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  • Analytical Chemistry and Spectroscopy  (96)
  • SOLAR PHYSICS  (83)
  • 1980-1984  (179)
  • 1984  (179)
  • 1
    Electronic Resource
    Electronic Resource
    15N and 13C NMR study of the effects of hydrogen bonding and protonation in linear schiff bases: Models for structural studies of rhodopsin and bacteriorhodopsinPart 4 of the series ‘Spectral Studies of Visual Pigments and Related Systems.’ For part 5, see Ref. 9. Dedicated to the memory of Professor Margaret Avram. (1984)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 22 (1984), S. 121-124 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of protonation and hydrogen bonding in linear Schiff bases obtained from n-butylamine with butyraldehyde, crotonaldehyde, sorbaldehyde and all-trans-retinal were studied by means of 15N and 13C NMR. The protonation-induced chemical shifts (Δδ) are an order of magnitude larger for 15N than for 13C. For 15N, this effect was found to increase with the extent of conjugation, culminating in the retinylideneimine (Δδ = -146 ppm), which constitutes a model for the study of the structure of the Schiff base linkage in visual pigments and related systems. Theoretical calculations of protonation-induced Δδ values based on MINDO/ 3 are in agreement with experimental results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270220214
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    HPLC, mass spectrometry, and LC/MS of gossypol and its derivatives (1984)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 7 (1984), S. 196-202 
    Details
    ISSN: 0935-6304
    Keywords: Liquid chromatography, HPLC ; LC/MS ; Mass spectrometry ; Field desorption ; Chemical ionization ; Gossypol ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conditions are reported for the reverse-phase HPLC analysis of gossypol and of some of its derivatives, including anhydrogossypol, gossypolone, gossypol hexaacetate, and Schiff's base derivatives. It is shown that field desorption (FD) and chemical ionization (CI) mass spectrometry have advantages over electron impact (EI) mass spectrometry for the characterization of these compounds and that combined high-performance liquid chromatography/mass spectrometry (LC/MS), especially when used in the CI mode, is particularly effective.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240070405
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A 13C and 1H NMR study of the geometries of the 1,3-dicyanoallyl anion: Thermal and photochemical interconversion (1984)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 22 (1984), S. 167-170 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glutacononitrile (1,3-dicyanopropene) (2) was converted to its anion (1) by treatment with sodium hydride in tetrahydrofuran. Both 13C and 1 NMR showed that the sodium salt of 1 in THF existed in three slowly interconverting geometries (U, W and S). These geometries were present in similar amounts but the relative amounts of each proved to be concentration dependent. Irradiation of a 0.01 M solution of 1 at -80°C led to the conversion of a mixture of the U, W and S forms of 1 to only the W and S forms. Upon warming to 0°C equilibrium was re-established with a half-life of approximately 8 h.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270220307
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  • 4
    Electronic Resource
    Electronic Resource
    A comparison of thermospray and direct liquid introduction high-performance liquid chromatography/mass spectrometry for the analysis of candidate antimalarials (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 616-621 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analysis of antimalarials by high-performance liquid chromatography (HPLC)/mass spectrometry demonstrates a new dimension in specificity along with increased sensitivity compared to conventional HPLC detection methods. Both direct liquid introduction and thermospray HPLC/mass spectrometry interfaces provided molecular weight information as well as characteristic fragment ions for antimalarials not normally amenable to direct probe or gas chromatographic/mass spectrometric techniques. The direct liquid introduction interface, which incorporated a 1/100 split, showed a detection limit of 30 ng using selected ion monitoring. The thermospray technique showed less than 1 ng detection limits using selected ion monitoring.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200111205
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  • 5
    Electronic Resource
    Electronic Resource
    Quantitative light element analysis using an energy dispersive detector. 1-Dead time and the low-energy spectrum (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 13 (1984), S. 69-77 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A study of the low-energy region (below 1. 5 keV) of energy dispersive x-ray spectra has been carried out. Firstly, because some counting systems do not provide a reliable dead time correction, a new method of dealing with the problem is given. Next, the effects of different positioning of the energy discriminator within the analyser circuitry are discussed with reference to the consequences for light element analysis. Electronic noise counts can present a problem for analysis of x-rays of less than 300 eV and a straightforward method for noise removal is described. Finally, an unexpected artifact in the spectrum below 500 eV is identified; its size is related to the total number of counts in the spectrum and a practical method of dealing with it is demonstrated. Once the above factors have been taken into account a low energy spectrum is produced, consisting solely of characteristic x-ray lines and a true continuum background.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300130207
