中国中学数学函数概念百年演变考

1 前言 对动态和变量的描述,推进了函数思想的产生,并且随其发展,函数及其思想方法逐渐在整个数学中占有越来越重要的地位.在中学代数中,函数逐渐从方程图解中分离开,并且函数解析式与函数图象成为联系中学代数与几何的重要纽带.     

Er~(3+),Yb~(3+):glass-Co~(2+):MgAl_2O_4 diffusion bonded passively Q-switched laser

A Co~(2+):spinel passively Q-switched erbium-ytterbium-phosphate glass bonded laser pumped at 940 nm is reported.A pulse energy of 210 μJ, a peak power over 70 kW, and beam quality M~2 parameter of 1.2 are obtained under a pump power of 235 mW. An unbonded laser output experiment with the same dimension of the active material and the saturable absorber as the bonded laser output experiment is carried out. The reason why the output in the bonded laser is improved is determined.