Particular foods have been shown to boost the production of these neurotransmitters but usually not by enough to make a perceptible difference in the brain.

某些特定食物确实被证明能够促进这些神经递质的产生，但还不足以使大脑产生可见变化。

youdao

At the age I am writing these reminiscences a difference of 4 years is not perceptible.

以我现在写回忆录时的年纪，四年的年龄差别是看不出来的。

youdao

The difference is scarcely perceptible to the average reader.

这种差别一般读者几乎是察觉不到的。

youdao

As he sees it, there's no perceptible difference between the two up to ISO 1600, though looking at his video test we're also hard pressed to distinguish any notable discrepancies at the maximum 6400 setting.

ENGADGET: Canon Rebel T2i / 550D squares off with EOS 7D in video performance test

The other immediately perceptible difference is verticality.

FORBES: BioShock Infinite Preview - Oh, Amber Waves of Pain

President Bushs ability to appeal to the vast majority of Americans who oppose rewarding those who violate our immigration laws will be undercut if no perceptible difference exists between his partys amnesty and the more sweeping one John Kerry promises promptly to enact if elected President.

CENTERFORSECURITYPOLICY: ��Kerry Republicans��