本文研究非线性四阶边值问题 u^(4) (t) = f(t,u(t)),0 〈 t〈 1,u(0) = u'(1) = u″(0) = u"(1) = 0, 的涉及第一特征值π^4/16的正解,其中f(t,x)具有时间和空间的奇异性.在某些适当的假设下证明如果满足下列条件之一,则此问题有一个正解: (i)∫^1 0lim x→+0sup f(t,x)/xdt〈π^4/16 and ∫^1 0 lim inf x→∞ f(t,x)/xdt〉π^4/16; (ii)∫^1 0lim x→+0f(t,x)/xdt〉π^4/16 and ∫^1 0 lim inf x→∞ f(t,x)/xdt〉π^4/16.
In this paper,we study the positive solution concerned with the first eigenvalue π^4/16 Of the nonlinear fourth-order boundary value problem u^(4) (t) = f(t,u(t)),0 〈 t〈 1,u(0) = u'(1) = u″(0) = u"(1) = 0, where f(t,x) has the time and space singularities. Under some suitable assumptions,we prove that the problem has a positive solution if one of the following conditions is satisfied: (i)∫^1 0lim x→+0sup f(t,x)/xdt〈π^4/16 and ∫^1 0 lim inf x→∞ f(t,x)/xdt〉π^4/16; (ii)∫^1 0lim x→+0f(t,x)/xdt〉π^4/16 and ∫^1 0 lim inf x→∞ f(t,x)/xdt〉π^4/16.