How do journal/conference reviewers make sure of the results' integrity for submitted research papers?
They don't. Reviewing papers is volunteer work, which has to be done besides the regular job. So no more than half a day is spent on reading the paper and writing the review. That is enough to filter out obvious scams. But for more sophisticated fraud we rely on people trying to use the results once published and finding out that it does not work. The threat of the subsequent sanctions (and for most, the internalized honor code) is hoped to prevent most fraud.