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81.
82.
83.
The way data is presented can seriously affect the ease with which it can be understood. The objectives and results of a survey of different types of presentation are given. Some psychological aspects of the problem are analysed. 相似文献
84.
The recent growth in the use of digital radio is reviewed. The technology used to implement low-power digital radio in the local exchange loop plant is discussed. The integration of digital radio subscriber loops withnetwork intelligence is explored. The relationship between low-power digital radio loops and broadband fiber loops is briefly examined, and standards and frequency allocation activities are summarized 相似文献
85.
Iron(III) oxide tablets were electrolytically reduced to iron in molten sodium hydroxide at 530 °C and recovered to produce
iron with 2 wt.% oxygen suitable for re-melting. The cell was operated at 1.7 V and an inert nickel anode was used. The thermodynamics
and mechanism of the process was also investigated. By controlling the activity of sodium oxide in the melt, the cell could
be operated below the decomposition voltage of the electrolyte with the net sequence of events being the ionization of oxygen,
its subsequent transport to the anode and discharge leaving behind iron at the cathode. A reduction time of 1 h was achieved
for a 1 g oxide tablet (close to the theoretical reduction time predicted by Faraday’s laws) at a current density of 520 mA cm−2 with iron phase yields of ∼90 wt.%. The energy consumption was 2.8 kWh kg−1. 相似文献
86.
This paper analyses inter-organizational networks that link together firms operating in the food processing and distribution industry in the UK. In doing so, the paper draws on insights recently developed by Mark Casson that treat inter-firm networks as an institutional response to the changing costs and opportunities of information management. Detailed analysis of product innovation and supply-chain management issues within the industry, exemplified by the growth of chilled ready-meals, leads to the identification of two distinct but complementary inter-firm networks: a network of control and a network of innovation. In each case, the study finds that the critical information is derived from the retailers' interface with consumers and thus that these information-based networks are effectively controlled by the leading supermarket chains. The study's conclusions are considered in relation to the recent findings of the UK Competition Commission following its investigation into grocery retailing in Britain. 相似文献
87.
M. J. Hendrickson R. P. Cox J. C. Konen 《Journal of the American Oil Chemists' Society》1948,25(3):73-77
Conclusions An alkaline-solution technique has been developed permitting the study of the drying and aging process of an oil film using
the ultraviolet spectrophotometer. This technique has been found to be a valuable tool for investigating some of the chemical
changes which occur as a vegetable oil film dries and ages.
The drying or autoxidation of an oil film has been shown to proceed along the general lines of a three-stage reaction with
the short initial stage being characterized by an accumulation of conjugated diene and triene structures which reaches a maximum
at the time the film has set up or becomes continuous. The second or curing stage was characterized by a slow decrease in
the measurable conjugated diene and triene structures. The third or deterioration stage was not investigated; however, this
method should be readily adaptable to studies involving film breakdown as represented by phenomena such as after-yellowing
since the development of absorption peaks characteristic of linolenic ketones, for example, would permit an early prediction
of yellowing long before the concentration of the chromophore groups became great enough for visual observation.
During the initial stage of drying there was also evidence for an increase in the alpha-keto structures capable of enolizing
in alkali to give absorption maxima characteristic of triene and tetraene conjugated systems. These enolizable structures
also decreased in amount during the film curing period and are not characterizable on the basis of observed absorption maxima
and published information.
The method of obtaining a spectral solution of a dry, infusible oil film through the medium of alcoholic KOH was applied to
investigations on the relationship existing between the light absorption of the film solution and the durability or weather
resistance of the straight oil film. The results obtained verified the principle previously reported that the quantity of
light absorbed by an oil film in the region of 320–400 mμ was indicative of the durability of the film upon exposure to accelerated
weathering conditions. 相似文献
88.
Human gene for physical performance 总被引:2,自引:0,他引:2
89.
SL Alam JD Satterlee JM Mauro TL Poulos JE Erman 《Canadian Metallurgical Quarterly》1995,34(47):15496-15503
The cyanide-ligated form of the baker's yeast cytochrome c peroxidase mutant bearing the mutation Asn82-->Ala82 ([N82A]CcPCN) has been studied by proton NMR spectroscopy. This mutation alters an amino acid that forms a hydrogen bond to His52, the distal histidine residue that interacts in the heme pocket with heme-bound ligands. His52 is a residue critical to cytochrome c peroxidase's normal function. Proton hyperfine resonance assignments have been made for the cyanide-ligated form of the mutant by comparison with 1-D and NOESY spectra of the wild-type native enzyme. For [N82A]CcPCN, proton NMR spectra reveal two significant phenomena. First, similar to results published for the related mutant [N82D]CcPCN [Satterlee, J. D., et al. (1994) Eur. J. Biochem. 244, 81-87], for Ala82 mutation disrupts the hydrogen bond between His52 and the heme-ligated CN. Second, four of the 24 resolved hyperfine-shifted resonances are doubled in the mutant enzyme's proton spectrum, leading to the concept that the heme active site environment is dynamically microheterogeneous on a very localized scale. Two magnetically inequivalent enzyme forms are detected in a pure enzyme preparation. Varying temperature causes the two enzyme forms to interconvert. Magnetization transfer experiments further document this interconversion between enzyme forms and have been used to determine that the rate of interconversion is 250 (+/- 53) s-1. The equilibrium constant at 20 degrees C is 1.5. Equilibrium constants have been calculated at various temperatures between 5 and 29 degrees C leading to the following values: delta H = 60 kJ mol-1; delta S = 0.20 kJ K-1 mol-1. 相似文献
90.