固相萃取–超高效液相色谱法测定土壤中土霉素、四环素及金霉素

建立土壤中土霉素、四环素、金霉素残留量检测的固相萃取-超高效液相色谱法.向样品中加入Na2EDTA–Mcllvaine–甲醇提取液,振荡离心后,上清液过HLB固相萃取柱净化富集.采用Agilent C18色谱柱(250 mm×4.6 mm,4.6μm),以甲醇–乙腈–0.01 mol/L草酸溶液(体积比为8:8:84)...     

Coherent combining of a fiber laser array via cascaded internal phase control technique

We experimentally demonstrated a cascaded internal phase control technique. A laser array with 12 channels was divided into three sub-arrays and a stage array, and phases of the sub-arrays and the stage array were locked by four phase controllers based on the stochastic parallel gradient descent(SPGD) algorithm, respectively. In this way, the phases of the whole array were locked, and the visibility of the interference pattern of the whole emitted laser array in the far field was ～93%. In additi...     

预应力CFRP筋型钢混凝土受拉构件抗裂度理论分析

为建立预应力CFRP筋型钢混凝土受拉构件抗裂度的计算方法,本文结合规范和文献提出两种抗裂度计算理论:第一种方法是基于开裂阶段中和轴的三种位置分布和平截面假定而提出的一般叠加法;第二种方法是通过界定截面拉压区,并考虑相对偏心距和截面刚度差影响的简化叠加法.借助11根预应力CFRP筋型钢混凝土构件的受拉试验,运用提出的两种方法分别计算抗裂度,结果表明均能较好满足精度要求:一般叠加法的计算结果误差均值约为11％,计算步骤较多;简化叠加法提出了相对偏心距系数和刚度削弱系数,大大优化了计算步骤,最终抗裂度计算值和试验值的平均误差仅约为3％.