This is the 2344th most frequent Chinese word.
体内
Inside the body.
体内 is used to refer to something located within the body, emphasizing the internal processes or systems.
科学家发现了一种能够提高体内免疫系统的方法。
Scientists have discovered a method to boost the immune system inside the body.
体内 here describes the location where the medication acts, emphasizing the interior context.
药物能够迅速在体内传播并发挥作用。
The medication can quickly spread within the body and take effect.
体内 specifies that the subject of the discussion, hormone levels, resides within the body, highlighting relevance to internal states.