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建立了同时测定人尿液中烟碱及其9种代谢物的高效液相亲水作用色谱-串联质谱分析方法。尿液样品经乙腈和甲醇混合溶剂(体积比3∶1)稀释20倍,过0.22 μm滤膜后直接进样。采用Atlantis HILIC Silica 柱(3.0 mm × 100 mm,3.0 μm),以10 mmol/L甲酸铵水溶液(用甲酸调至pH 3.0)-乙腈为流动相进行梯度分离,电喷雾正离子电离模式和多反应监测扫描模式下测定,以同位素内标法定量。结果表明,烟碱及其9种代谢物在各自的质量浓度范围内线性关系良好,相关系数(r)均大于0.997,检出限(LOD)和定量下限(LOQ)分别为0.03~0.24 ng/mL和0.10~0.80 ng/mL;在低、中和高3个加标水平下的加标回收率为81.9%~110%,日间和日内相对标准偏差(RSD)为0.50%~6.7%。该方法操作简单、灵敏度高、稳定性好,能够满足大批量人尿液中烟碱及其9种代谢物的检测需求。 相似文献
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考虑非线性自回归模型xt=f(xt-1,…,xt-p,θ)+∈t,其中θ为q维未知参数,{∈t}为随机误差.在允许误差方差无穷的重尾条件下,构造θ的自加权M-估计,并证明了该估计的渐近正态性.最后通过数值模拟,在随机误差服从某些重尾分布的条件下,说明自加权M-估计比最小二乘和L1估计更有效. 相似文献
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本文就对0.4k V三相四线制系统中性线产生的断线危害进行分析,并找出中性线断线的原因及对策。 相似文献
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A novel neonicotinoid analogue(C13H19N5O5,3a)had been synthesized,the structure was characterized by elemental analysis,IR and 1H NMR spectra,and the S-(+)-(E)-configuration was confirmed by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21 with a = 8.7076(17),b = 8.3211(17),c = 10.642(2),β = 92.370(3)o,V = 770.4(3)3,Z = 2,Dc = 1.402 g/cm3,μ = 0.110 mm-1,Mr = 325.33,F(000)= 344,S = 1.027,R = 0.0543 and wR = 0.1229 for 3601 unique reflections with 2919 observed ones(I > 2σ(I)).Compound 3a is stabilized by intramolecular hydrogen bonds and intermolecular force.In addition,the structure of compound 3a was optimized by the B3LYP/6-31G(d,p).DFT/B3LYP optimizations were performed based on X-ray geometries applying 6-31G(d,p)basis set.The optimized structure of compound 3a by the B3LYP/6-31G(d,p)method is more bent than in the crystal.IR spectrum of the solid compound is consistent with the X-ray structure.The HOMO-LUMO gap in 3a(5.3 eV)indicates high kinetic stabilities of compound 3a.The preliminary bioassay test showed that 3a exhibited good activities against Nilaparvata legen,Pseudaletia separate Walker and Aphis medicagini at 500 mg/L. 相似文献
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