1. A syringe with a locking structure, comprising: a cylindrical body with a shoulder； a rod； a unidirectional engaging member including a push part protruding from the rod and in contact with the shoulder, as well as a flexible bracket protruding from the rod and separated from the push part the diameter of the flexible bracket is larger than the outer diameter of the pushing part； therefore, when the rod is pushed forward relative to the cylindrical body, causing the pushing part and flexible bracket to pass through the shoulder, the shoulder rests against bkuyu bracket, deflecting it back, and when the rod is pushed back relative to the cylindrical member, the flexible bead locks skobu.2. The syringe according to claim 1, wherein the cylindrical body comprises a cylinder and a needle holder integrated with the cylinder, the bead formed on the inner surface of the cylinder, the rod comprising a stem housing section and an engaging section extending from the stem housing section and placed in the needle holder, sections of the stem body protrude the pushing part and the flexible bracket so that when the stem is pushed back relative to the cylindrical body, the shoulder abuts against the flexible bracket, deflecting it forward, after which the pushing part locked with a flexible bracket. 3. The syringe according to claim 1, wherein the cylindrical body comprises a cylinder and a needle holder integrated with the cylinder, the needle holder comprising a mounting section and a bead formed on the inner surface of the needle holder, wherein the stem comprises a stem body section engaging a section extending from the stem body section and placed in the needle holder and the upper stem section extending1. Шприц с блокирующей конструкцией, содержащий:цилиндрический корпус с буртиком；шток；однонаправленный зацепляющий элемент, включающий в себя толкательную часть, выступающую от штока и соприкасающуюся с буртиком, а также гибкую скобу, выступающую от штока и отделенную от то
