Finding English-language scholarly articles in Slavic & East European Studies is not very different from finding them for any other topic in the humanities and social sciences. The place to start is with your favorite aggregator (though I recommend trying out several, as they all work differently and have different coverage and relevancy ranking). These tools also increasingly index non-English content. Here is a list of aggregators to try (open as well as those the Library pays for):
Provides access to the highest-quality current and archival scholarly journals, books and grey literature in the humanities and social sciences from and about Central and Eastern Europe.