| In the first chapter,we briefly introduce the research background and the main results.In the second chapter,we study the following fractional Kirchhoff equation where a,b>0(-△)α is the fractional Laplacian operator with α∈(3/2-3/p,1);Hα(R3)is the fractional Sobolev space;2α*=6/3-2α is the critical Sobolev exponent with 0<μ<2α;g satisfies the Berestycki-Lions-type condition.By using pohozaev identity,truncation technique and the parameter dependent compactness lemma,we prove the existence of positive solutions for small b and large λ.Moreover,we deduce the decay rate of the positive solution as |x|→∞ and its asymptotic behavior as b→0,λ→∞.In the third chapter,we study the following fractional Choquard-Kirchhoff equation where ε>0 is a parameter;s ∈(0,1),a,b>0 are constants,0<μ<2s;(-△)As is the fractional magnetic Laplacian;A:R3→R3 is a magnetic potential;V:R3→R is a positive potential with a local minimum and f is a continuous nonlinearity with subcritical growth.By using the variational methods and the Ljusternik-Schnirelmann theory,we investigate the multiplicity and concentration of positive solutions for the above problem. |