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661.
662.
Paul F. Conrad 《Mathematische Annalen》1971,190(4):306-312
663.
Formaggio JA Zimmerman ED Adams T Alton A Avvakumov S de Barbaro L de Barbaro P Bernstein RH Bodek A Bolton T Brau J Buchholz D Budd H Bugel L Case S Conrad JM Drucker RB Fleming BT Frey R Goldman J Goncharov M Harris DA Johnson RA Kim JH Koutsoliotas S Lamm MJ 《Physical review letters》2000,84(18):4043-4046
The E815 (NuTeV) neutrino experiment has performed a search for a 33. 9 MeV/c(2) weakly interacting neutral particle produced in pion decay. Such a particle may be responsible for an anomaly in the timing distribution of neutrino interactions in the KARMEN experiment. E815 has searched for this particle's decays in an instrumented decay region; no evidence for this particle was found. The search is sensitive to pion branching ratios as low as 10(-13). 相似文献
664.
In this article, it will be shown that every -subgroup of a Specker -group has singular elements and that the class of -groups that are -subgroups of Specker -group form a torsion class. Methods of adjoining units and bases to Specker -groups are then studied with respect to the generalized Boolean algebra of singular elements, as is the strongly projectable hull of a Specker -group. 相似文献
665.
Brian Conrad Fred Diamond Richard Taylor 《Journal of the American Mathematical Society》1999,12(2):521-567
We show that certain potentially semistable lifts of modular mod representations are themselves modular. As a result we show that any elliptic curve over the rational numbers with conductor not divisible by 27 is modular.
666.
Colorless single crystals of Sr[ReO4]2 were obtained from halide melts at 1123 K in open corundum crucibles. X-ray diffraction revealed that Sr[ReO4]2 crystallizes in the monoclinic space group P21/n with the lattice parameters a = 627.31(4) pm, b = 1004.56(7) pm, c = 1271.25(9) pm and β = 97.118(3)° for Z = 4. The crystal structure contains a unique Sr2+-cation site surrounded by eight crystallographically different oxygen atoms forming distorted bicapped trigonal prisms. All corners of these [SrO8]14– polyhedra (d(Sr–O) = 259–268 pm) are shared with tetrahedral meta-perrhenate units [ReO4]– (d(Re–O) = 166–173 pm) formed from two crystallographically different Re7+ cations surrounded by four O2– anions each, building up the three-dimensional mosaic-like structure of Sr[ReO4]2. Single-crystal Raman data confirm the presence of two different kinds of symmetry-free meta-perrhenate units [ReO4]– and match well with results known from literature. 相似文献
667.
The novel Pd-catalyzed C(sp(2))-H/C(sp(2))-H cross-coupling of unactivated xanthines with unactivated arenes utilizing a combination of Ag(I) and O(2) as oxidants exclusively yields C-8 arylated xanthines in a single synthetic operation. 相似文献
668.
Pfister J Schon C Roth W Kaiser C Lambert C Gruss K Braunschweig H Fischer I Fink RF Engels B 《The journal of physical chemistry. A》2011,115(15):3583-3591
The structures and energetics of the ground and first excited states of [2.2]paracyclophane (PC) and its pseudo-para- (p-DHPC) and pseudo-ortho-dihydroxy (o-DHPC) as well as monohydroxy derivates (MHPC) are investigated by quantum chemical calculations, X-ray crystallography, and resonance-enhanced multiphoton ionization spectroscopy (REMPI) in a free jet. We show that substitution of the aromatic hydrogens in PC causes significant changes of the structure and in particular its change between the ground and the excited state. The structural changes include a breathing mode as well as shift and rotation of the benzene moieties and are rationalized by the electronic structure changes upon excitation. Spin-component-scaled second-order M?ller-Plesset perturbation method (SCS-MP2) reproduces the experimental X-ray structure correctly and performs significantly better than ordinary MP2 and the B3LYP methods. The parent propagation method, SCS-approximate coupled cluster second order (SCS-CC2), yields adiabatic excitation energies within 0.1 eV of the experimental values for PC and the investigated hydroxyl derivates as well as the related aromatic molecules benzene and phenol. It is shown that zero-point vibration energy corrections at the time dependent density functional (B3LYP) level are no more accurate enough for that level of theory and have to be substituted by SCS-CC2 values. While the structures of PC and o-DHPC are only slightly modified upon excitation, p-DHPC changes its structural parameters substantially. This is in line with [1 + 1] REMPI-spectra of these substances, which are interpreted with the help of Franck-Condon simulations. 相似文献
669.
Chitnis SS Peters B Conrad E Burford N McDonald R Ferguson MJ 《Chemical communications (Cambridge, England)》2011,47(45):12331-12333
Reactions of trimethylphosphine or diphosphines with SbCl(3) in the presence of AlCl(3) or Me(3)SiSO(3)CF(3) give ligand stabilized stibenium and stibinidenium cations. The geometry at each antimony center reveals a variety of environments for antimony that describes new bonding and highlights new directions in the chemistry of the pnictogen elements. 相似文献
670.
Shaheer H. Khan Conrad F. Piskorz Khushi L. Matta 《Journal of carbohydrate chemistry》2013,32(7):1025-1035
Abstract 4-Nitrophenyl 2,3-O-isopropylidine-α-D-mannopyranoside 2 was condensed with O-(2,3,4,6-tetra-O-acetyl-α-D-mannopyranosyl)-(1→2)-3,4,6-tri-O-acetyl-α-D-mannopyranosyl bromide 1 and 2,3,4,6-tetra-O-acetyl-α-D-mannopyranosyl bromide 11 in the presence of mercuric cyanide. Products were deprotected to yield, respectively, 4-nitrophenyl O-α-D-mannopyranosyl-(1→2)-O-α-D-mannopyranosyl-(1→6)-α-D-mannopyranoside 6 and 4-nitrophenyl O-α-D-mannopyranosyl-(1→6)-α-D-mannopyranoside 14. The 4-nitrophenyl group of 6 was reduced to give title trisaccharide. Bromide 1 was also condensed with methyl 2,3,4-tri-O-benzyl-α-D-manopyranoside 3 in the presence of silver trifluoromethanesulfonate and tetramethylurea to give protected trisaccharide derivative which was deprotected to furnish, methyl O-α-D-mannopyranosyl-(1→2)-O-α-D-mannopyranosyl-(1→6)-α-D-mannopyranoside 10. The identities of all protected and deprotected compounds were supported by 1H and 13C NMR spectral data. 相似文献