This is the 3344th most frequent Russian word.
победителями
"Победителями" means "winners" or "victors" in English.
Here, 'победители' refers to individuals who have won scientific conferences, indicating a nominative case usage.
Эти студенты — победители научных конференций.
These students are the winners of scientific conferences.
Here, 'победителями' indicates that the subjects achieved victory in the competitions by its instrumental case usage.
Они стали победителями соревнований.
They became the winners of the competition.
In this sentence, 'победителями' is used in the instrumental case to express pride about the winners.