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141.
Caroline Joannesse Craig P. Johnston Louis C. Morrill Philip A. Woods Madeleine Kieffer Dipl.‐Chem. Tobias A. Nigst Prof. Herbert Mayr Dr. Tomas Lebl Prof. Douglas Philp Dr. Ryan A. Bragg Dr. Andrew D. Smith 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(8):2398-2408
The structural motif within a series of tetrahydropyrimidine‐based isothioureas necessary for generating high asymmetric induction in the asymmetric Steglich rearrangement of oxazolyl carbonates is fully explored, with crossover and dynamic 19F NMR experiments used to develop a mechanistic understanding of this transformation. 相似文献
142.
Inhibition of Cu‐Amyloid‐β by using Bifunctional Peptides with β‐Sheet Breaker and Chelator Moieties
143.
144.
Antigoni Kotali Despina A. Nasiopoulou Philip A. Harris Madeleine Helliwell John A. Joule 《Tetrahedron》2012,68(2):761-766
The transformation of a hydroxyl into an acyl group, a transformation which has been extensively investigated on the benzene nucleus of several substrates, is now applied successfully for the first time to a heterocyclic ring and specifically to the pyrone ring of coumarin to yield novel 3,4-diacylcoumarins in good yields. The reaction involves formation of a new C–C bond. 相似文献
145.
Physical gelation is the process of crosslinking which reversibly transforms a solution of polymers into a gel. The crosslinks of the network have a physical origin (hydrogen bonding, Van der Waals forces... ) and therefore are sensitive to variations of temperature, pH, ionic content, etc. (non-permanent crosslinks). Physical and chemical gelation have been extensively studied in quiescent conditions, where rheology experiments have been performed to follow the network formation without disturbing the process. In this study we consider gelation of a well known physical, thermoreversible, gel (gelatin gel), which proceeds under flowing conditions. The gelling solution is submitted to a shearing, with imposed, permanent shear stresses or imposed, permanent, shear rates. Under flow, a competition arises between the formation of clusters by physical crosslinking and their disruption by the shear forces. This investigation defines the flowing conditions which either allow or impede gel formation. In particular, a critical shear rate
, related to the gelation temperature and gelatin concentration, is identified which separates the two regimes. A microscopic model is proposed, based on the analysis of flow curves and dynamic measurements, which describes the structure of the gelling solution: microgel particles grow to a maximum size which depends on the flow. When the volume fraction of particles is high enough, percolation between particles occurs suddenly and a yield stress fluid is formed (particulate gel). The differences between gels made in quiescent conditions and gels made under flow are underlined. 相似文献
146.
Two methods of analysis were developed to permit detection of counterfeit Scotch whisky samples using a novel attenuated total reflectance (ATR) diamond-tipped immersion probe for mid-infrared (MIR) spectrometry. The first method allowed determination of the ethanol concentration (35–45% (v/v)) in situ without dilution of the samples; the results obtained compared well with the supplied concentrations (average relative error of 1.2% and 0.8% for univariate and multivariate partial least squares (PLS) calibration, respectively). The second method involved analysis of dried residues of the whisky samples and caramel solutions on the diamond ATR crystal; principal component analysis (PCA) of the spectra was used to classify the samples and investigate the colorant added. Seventeen test whisky samples were successfully categorised as either authentic or counterfeit in a blind study when both MIR methods were used. 相似文献
147.
Although the reactions of ketenes and three-membered heterocycles containing one hetero atom are well known,1,2 only one investigation of similar recations with three-membered rings containing two hetero atoms has been reported.3 The reaction of 2-ethyl-3-phenyloxaziridine with diphenylketene was found to afford among other minor products an oxazolidinone derivative (1) and benzaldehyde in yields of 38% and 50% respectively. 相似文献
148.
149.
M. Th. François A. Boutaric Madeleine Roy H. C. S. Snethlage G. Scatchard P. T. Jones und S. S. Prentiss 《Fresenius' Journal of Analytical Chemistry》1933,95(7-8):265-267
Ohne Zusammenfassung 相似文献
150.