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71.
氟钽酸钾中碳存在形式的探讨 总被引:2,自引:0,他引:2
本文从氟钽酸钾(K2TaF6)的生产工艺论述了有机物存在于D2TaF6的可能性。通过K2TaF6低温通氧燃烧前后测定碳的结果比较,以及X射线能谱仪表面分析结果,证实了碳的来源是残留的有机萃取剂。 相似文献
72.
Debprasad Patra Poulami Pattanayak Jahar Lal Pratihar Surajit Chattopadhyay 《Polyhedron》2007,26(18):5484-5490
The reactions of HL 1 [where HL is 1N-(2-pyridyl-2-methyl)-2-arylazoaniline and is formulated as ArN = NC6H4N(H)(CH2C5H4N); Ar = C6H5 (for HL1) or p-MeC6H4 (for HL2) or p-ClC6H4 (for HL3)] with K2PtCl4 and Co(ClO4)3 · 6H2O afforded the (L)PtCl and [(L)2Co]ClO4 complexes, respectively. The HL ligands bind the platinum(II) and cobalt(III) centres in a tridentate (N,N,N) fashion, forming new diazoketiminato chelates upon dissociating the amino proton. The X-ray structures of (L3)PtCl and [(L3)2Co]ClO4 were determined. Redox properties of the new complexes have been examined. 相似文献
73.
Jacques Barrau Ghassoub Rima Tajani El Amraoui 《Journal of organometallic chemistry》1998,570(2):8645
The reactions of the divalent species (ArO)2M (Ar=2,4,6-[(CH3)2NCH2]3C6H2; M=Ge, Sn) with either Me3SiN3, elemental S8, Se or transition metal complexes M′(CO)n+1 (M′=Fe, n=4; M′=Cr, W; n=5) (Ph3P)2Pt·C2H4 have resulted in the isolation of either the new stable formal metallanimines (ArO)2M=N–SiMe3, germanethione, -selone (ArO)2Ge=E (E=S, Se) (the expected formations of the stannanethione and -selone were not observed), or the (ArO)2M=M′(CO)n, (ArO)2M=Pt(PPh3)2 complexes, respectively. The direct oxidation of the (ArO)2M species with various oxidizing agents led to the formation of the corresponding metalloxanes [(ArO)2M–O–]2. All of the chalcogenido- and transition metal–metal 14 complexes have been physicochemically and chemically characterized. The reactions of the (ArO)2Ge=E (E=S, Se) compounds with 3,5-di-tert-butyl-1,2-benzoquinone produced, by extrusion of sulfur or selenium, the dioxametalloles corresponding to the formal addition of the divalent species (ArO)2M to the benzoquinone. A substitution reaction of chalcogen (S/Se) has been observed permitting to go from germaneselone to germanethione. 相似文献
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《Arabian Journal of Chemistry》2022,15(4):103707
Alsophila spinulosa is a tree-like fern, and many evidences suggested that plant polyphenols had the potential therapeutic for Alzheimer s disease (AD). Herein, polyphenols (ASP) was isolated from A. spinulosa leaves and its major constituent were isoorientin and vitexin. ASP displayed excellent antioxidant activity and obvious anti-lipid peroxidation capacity in vitro. ASP improved the survival rate of C. elegans under high temperature by enhancing the antioxidant enzymes activities and decreasing the lipid peroxidation level. Moreover, ASP alleviated β-amyloid (Aβ) induced paralysis and reduced Aβ deposition, decreased reactive oxygen species (ROS) accumulation and improved the level of skn-1 mRNA. In addition, ASP decreased the levels of pdk-1 and akt-1 mRNA in P13K/AKT signaling pathway. In conclusion, ASP may be a potential ingredient for the alleviation of AD. 相似文献
76.
Arsenic-speciation analysis in marine samples was performed by high-pressure liquid chromatography (HPLC) with ICP–MS detection.
Separation of eight arsenic species—AsIII, MMA, DMA, AsV, AB, TMAO, AC and TeMAs+—was achieved on a C18 column with isocratic elution (pH 3.0), under which conditions AsIII and MMA co-eluted. The entire separation was accomplished in 15 min. The HPLC–ICP–MS detection limits for the eight arsenic
species were in the range 0.03–0.23 μg L−1 based on 3σ for the blank response (n=5). The precision was calculated to be 2.4–8.0% (RSD) for the eight species. The method was successfully applied to several
marine samples, e.g. oysters, fish, shrimps, and marine algae. Low-power microwave digestion was employed for extraction of
arsenic from seafood products; ultrasonic extraction was employed for the extraction of arsenic from seaweeds. Separation
of arsenosugars was achieved on an anion-exchange column. Concentrations of arsenosugars 2, 3, and 4 in marine algae were
in the range 0.18–9.59 μg g−1.
This paper was presented at the European Winter Conference 2005 相似文献
77.
《应用光谱学评论》2013,48(1):19-55
ABSTRACT This review is intended to present an introduction to the use of thermal neutron activation analysis (TNAA) as an analytical technique for the determination of elements in almost all kinds of matrices. This method of analysis is generally multi-element and experimental conditions can be designed to be nondestructive to the sample. This review will focus on thermal neutron activation as this technique allows determination of approximately two-thirds of the elements on the periodic chart. There are also more and wider spread facilities in the United States that offer these services. The available facilities are located across the United States and are generally accessible to everyone. The review will also detail the advantages and disadvantages of TNAA compared to other common spectroscopic methods. An outline of the general procedure for performing the analysis of the elements using activation analysis is presented to emphasize the ease of using this technique. The outline is divided into sections that give the general procedure, how to choose the correct nuclear reaction and reaction product, and the main sources of errors that can affect the results of the study. These sources of error are subdivided into general types of errors. The general types of errors are divided into those related to pre-chemistry, problems associated with the irradiation of the samples, errors associated with the use of nuclear constants (cross sections, half-lives, transition probabilities, etc.), the choice of the correct reaction and reaction product, and those associated with the counting of the irradiated samples. The general theory of activation analysis is presented and summarizes the derivation of the equations used and the development of the comparator method of analysis. The comparator method is used to simplify the method by irradiating samples along with standards. This reduces the need for using the nuclear constants and thus reducing errors. The use of radiochemical separations to isolate analytes of choice from the radioactive matrix is also described. Some current literature is also included to give a feel for current applications of the use of thermal neutron activation analyses. The summary also describes some of the different matrices that have been used for analyses. 相似文献
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