sign change meaning in English

符号变换
符号改变
正负变换

Two positive solutions for second order three point boundary value problems with sign changing nonlinearities
具有变号非线性项的二阶三点边值问题的两个正解
3 . by using the techniques of an explicit criterion to determine the number of real roots of a univariate polynomial in ( [ 13 ] , [ 73 ] ) ; b - net form of bivariate splines function ; discriminant sequence of polynomial ( cf . [ 13 ] , [ 73 ] ) and the number of sign changes in the sequence of coefficients of the highest degree terms of sturm sequence , this paper determines the number of real intersection points two piecewise algebraic curves whose common points are finite . a lower bound of the number of real intersection points is obtained in terms of method of rotation degree of vector field
大连理工大学博士论义：分片代数价线i片代数簇的若十m穴3 ：利用杨路，张景中，侯晓荣在文献v13 ， 73 ）中关于一元多项式实根的显式判准，以及二元样条函数的b网形式，多项式的判别序列和sturm序列的最高次数项系数序列的变号数，本文给出了两个分片代数曲线的丈交点数（假设公共点是有限的）的计算公式。