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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 12 (1979), S. 391-392 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isomeric cyclodiphosphazane selenides, R(X)P(NBu1)2P(Y)R (R=OMe or NMe2, X=Se, Y=lone pair; R=OMe or NMe2, X=Y=Se) display large differences (34-122 ppm) in 77Se chemical shift. The 77Se shifts of these and related amino derivatives are well to low field of the 77Se shifts of analogous acyclic phosphorus selenides.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 813-824 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Wurtz-type coupling of a number of representative classes of substituted dichlorosilane monomers was investigated in considerable detail. Low temperature polymerization techniques, including ultrasonic activation, were also studied. Similarly, the effect of dipolar additives on the polymerization process was examined. The conclusions drawn from these studies provide some insight into the selection of useful polymerization conditions for the conversion of various monomer types into linear high polymers.
    Additional Material: 5 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 107-112 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A simple 13C-NMR method for the quantitative determination of polyflavonoid tannin characteristics was developed. The system is effective for use on concentrated (25-50%) solutions of natural and modified tannins. It allows the determination of the average degree of polymerization (DPn) of the polyflavonoid, resorcinol vs. phloroglucinol proportion of the A-ring and catechol vs. pyrogallol proportion of the B-ring. The results obtained are consistent with existing data determined by other techniques. The method was also tried with tannin extract that was modified to form thermosetting adhesive intermediates, and with tannin modified by sulfonation, a common commercial modification for these materials. The results were again consistent with what was expected. The method affords the possibility to follow by a simple technique the variations in DPn and MM̄n (number-average molecular weight) induced by chemical modifications of polyflavonoid tannin extracts and thus to correlate them with relevant structural modifications affecting these parameters. The method is not capable of distinguishing the relative proportions of the four important flavonoid units present in commercial polymeric tannin extract. It can only distinguish the relative proportions of (i) (procyanidins + prodelphinidins) vs. (profisetinidins + prorobinetinidins) and (ii) (prorobinetinidins + prodelphinidins) vs. (profisetinidins + procyanidins). © 1995 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1429-1437 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The crystal orientation distribution in injection-molded bars made from several polypropylene compounds has been investigated using pole figure analysis. The fillers used were glass fibers, chalk, and talc, and some compounds contained one filler and others contained glass fibers plus one or both of the others. All compounds showed strong orientation in the skin with the b-axis of the monoclinic crystals lying preferentially normal to the flow direction and in many cases parallel to the normal to the bar face. This normal direction orientation was very strong in compounds containing talc and is probably caused by crystals forming with their (010) planes on the talc platelet faces, which align themselves parallel to the mold face. Strong orientation persists into the interior of the moldings containing talc, whereas in the other compounds, the orientation at intermediate depths is much less pronounced than in the skin. © 1992 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 5
    Publication Date: 2019-07-13
    Description: The structure of unconfined flames stabilized on a NASA contra-swirl can has been examined. The structure depends on reference velocity and fuel-air ratio, and photographic illustrations of representative examples of each flame type are shown. A highly compact flame is obtained over a narrow band of fuel-air ratios, within the total range over which flames may be stabilized, at high reference velocity (27.8 m/s). The compact structure can only be obtained with careful fuel nozzle location. Chemical concentration profiles, temperature profiles and sodium chloride seeding experiments all confirm the visual impression of compactness. A flame with 50% greater fuel throughput has a much less compact structure, which is reflected in lower maximum temperature, much more complex chemical concentration distributions and a more diffuse recirculation boundary as observed by sodium chloride seeding than in the compact flame. Each of these flames has not only an evident axial recirculation core but also a toroidal recirculation region over the bluff region between the inner and outer swirlers. In contrast, laser Doppler velocimetry measurements carried out on a flame with lower reference velocity (5.65 m/s) do not indicate the presence of a secondary recirculation region in this flame.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Spring Technical Meeting; Mar 28, 1977 - Mar 30, 1977; Cleveland, OH
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  • 6
    Publication Date: 2019-07-13
    Description: The effect of preheat on the temperature and species distributions in propane flames stabilized on a NASA contraswirl can has been examined. Flames with compact stable structure, inner-swirler airflow of 0.0091 kg/s, outer-swirler-plus-bypass airflow of 0.0203 kg/s, and propane injected 1 mm upstream of the inner swirler hub have been selected for detailed study. Over the inlet-air-temperature range from 300 to 673 K the maximum temperature in the flame increased by 40 to 60 K per 100-K increase in inlet air temperature. The point of maximum temperature on the center line approached the exit plane as inlet air temperature was increased. Oxygen, CO, H2, and methane were found together in gas samples taken from the flame, including the regions of maximum flame temperature.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: AIAA PAPER 78-28 , Aerospace Sciences Meeting; Jan 16, 1978 - Jan 18, 1978; Huntsville, AL
    Format: text
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  • 7
    Publication Date: 2019-07-13
    Description: Results are presented for an investigation of the structure of unconfined propane flames stabilized on a NASA contra-swirl can. General flame characterization, flame visualization by sodium chloride, temperature measurements, combustion products analysis, nitric oxide concentrations, and laser anemometer studies are considered. The results are discussed relative to sodium chloride visualization, temperature distributions, chemical composition of flames, nitric oxide distributions, and velocity distributions. It is shown that unconfined propane-air flames can be stabilized downstream of a NASA contra-swirl can under a wide range of airflow rates and fuel-air ratios. However, on increasing fuel input from the lowest at which flames can be stabilized, a compact recirculation zone-stabilized flame is formed. The effect of confinement on changes in flame shape and structure is determined.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: ASME PAPER 78-GT-163 , American Society of Mechanical Engineers, Gas Turbine Conference and Products Show; Apr 09, 1978 - Apr 13, 1978; London
    Format: text
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