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  • 6
    Electronic Resource
    Electronic Resource
    Quantitative determination of nitroglycerol in human plasma by gas chromatography negative ion mass spectrometry using 15N labelled nitroglycerol as internal standard (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1984), S. 276-277 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Negative ionization resulted in the simplification of a previously published method. The new method permits the determination of 0.25 nmol l-1 nitroglycerol in plasma with a coefficient of variation of 9.1%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200110605
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  • 7
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    Thermal bifurcation in the upper photosphere inferred from heterodyne spectroscopy of OH rotational lines (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Low-noise (S/N greater than 100), high spectral resolution observations of two pure rotation transitions of OH from the solar photosphere are used to make inferences concerning the thermal structure and inhomogeneity of the upper photosphere. It is found that the v = O R22(24.5)e line strengthens at the solar limb, in contradiction to the predictions of current one-dimensional photospheric models. The results for this line support a two-dimensional model in which horizontal thermal fluctuations in the upper photosphere are of the order plus or minus 800 K. This thermal bifurcation may be maintained by the presence of magnetic flux tubes and may be related to the solar limb extensions observed in the 30-200-micron region.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 94; 57-74
    Format: text
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  • 8
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    A reexamination of rotational and tangential discontinuities in the solar wind (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: An analysis is made of interplanetary tangential and rotational solar wind discontinuities (TD and RD) and comparisons are made between the features of RDs and TDs. An ISEE 3 field and positive ion data set from 1978 includes high time resolution magnetometer data and is used for the comparisons, as are data from a positive ion analyzer. The field magnitude of RDs remains constant as the field rotates, while that of a TD passes through a local minimum. First and second adiabatic invariants for protons and He abundances are usually also conserved for RDs but not for TDs. The velocity change for an RD across a discontinuity is smaller than that predicted by MHD theory. Finally, plasma conditions at a discontinuity more closely resemble RDs than TDs.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 5395-540
    Format: text
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  • 9
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    On the identification of normal modes of oscillation from observations of the solar periphery (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The decomposition of solar oscillations into their constituent normal modes requires a knowledge of both the spatial and temporal variation of the perturbation to the Sun's surface. The task is especially difficult when only limited spatial information is available. Observations of the limb darkening function, for example, are probably sensitive to too large a number of modes to permit most of the modes to be identified in a power spectrum of measurements at only a few points on the limb, unless the results are combined with other data. A procedure was considered by which the contributions from quite small groups of modes to spatially well resolved data obtained at any instant can be extracted from the remaining modes. Combining these results with frequency information then permits the modes to be identified, at least if their frequencies are low enough to ensure that modes of high degree do not contribute substantially to the signal.
    Keywords: SOLAR PHYSICS
    Type: NASA-CR-173667 , NAS 1.26:173667
    Format: application/pdf
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  • 10
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    Polar rain: Solar coronal electrons in the Earth's magnetosphere (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Low energy electron measurements collected by ISEE 1 reveal the frequent presence of field-aligned fluxes of few hundred eV electrons in he geomagnetic tail lobes. In the northern tail lobe these electrons are most prominent when the interplanetary magnetic field is directed away from the Sun. This characteristic helps identify the electrons as polar rain electrons. By mapping the tail lobe velocity distribution function into the solar wind, previous suggestions that the polar rain is indeed of solar wind origin and is due to the access of electrons to the magnetotail lobe were confirmed. It was demonstrated that the moe energetic component of the polar rain is composed of electrons from the solar wind strahl - a field-aligned component of the solar wind which is difficult to measure but which is thought to be caused by the collisionless transit of hundred eV electrons from the inner solar corona to 1 AU.
    Keywords: SOLAR PHYSICS
    Type: NASA-TM-86150 , NAS 1.15:86150
    Format: application/pdf
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