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21.
George Ellis 《Foundations of Physics》2018,48(10):1226-1245
The present day standard cosmological model is a great theoretical achievement. This chapter surveys the main themes that have arisen and issues that are still oustanding. 相似文献
22.
Titanium Auger electron spectra undergo radical changes similar to oxidation in forming the U2Ti intermetallic compound, whereas uranium spectra are relatively unmodified. These results indicate that Ti is an electron donor species in U2Ti compound formation. 相似文献
23.
B. Ellis J.P. Doumerc P. Dordor M. Pouchard P. Hagenmuller 《Solid State Communications》1984,51(12):913-917
Electrical conductivity and thermoelectric power of polycrystalline Na1?xSrxNbO3 have been measured between 5 and 300 K for various compositions. The results suggest that the density of states is finite at the Fermi level, whilst the carrier mobility is activated. The observed behavior is attributed to an Anderson localization of states at the Fermi level due to disorder resulting from either a random distribution of Sr2+ and Na+ ions or from the polycrystalline character of the samples or from both effects. 相似文献
24.
Ellis PC Pivarnik LF Thiam M Ellis PC Pivarnik LF Thiam M 《Journal of AOAC International》2000,83(4):933-943
Nine collaborating laboratories tested a combination of 23 seafood samples for volatile bases using an ammonia ion selective electrode. Results were reported as mg NH3/100 g fish, but the method reflected levels of both ammonia and trimethylamine, which permeated the ammonia membrane. The 23 samples were broken down into 8 blind duplicate pairs, 2 Youden matched pairs, and 3 single samples covering fresh to spoiled product ranging from 8 to 82 mg NH3/100 g. Seven species were evaluated: Atlantic cod, squid, Atlantic halibut, gray sole, monkfish, dogfish, and Atlantic mackerel. The ammonia electrode assay was performed on an aqueous homogenate consisting of 95 mL distilled water and 5.0 g sample tissue. Alkaline ion strength adjusting solution (2 mL) was added to the homogenate to liberate ammonia that was sensed by the ion specific electrode and measured on a precalibrated portable meter. Repeatability standard deviations (RSDr) ranged from 4.2 to 17%; reproducibility standard deviations (RSDR) ranged from 8.8 to 21%. A standard ammonium chloride solution was provided to all laboratories to spike 3 different samples at 10 mg NH3/100 g. Recoveries of added ammonia as ammonium chloride for fresh, borderline, and spoiled samples were 88.6, 107, and 128%, respectively. 相似文献
25.
Photoionization threshold measurements have been carried out for small Li(NH3)n clusters (n = 1-5) and have been combined with ab initio calculations to determine structural information. The calculated adiabatic ionization energy for the lowest-energy isomer of each cluster is found to be in excellent agreement with the corresponding experimental photoionization threshold, providing evidence that the calculated structures are correct. The combination of the photoionization efficiency curve and the calculated adiabatic ionization energies also confirms the tentative assignment of the infrared spectrum of Li(NH3)4 reported by Salter and co-workers (J. Chem. Phys. 2006, 125, 34302); i.e., the 3 + 1 isomer does not contribute and the spectrum is due solely to the 4 + 0 isomer. The findings are consistent with an inner solvation shell that can hold a maximum of four ammonia molecules around the central lithium atom. 相似文献
26.
Nicole A.S. White Henry A. Ellis Peter N. Nelson Paul T. Maragh 《The Journal of chemical thermodynamics》2011,43(4):584-590
Thermotropic phase transition temperatures, enthalpies and entropies of phase changes and odd–even alternation, in a homologous series of anhydrous lithium n-alkanoates, LiCnH2n?1O2 (LiC8–19 inclusive), have been investigated by differential scanning calorimetry (d.s.c.), hot stage polarizing microscopy and solid state 13C NMR spectroscopy. The number of phases observed, between the room temperature microcrystalline solid and isotropic melt, shows a clear dependence on chain length. For LiC8–13, only one intermediate lamellar II crystalline phase is observed. For LiC14–19, a lamellar II and high temperature phase are evident. The high temperature phase is characterized by pre-melting and disordering of hydrocarbon chains as they change from nearly all-trans to one with increased gauche conformers. It is probably a solid rotator phase. Odd–even alternation in melting temperature, density and some thermodynamic data result from the relative distance between methyl groups, from opposite layers in a bi-layer. Molecular models indicate that the methyl groups in odd chains are more favourably orientated which lead to a more energetically favoured staggered conformer. As a consequence, the methyl groups, for odd chains, are in closer proximity than even chains. This subtle change in the molecular lattice could account for the presence of polymorphic structures on cooling from the melt. 相似文献
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The structure of the product obtained from the reaction of potassium amide in liquid ammonia on 1,5-naphthyridine has been identified as 4-amino-1,5-naphthyridine by comparison with a known sample. The 2-amino isomer was not detected in the mixture. The NMR spectra for 2-and 4-amino-1,5-naphthyridine along with the corresponding chloroisomers are described. 相似文献
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