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人参中农药多残留的超高效液相色谱-串联质谱分析方法研究 总被引:2,自引:0,他引:2
以传统中药人参为研究对象, 建立一种同时检测人参中46 种农药多残留的基质固相分散-超高效液相色谱-串联质谱(MSPD-UPLC-MS/MS)方法. 前处理方法分别采用N-丙基乙二胺(PSA)和乙腈作为MSPD的分散剂和洗脱剂, 检测方法采用正负离子同时扫描, 利用超高效液相色谱-串联质谱在分时段多反应监测模式下进行定量和定性分析. 大部分农药在5~500 μg/kg 范围内线性关系良好, 在低(10 μg/kg)、中(50 μg/kg)、高(100 μg/kg)三个浓度水平上的添加回收率平均值在70%~110%之间, 相对标准偏差(RSD)小于15% (n=3), 定量限小于0.01 mg/kg, 能够满足农药多残留分析要求. 该方法通用性强、选择性好、灵敏度高、简单廉价. 相似文献
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We report the temperature dependence of the spin pumping effect for Y3Fe5O12 (YIG, 0.9 μm)/NiO (tNiO)/W (6 nm) (tNiO = 0 nm, 1 nm, 2 nm, and 10 nm) heterostructures. All samples exhibit a strong temperature-dependent inverse spin Hall effect (ISHE) signal Ic and sensitivity to the NiO layer thickness. We observe a dramatic decrease of Ic with inserting thin NiO layer between YIG and W layers indicating that the inserting of NiO layer significantly suppresses the spin transport from YIG to W. In contrast to the noticeable enhancement in YIG/NiO (tNiO ≈ 1-2 nm)/Pt, the suppression of spin transport may be closely related to the specific interface-dependent spin scattering, spin memory loss, and spin conductance at the NiO/W interface. Besides, the Ic of YIG/NiO/W exhibits a maximum near the TN of the AF NiO layer because the spins are transported dominantly by incoherent thermal magnons. 相似文献
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素质教育要求学生要学有价值的、必需的数学 ,能运用数学知识从实际问题中抽象成数学模型并解决问题 .近几年中考的数学命题也强调数学在实际生产、生活中的应用 ,这就要求学生要有较强的阅读能力和应用数学的意识 .一次函数是最基本的、又是重要的初等函数 ,是学习其他函数的基础 ,在实际生活、生产实践中有着广泛的应用 .本文就如何根据实际问题写出函数关系式、确定自变量的取值范围和画出函数的图象谈谈自己的一些看法 .一 .正确写出实际问题中的函数关系式写出实际问题中的函数关系式 ,关键是找出自变量和函数的等量关系 ,再依照等量关系列出函数关系式 .二 .正确写出函数自变量的取值范围在实际问题中 ,函数和自变量的取值往往会受到某些条件的限制 ,如时间、路程、油量等等都是非负的 ;三角形的边长、半径、圆的面积等都是正数 .因此 ,写出函数关系式后必须注明自变量的取值范围 ,并用小括号括起来 .若自变量的取值范围是全体实数 ,则无需注明 .要确定自变量的取值范围 ,应根据实际问题中函数和自变量所受限制列出等式或不等式 ,再通过解方程或不等式求得自变量的取值范围 .三 .正确画出一次函数的图象我们知道一次函数的图象是一条直线 ,... 相似文献
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Magnonic devices based on spin waves are considered as a new generation of energy-efficient and high-speed devices for storage and processing of information. Here we experimentally demonstrate that three distinct dominated magneto-dynamic modes are excited simultaneously and coexist in a transversely magnetized ferromagnetic wire by the ferromagnetic resonance(FMR) technique. Besides the uniform FMR mode, the spin-wave well mode, the backward volume magnetostatic spin-wave mode, and the perpendi... 相似文献
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Thickness-dependent magnetic properties in Pt/[Co/Ni]n multilayers with perpendicular magnetic anisotropy
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Chunjie Yan 《中国物理 B》2023,32(1):17503-017503
We systematically investigated the Ni and Co thickness-dependent perpendicular magnetic anisotropy (PMA) coefficient, magnetic domain structures, and magnetization dynamics of Pt(5 nm)/[Co($t_{\rm Co}$)/Ni($t_{\rm Ni}$)]$_{5}$/Pt(1 nm) multilayers by combining the four standard magnetic characterization techniques. The magnetic-related hysteresis loops obtained from the field-dependent magnetization $M$ and anomalous Hall resistivity (AHR) $\rho_{{xy}}$ showed that the two serial multilayers with $t_{\rm Co} = 0.2$ nm and 0.3 nm have the optimum PMA coefficient $K_{\rm U}$ as well as the highest coercivity $H_{\rm C}$ at the Ni thickness $t_{\rm Ni}= 0.6 $ nm. Additionally, the magnetic domain structures obtained by magneto-optic Kerr effect (MOKE) microscopy also significantly depend on the thickness and $K_{\rm U}$ of the films. Furthermore, the thickness-dependent linewidth of ferromagnetic resonance is inversely proportional to $K_{\rm U}$ and $H_{\rm C}$, indicating that inhomogeneous magnetic properties dominate the linewidth. However, the intrinsic Gilbert damping constant determined by a linear fitting of the frequency-dependent linewidth does not depend on the Ni thickness and $K_{\rm U}$. Our results could help promote the PMA [Co/Ni] multilayer applications in various spintronic and spin-orbitronic devices. 相似文献