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221.
In this report, we describe an iron(III) complex containing a carbazole-based tridentate ligand that catalyzes highly enantioselective asymmetric epoxidation of (E)-alkenes at room temperature. The non-heme iron(III) complex has a five-coordinated trigonal-bipyramidal structure, and its two-electron oxidized state has the similar electronic structure as that of iron porphyrins. 相似文献
222.
W. Bell K. Braune G. Claesson D. Drijard M. A. Faessler H. G. Fischer H. Frehse R. W. Frey S. Garpman W. Geist C. Gruhn P. Hanke M. Heiden W. Herr P. G. Innocenti T. J. Ketel E. E. Kluge I. Lund G. Mornacchi T. Nakada I. Otterlund B. Povh A. Putzer B. Rensch E. Stenlund T. J. M. Symons R. Szwed O. Ullaland M. Wunsch CERN-Heidelberg-Lund Collaboration 《Zeitschrift fur Physik C Particles and Fields》1984,22(2):109-118
Two-particle rapidity correlations have been studied for αα, αp, andp p interactions at the CERN ISR using the Split-Field Magnet (SFM) detector. In order to isolate the true two-particle correlations, the analysis was performed at fixed charged multiplicity. In the framework of a simple cluster model, it is found that cluster widths as well as cluster multiplicities are the same for αα, αp, andp p interactions, and both decrease with increasing charged multiplicity. 相似文献
223.
The European Physical Journal C - LHCb is a dedicated experiment to study CP violation and other rare processes in the B meson system at LHC. It is designed to exploit the large sample of Bd and Bs... 相似文献
224.
1H-F-Alkene-1-phosphonates, easily accessible from F-alkanoyl chlorides, underwent dephosphorylation on treatment with a catalytic amount of fluoride ion at O°C to room temperature to give terminal F-alkylacetylenes in good yields. 相似文献
225.
Title azaannulenes, the paratropic and diatropic vinylogues of pyridine, were synthesized starting from the annulenones. 相似文献
226.
A. Breakstone R. Campanini H. B. Crawley G. M. Dallavalle M. M. Deninno K. Doroba D. Drijard F. Fabbri A. Firestone H. G. Fischer H. Frehse W. Geist G. Giacomelli R. Gokieli M. Gorbics P. Hanke M. Heiden W. Herr D. Isenhower E. E. Kluge J. W. Lamsa T. Lohse W. T. Meyer G. Mornacchi T. Nakada M. Panter A. Putzer K. Rauschnabel B. Rensch F. Rimondi M. Schmelling G. P. Siroli J. D. Skeens R. Sosnowski M. Szczekowski O. Ullaland D. Wegener R. Yeung Ames Collaboration Bologna Collaboration CERN Collaboration Dortmund Collaboration Heidelberg Collaboration Warsaw Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,43(3):522-522
Data are presented for the first time on inclusive Pomeron-Pomeron interactions which produce a central systemX (composed mainly of multimeson states) in proton-proton collisions at \(\sqrt s \) at the CERN ISR. The systemX has a Feynman-x distribution which is sharply peaked atx f=0, is inconsistent with any significant contributions from Reggeon exchange processes, and has an invariant mass dependence in good agreement with the predicted formM x ?2 . Kaon production is about 15% of pion production, nearly independent ofM x, while proton-antiproton production averages about 5% of pion production and increases withM x. The structure of the central systemX develops into a jetlike shape, asM x increases, as would be expected from a model of Pomeron fragmentation. The shape of thex f(π) distribution in the center of mass of theX system (although not proving existence) is consistent with asoft partonic substructure of the Pomeron. 相似文献
227.
A. Breakstone R. Campanini H. B. Crawley M. Cuffiani G. M. Dallavalle M. M. Deninno K. Doroba D. Drijard F. Fabbri A. Firestone H. G. Fischer H. Flöge H. Freshe W. M. Geist L. Gesswein G. Giacomelli R. Gokieli M. Gorbics M. Gorski P. Hanke M. Heiden W. Herr D. Isenhower S. Kersting E. E. Kluge J. W. Lamsa T. Lohse R. Mankel W. T. Meyer T. Nakada M. Panter A. Putzer K. Rauschnabel B. Rensch F. Rimondi M. Schmelling G. P. Siroli R. Sosnowski C. Stubenrauch M. Szczekowski O. Ullaland D. Wegener R. Yeung 《Zeitschrift fur Physik C Particles and Fields》1987,36(4):567-576
Events are analyzed in which a high transverse momentum proton was produced at polar angles of 10°, 20° and 45°. The experiment was performed with the Split Field Magnet detector at the CERN ISR at \(\sqrt s \) =62 GeV. A 4-jet structure of these events is found [1]. The measured charge structure of spectator jets is compatible with proton production from hard diquark scattering. This is supported by a study of baryon number compensation in the towards jets. The observed charge compensation in the towards jets suggests dominance of hard (ud) scattering. Evidence forΔ ++ production at high transverse momentum indicates the presence of an additional (uu) scattering component. The properties of the recoiling away jets are compatible with the fragmentation of a valence quark and/or of a gluon as in the case of meson triggers. 相似文献
228.
229.
Keiko Takahashi Yutaka Ohtsuka Souichi Nakada Kenjiro Hattori 《Journal of inclusion phenomena and macrocyclic chemistry》1991,10(1):63-68
6N(N-formyl-D-phenylalanyl)-deoxyamino--cyclodextrin and 6N(N-formyl-L-phenylal-anyl)-deoxyamino--cyclodextrin (I andII) were prepared. These new hosts formed intramolecular host-guest complexes and included naphthyl derivatives preferentially with a stoichiometry of 1:1. The inclusion behavior was different between I and II because the cavity shape formed with the CD cavity and the phenylalanine moiety of I was different from that of II. 相似文献
230.
This work describes the development of a new tridentate ligand effective for the asymmetric catalysis of Nozaki-Hiyama allylation and methallylation. Various aldehydes were allylated or methallylated with good enantioselectivity (86-96%), and a key intermediate of calcitriol lactone synthesis was also obtained with excellent diastereoselectivity (97% de, 91%). The enantioselective reaction catalyzed by this Cr-ligand complex is applicable to a broad range of aldehydes and has great potential for natural product synthesis. Another remarkable feature of this ligand is the stability of the Cr-ligand complex which was recovered after the enantioselective reaction and recycled twice without diminishing the enantioselectivity and yield. 相似文献