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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 340 (1989), S. 609-616 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The crystal structure of R-state glycogen phosphorylase b has been determined at 2.9 Å resolution. A comparison of T-state and R-state structures of the enzyme explains its cooperative behaviour on ligand binding and the allosteric regulation of its activity. Communication between catalytic ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 336 (1988), S. 215-221 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A comparison of the refined crystal structures of dimeric glycogen phosphorylase b and a reveals structural changes that represent the first step in the activation of the enzyme. On phosphorylation of serine-14, the N-terminus of each subunit assumes an ordered helical conformation and binds to the ...
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Atlantic economic journal 17 (1989), S. 55-62 
    ISSN: 1573-9678
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Atlantic economic journal 13 (1985), S. 91-92 
    ISSN: 1573-9678
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 168 (1989), S. 95-108 
    ISSN: 1615-6110
    Keywords: Cladistics ; phenetics ; phylogeny ; evolutionary taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phenetic classification corresponds to no biological model and lacks a sound philosophical basis. Cladistics (ignoring meaningless “transformed cladistics”) assumes divergent evolution and, usually, that best estimates of phylogeny are obtained by parsimony principles, both questionable assumptions at times. It is better than phenetics since more-or-less testable hypotheses are generated, but pitfalls are many, in data selection and interpretation (as to homology), and in commensurability of units and direction of change. Above all we learn: homoplasy is rife in nature. Much bad cladistics has been done. If it is to reflect phylogeny, classification cannot be artificially stabilized, but is its only aim to express (hypothesized) cladistic patterns? And can it do that with any degree of overall assurance? Biologists are legitimately interested in defining grades as well as clades. Recognition of an unequivocal clade-grade frequently leaves a paraphyletic grade residue that cannot itself be unequivocally resolved. This is a real problem that requires attention in formal taxonomy and in applying cladistics. Primarily morphological cladistics will be increasingly supplanted by molecular (nucleotide-sequence) cladistics. The role of evolutionary taxonomy will change accordingly.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 158 (1989), S. 697-702 
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In this study, Harderianectomy (Hdx) has been shown to differentially modify circulating levels of the thyroid hormones, T4 and T3, in male and female golden hamsters exposed to low photic intensities or to moderately low temperatures. Specifically, low photic intensities depress circulating levels of T4 in both control and Harderianectomized (Hdx) male and female hamsters. In addition, T3 is decreased in both control and Hdx males but not in females, as a consequence of reduced levels of illumination. Moderately low temperatures (10°C) depress T4 in both control and Hdx males but not in females, while T3 is increased in both control male and female hamsters, and in Hdx males, but not Hdx females. The data suggest that the Harderian gland of males enhances the sensitivity of the TSH-thyroid axis to photic intensity and to lower temperatures, and further, that there is a considerable sexual difference in the role the Harderian glands may play in response to these two environmental factors.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1999-1999 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Plasmas have been formed in the tokamak fusion test reactor (TFTR) which separate completely from the limiter and are called detached plasmas. The physical evidence for the separation from the limiter is that all the ohmic input power is radiated away at the plasma boundary which can be 10→30 cm inside the limiter. The 10-chord multichannel MIRI interferometer system has been used to diagnose this region and follows the formation of the detached state through a MARFE. MIRI indicates that a plasma ∼0.5→1×1013 cm−3 occurs in the region between the luminous boundary and the limiter. This work was supported by U.S. DOE Contract No. DE-AC02-76-CHO-3073.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 840-842 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The x-ray pulse-height analysis (PHA) diagnostic uses a liquid-nitrogen cooled array of 5 Si(Li) and one HpGe detectors to do time-resolved (5–100 ms) x-ray spectroscopy of the central horizontal chord of the Tokamak Fusion Test Reactor (TFTR) plasmas in the 1–50-keV range. Central electron temperature Te and concentration of medium and low-Z impurities are derived from the spectra. Remotely selectable absorber-foil arrays provide selection of the energy range. Fixed and movable aperture arrays allow approximate equalization of count rates in different energy bands and extend dynamic range. Amplifier pulse shapes are approximately triangular. Main amplifier peaking time is 4 μs yielding 230-eV FWHM at 5.9 keV. Pileup inspection times are selectable at 0.13, 0.4, or 0.9 μs. Throughput is up to 42 kHz. The PHA has been used to study temperature and impurities over a wide range of TFTR operational parameters. Dramatic variations in metal impurities with density, plasma current, and major radius have been observed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 325 (1987), S. 62-65 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Plasma levels of tracer radio-labelled 25-hydroxyvitamin D (25(OH)D) exhibit a biphasic exponential decline10 after intravenous injection. In rats the initial rapid phase is followed by a longer phase with a half-time (fi-25(OH)D) of several days. When vitamin D supply is limited, the long-phase ...
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 27 (1988), S. 6733-6741 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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