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1.
An iron-sulfur compound (Fe3S2) was synthesized at pressures greater than 14 gigapascals in the system Fe-FeS. The formation of Fe3S2 changed the melting relations from a simple binary eutectic system to a binary system with an intermediate compound that melted incongruently. The eutectic temperature in the system at 14 gigapascals was about 400°C lower than that extrapolated from Usselman's data, implying that previous thermal models of Fe-rich planetary cores could overestimate core temperature. If it is found in a meteorite, the Fe3S2 phase could also be used to infer the minimum size of a parent body. 相似文献
2.
Interactions between soil humic substances and metal ions I. Isolation and characterization of the soil humic substances From two horizons of a podzol humic acids and fulvic acids were isolated by two different methods. The obtained samples were characterized by elemental analysis, the determination of the ash and moisture content, functional group analysis as well as FTIR-, 1H-NMR-, and 13C-NMR-spectroscopic examinations. In spite of the different isolation methods humic and fulvic acids show great similarities. A higher oxidized state and a lower content of aromatic structural features are clearly observed in the fulvic acids in contrast to humic acids. Besides aromatic structural elements, distinct aliphatic sections were detected in the investigated samples, which showed a lower concentration in the less transformed fractions of the Ahe-horizon. 相似文献
3.
K.H. Finger 《New Zealand veterinary journal》2013,61(3)
Extract In Europe, during the 18th century, the farm animal population was seriously reduced by the spread of disease due to increased travel and wars between states. At that time, there were no specialists in animal health, but this need was soon met by the founding of veterinary schools in France, Germany and England. 相似文献
4.
5.
Several high-intensity synchrotron x-ray sources have been constructed over the past few years in the United States, West Germany, Great Britain, Japan, France, Italy, and the Soviet Union. Crystallographers have begun to use these facilities for experiments that take advantage of the characteristics of synchrotron radiation, namely, a broad distribution of wavelengths, high intensity, low divergence, strong polarization, and a pulsed time structure. In addition to more familiar diffraction experiments on single crystals and powdered samples, new types of crystallographic studies, for example, energy-dispersive and surface diffraction studies, have progressed rapidly with more general accessibility of synchrotron sources. These high-intensity sources allow diffraction experiments to be performed on very small crystals or on large biological molecules, and permit weak magnetic scattering to be detected Anomalous dispersion experiments can exploit he ability to vary the wavelength of the radiation, and the pulsed time structure of the beam makes possible fast time-resolved experiments. Because of the availability of synchrotron x-radiation, these and other kinds of experiments will be in the forefront of crystallographic research for the next several years. 相似文献
6.
Interaction between soil humic substances and metal ions. II. Investigation of soil humic substances by gel permeation chromatography and vapour pressure osmometry By gel permeation chromatography and vapour pressure osmometry average molar masses of soil fulvic and soil humic acids from two horizons of a podzol were determined. For the fulvic acids average molar masses of 9000 g/mol were obtained by the chromatographic method, while 5000 g/mol were obtained by the osmometric method. In contrast to these results for the humic acids values were measured which are 3 - 4 times larger when measured by gel permeation chromatography and 2 - 3 times smaller when measured by vapour pressure osmometry. The average molar masses found show that the applied methods of isolation and purification as well as the different determination methods with the experimental conditions attached to them have a considerable influence on the molecular size of the isolated humic substances. 相似文献
7.
L R Finger R C Harvey R C Moore L C Showe C M Croce 《Science (New York, N.Y.)》1986,234(4779):982-985
The chromosomal breakpoint involved in the t(8;14)(q24;q11) chromosome translocation in the SKW-3 cell line, which directly involves the 3' flanking region of the c-myc gene, was cloned and sequenced. The breakpoint on chromosome 8 mapped to a position 3 kb 3' of c-myc while the chromosome 14 breakpoint occurred 36 kb 5' of the gene for the constant region of the alpha chain of the T-cell receptor (TCR). The translocation resulted in a precise rearrangement of sequences on chromosome 8 and what appears to be a functional J alpha segment on chromosome 14. Signal sequences for V-J joining occurred at the breakpoint positions on both chromosomes 14 and 8, suggesting that the translocation occurs during TCR gene rearrangement and that it is catalyzed by the enzymatic systems involved in V-J joining reactions. The involvement of c-myc in the translocation and the association of joining signals at the breakpoints provides a parallel to the situation observed in the translocations involving c-myc and the immunoglobulin loci in B-cell neoplasms and suggests that common mechanisms of translocation and oncogene deregulation are involved in B- and T-cell malignancies. 相似文献
8.
Mao HK Jephcoat AP Hemley RJ Finger LW Zha CS Hazen RM Cox DE 《Science (New York, N.Y.)》1988,239(4844):1131-1134
The crystal structure and equation of state of solid hydrogen have been determined directly to 26.5 gigapascals at room temperature by new synchrotron x-ray diffraction techniques. Solid hydrogen remains in the hexagonal close-packed structure under these pressure-temperature conditions and exhibits increasing structural anisotropy with pressure. The pressure-volume curve determined from the x-ray data represents the most accurate experimental measurement of the equation of state to date in this pressure range. The results remove the discrepancy between earlier indirect determinations and provide a new experimental constraint on the molecular-to-atomic transition predicted at higher pressures. 相似文献
9.
Two gustatory systems: facial and vagal gustatory nuclei have different brainstem connections 总被引:3,自引:0,他引:3
The gustatory sense in catfish consists of two dissociable components, a facial nerve system used for food selection and a vagal nerve system involved in swallowing. Neural tracing experiments demonstrate that the primary sensory nucleus for the facial gustatory system is connected to the reticular formation and trigeminal nuclei. In contrast, the primary sensory nucleus for the vagal gustatory system is connected to the motoneurons that mediate swallowing. These results provide anatomical evidence for parallel gustatory systems within the vertebrate central nervous system. 相似文献
10.