Historical temperature trends have negative impacts on maize yield gains in most countries such as China approximately at -7 with the important exception of the United States no change按照nature food期刊的

按照Nature Food期刊的标准，检查上面句子的语法。

Historical temperature trends have negative impacts on maize yield gains in most countries, such as China (approximately at -7%), with the important exception of the United States (no change).

该句语法上没有明显错误，符合Nature Food期刊的标准。