Allowance is made in this Pharmacopeia for the detection of foreign substances by unofficial methods.

该药典中允许通过非法定的方法检测外来物质。

youdao

Jawed vertebrates have the ability to form specific antibodies in response to many foreign substances.

颌类脊椎动物有一种能产生特定抗体以此抵抗外来物质的能力。

youdao

This program studies the human body's response to invasive foreign substances, parasites, and pathogens.

这一方案研究人体对入侵的外来物质的反应，例如寄生虫和病原体。

youdao

Normally, T cells travel throughout the body to detect and fight off foreign substances, such as viruses or bacteria.

CNN: Psoriasis

Another theory is that the initial illness may have created an autoimmune reaction, causing the body's immune system to attack normal cells as if they were foreign substances.

CNN: Post-polio syndrome

One theory to explain why early introduction is important holds that if babies aren't exposed early enough to certain foods, their immune systems will treat them as foreign substances and attack them, resulting in an allergy.

WSJ: Food Allergy Advice for Parents: Start Peanuts, Eggs and More Sooner