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利用高频燃烧红外吸收碳硫仪测定铅精矿中的硫含量。低硫含量(S<5%)铅精矿样品直接称样测定;高硫含量(S>5%)铅精矿样品添加稀释剂后称样测定。对样品称样量、助熔剂类型及用量等条件进行了研究,获得最佳分析条件。通过空白实验测得方法检出限为0.0010%,利用铅精矿有证标准物质进行精密度和准确度验证,方法的标准偏差在0.295%~1.3%之间,结果表明该方法精密度高、准确度好,能够满足铅精矿中硫含量的快速准确测定。 相似文献
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采用微波消解溶解样品,建立ICP-MS法测定硅石中锰、铜、钒、钛、铬5种杂质元素的方法。探讨了溶解样品及消除干扰的最佳方式,选用Sc(10μg/L)为内标,动态反应池(DRC)模式进行测定。方法检出限为0.1mg/kg(51V)~1.66 mg/kg(47Ti),加标回收率在88.6%~109%,相对标准偏差均小于3%。方法快速准确,精密度好,检出限低,适合硅石中5种杂质元素的测定。 相似文献
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烟草中多酚类物质的种类及含量对烤后烟叶的香气品质、烟叶色泽及香吃味有重要影响,有效提取分离与确定烟草中的多酚类物质可提高烤后烟叶的品质,增加烟草制品的经济利用价值。本文详细介绍了溶剂萃取、超声辅助提取、微波辅助提取和超临界流体萃取四种提取烟草多酚的常用方法,以及高效液相色谱法(HPLC)、高效液相色谱-串联质谱法(HPLC-MS/MS)和近红外光谱法三种测定烟草多酚的分析方法,综述了提取分离及分析烟草多酚新技术的研究现状,同时对各方法的优缺点进行比较,并探讨了当前亟待解决的问题及工业化利用前景,使烟草多酚能更广泛地应用于食用、药用等领域,增加烟草多酚的实际应用价值。 相似文献
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Developments of many cardiovascular problems have been shown to have a close relationship with arterial flow conditions.However,current ultrasound/Doppler imaging techniques cannot resolve the complex nature of arterial blood flow.We have recently developed a novel contrast-based echo particle imaging technique(Echo PIV) without angel dependence for non-invasively measuring multi-component flow vectors.This study introduces the Echo PIV principles,system characterization and utility examination to characterize hemodynamics in pipe laminar flow and rotating flow.Echo PIV measurement results show its capability to resolve the complex hemodynamics including proximal flow velocity vectors,and velocity mapping. The Echo PIV method provides an easy,direct and accurate means of quantitatively yet non-invasively characterizing the complex vascular hemodynamics. 相似文献
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Siquan Feng Miao Jiang Xiangen Song Panzhe Qiao Li Yan Yutong Cai Bin Li Cunyao Li lili Ning Siyue Liu Weiqing Zhang Guorong Wu Jiayue Yang Wenrui Dong Xueming Yang Zheng Jiang Yunjie Ding 《Angewandte Chemie (International ed. in English)》2023,62(30):e202304282
Sulfur poisoning and regeneration are global challenges for metal catalysts even at the ppm level. The sulfur poisoning of single-metal-site catalysts and their regeneration is worthy of further study. Herein, sulfur poisoning and self-recovery are first presented on an industrialized single-Rh-site catalyst (Rh1/POPs). A decreased turnover frequency of Rh1/POPs from 4317 h−1 to 318 h−1 was observed in a 1000 ppm H2S co-feed for ethylene hydroformylation, but it self-recovered to 4527 h−1 after withdrawal of H2S, whereas the rhodium nanoparticles demonstrated poor activity and self-recovery ability. H2S reduced the charge density of the single Rh atom and lowered its Gibbs free energy with the formation of inactive (SH)Rh(CO)(PPh3-frame)2, which could be regenerated to active HRh(CO)(PPh3-frame)2 after withdrawing H2S. The mechanism and the sulfur-related structure–activity relationship were highlighted. This work provides an understanding of heterogeneous ethylene hydroformylation and sulfur-poisoned regeneration in the science of single-atom catalysts. 相似文献
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