| This thesis studies the following Kirchhoff type equation-(a+b∫RN|(?)u|~2dx)(?)u+V(X)u=λf(x,u)+|u|2*-2u,u(?)H~1(RN),where dimensionN≥4,a,b,λ>0,V is a positive potential.WhenN=4,f(x,u)=g(x)|u|q-2u,for q=2,we obtain that the above equation has a positive ground state by employing the mountain pass theorem,energy estimation,Nehari manifold and a deduction of Ekeland variational principle;for(?)(2,4),applying Jeanjean monotonicity trick,Pohozaev identity,global compactness lemma,we prove the the existence of ground state for the above equation.Secondly,when N≥5,considering the general nonlinear term f(x,u),we prove the existence of two nontrival solutions for the above equation by defining fibering maps and extremal parameters,combining with the weakly lower semi-continuity of functional and(PS)condition.Finally,utilizing a new method of modifying the minimizing sequence,we solve a problem coming from Remark 1.2 in Xu[J.Math.Anal.Appl,2020]. |