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21.
Fabian Gerson William B. Martin Georges Plattner Franz Sondheimer Henry N. C. Wong 《Helvetica chimica acta》1976,59(6):2038-2048
ESR. studies are reported for the radical anions of 5,6-didehydro- and 5,6,11,12-tetradehydro-dibenzo[a,e]cyclooctene (III and IV, resp.), in addition to that of dibenzo[a,e]cyclooctene (II) itself, the spectrum of which has been reexamined. Comparison of the proton and 13C coupling constants for II·?, III·? and IV·? indicates that the three radical anions do not differ greatly in their electronic and molecular structures. This statement implies that II·? should also be substantially planar, i.e., the tub-shaped eight-membered ring in II is expected to flatten on passing from the neutral molecule to its radical anion. Support for postulating such a change in geometry, analogous to that encountered with the parent cyclooctatetraene (I), is provided by INDO calculations. 相似文献
22.
23.
Complexes of aromatic or α,β-unsaturated nitriles YCN of the type (YCN)2(PR3)2Mo(CO)2 and (YCN)(PR3)3Mo(CO)2 are new chromophores. Their intense electronic absorption band in the visible spectrum is strongly influenced by substituents and solvent polarity. Acceptor properties of nitriles are discussed on the basis of CNDO-calculations. CT-character and solvato-chromism can be interpreted in terms of the back-bonding ability of the nitriles in electron-rich metal complexes. 相似文献
24.
Franz Wochner Laszlo Zsolnai Gottfried Huttner Hans H. Brintzinger 《Journal of organometallic chemistry》1985,288(1):69-77
Ethylene-bridged titanocene and zirconocene derivatives with permethylated ring ligands, C2H4(C5(CH3)4)2TiCl2 and C2H4(C5(CH3)4)2ZrCl2, have been synthesized and their crystal structures determined. 相似文献
25.
Franz Troxler 《Helvetica chimica acta》1973,56(5):1815-1818
The main product of the reaction between 1-methyl-1, 4, 5, 6-tetrahydronicotin-amide and ethyl bromoacetate is shown to be the 2-(1-methyl-1, 4, 5, 6-tetrahydropyridyl-3)-2-oxazoline-4-one which on partial hydrogenation followed by reaction with alkali affords O-(1-methylnipecotinoyl)glycolic amide, presumably via the tautomeric cyclol. 相似文献
26.
27.
Franz Kalhoff 《Journal of Geometry》1990,38(1-2):59-77
As we have shown in [27] there do exist projective planes of Lenz-Class III which are not isomorphic to any (generalized) Moulton plane. We will go into some detail concerning the construction of these planes, present a wide variety of non-Moulton planes of Class III.1 and III.2, and determine their spaces of orderings. In particular, for any two-power z, we construct a Cartesian group C which satisfies Yaqub's criterion and whose distrubutor has index z in the multiplicative loop of C. 相似文献
28.
Franz Merkl 《Probability Theory and Related Fields》2003,126(3):307-338
This article describes the almost sure infinite volume asymptotics of the ground state energy of random Schr?dinger operators
with scaled Gibbsian potentials. The random potential is obtained by distributing soft obstacles according to an infinite
volume grand canonical tempered Gibbs measure with a superstable pair interaction. There is no restriction on the strength
of the pair interaction: it may be taken, e.g., at a critical point. The potential is scaled with the box size in a critical
way, i.e. the scale is determined by the typical size of large deviations in the Gibbsian cloud. The almost sure infinite
volume asymptotics of the ground state energy is described in terms of two equivalent deterministic variational principles
involving only thermodynamic quantities. The qualitative behaviour of the ground state energy asymptotics is analysed: Depending
on the dimension and on the H?lder exponents of the free energy density, it is identified which cases lead to a phase transition
of the asymptotic behaviour of the ground state energy.
Received: 24 June 2002 / Revised version: 17 February 2003
Published online: 12 May 2003
Mathematics Subject Classification (2000): Primary 82B44; Secondary 60K35
Key words or phrases: Gibbs measure – H?lder exponents – Random Schr?dinger operator – Ground state – Large deviations 相似文献
29.
R. Albrecht T. C. Awes P. Beckmann F. Berger D. Bock R. Bock G. Claesson G. Clewing L. Dragon A. Eklund R. L. Ferguson A. Franz S. Garpman R. Glasow H. Å. Gustafsson H. H. Gutbrod G. Hölker J. Idh P. Jacobs K. H. Kampert B. W. Kolb P. Kristiansson H. Löhner I. Lund F. E. Obenshain A. Oskarsson I. Otterlund T. Peitzmann F. Plasil A. M. Poskanzer M. Purschke H. G. Ritter R. Santo S. Saini H. R. Schmidt S. P. Sørensen K. Steffens D. Stüken E. Stenlund M. Tincknell G. R. Young 《Zeitschrift fur Physik C Particles and Fields》1991,51(1):1-10
The production of direct photons has been investigated in reactions ofp and16O projectiles at 60 and 200A·GeV with C and Au nuclei. Photon and 0 spectra have been measured in the pseudorapidity range 1.52.1 for the transverse momentum region 0.4 GeV/cp
T
2.8 GeV/c employing the lead-glass spectrometer SAPHIR. An upper limit of 15% at the 90% confidence level for the direct photon signal relative to the neutral pion production is obtained from the comparison of measured photon spectra with Monte Carlo simulations of the hadronic background based on the reconstructed yield of 0 and mesons. Consequences for a possible phase transition to a quark-gluon plasma are discussed. 相似文献
30.
Franz H. Asthalter T. Dommach M. Ehnes A. Messel K. Sergueev I. 《Hyperfine Interactions》2002,141(1-4):131-134
The present status of the new nuclear resonance beamline PETRA 1 at HASYLAB, DESY, Hamburg is described. Besides an overview
of the experimental setup some examples of recent experiments are given. Those cover the main applications, i.e., inelastic
scattering from iron alloys and quasielastic scattering from glass-forming liquids.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献