Sign-changing solutions for quasilinear Schrödinger equations with restraint

We study the existence of sign-changing solutions for the quasilinear Schrödinger equation −△u+V(x)u−12u△u2=λ|u|p−1uinRN, with the restraint ∫RN|u|p+1dx=1∫RN|u|p+1dx=1, where λλ appears as a Lagrangian multiplier, 4≤p+1<4NN−2 and V=V(x),x∈RNV=V(x),x∈RN is a given potential.