of but in biology it seems a lot more attention is given to positive results. Some of that makes sense, if an experiment discovers nothing it might be inherently less interesting, but it depends on what kind of experiment you're doing. With clinical trials, a negative result is very important. In physics, maybe not as much.