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101.
LoSecco JM Bionta RM Biewitt G Bratton CB Casper D Chrysicopoulou P Claus R Cortez BG Errede S Foster GW Gajewski W Ganezer KS Goldhaber M Haines TJ Jones TW Kielczewska D Kropp WR Learned JG Lehmann E Park HS Reines F Schultz J Seidel S Shumard E Sinclair D Sobel HW Stone JL Sulak L Svoboda R van der Velde JC Wuest C 《Physical review letters》1985,54(21):2299-2301
102.
103.
R.?Mitchell C.?M.?CarrEmail author M.?Parfitt J.?C.?Vickerman C.?Jones 《Cellulose (London, England)》2005,12(6):629-639
The surface chemical composition of raw unscoured cotton was successfully investigated by the surface analytical techniques
X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The presence of non-cellulosic
material at the fibre surface was established and determined to be a complex mixture of fatty acids, alcohols, alkanes, esters
and glycerides. The effect of scouring and bleaching was to reduce the surface concentration of these materials but even after
aqueous processing some non-cellulosic material residue was still detected at the fibre surface. 相似文献
104.
Bulloch EM Jones MA Parker EJ Osborne AP Stephens E Davies GM Coggins JR Abell C 《Journal of the American Chemical Society》2004,126(32):9912-9913
(6S)-6-Fluoroshikimate has antimicrobial activity. The molecular basis of this effect had not been identified, but there was speculation that (6S)-6-fluoroshikimate is first converted in vivo into 2-fluorochorismate, which then could inhibit 4-amino-4-deoxychorismate synthase (ADCS). 2-Fluorochorismate was prepared from E-fluorophosphoenolpyruvate and erythose-4-phosphate by the sequential reactions of DAHP synthase, dehydroquinate synthase, dehydroquinase, shikimate dehydrogenase, EPSP synthase, and chorismate synthase. Inhibition studies on ADCS showed that it was inhibited rapidly and irreversibly by 2-fluorochorismate. Electrospray mass spectrometry of the inactivated enzyme showed an additional mass of 198 +/- 10 Da. A novel peptide of 1087.6 Da was identified in the HPLC trace for the tryptic digest of 2-fluorochorismate-inactivated ADCS. Sequencing of this peptide by MS/MS showed that the peptide corresponded to residues 272-279 with a modification of 206.1 Da on Lys-274. This observation is particularly exciting in the context of a recent proposal for the catalytic mechanism of ADCS. 相似文献
105.
H. W. Sarkas S. T. Arnold J. H. Hendricks L. H. Kidder C. A. Jones K. H. Bowen 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,26(1):46-50
We present preliminary evidence for catalytic activity by unsupported mixed metal oxide nanocrystalline materials. The results of this study show that a nanophase form of Li-MgO has begun to exhibit catalytic activity by 300 °C. This is at least 200 degrees below the temperature at which conventional Li-MgO catalysts exhibit comparable activity. Furthermore, at higher temperatures, the same nanophase composition shows enhanced activities and somewhat improved hydrocarbon selectivities over conventional Li-MgO catalysts. 相似文献
106.
W.E. Falconer G.R. Jones W.A. Sunder M.J. Vasile Annabel A. Muenter T.R. Dyke W. Klemperer 《Journal of fluorine chemistry》1974,4(2):213-234
Most known non-radioactive pentafluorides have been examined by molecular-beam mass spectrometry and by the deflection of molecular beams in inhomogeneous electric fields. Extensive association of the vapors occurs for all but the lighter pentafluorides and the interhalogens. The interhalogen pentafluorides are strongly polar, consistent with the accepted C4v symmetry. The transition-metal and Group V pentafluorides are all non-polar, except VF5 and CrF5 for which temperature-dependent polarity is observed. However, uncertainty exists as to whether these observations are applicable to monomeric pentafluorides in all cases. Mass-spectral cracking patterns are presented for all species. 相似文献
107.
We report the synthesis and radioligand binding analysis of a series of naphthalenic melatonin receptor ligands, N-[2-(7-alkoxy-2-methoxy-1-naphthyl)ethyl]propionamide. This series of ligands exhibits subpicomolar binding affinity to both MT1 and MT2 melatonin receptors expressed in chinese hamster ovary (CHO) cells. 相似文献
108.
Current status of knowledge on the biological reduction of CC and CO is briefly reviewed. It is Argued that the crucial event in the reduction of CC is the addition of a proton to the more electron-rich terminal of the double bond to produce an electron-deficient species which is then neutralized through hydride transfer from NADPH. The activation for the reduction of a CO group may also be achieved by a related process in which the carbonyl oxygen is polarized by H-bonding to an acidic group on the enzyme, prior to hydride transfer from NAD(P)H.Thus with both these systems an early event in catalysis is the protonation of the substrate for which, normally, strong adds win be required. Since the groups available at the active-met of enzymes are weak acids, a mechanism through which powerful proton donating species could be transiently generated from them is proposed. The salient features of this mechanism may be enuinciatcd as follows: Let us consider the enzyme-substrate complex (A) in which an imidazolium group is about to play a role as a proton donating species. It is argued that rearrngement of initial complex(A)to the catalytic-complex(B), in which the negatively chared counter ion is removed away from the imidazolium cation, would transiently convert the latter group into a powerful proton danating species. the rearrangement (A)→(B) could occur through a protein conformational change or via a charge-relay system or a combination of both processes. 相似文献
109.
110.
Non-conjugated -dialkylated alkenes were oxidized to aldehydes in the presence of α,β-unsaturated carbonyl functional groups, providing a new synthesis of and a synthesis of that led to a revised structure for gastrolactone. 相似文献