This is the 485th most frequent Russian word.
основе
"Основе" means "basis" or "foundation."
The phrase 'на основе' indicates that the story was created using an ancient legend as a foundation or base.
Этот рассказ был написан на основе старинной легенды.
This story was written based on an ancient legend.
The usage 'на основе' again signifies 'using as a basis or foundation,' emphasizing that the research served as the groundwork for the conclusion.
На основе их исследований был сделан вывод.
Based on their research, a conclusion was made.
Here, 'в основе' means 'at the core' or 'at the fundamental level,' referencing the structural essence of the chemical substance.