過去形と現在完了形の意味の違い

過去形も現在完了形も、過去のある時点に起きた事柄を表すときに使えます。しかし過去形と現在完了形の決定的な違いは、その出来事が現在と何かしら関連性があるかどうかという点です。

例文：”We found him.”　「我々は彼を見つけた。」

It indicates that the action of finding “him” occurred at some point in the past, and there is no specific reference to the present. It’s a straightforward statement of a past event.

例文：”We have found him.” 「我々は彼を見つけた。」

It indicates that the action of finding “him” happened in the past, but there is a connection to the present. It implies that the result of finding “him” is relevant or important in the present context. This tense is often used when the time of the action is not specified or when there’s a focus on the current situation resulting from the action.

例文：”We have found him, and he is on his way here now.”

（参照：chat.openai.com）

同様の説明は、英文法の教科書でも見られます。

The present perfect suggests a connection between something that happened in the past and the present time. The situation or event does not have to continue until the time of speaking, only to have some connection or relevance to the present time.

(Unit 8 Present and past time: review,  page 16, Advanced Grammar in Use Third Edition by Martin Hewings, Cambridge University Press)

現在完了形が論文で使われている例

例文：Ribosome collisions have been shown to be the key cellular trigger for ribosome-mediated quality control in eukaryotic cells that targets problematic mRNAs (Yan and Zaher, 2019).　（引用元：https://www.cell.com/cell/fulltext/S0092-8674(20)30693-0）