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441.
针对叉车的工作特点,探讨了叉车自动称重系统的设计方法,分析了叉车的受力情况,对系统的组成、信号采集、数据处理进行了研究.重点阐述了二维测力和模糊修正的组合新方法,实现了称重的智能化,保证了受载信号的精确度,同时论述了称重时货物的偏载影响及消除这些影响的措施,实验证明了本系统的有效性. 相似文献
442.
A new method for determination of trace gold (Au), palladium (Pd), and platinum (Pt) in environmental and geological samples by electrothermal vaporization (ETV)-inductively coupled plasma atomic emission spectrometry (ICP-AES) with the use of chelating resin YPA4 as both solid phase extractant and chemical modifier has been developed. The resin loaded with analytes was prepared to slurry and directly introduced into the graphite furnace without any pretreatment. The factors affecting the vaporization behaviors of Au, Pd, and Pt were investigated in detail. It was found that, in the presence of YPA4, Au and Pd could be quantitatively vaporized at lower vaporization temperature of 1900 °C. Compared with the conventional electrothermal vaporization, the vaporization temperature was decreased by 700 °C, and the detection limits for Au and Pd was decreased by a three-fold. However, a little effect of YPA4 on the ETV-ICP-AES determination of Pt was found. Under the optimized conditions, the detection limits (3σ) of Au, Pd, and Pt for this method are 75, 60, and 217 pg, respectively; and their relative standard deviations (R.S.D.) are 4.4, 5.6, and 3.7%, respectively (n=9, C=0.2 μg ml−1). The proposed method has been applied to the determination of trace Pd and Pt in sewage sludge, and the results well agreed with the recommended values. In order to further verify the accuracy of the developed method, a GBW07293 certified geological reference material and an auto catalyst NIST SRM 2557 reference material were analyzed, and the determined values coincided with the certified values very well. 相似文献
443.
444.
本文以硝酸钙为基体改进剂,研究了石墨护原子吸收法测定有机锗化合物和煤飞灰中的痕量锗,同时还研究了各种基体及溶液介质对测定结果的影响。所建立的方法具有简单快速灵敏的特点,适应于测定某些样品中的痕量锗。 相似文献
445.
Cadmium is determined in urine samples collected from patients with age-related diseases. The urine is simply diluted 1:1 with water and placed on a tungsten coil electrothermal vaporizer treated with 200 μg of a permanent Pd modifier. A straightforward vaporization program is used to deliver the Cd vapor to an inductively coupled plasma atomic emission spectrometer. A high resolution spectrometer and a charge coupled device detector provide spectra across a 4.8 nm window encompassing two separate Cd emission lines: 226.5 and 228.8 nm. The limit of detection is 0.2 μg/L at each wavelength, and the linear dynamic range spans three orders of magnitude. The accuracy as measured with a urine standard reference material is 94%. The Pd modifier continues to be effective even after 150 vaporization cycles. Direct analysis of urine with the Pd modifier using simple aqueous calibration solutions provides results that are comparable to those observed after a much more complex method: chelation, extraction, and internal standardization without the modifier. The mean concentrations found by the two techniques differ by only 9%. The permanent Pd modifier allows direct analysis of limited sample volumes with decreased risks of contamination. 相似文献
446.
447.
Summary Gradient elution in micellar electrokinetic chromatography has been proposed as a technique for extending the elution range and adjusting retention factors for optimum values. It is shown that this approach in practice has not only to be evaluated for adjustment of retention factors but also for the reduced efficiency of the chromatographic system arising from alterations in the separation buffer during the run. Stepwise gradient elution, feasible with commercial instrumentation, results in marked peak broadening attributable to effects of the border zone passing the solute zone. 相似文献
448.
449.
塞曼原子吸收光谱法测定含盐调味品中微量铅 总被引:5,自引:0,他引:5
以氯化钯—硝酸作基体改进剂,利用塞曼石墨炉原子吸收法光谱法直接测定调味品中微量铅,免去了复杂的前处理过程,消除了氯化钠的背景干扰,提高了检测效率。方法的加标回收率为88.0%~99.0%,相对标准偏差小于5.0%。 相似文献
450.