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  • Articles: DFG German National Licenses  (23)
  • 1985-1989  (12)
  • 1980-1984  (10)
  • 1970-1974  (1)
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  • Articles: DFG German National Licenses  (23)
Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Search forγ-ray transitions within the5Li groundstate (1983)
    Springer
    The European physical journal 310 (1983), S. 243-245 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A search forγ-ray transitions within the broad groundstate of5Li has been carried out via the4He(p, γp *)4He reaction atE p (lab)=1.5−7.0 MeV. Differentially pumped gas targets of the extended and quasi-point types have been used. The results show that the set-up and detection techniques utilized are not sensitive enough to observe such intrastate transitions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415229
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The12C+12C reaction at subcoulomb energies (II) (1981)
    Springer
    The European physical journal 303 (1981), S. 305-312 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The reaction12C+12C has been studied in the energy range Ec.m.=2.8–6.3 MeV by charged-particle spectroscopy. Angular distributions of the proton and α-particle exit channels were obtained. The excitation functions do not reveal evidence for the phenomenon of absorption under the barrier. The data have been extrapolated to the energy region of astrophysical interest. The existence of reported and new intermediate resonance structures is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01421528
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The parity of the 3134 keV,J=1 State in18F (1972)
    Springer
    The European physical journal 249 (1972), S. 312-320 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The16O(3He,ϱγ)18F reaction atE(3He)=2.95 MeV was used to study the low-lying states in18F belowE x =3.2 MeV. A combination of γ-ray angular distribution and linear polarization measurements using a single planar Ge(Li) polarimeter resulted in aJ π =1− assignment to the 3134 keV state. In addition, the positive parity assignments to the 937(3+) and 1702(1+) keV states have been verified. Information on branching and mixing ratios as well as on lifetimes are reported. The results are discussed in terms of the weak-coupling and strong-coupling models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01379724
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The4He(12C, γ)16O reaction at stellar energies (1982)
    Springer
    The European physical journal 308 (1982), S. 73-94 
    Details
    ISSN: 1434-601X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The capture reaction4He(12C, γ)16O (E c.m.= 1.34–3.38 MeV) as well as the elastic scattering process4He(12C,12C)4He (E c.m.=1.44–3.38 MeV) have been investigated with the use of an intense12C beam and a windowless and4He recirculating gas target system. The measurements involved two large NaI(T1) crystals in close geometry to an extended gas target, whereby angle-integrated γ-ray yields were obtained. A large area plastic detector was used for the suppression of time-independent background. A search for cascade γ-ray transitions was carried out by coincidence techniques. The measurement of absolute cross sections is also reported. Theoretical fits of the excitation function for the groundstate γ-ray transition requireE1 as well asE2 capture amplitudes, which are of equal importance at stellar energies. This result increases significantly the stellar burning rate of4He(12C, γ)16O and leads to16O as the dominant product at the end of helium burning in massive stars. The observed capture yield to the 6.92 MeV state is dominated by the direct capture mechanism and plays a small role at stellar energies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415851
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Cultured cells of Arachis hypogaea susceptible to induction of stilbene synthase (resveratrol-forming) (1981)
    Springer
    Plant cell reports 1 (1981), S. 83-85 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Callus cultures were established from cotyledons of Arachis hypogaea. The cultured cells were shown to produce stilbene synthase (resveratrol-forming) if the cells were irradiated with 254 nm UV light. The lag period after which the stilbene synthase activity appeared was similar for cultured cells and intact cotyledons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269281
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Cell-suspension culture of Arachis hypogaea L.: model system of specific enzyme induction in secondary metabolism (1987)
    Springer
    Planta 172 (1987), S. 238-244 
    Details
    ISSN: 1432-2048
    Keywords: Arachis ; Cell culture ; Enzyme induction (cell culture) ; Phenylalanine ammonia-lyase ; Phytoalexin ; Stilbene synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A peanut (Arachis hypogaea L.) cell-suspension culture susceptible to selective induction of stilbene formation was established. The principles of defense responses of the whole plant were found to be retained in the artificial system. The suspension culture was characterized by its growth curve and by various biochemical parameters. In the stationary phase, reached 8 d after transfer to a new medium, the formation of stilbenes and stilbene synthase could be induced without altering the levels of other enzymes. Eighteen hours after applying an artificial elicitor (ultraviolet-C light) or 4 h after eliciting with a crude preparation of Phytophthora cambivora cell walls, phenylalanineammonia-lyase activity was increased eightfold and stilbene-synthase activity 20-fold. The activity of phenylalanine ammonia-lyase reached its peak at a slightly different time from that of stilbene synthase. The main products of L-phenylalanine metabolism in the induced cells were resveratrol, 3,3′,5-trihydroxy-4′-methoxystilbene and isopentenylresveratrol. Likewise, feruloyl-CoA reductase, as a parameter of lignin formation, was enhanced following induction, albeit with a different time course and with a less steep increase than found for phenylalanine ammonia-lyase and stilbene synthase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394593
