This is the 3728th most frequent Russian word.
ученых
The Russian word "ученых" means "scientists" in English.
The word 'ученых' is used here in the context of the genitive plural form of the word 'учёный' (scientist), indicating belonging or association with individuals studied or focused on science.
В конференции принимали участие ученых из разных стран.
Scientists from different countries participated in the conference.
In this sentence, 'ученых' again is in the genitive plural form following 'открытия', showing possession or attribution of the discoveries to the scientists.
Научные открытия ученых изменили мир.
The scientific discoveries of scientists have changed the world.
Here, 'ученых' is in the plural genitive form following the preposition 'о', meaning it is used with a descriptive phrase discussing the works done by scientists.