| 摘要 |
A hypodermic syringe (1) comprises a barrel (2) and a needle (3) with an adjustable stop (6) to limit the needle penetration depth. The barrel contains a spring-loaded piston (5) forming a variable-volume chamber (8) which is filled with the fluid to be injected when the piston is withdrawn against the action of the spring. The piston spring is fitted with one end against the piston and the other against a stopper in the end of the barrel, which has an aperture through it for the piston rod, tipped by a stabiliser. The piston can be held in the retracted position by an anchoring element until required for use.
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