共查询到20条相似文献,搜索用时 58 毫秒
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运用毛细管柱气相色谱及外标法定量测定土壤中的氧化乐果、久效磷及乐果等9种有机磷农药残留,相对标准偏差为1.9%~5.3%,两种加标水平的回收率为84.0%~102.8%和80.0%~104.0%.结果表明该分析方法的灵敏度高、精密度好、回收理想、结果准确,完全适用于土壤样品的分析. 相似文献
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采用气相色谱仪配备火焰光度检测器测定蒜苗中8种有机磷农药的残留.试样在前处理过程中先进行微波处理,比较不同微波功率及微波时间对去除含硫化合物的影响,结果证明试样经640W功率下微波处理40s后硫化物去除效果理想,且对8种有机磷农药影响较小.在0.04mg/kg、0.1 mg/kg和0.2mg/kg三个加标水平下,8种有机磷农药的回收率为71.6%~97.1%,相对标准偏差为1.9%~8.6%,检出限为0.007~0.018mg/kg.试验结果均符合蔬菜有机磷农药的检测. 相似文献
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设计了一种十字架金属微结构的太赫兹波吸收器,其结构是将金属十字架置于硅基体之上,基体的背面再覆盖一层金属,以此为单元结构经周期排列组成.针对该太赫兹波吸收器提出了一种等效电路分析模型,通过仿真和加工测试证实了该吸收器的中心吸收频率位于0.571THz,吸收率为99.6%,反射率为0.38%,透过率为0,吸收带宽为29GHz.等效电路模型计算结果与测试结果相吻合.结果表明,提出的等效电路模型分析方法是简单有效的,从而为今后太赫兹波器件的研究提供了一种很好的思路. 相似文献
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研究了AN-AN-TNT-DNT、AN-TNT-DNT-Al两种军民两用硝铵炸药的配方和某些爆炸性能之间的相互关系.结果发现:对于AN-TNT-DNT炸药,随着DNT含量由0%增加到5%,炸药的爆热Qv减少1.6%,比容V0增加1.0%,Qv V0的乘积下降0.6%;随着氧平衡由0%降低-2.50%,炸药的爆热Qv减少2.2%,比容V0增加0.7%,Qv V0的乘积下降1.5%.对于AN-TNT-DNT-Al炸药,随着铝粉含量由0%增至14%,炸药的爆热Qv增加58.34%,比容V0下降15.7%,Qv V0的乘积增加33.5%. 相似文献
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A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling. 相似文献
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An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a
rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate
agreement is demonstrated between the derived relations and experimental data. 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue. 相似文献
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水三相点是开尔文热力学温度的唯一基准点,也是ITS-90国际温标重要的定义固定点。因此,水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来,中国计量科学研究院研制出一系列高质量的水三相点容器,加强了水三相点的研究,为不确定度的分析提供了更为可靠的实验依据。同时,不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此,根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明,其扩展不确定度为0.16mK(k=2.69,P=0.99)。 相似文献
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