It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
Search filters are evaluated on their performance (e.g., validity, sensitivity, specificity, and precision) and are often (but not always) published after their evaluation.
Example of a search filter for randomized control trials:
(Haynes et all., 2005)
The search filters you use will be dependent on your academic field and study type. Below are some starting points to guide you in the right direction. Please note these filters may or may not be well validated.