Abstract: Disclosed in the present disclosure is a support structure and a seat, relating to the technical field of mechanical structures, including a seat frame assembly, a footrest assembly, and a motion-driving assembly, wherein the support structure further includes a first reset elastic member provided on the seat frame assembly and connected to the motion-driving assembly or the footrest assembly, and the first reset elastic member applies a reset elastic force to directly or indirectly drive the footrest assembly to rotate with respect to the seat frame assembly to retract. The support structure and the seat provided in the present disclosure adopts a first reset elastic member to assist footrest retraction, reducing a force required to retract the footrest assembly, with fast retraction speed, providing advantages of convenience, labor-saving and swiftness.

Abstract: Provided is a method for preparing a recombinant human nerve growth factor, which can be used as a therapeutic drug.

Abstract: A switching amplifier includes a plurality of cascade elements, each bridge circuit includes an inductive load coupled between a first leg terminal of one of the at least two leg circuits and a second leg terminal of another one of the at least two leg circuits. A first leg voltage of the first leg terminal have a phase shift relative to a second leg voltage of the second leg terminal, the phase shift is used for causing the inductive load to store electric energy and generating a minimum circulating current?I min or I min sufficient to effect conducting of a corresponding diode; each of the switches is configured to be turned on if the corresponding diode conducts current to effect zero voltage switching of the corresponding switch. The minimum circulating current?I min or I min is equal to a constant value.

Abstract: A switching amplifier includes a plurality of cascade elements, each bridge circuit includes an inductive load coupled between a first leg terminal of one of the at least two leg circuits and a second leg terminal of another one of the at least two leg circuits. A first leg voltage of the first leg terminal have a phase shift relative to a second leg voltage of the second leg terminal, the phase shift is used for causing the inductive load to store electric energy and generating a minimum circulating current—I min or I min sufficient to effect conducting of a corresponding diode; each of the switches is configured to be turned on if the corresponding diode conducts current to effect zero voltage switching of the corresponding switch. The minimum circulating current—I min or I min is equal to a constant value.