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Intrastate γ-transitions: A spectroscopic tool? (1987)
    Springer
    The European physical journal 328 (1987), S. 291-299 
    Details
    ISSN: 1434-601X
    Keywords: 23.20 ; 21.10.-k
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In the framework of a potential model we have calculated the various bremsstrahlung cross sections into the5Li ground state, includingM 1 andE 2 γ-transitions leading from the high energy wing of the5Li ground state resonance into states belonging to the same resonance at lower energy (intrastate transition). Our calculation supports the hypothesis of Schmalbrock et al. [1] that intrastate transitions ofM 1 andE 2 multipolarity exist. While we find a maximum cross section of roughly 1.4 nb for theE 2 transition, we predict the cross sections forM 1 intrastate transition to be less than 3·10−5nb. An experimental observation of the intrastate γ-ray emission appears to be very difficult due to the dominance of competing resonant (M 1) and direct (E 1) capture processes. Schmalbrock et al. have suggested to deduce magnetic dipole and electric quadrupole moments of resonant states from the measurements of the respectiveM 1 andE 2 intrastate transitions. We will show that theM 1 intrastate cross sections do not yield the appropriate information to determine the magnetic dipole moment. We will also discuss thatE 2 intrastate transitions do not seem to be a suited tool to find the quadrupole moment of an unstable state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01290497
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    The cross section of14N(n, p)14C at stellar energies and its role as a neutron poison forS-process nucleosynthesis (1988)
    Springer
    The European physical journal 330 (1988), S. 167-172 
    Details
    ISSN: 1434-601X
    Keywords: 95.30.C ; 97.10.C ; 25.70
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The absolute average cross section 〈σ〉 of the14N(n, p)14C reaction has been measured using neutron spectra that closely resemble Maxwell-Boltzmann distributions with thermal energies of kT=25.0 and 52.4 keV: 〈σ〉=0.81±0.05 and 0.52±0.06 mb, respectively. The resulting reaction rates are nearly the same at T9=0.29 and 0.61, and their average, NA〈συ〉=(1.3±0.1)×105 cm3 s−1 mol−1, is about a factor of three smaller than the previously adopted values obtained by extrapolation between thermal and higher-energy data. Thus, the14N(n, p)14C reaction plays a correspondingly smaller role as a neutron poison fors-process nucleosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01293392
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Helium burning of22Ne (1989)
    Springer
    The European physical journal 334 (1989), S. 491-510 
    Details
    ISSN: 1434-601X
    Keywords: 25.55 ; 97.10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The22Ne(α, γ)26Mg and22Ne(α, n)25Mg reactions were investigated forE α(lab) from 0.71 to 2.25 MeV. Neon gas enriched to 99% in22Ne was recirculated in a differentially pumped gas target system of the extended type. Theγ-ray transitions were observed with Ge(Li) detectors and the neutrons with3He ionization chambers. A previously known resonance at ER(lab)=2.05 MeV was verified and 15 new resonances were found in the energy range covered, with the lowest at ER(lab)=0.83 MeV. Information on resonance energies, widths, strengths,γ-ray branching ratios, as well asJ π assignments, is reported. The energy range investigated corresponds to the important temperature range ofT 9 from 0.3 to 1.4 (109 K), for which the astrophysical rates were determined for both reactions. The results show that the ratios of the rates for22Ne(α, n)25Mg and22Ne(α, γ)26Mg are significantly smaller than the previously adopted values, e.g., by at least a factor of 60 nearT 9=0.65. Thus, the22Ne(α, n)25Mg reaction will likely play a smaller role as a neutron source fors-process nucleosynthesis, than has frequently been assumed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01294757
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  • 10
    Electronic Resource
    Electronic Resource
    Low-energy cross sections for11B(p, 3α) (1987)
    Springer
    The European physical journal 327 (1987), S. 341-355 
    Details
    ISSN: 1434-601X
    Keywords: 25.85.−w ; 24.90.+d ; 95.30.−k
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The11B(p, 3α) reaction has been investigated in the energy range fromE c.m.=22 to 1100 keV with the use of either a proton beam and a11B solid target or with the use of a11B heavy ion beam incident on a hydrogen jet gas target. The reaction mechanisms have been studied via kinematically complete coincidence measurements showing that the reaction proceeds predominantly by a sequential decay via8Be. The measurement of absolute cross sections,α-angular distributions and excitation functions is reported. The astrophysicalS(E) factor has been described by means of an empirical fit to the data, leading to a zero-energy intercept ofS(0)=197±12 MeVb. Conclusions drawn on the use of this reaction as an advanced fuel in fusion reactors remain essentially unchanged by the present data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01284459
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    Paper (German National Licenses)
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