  A recent research shows that particles with a spectrum of a relativistic
Maxwellian plus a high-energy tail can be accelerated by relativistic
collisionless shocks. We investigate the possibility of the high-energy
particles with this new spectrum injected in pulsar wind nebulae (PWNe) from
the terminate shock based on the study of multiwavelength emission from PWNe.}
{The dynamics of a supernova remnant (SNR) and multiband nonthermal emission
from the PWN inside the remnant are investigated using a dynamical model with
electrons/positrons injected with the new spectrum. In this model, the
dynamical and radiative evolution of a pulsar wind nebula in a non-radiative
supernova remnant can be self-consistently described.} {This model is applied
to the three composite SNRs, G0.9+0.1, MSH 15-52, G338.3-0.0, and the multiband
observed emission from the three PWNe can be well reproduced.} {Our studies on
the three remnant provide evidence for the new spectrum of the particles, which
are accelerated by the terminate shock, injected into a PWN.
