| 摘要 |
A safety hypodermic syringe in which the needle hub of the needle assembly has two sliding grooves respectively coupled to respective small stub rods in the socket at the front side of the barrel so that the needle assembly is moved backwards and received inside the barrel upon a return stroke of the plunger after the service of the safety hypodermic syringe and after a rotation of the plunger through an angle relative to the barrel.
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