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991.
992.
The Lewis acidic site in a hydrophobic environment promoted binding of amines/oligopeptides efficiently: a binding constant of H-His-Leu-His-NHC10H7 to bisporphyrin was 9.4 x 10(5) M-1 in water at 25 degrees C. 相似文献
993.
994.
[reaction: see text] A new strategy directed toward the total synthesis of stachyflin, a potent and novel anti-influenza A virus agent isolated from a microorganism, has been presented through the enantioselective synthesis of the tetracyclic core structure. The synthetic method features a BF(3) x Et(2)O-induced domino epoxide-opening/rearrangement/cyclization reaction as the key step. 相似文献
995.
Barrett AG Hamprecht D James RA Ohkubo M Procopiou PA Toledo MA White AJ Williams DJ 《The Journal of organic chemistry》2001,66(7):2187-2196
Stepwise macrocyclization of the all syn-trans-1,15-quinquecyclopropanedimethanol (4) with iso- and terephthaloyl chlorides and 4,4'-methanediyl-dibenzoic acid (28) gave the corresponding coronanes 22, 23, and 32. The same protocol was used with all syn-trans-1,21-septecyclopropanedimethanol (5) and 2,3-naphthalenedicarboxylic acid to obtain the macrolide 27. Direct macrocyclization of diol 4 and 1,10-phenanthroline-2,9-dicarbonyl chloride (33) and 2,2'-bipyridine-4,4'-dicarbonyl chloride (35) gave the coronanes 34 and 36, respectively. Ring closing metathesis (RCM) of the diene 42 using Cl2(Cy3P)2Ru=CHPh (48) (Grubbs's catalyst) gave the macrocyclic lactone 45. The structures of coronanes 22, 23, 32, 34, 36, and 45 were confirmed by X-ray crystallographic studies which showed the cyclopropyl chain to adopt very differing conformations throughout the series. Several of the macrocycles have significant free pathways through their ring centers, and in the case of compound 34 there is a water molecule hydrogen bonded within the ring. This latter compound has the potential to act as a chiral ligand to metal centers. 相似文献
996.
997.
Synthesis of 2,3-dimethylene-7-isopropylidenebenzonorbornene () and its cycloaddition reactions with dichloroketene and dienophiles are described. 相似文献
998.
F.?MichelEmail author S.?Ohkubo 《The European Physical Journal A - Hadrons and Nuclei》2004,19(3):333-339
We investigate the properties of a global optical potential, which describes the 12C + 12C elastic-scattering data between 70 and 130 MeV, within the nearside/farside and barrier-wave/internal-wave decomposition techniques. Particular emphasis is laid on the discussion of the incomplete absorption features of this system, and especially on the properties of the Airy minima which are observed in the experimental
excitation function. The complicated angular and energy evolution of the data is explained in terms of the interference of a small set of scattering subamplitudes with a much simpler behavior.Received: 2 September 2003, Revised: 25 September 2003, Published online: 5 February 2004PACS:
24.10.-i Nuclear reaction models and methods - 24.10.Ht Optical and diffraction models - 25.70.Bc Elastic and quasielastic scattering 相似文献
999.
Tadashi Ikuta Kazuhisa Shima 《Proceedings of the American Mathematical Society》2003,131(5):1471-1479
The purpose of this paper is to investigate the spectra of the Dirac operator . The local compactness of is shown under some assumption on . This method enables us to prove that if as , then and to give a significant sufficient condition that or has a purely discrete spectrum.
1000.
Matsushima S Sasaki F Sarumaru S Ohta D Era S Sogami M Inaba T Kinosada Y 《Magnetic resonance imaging》2003,21(9):1045-1047
In the breast carcinamas, sentinel lymph node biopsy (SLNB) attracts attention as technique to be settled by axillary lymph node metastasis, but existence of a false negative case is a problem. Equivalent cross relaxation rate image (ECRI) is the measurement method that we can evaluate a change of organization structure quantitatively by magnetic resonance imaging. We executed axillary ECRI as a purpose with decreasing a false negative case of SLNB. ECRI related to a macroscopic image, and it was possible to evaluate yes or no of axillary lymph node metastasis. ECRI is the useful method to evaluate adaptability of SLNB. 相似文献