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41.
S2(B-X) chemiluminescence, primarily from ν′ = 0 and 1, has been observed in alkali atom—SCl2 reactions. The addition of He or Ar buffer gas to the reaction chamber alters the reaction dynamics, and at certain buffer gas pressures the S2 emission originates exclusively from the ν′ = 6–9 vibrational levels of the B(3Σu?) state. 相似文献
42.
Ron Wright 《International Journal of Theoretical Physics》1977,16(8):567-573
A projection-valued state is defined to be a completely orthoadditive map from the projections on one Hilbert space into the projections on another Hilbert space, which preserves the unit. Any such mapping is shown to have the formP U
1(P 11)U
1
–1
U
2(P 12)U
2
–1
, whereU
1 is unitary andU
2 is antiunitary, generalizing Wigner's theorem on symmetry transformations. A physical interpretation is given and the relation to quantum logic is discussed.The contents of this paper are a portion of the author's dissertation at the University of Massachusetts at Amherst. 相似文献
43.
Jimmy Orjala Anthony D. Wright Clemens A. J. Erdelmeier Otto Sticher Topul Rali 《Helvetica chimica acta》1993,76(4):1481-1488
Five New unusual monoterpene-substituted dihydrochalcones, the adunctins A–E (1″S)-1-{2′-hydroxy-4′-methoxy-6′-[4″-methyl-1″-(1?-methylethyl)cyclohex-3″ -en-1″ -yloxy]phenyl}-3-phenylpropan-1-one ( 1 ), (5aR*,8R*,9aR*)-3-phenyl-1-[5′,8′,9′,9′a-tetrahydro-3′-hydroxy-1′-methoxy-8′-(1″-methylethyl)-5′-a-methyldibenzo-[b,d]furan-4′-yl]propan-1-one ( 2 ), (2′R*,4″S*)-1-{6′-hydroxy-4′-methoxy-4″-(1?-methylethyl)spiro[benzo[b]-furan-2′(3′H),1″ -cyclohex-2″ -en]-7′-yl}-3-phenylpropan-1-one ( 3 ), (2′R*,4″R*)-1-{6′-hydroxy-4′-methylethyl-4″-(1?-methylethyl)spiro[benzo[b]furan-2′(3′H),1″-cyclohex-2″-en]-7′-yl}-3-phenypropan-1-one ( 4 ), and (5′aR*,6′S*, 9′R*,9′aS*)-1-[5′a,6′,7′,8′,9′a-hexahydro-3′,6′-methoxy-6′-methyl-9′-(1″-methylethyl)dibenzo[b,d]-furan-4′-yl]-3-phenylpropan-1-one ( 5 ) were isolated from the leaves of Piper aduncum (Piperaceae) by preparative liquid chromatography. In addition, (?)-methyllindaretin ( 6 ), trans-phytol, and α-tocopherol ( = vitamin E) were also isolated and identified. The structures were elucidated by spectroscopic methods, including 1D- and 2D-NMR spectroscopy as well as single-crystal X-ray diffraction analysis. The antibacterial and cytotoxic potentials of the isolates were also investigated. 相似文献
44.
Bond AD Doyle EL García F Kowenicki RA McPartlin M Riera L Wright DS 《Chemical communications (Cambridge, England)》2003,(24):2990-2991
The in situ reaction of the phosphazane dimer [CIP(mu-N-2-NC5H4)]2 (2) with CuCl in the presence of CsH5N/H2O gives the title complex [(P(mu-N-2-NC5H4))2(mu-O)]2(CuCl x (C5H5N)2)4 (1), containing a tricyclic [(P(mu-N-2-NC5H4))2(mu-O)]2 ligand which is isoelectronic with species of the type [(P(mu-NR))2NR]2. 相似文献
45.
Doyle EL García F Humphrey SM Kowenicki RA Riera L Woods AD Wright DS 《Dalton transactions (Cambridge, England : 2003)》2004,(5):807-812
The reaction of [ClP(mu-NtBu)]2 (1) with H2O (1 : 2 equivalents) in the presence of excess Et3N gives the new chain compound [(mu-O)[P(mu-NtBu)2P(H)=O]2] (3), consisting of two P2N2 rings linked by a mu-O atom and terminating in P(V)(H)=O groups. A similar chain species is obtained from the reaction of the lithiate of [(tBuNH)P(mu-NtBu)2P(H)=O] (5) with [ClP(mu-NtBu)2P(NHtBu)] (2), the product being [(mu-O)[P(mu-NtBu)2P(NHtBu)]2] (6). Compounds 3 and 6 are the first examples of O-bridged chain phosphazanes and potential precursors to new phosphorus-nitrogen macrocycles. The syntheses and X-ray structures of 3, 5 and 6 are reported. 相似文献
46.
