排序方式: 共有30条查询结果,搜索用时 515 毫秒
1.
2.
3.
Ce-MCM-48介孔分子筛的合成、表征和催化性能 总被引:7,自引:0,他引:7
尝试以混合模板剂pH调节水热合成掺入铈的介孔分子筛CeMCM48,并采用X射线衍射、高分辨透射电镜、紫外可见漫反射、X射线荧光光谱、氮气吸附脱附测试手段对样品进行表征.结果表明,新合成的掺铈介孔材料仍保持立方介孔的有序结构,有序性及吸附性能得到改善.所合成的掺铈的立方介孔分子筛对环己烷的液相氧化反应的催化活性和选择性较高.CeMCM48催化环己烷氧化反应的转化率较MCM48催化的转化率提高了8.3%~14.2%,对主要产物的选择性提高了63.4%~68.8%. 相似文献
4.
In the past two decades, the in situ X-ray fluorescence (XRF) technology has been developed rapidly in China, which is mainly due to the rapid development of China's economy and the great demand for rapid qualitative and quantitative analysis of elements in geological exploration, environmental protection, and industrial process analysis. In this article, the development of in situ XRF analysis technology in China is reviewed from three aspects, namely in situ XRF analyzers, in situ XRF analysis technology, and applications of in situ XRF analysis technology. The in situ XRF analyzers are divided into four generations, and the technical characteristics of each generation of analyzers are discussed from the perspectives of X-ray excitation source, detector, electronic circuit unit, and digital signal processing. The progress of X-ray spectrum analysis, matrix effect correction, and correction of uneven effect and humidity effect is reviewed. The representative applications of XRF analysis technology in geological and mineral survey, environmental pollution investigation, cultural relic identification, and alloy analysis are introduced. 相似文献
5.
月表Th 元素分布特征对于分析月表岩石成因及化学特征等提供了重要依据。为了减小嫦娥二号伽玛谱(CE2-GRS) 噪声对获取Th 元素分布特征的影响,提出了一种基于噪声调整的奇异值分解(NASVD) 去噪算法。通过伽玛谱预处理、去噪、本底扣除及净峰面积求解等步骤,获得月表放射性元素Th计数率全月分布图。通过与国内外其他方法所获得的Th 元素计数率分布图对比有较高的一致性。与传统伽玛谱去噪算法比较,聚类NASVD算法能有效地去除统计涨落噪声影响,提取出嫦娥二号伽玛谱中的特征峰信息。The distribution of thorium on the lunar surface provides the important evidence for lunar evolution history. It is difficult to obtain the distribution of thorium on the lunar surface from CE2-GRS because of noise in the spectrum. The method for smoothing the spectrum is proposed which is based on cluster NASVD. The counting rate map of thorium on the lunar surface is achieved from CE2-GRS. Counting rate map of thorium gamma-rays shows a surface thorium distribution that is in general agreement with other measurement from LP-GRS and SLENE GRS which have better accuracy. It is more effectively to reduce the noise and get the weak information of characteristic peak used the method of cluster NASVD than other traditional methods for smoothing gamma-ray spectrum. 相似文献
6.
从新疆采集了13件岩矿石样品,用于研究蚀变过程中矿物的元素含量变化特征。成都理工大学研制的IED-6000型原位微区X射线荧光分析仪被应用于获得蚀变过程中矿物的化学和物理数据。这种无损的微区X射线荧光分析仪主要是以低功耗X光管和电致冷Si-PIN半导体探测器为基础,采用毛细管X射线透镜实现微区测量的功能,并且能够集成到任何显微镜上进行测量,焦斑长轴直径约110 μm。通过微区X射线荧光测量,将黝铜矿更正为黄铁矿,提高了矿物鉴定的效率及准确性;在蚀变剖面研究中,矿化岩石样品的长石颗粒都富含Cu和Zn元素,可以作为找矿直接指示元素。Cr,Mn和Co等元素含量与矿化程度呈负相关。 相似文献
7.
8.
Fei Li Zhixing Gu Liangquan Ge Di Sun Xutao Deng Shun Wang Bo Hu Jingru Xu 《X射线光谱测定》2019,48(2):138-150
X-ray fluorescence (XRF) is widely applied as a mature nondestructive testing method, and appropriate improvement of quantitative analysis methods can improve the accuracy of XRF. Artificial neural network is an intelligent information processing system, its developments and application in XRF are reviewed, and representative models (back propagation, radial basis function, genetic algorithm artificial neural network, and others) are discussed in more details in overfitting, generalization, and algorithm efficiency. Potential directions of developing artificial neural network applied in XRF are proposed in this review as a further study. 相似文献
9.
Zhao Jiankun Xing Yiqiang Ge Liangquan Wang Yun Li Tianbin Zhang Qingxian Wu Hexi Li Xiaoyan Liu Yibao 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(9):3807-3817
Journal of Radioanalytical and Nuclear Chemistry - High sensitivity analytical techniques, such as ICP-MS, MIP-AES, XRF etc., in rare earth hydrometallurgy, have drastically developed products... 相似文献
10.
探讨了Th、Sr元素与U伴生的地质学依据以及伴生元素的存在对U含量的FPXRF分析的干扰机理:铀样品中Th、Sr元素的影响主要表现为FPXRF仪器谱上ThLα和SrKα特征X射线对ULα特征X射线的干扰。结果表明,采用U、Th、Sr多元回归模型能有效地校正谱线重叠干扰,应用FPXRF分析铀矿样品中铀含量与推荐值相对误差控制在一定范围内,基本满足野外生产要求。 相似文献