共查询到19条相似文献,搜索用时 62 毫秒
1.
2.
3.
应用元素分析-同位素质谱仪(EA-IRMS)和多用途气体制备-连续流稳定同位素质谱仪(GasBench-IRMS)分别测定了来自国内外7个不同国家(澳大利亚、新西兰、西班牙、德国、奥地利、意大利和中国)的83件牛奶样品中碳、氮、氢、氧的稳定同位素比值(δ13 C、δ15 N、δ2 H和δ18 O)。对所测得的数据用SPSS 20.0软件分别进行了方差分析、聚类分析以及牛奶产地的判别分析。从所得结果可见,上述4项稳定同位素比值中的每一项都可获得相关牛奶样品产地来源的若干信息,但还不足以作为相关牛奶样品的溯源地判别的充分依据。而将测试结果进行组合后,对δ13 C、δ15 N和δ2 H三项指标组合交叉检验整体判别正确率达到84.3%,据此采用3项组合指标对牛奶产地进行判别分析,并在此项组合指标的基础上建立了产自7个国家的牛奶的判别模型。对自来这7个不同国家的牛奶盲样进行判别时,可将所测得样品中上述3项稳定同位素的δ值代入所建立的模型中,并比较各模型所得的Y值的大小,其中Y值最大的,即归属于此模型所代表的国家。 相似文献
4.
5.
鸡肉中稳定同位素组成与饲料和饮水关系的研究 总被引:3,自引:0,他引:3
通过稳定同位素质谱技术分析了鸡肉中的稳定同位素1δ3C和2δH值、饲料中的1δ3C值,及饮水中的1δ8O值,研究鸡肉中稳定同位素组成与肉鸡的饲料和饮水的关系,从而为动物产品的溯源技术奠定基础。分别从不同地区采集鸡肉、饲料及饮水样品,测定其1δ3C、2δH及1δ8O值。结果表明:鸡肉和饲料中的1δ3C值呈极显著的正相关(相关系数达0.782,P<0.01),鸡肉中的2δH值和饮水中的1δ8O值呈高度正相关(相关系数达0.816,P<0.01)。说明可以根据鸡肉中的1δ3C、2δH值推断肉鸡的饲料和产地。 相似文献
6.
键合偶联双奎宁手性固定相的制备和手性拆分性能;手性固定相;奎宁;高效液相色谱;拆分 相似文献
7.
含双噻唑高分子及其螯合物的制备和磁性能研究进展 总被引:2,自引:0,他引:2
设计和合成有机及高分子磁性材料是当前国内外十分关注的课题,本课题组在先前研究的基础上,以电子理论和磁性理论为指导,从分子设计出发,合成出含双噻唑新型芳杂环聚合物及其过渡金属离子或稀土离子螯合物,测定了它们的磁性能,研究高分子结构、螯合物组成与磁性能的关系,探索产生磁性的机理.发现本研究体系的高分子螯合物具有顺磁居里温度(Tp)高,剩余磁场(Mr)少,矫顽力(Hc)低,是一类很好的软磁性材料,呈现出有一定特色的磁性能.本文综述了含双噻唑高分子过渡金属螯合物、稀土金属螯合物、纳米碳管接枝高分子及其螯合物的制备和磁性能研究,以及典型螯合物的非常规磁性现象的发现和机理探索研究. 相似文献
8.
9.
10.
11.
12.
O. Gropen M. Sjøvoll H. Strømsnes E. Karlsen O. Swang K. Fægri Jr 《Theoretical chemistry accounts》1994,87(4-5):373-385
Summary Relativistic effective core potential calculations have been carried out for the reactions of Pt, Os, Ir, and Re with H2. The calculations demonstrate the importance of a singly occupied 6s orbital for forming a strong bond. Pt and Ir have low-lying states with such occupancy, whereas Os and Re only attains this through a rather costly excitation. In consequence, the reaction barriers are considerably smaller for Pt and Ir than for Os and Re. 相似文献
13.
14.
15.
Andrey G. Kazakov Julia S. Babenya Taisya Y. Ekatova Sergey S. Belyshev Vadim V. Khankin Alexander A. Kuznetsov Sergey E. Vinokurov Boris F. Myasoedov 《Molecules (Basel, Switzerland)》2022,27(5)
Nowadays, cobalt isotopes 55Co, 57Co, and 58mCo are considered to be promising radionuclides in nuclear medicine, with 55Co receiving the most attention as an isotope for diagnostics by positron emission tomography. One of the current research directions is dedicated to its production using electron accelerators (via photonuclear method). In our work, the yields of nuclear reactions occurring during the irradiation of natNi and 60Ni by bremsstrahlung photons with energy up to 55 MeV were determined. A method of fast and simple cobalt isotopes separation from irradiated targets using extraction chromatography was developed. 相似文献
16.
Kazuhiro Yamamura Makoto Wakeshima Yukio Hinatsu 《Journal of solid state chemistry》2006,179(3):605-612
Structures and magnetic properties for double perovskites Ba2CaMO6 (M=W, Re, Os) were investigated. Both Ba2CaReO6 and Ba2CaWO6 show structural phase transitions at low temperatures. For Ba2CaReO6, the second order transition from cubic to tetragonal I4/m has been observed near 120 K. For Ba2CaWO6, the space group of the crystal structure is I4/m at 295 K and the transition to monoclinic I2/m has been observed between 220 K. Magnetic susceptibility measurements show that Ba2CaReO6 (S=1/2) and Ba2CaOsO6 (S=1) transform to an antiferromagnetic state below 15.4 and 51 K, respectively. Anomalies corresponding to their structural phase transition and magnetic transition have been also observed through specific heat measurements. 相似文献
17.
18.
De Domenico G. Lister D. G. Maschio G. Stassi A. 《Journal of Thermal Analysis and Calorimetry》2001,66(3):815-826
A simple method for the on-line calibration, in which both the heat transfer coefficient and the heat capacity of the reactor
contents are determined, is described for laboratory scale heat transfer calorimeters. The calorimeter is operated in the
isoperibolic mode for the calibration and a constant power is supplied to a resistor placed inside the reactor. The reactor
heat balance differential equation is used to produce a set of linear simultaneous equations with each data acquisition cycle
giving one equation. The heat transfer coefficient and the heat capacity are obtained from this set of equations by linear
least squares. The application of the calibration procedure is illustrated by experiments in which the heat of reaction is
determined on-line fora simulated reaction with first order kinetics and for the hydrolysis of acetic anhydride.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
将镁铝层状双氢氧化物分散在锌盐与尿素的混合液中,加热使尿素水解、锌离子沉淀,经洗涤、干燥、煅烧,再用碳酸钠溶液浸渍、煅烧,得到还原后的氧化锌/镁铝复合氧化物。用X-射线衍射(XRD)、透射电子显微镜(TEM)、氮等温吸附和傅里叶红外光谱(FTIR)等方法对所制备的氧化锌/镁铝复合氧化物的结构和性能进行了表征。以酸性红G为模型污染物评价了其去除效率及光催化活性。碳酸钠还原处理过的氧化锌/镁铝复合氧化物结构发生了改变,氧化锌的晶粒变小,复合氧化物变成了片状结构,其对酸性红G的去除效率也明显提高,质量比为2∶1的氧化锌/镁铝复合物经还原后表现出了良好的光催化活性。 相似文献