John Raymond O'Lear Larry Gene Wright John Nathan Louris R. Graham Cooks 《Journal of mass spectrometry : JMS》1987,22(6):348-358
A new scan is described which responds to ions that are intermediates in the dissociation of a mass-selected parent ion (mp) to give a mass-selected daughter ion (md). The scan gives a simple mass v. abundance output for ions which satisfy this condition. It is implemented here on a BEQQ hybrid mass spectrometer using, in sequence, collision-induced dissociation occurring at high energy in the first reaction region, and low-energy collisional activation in the collision quadrupole. The experiment provides information on reaction sequences not available from single scans of other types. In the several cases examined, it is demonstrated that, among many conceivable fragmentation routes connecting a parent ion with a particular fragment ion, only a few are significant. Examination of reaction intermediate spectra also appears to be a fruitful new approach to mechanistic questions, as illustrated by consideration of the behavior of several isomeric octanones. These new spectra also have analytical value: they show good signal-to-noise ratios and allow ready distinction between isobaric and isomeric ions. A comparison of the reaction intermediate spectrum with a daughter spectrum obtained by the B/E linked-scanning technique reveals the contributions of artifact peaks which result from poor parent ion mass resolution in the latter. Reaction intermediate spectra combine information from the daughter spectra of mp and the parent spectra of md and, as a specified portion of this data domain, have unique characteristics. 相似文献
47.
R. Göttgens J. M. Kohli P. Sixel U. Gensch H. Vogt Y. Goldschmidt-Clermont D. R. O. Morrison R. T. Ross S. Squarcia J. Chwastowski M. W. Krasny L. Suszycki W. Zielinski P. Girtler D. Kuhn K. W. J. Barnham P. R. S. Wright M. Zomorrodian D. I. Patalakha A. M. Moissev J. MacNaughton F. Mandl M. Markytan J. Mittendorfer M. Bardadin-Otwinowska A. Jachołkowska M. Szczekowski 《Zeitschrift fur Physik C Particles and Fields》1983,19(4):283-290
The inclusive proton diffraction dissociation cross sections in 16, 32, and 110 GeV/cK ? p interactions are determined from the spike nearx=1 in the inclusive negative particle spectra and are compared to those obtained inK?p interactions using other selection methods at various energies. The same procedure is applied to events containing aV 0 in order to obtain the cross section for diffractive \(s\bar s\) production. While the total cross section for proton diffraction is found to be approximately constant in the energy range studied here, proton diffraction yielding an \(s\bar s - pair\) is found to increase significantly. In particular it is almost constant at 85 μb forΛ 0 and Σ production but for \(NK\bar K\) it rises from zero at 16 GeV.c to about 200 μb at 110 GeV/c. From the result for \(s\bar s\) diffractive production an estimate for the \(c\bar c\) diffractive production cross section of approximately 1–10 μb at 110 GeV/c is obtained. 相似文献
48.
Karen Wright Fernando FormaggioClaudio Toniolo Roland TörökAntal Péter Michel WakselmanJean-Paul Mazaleyrat 《Tetrahedron letters》2003,44(22):4183-4186
Resolution of trans 3-(9-fluorenylmethyloxycarbonylamino)-1-oxyl-2,2,5,5-tetramethylpyrrolidine-4-carboxylic acid (Fmoc-POAC-OH) was quickly achieved upon esterification with (aR)-1,1′-binaphthyl-2,2′-diol, chromatographic separation of the obtained diastereomers, and facile saponification of the aryl ester function with removal of the chiral auxiliary. 相似文献
49.
In diatoms, silica synthesis occurs by use of complex posttranslationally modified peptides, termed silaffins, and highly complex biological polyamine structures. Silaffin peptides have lysine residues that are modified to long-chain polyamine moieties of N-methyl derivatives of polypropylenimine to drive silica synthesis at slightly acidic pH conditions. Using polypropylenimine (PPI) and PAMAM amine-terminated dendrimers as a biomimetic analogue of the polyamine modifications of silaffins, we have demonstrated the condensation of silica nanospheres. We have shown that the dendrimers react in an amine concentration-dependent fashion yielding silica nanospheres with a distinct size distribution reminiscent of the structures produced from both the modified and nonmodified peptides extracted from diatoms. Additionally, the templates were encapsulated by the growing nanospheres and precipitated from solution in a manner similar to that previously described for the bioactive peptides and polyamines. 相似文献
50.
At about 300° the title compounds yield fragments attributed to cyclisation to isoxazolines and subsequent cycloreversion. Isoxazolines are formed at about 200° and can usually be isolated. At 300° they yield the same products as the oximes.Thus benzalacetophenone oxime gives 3,5-diphenylisoxazoline which then largely undergoes two distinct cycloreversions: (a) 1,3-cleavage (numbers refer to isoxazoline bonds) yielding benzonitrile and acetophenone and (b) reductive 1,4-cleavage yielding benzaldehyde and 1-phenylethylimine hydrolysis products. By-products are 2,4,6-triphenylpyridine, water and ammonium benzoate. With α-methylchalcone oxime reductive 1,4-cleavage is suppressed and with β-methylchalcone oxime both modes of cleavage are suppressed and 5-methyl-3,5-diphenylisoxazole is the stable product. An analogue of α-methylchalcone oxime, 2-methyl-1-phenyl-3-(2-thienyl)prop-2-ene-1-one oxime gives fragments attributed to both cleavage modes of an unisolatable and hitherto unknown isoxazoline.Possible mechanisms for the cyclisation and cycloreversions are discussed and the reductive 1,4-cleavage is believed to be a cycloreversion of a vinyl-nitrene. 相似文献