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91.
面粉、米粉中铅的悬浮进样石墨炉原子吸收法测定 总被引:3,自引:0,他引:3
在食品材料的微量元素分析中。已广泛采用石墨炉原子吸收法作为测试手段,固体进样技术的发展摆脱了繁琐的样品消解过程,从而在很大程度上克服了长期以来令人头痛的化学沾污问题。然而,由于直接固体进样技术称样量小,它要求样品具有高度的 相似文献
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Tafeng Hu Xuxiang Li Jungang Dong Bo Rong Zhenxing Shen Junji Cao Shun-Cheng Lee Judith C. Chow John G. Watson 《中国颗粒学报》2006,4(6):346-351
Indoor dusffall samples were collected in Pit 1 and Pit 2 of Emperor Qin's Terra-cotta Warriors and Horses Museum in Xi'an, Shaanxi Province, China. The morphological and elemental analysis for long-term (〉10 years) and short-term (~0.5 year) dusffall particles and lacquer pieces on the faces of partly assembled warriors were performed with scanning electron microscopy with energy dispersive X-ray spectrometer (SEM/EDX). The results showed that the majority of dusffall samples appeared to be composed of mineral dust particles, fly ash, and biological particles with different elemental compositions. Most of the mineral particles had irregular shapes with smooth edges. Small floccules of calcium sulfate were more frequently observed in long-term dusffall samples than in short-term samples, implying a progressive chemical reaction between continuous dusffall particles and atmospheric sulfur dioxide. Crystals of calcium sulfate were also found near pits on both inner and outer surfaces of lacquer pieces, revealing an acid chemical reaction between sulfur dioxide and lacquer material as the cause of the formation of erosion pits and cracks on surface of lacquer pieces. 相似文献
96.
对槽道纤维悬浮流进行染色线流动显示和流场PIV实验测量,实验中选用的是直径为20μm、长径比为20~100的尼龙纤维。PIV2100处理器被用来加工处理采集的实验数据。槽道长度1.5m,横截面为矩形,尺寸为105×19mm。实验结果说明在Reynolds数相同的情况下,纤维悬浮流比对应的牛顿流更不容易失稳,悬浮流中的纤维起着抑制流场失稳的作用,而且随着纤维体积分数和长径比的增大,抑制失稳的程度也提高。扰动衰减率的最小值随纤维体积分数和长径比的增加而增大,这一效果在大Re数时更明显。 相似文献
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XianaiaoLiu HuizhouLiu JianminXing YuepingGuan ZhiyaMa GuobinShan chengliYang 《中国颗粒学报》2003,1(2):76-79
Superparamagnetic poly(styrene-divinylbenzene-glycidyl methacrylate) (Pst-DVB-GMA) microparticles were prepared via a modified suspension polymerization process. A magnetic fluid was first prepared by a chemical co-precipitation method. Then magnetic microparticles were produced by mixing the monomers and the magnetic fluid with water in the presence of a stabilizer poly(vinyl pyrrolidone) (PVP) to form a suspension, and finally benzoyl peroxide was added to initiate the co-polymerization. The morphology and magnetic properties of the microparticles were examined by TEM and VSM. The spherically shaped microparticles, with a size range of 4 to 7 pm, showed distinct superparamagnetic characteristics. XRD was used to investigate the structure of the magnetite particles dispersed in the polymer matrix. The microparticles with epoxy groups on their surface can be applied directly to the seoaration of biomolecules. 相似文献
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In this study, a coupled regional air quality modeling system is applied to investigate the time spatial variations in airborne particulate matters (PM10), originating from Mentougou to Beijing municipal area in the period of April 1-7, 2004, and the influences of complex terrain and meteorological conditions upon boundary layer structure and PM10 concentration distributions. An intercomparison of the performance with CALPUFF against the observed data is presented and an examination of scatter plots is provided. The statistics show that the correlation coefficient and STD between the modeled and observed data are 0.86 and 0.03, respectively. Analysis of model results illustrates that the pollutants emitted from Mentougou can be transported to Beijing municipal area along certain transport pathways, and PM10 concentration distributions show heterogeneity characteristics. Contributions of the Mentougou sources to the PM10 concentrations in Beijing municipal area are up to 0.1-15 μg/m^3. 相似文献
99.
Dynamic characteristic analysis of a 3-D semi-submerged body as a fluid-structure interaction system
An Arnoldi‘s method with new iteration pattern, which was designed for solving a large unsymmetric eigenvalue problem introduced by displacement-pressure FE (Finite Element) pattern of a fluid-structure interaction system, was adopted here to get the dynamic characteristics of the semi-submerged body. The new iteration pattern could be used efficiently to obtain the Arnoldi‘s vectors in the shift-frequency technique, which was used for the zero-frequency problem. Numerical example showed that the fluid-structure interaction is one of the important factors to the dynamic characteristics of large semi-submerged thin-walled structures. 相似文献
100.
浓悬浮体的屈服应力和最大填充率 总被引:2,自引:0,他引:2
对剪切稀化的浓悬浮体,假设在剪切状态下结构参数变化的速率服从一级动力学关系,在此基础上导出浓悬浮体最大填充率与剪应力、屈服应力与填充率之间关系的数学模型.用硅粉-甘油水溶液及可可粉-可可脂两种悬浮体的实验确认了模型对工业微米级颗粒悬浮体的适用性 相似文献