美国的科技论文的数量在在研究的时间段里仍然是第1名，但是它的份额从多于四分之一跌倒了五分之一。

The United States was in first place in both time periods, but its share of publications dropped from more than one in four to about one in five.

youdao

美国的科技论文的数量在在研究的时间段里仍然是第1名，但是它的份额从多于四分之一跌倒了五分之一。

The United States was in first place in both time periods, but its share of publications dropped from more than one in four to about one in five.

youdao