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31.
A. Berglund T. Buran P.J. Carlson C.J.S. Damerell I. Endo A.R. Gillman V. Gracco R.J. Homer M.J. Hotchkiss A. Lundby M. Macri B.N. Ratcliff A. Santroni T. Tso F. Wickens J.A. Wilson 《Physics letters. [Part B]》1975,57(1):100-104
For the first time, the reactions π+p→K+∑+ and K?p→π?∑+ have been studied in the same apparatus. This has been done at an adequately high momentum (10.1 GeV/c) to allow a check of the prediction of exchange degeneracy, that the differential cross sections should be converging at high energy. We have measured the cross section for momentum transfers t between tmin and t = ?0.3 (GeV/c)2. We find that for both reactions the differential cross section shows an exponential fall, with no deviations right in to t =tmin (where some other experiments have shown a dip in the cross section). Furthermore, we find the magnitude of the differential cross sections to be closely similar at t = 0, with a ratio However, the slope for the positive reaction is about 19% steeper than that for the negative reaction. 相似文献
32.
Rates of ring inversion in some isomeric octa- and deca-fluorocyclohexanes and in perfluorocyclohexane have been determined by dynamic 19FNMR spectroscopy and compared with data for other compounds. ΔG2cb varies over the range 39–49 kJ mol-1. Surprisingly the barriers in the diastereomeric octafluorocyclohexanes lie at opposite ends of the range. It seems that 1,3-diaxal interactions are less important than supposed hitherto; other factors which may affect the barriers are discussed. 相似文献
33.
34.
Jay W. Hotchkiss Benjamin G. R. Mohr Stephen G. Boyes 《Journal of nanoparticle research》2010,12(3):915-930
Poly(acrylic acid) (PAA) surface-modified gold nanorods, contained in deionized ultra filtered (DIUF) water, served as templates
for the formation of gold (Au), palladium (Pd), and platinum (Pt) nanoparticles upon reduction with NaBH4. This provided nanoparticles with respective diameters of 7.0 ± 0.7, 4.1 ± 0.4, and 5.1 ± 0.5 nm. Varying amounts of Pt metal
salt were used in EG, which acts as both a solvent and a reducing agent, ranging from 0.1, 0.2, and 1.0 mg/mL, to provide
control over nanoparticle diameters of 2.0 ± 0.5 nm, to 4.0 ± 0.5 nm, and 6.2 ± 1.9 nm, respectively. Nanoparticle diameter
was also controlled in DIUF water by varying the amount of Pt metal salt from 0.1, 0.2, and 1.0 mg/mL, producing Pt particle
diameters, respectively, increasing from 2.7 ± 0.3 nm to 4.1 ± 0.5 nm, and 6.0 ± 0.6 nm. 相似文献
35.
Marshall L. Fishman Hoa K. Chau David R. Coffin Peter H. Cooke Phoebe Qi Madhav P. Yadav Arland T. Hotchkiss 《Cellulose (London, England)》2011,18(3):787-801
The residue of sugar beet pulp from which pectin and alkaline soluble polysaccharides have been removed by microwave assisted
extraction or conventional heat was treated with sodium monochloroacetate under alkaline pH to convert the residual cellulose
present to carboxy methyl cellulose (CMC). Weight average molar masses ranged from about 96 to 220 × 103 Daltons, weight average intrinsic viscosity from 1.9 to 4.1 dL/g and degree of substitution from 1.38 to 0.59. HPSEC with
online molar mass detectors and Atomic Force Microscopy revealed that CMC was comprised of aggregated linear moieties in contact
with spherical bodies. The linear portion was a mixture of rods and segmented rods. Some of the rods had long branches. 相似文献
36.
Three sharp absorption features in the energy range 2.36–2.55 eV have been detected in the transmission spectrum of Co-diffused ZnSe, and a number of luminescence transitions originating from the lowest of these states at 2.361 eV have been observed. Photoluminescence excitation spectra prove that these are high energy excited states of the Co2+Zn impurity, a conclusion confirmed by comparison of measured and predicted luminescence energies. This represents the first identification of luminescence branching from a higher excited state of a transition metal ion in any semiconductor. The sharp, weakly phonon-coupled transitions involve either intra-impurity excitation or transitions from the impurity to localised states split off from a minimum in the conduction band. The implications of these observations for the mechanism of host-impurity energy transfer and for the nature of the excited state wavefunctions are discussed. 相似文献
37.
38.
A primary alcohol can be protected as a highly stable p-anisyl ether, which undergoes mild oxidative deprotection by ceric ammonium nitrate. 相似文献
39.
A. Berglund T. Buran P.J. Carlson C.J.S. Damerell I. Endo A.R. Gillman V. Gracco R.J. Homer M.J. Hotchkiss A. Lundby M. Macri B.N. Ratcliff A. Santroni T. Tso F. Wickens J.A. Wilson 《Nuclear Physics B》1978,137(3):276-282
The reaction has been studied at 10.1 GeV/c in the ?t interval from 0.15 to 1.5 (GeV/c)2. A line-reversal comparison with backward elastic scattering π+p → pπ+ shows good agreement for ?t > 0.3 (GeV/c)2. 相似文献
40.
The title compounds have been fluorinated with elemental fluorine of low oxygen content to give products derived from fluorine addition, accompanied by dimerisation and oligomerisation of radical intermediates in the case of the dienes. The 1,4-diene is relatively unreactive towards fluorine and polymerisation did not occur. Acid fluorides, of the type formed using fluorine produced without precautions to minimise oxygen-containing species, were not produced in these reactions. 相似文献