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121.
H. Iwasaki T. Motobayashi H. Sakurai K. Yoneda T. Gomi N. Aoi N. Fukuda Zs. Fülp U. Futakami Z. Gacsi Y. Higurashi N. Imai N. Iwasa T. Kubo M. Kunibu M. Kurokawa Z. Liu T. Minemura A. Saito M. Serata S. Shimoura S. Takeuchi Y.X. Watanabe K. Yamada Y. Yanagisawa M. Ishihara 《Physics letters. [Part B]》2005,620(3-4):118-124
The excitation of the neutron-rich nucleus 28Ne has been investigated via heavy-ion inelastic scattering in reversed kinematics. The value was determined to be , which is smaller than expected from the low excitation energy of the first state. A comparison with theoretical predictions suggests that the suppressed collectivity in 28Ne is characteristic of nuclei lying on the boundary of the ‘island of inversion’. 相似文献
122.
123.
124.
O. Schneider M. Bourquin R. M. Brown H. J. Burckhart P. Extermann M. Gailloud C. N. P. Gee W. M. Gibson P. Jacot-Guillarmod P. W. Jeffreys J. Perrier K. J. Ragan Ph. Rosselet B. J. Saunders P. Schirato H. W. Siebert V. J. Smith K. -P. Streit R. Weill C. Yanagisawa 《Zeitschrift fur Physik C Particles and Fields》1990,46(3):341-348
In an experiment using the CERN SPS hyperon beam, we have measured the cross sections for inclusive production of Ξ0 (accompanied by a charged particle), Ξ(1530)- and Ξ(1530)0 in Ξ--beryllium collisions at 116 GeV/c. All differential cross sections are found to be well described by the from (1?x F )n exp (?bp T 2 ) over the whole accessible kinematical region (x F >0.3). The invariant production spectra for Ξ0, Ξ(1530)- and Ξ(1530)0, as well as those for Ξ-, and Ω- (obtained previously from the same data), are compared to theoretical predictions deduced from a two-component quark-diquark cascade model. 相似文献
125.
126.
Miho Katoh 《Tetrahedron letters》2005,46(31):5161-5163
A stereoselective synthetic route to Nuphar quinolizidine alkaloid, (−)-deoxynupharidine, was established by employing reductive carbon-nitrogen bond cleavage, followed by simultaneous recyclization of a proline derivative with samarium diiodide, and an intramolecular ring-closing metathesis, as the key steps. 相似文献
127.
128.
The shortest known type 1 copper binding loop (that of amicyanin, Ami) has been introduced into three different cupredoxin beta-barrel scaffolds. All of the loop-contraction variants possess copper centers with authentic type 1 properties and are redox active. The Cu(II) and Co(II) sites experience only small structural alterations upon loop contraction with the largest changes in the azurin variant (AzAmi), which can be ascribed to the removal of a hydrogen bond to the coordinating thiolate sulfur of the Cys ligand. In all cases, loop contraction leads to an increase in the pK(a) of the His ligand found on the loop in the reduced proteins, and in the pseudoazurin (Paz) and plastocyanin (Pc) variants the values are almost identical to that of Ami ( approximately 6.7). Thus, in Paz, Pc, and Ami, the length of this loop tunes the pK(a) of the His ligand. In the AzAmi variant, the pK(a) is 5.5, which is considerably higher than the estimated value for Az (<2), and other controlling factors, along with loop length, are involved. The reduction potentials of the loop-contraction variants are all lower than those of the wild-type proteins by approximately 30-60 mV, and thus this property of a type 1 copper site is fine-tuned by the C-terminal loop. The electron self-exchange rate constant of Paz is significantly diminished by the introduction of a shorter loop. However, in PcAmi only a 2-fold decrease is observed and in AzAmi there is no effect, and thus in these two cupredoxins loop contraction does not significantly influence electron-transfer reactivity. Loop contraction provides an active site environment in all of the cupredoxins which is preferable for Cu(II), whereas previous loop elongation experiments always favored the cuprous site. Thus, the ligand-containing loop plays an important role in tuning the entatic nature of a type 1 copper center. 相似文献
129.
Miho Kaneko 《Tetrahedron letters》2007,48(40):7085-7087
Our recent discovery that In(III) salts were able to activate halides catalytically under mild conditions for the intermolecular Friedel-Crafts cyclization prompted us to explore this highly efficient activation in intermolecular Friedel-Crafts reactions. The alkylation of p-xylene with allylic and benzylic halides was demonstrated under catalytic and mild condition to afford in some cases quantitative yields of the monoalkylated products without the need to employ large excesses of reactants. 相似文献
130.
Osamu Yamamoto Kikuko Hayamizu Masaru Yanagisawa 《Journal of organometallic chemistry》1974,73(1):17-25
The kinetic parameters of the bridge-terminal interconversion of triethylaluminum (TEA) in cyclopentane and in toluene as well as of tri-n-propylaluminum (TPA) in cyclopentane are obtained from the total line shape analysis of 13C NMR spectra with proton-decoupling. The enthalpies and entropies of activation of these aluminum alkyls and of trimethylaluminum (TMA) in both solvents are nearly the same, but the interconversion is faster in toluene than in cyclopentane, and also becomes faster as the alkyl chain of the aluminum compounds becomes longer. From these data and the heats of dissociation obtained thermochemically by M.B. Smith [J. Phys. Chem., 71 (1967) 365; J. Organometal. Chem., 21 (1970) 273, 46 (1972) 31 and 211], a possible mechanism of the bridge-terminal exchange is elucidated, in which the exchange proceeds “intramolecularly” for TMA and presumably TEA in cyclopentane. For the aluminum alkyls in toluene and for TPA in cyclopentane, on the other hand, the exchange may proceed “intermolecularly” with only a little contribution from an “intramolecular process”. 相似文献