1. 注射;打针
    If you have an injection, a doctor or nurse puts a medicine into your body using a device with a needle called a syringe.

    e.g. They gave me an injection to help me sleep...
           他们给我打了一针帮助我入睡。
    e.g. It has to be given by injection, usually twice daily.
           它必须通过注射摄入,通常一天两次。

2. (金钱或资源的)投入
    An injection of money or resources into an organization is the act of providing it with more money or resources, to help it become more efficient or profitable.

    e.g. An injection of cash is needed to fund some of these projects...
           需要现金投入来资助这其中的一些项目。
    e.g. The company is hoping to obtain a £50 million cash injection from the government.
           公司希望从政府那里得到5,000万英镑的现金投入。