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801.
The photoelectron spectrum of HCP has been obtained, Ionization potentials are found at 10.79 ± 0.01 eV (X2 Π) and 12.86 ± 0.01 eV (A 2 Σ). By comparison with HCP, a new interpretation of the first photoelectron band of HCN has been proposed which involves a Renner-Teller interaction in the Σ+ vibronic states of the molecular ion. 相似文献
802.
C. Schnier 《Journal of Radioanalytical and Nuclear Chemistry》2002,253(2):209-216
Many unexplained phenomena associated with the radioactive halos in very old minerals are described in the literature. In this paper these phenomena are enumerated. The new hypothesis that a primordial superheavy element (SHE) survived in the earth"s crust can help to solve the problems. According to this hypothesis, the SHE decays by spontaneous fission into fragments of very different mass. The heavy fragments, assumed to lie in the region of the natural decay series, exhibit many indications for a SHE. Additionally, the alpha decay of SHE may occur. Applying the methods of mass spectrometry and X-ray fluorescence can probably prove the existence of SHE. 相似文献
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807.
W. Goessler W. Maher K. J. Irgolic D. Kuehnelt C. Schlagenhaufen T. Kaise 《Analytical and bioanalytical chemistry》1997,359(4-5):434-437
A three-organism food chain within a rock pool at Rosedale, NSW, Australia, was investigated with respect to arsenic compounds by high performance liquid chromatography – hydraulic high pressure nebulization – inductively coupled plasma mass spectrometry (HPLC-HHPN-ICP-MS). Total arsenic concentration was determined in the seaweed Hormosira banksii (27.2 μg/g dry mass), in the gastropod Austrocochlea constricta (74.4 μg/g dry mass), which consumes the seaweed, and in the gastropod Morula marginalba (233 μg/g dry mass), which eats Austrocochlea constricta. The major arsenic compounds in the seaweed were (2′R)-dimethyl[1-O-(2′,3′-dihydroxypropyl)-5-deoxy-β-d-ribofuranos-5-yl]arsine oxide and an unidentified compound. The herbivorous gastropod Austrocochlea constricta transformed most of the arsenic taken up with the seaweed to arsenobetaine. Traces of arsenite, arsenate, dimethylarsinic acid, arsenocholine, the tetramethylarsonium cation, and several unknown arsenic compounds were detected. Arsenobetaine accounted for 95% of the arsenic in the carnivorous gastropod Morula marginalba. In Morula marginalba the concentration of arsenocholine was higher, and the concentrations of the minor arsenic compounds lower than in the herbivorous gastropod Austrocochlea constricta. 相似文献
808.
Zhu Q Hensen EJ Mojet BL van Wolput JH van Santen RA 《Chemical communications (Cambridge, England)》2002,(11):1232-1233
Fe-oxide species in Fe/ZSM-5 (prepared by chemical vapor deposition of FeCl3)--active in N2O decomposition--react with zeolite protons during high temperature calcination to give highly active cationic Fe species, this transformation being reversible upon exposure to water vapor at lower temperature. 相似文献
809.
The Galactosidase repressor (GalR) of Escherichia coli modulates the expression of the gal operon by binding to two DNA operators, OE and O1. The OE and O1 elements are 16 bp pallindromic DNA sequences, differing in four of the base pairs. OE and O1 DNA fragments, both free and complexed with repressor, were analyzed by "quantitative gel electrophoresis". By the criteria of that method, applied to the linear Ferguson plots of both DNA fragments and the linear ranges of those of the DNA-GalR complexes, it was shown that the apparent size of DNA increases upon repressor binding. Moreover, this size increase is greater for the complex with the O1 operator than for the complex with the OE operator in the case that GalR is located in the center of a 155 bp DNA fragment. This is not the case when GalR is located in a peripheral position. By contrast with their size differences, the centrally located GalR-O1 and GalR-OE complexes appear to possess indistinguishable net surface charge densities as judged from the intercepts with the mobility axis. The larger size of the complex with centrally located O1 fragment, as compared with that bearing the OE fragment, is interpreted as being due to bending of the DNA-protein complex, since an authentically bent fragment of a plasmid with bent upstream activator sequence also exhibits a larger slope of the Ferguson plot, and thus the larger size, than predicted on the basis of its DNA chain length (bp).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
810.
The reductive alkylation of amine with carbonyl compounds usingsodium hydrogen telluride has been investigated in recent years.Application of this method to the synthesis of N-alkyl derivativesof biologically important amino acids and their esters is described. 相似文献