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11.
α-(α'-Bromobenzyl)chalcone ( 3 ) reacts with primary amines (t-butyl, isopropyl,cyclohexyl) to give α-(α'-alkylaminobenzyl)chalcones ( 4, 5 and 6 ). When these allylic amines are treated with hydrogen bromide followed by reaction with base, they produce l-alkyl-2,4-diphenyl-3-benzoyl-azetidines ( 7,8 and 9 ). These azetidines were readily converted to their 3-deuterio derivatives ( 10 , 11 and 12 ) by treatment with sodium methoxide in deuteriomethanol. The configurations were assigned primarily by pmr spectra and mass spectra in reference to analogous compounds. 相似文献
12.
13.
Yusuf Musa Malcolm P. Stevens 《Journal of polymer science. Part A, Polymer chemistry》1972,10(2):319-327
Polyimides have been synthesized by the sensitized photoaddition of aliphatic and aromatic bismaleimides to benzene. The reaction involves 2+2 cycloaddition to give homoannular diene intermediate followed by Diels-Alder addition to give polymer. Proof of structure is based mainly on a comparison of infrared spectra with those of the corresponding polyimides prepared from maleic anhydride-benzene photoadduct and diamines. The very low solubility of the polymers indicates that crosslinking probably occurred during photolysis. All the polyimides appear to decompose by decyclization at about 420–485°C. Polymer yield was dependent on bismaleimide structure. 相似文献
14.
Abstract— Pulmonary macrophages obtained from neonatal rats contain approximately four times the activity of cyanide resistant superoxide dismutase and catalase compared with the cells from adult animals. The activity is highest immediately after birth and diminishes with age until the minimum level is reached at approximately 3 weeks of age. Superimposed upon this change in basal activity is the capability of neonatal cells to synthesize additional cyanide resistant superoxide dismutase and catalase when either the animals or isolated pulmonary macrophages are exposed to 95–100% oxygen. The inductive effect begins at 2–3 days after birth, peaks at 10 days, and disappears at approximately 15 days after birth. In contrast to adult rats, neonatal rats are extremely resistant to the toxic effects of oxygen. If, however, the oxygen mediated increase in both enzymes is prevented or the maximum effective pulmonary macrophage number is diminished in test animals, these animals become vulnerable to toxic effects of oxygen exposure, observed by gross and histologic examination of lung tissue, in a manner similar to adult animals. These data indicate that both cyanide-resistant superoxide dismutase and catalase may be part of the endogenous defense mechanisms which provide neonatal rats with an exceptional resistance to oxygen toxicity. 相似文献
15.
Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) have been used in conjunction with time-of-flight (TOF) and quadrupole ion trap (IT) mass spectrometry, respectively, to analyze various cytolysin proteins isolated from the sea anemone Stichodactyla helianthus and digested by the protease trypsin. By employing different ionization methods, the subsequent changes in ionization selectivity for the peptides in the digested protein samples resulted in ion abundance variation reflected in the mass spectra. Upon investigation of this variation generated by the two ionization processes, it has been shown in this study that enhanced protein coverage (e.g., >95% for cytolysin III) can be achieved. Additionally, capillary and microbore reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with ESI mass spectrometry (MS) as well as flow injection analysis by nanoflow ESI-MS afforded the necessary limit of detection (LOD) for detailed structural information of the cytolysin proteins by tandem mass spectrometry (MS/MS) methods. It can be concluded that cytolysins II and III correspond to sticholysins I and II, that "cytolysin I" is a mixture of modified forms of cytolysins II and III, and that "cytolysin IV" is an incompletely processed precursor of cytolysin III. 相似文献
16.
J. S. Ghotra G. C. Stevens D. Bloor 《Journal of polymer science. Part A, Polymer chemistry》1977,15(5):1155-1167
The thermal degradation of the monomer and polymer of bis(p-toluenesulfonate) of 2,4-hexadiyne-1,6-diol has been investigated. Decomposition during the latter stages of solid-state thermal polymerization at 80°C and of 100% polymer at 112°C was observed by mass spectrometry and the decomposition fragments identified. Mechanisms for this low-temperature degradation are suggested. Pyrolysis of the monomer and polymer between 400 and 1000°C was studied by gas chromatography and mass spectrometry. The principal pyrolysis products are triacetylene and p-toluenesulfonic acid. The fragmentation routes leading to and derived from these products are discussed. 相似文献
17.
B. A. Bushaw H. -J. Kluge J. Lantzsch R. Schwalbach J. Stenner H. Stevens K. Wendt K. Zimmer 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,28(4):275-281
The hyperfine spectra of the 5s4d 3 D 1-5s20f, 5s4d 3 D 2-5s23f, and 5s 4d 3 D 3-5s32f transitions of87Sr (I=9/2) have been measured by collinear fast beam laser spectroscopy. The structure in the upper configurations is highly perturbed by fine structure splitting that is of comparable size to the hyperfine interaction energy. These perturbations can be adequately treated with conventional matrix diagonalization methods, using the 5s-electron magnetic dipole interaction terma 5s and the unperturbed fine structure splittings as input parameters. Additionally, hyperfine constants for the lower 5s4d 3 D configurations, including theA- andB-factors and a separation of the individuals- andd-electron contributions to these factors, are derived. 相似文献
18.
Through NMR spectroscopic monitoring of barbituric acid addition to carbodiimide, a general synthetic procedure for the preparation of 5-diaminomethylenebarbiturates (DABA) was developed. This procedure is very simple and applicable to the preparation of large quantities of DABA derivatives. Through an X-ray structural study of one of the DABA derivatives, it was established that these compounds have an ylide-type structure with strong charge separation within the molecule. 相似文献
19.
20.
Stevens GC 《The Journal of the Operational Research Society》1982,33(10):921-929
An assessment of the effects of microcomputing on O.R. should take account of the impact of micros on other professional groups involved in the provision of information and analysis to managers. The paper examines the likely changes in the role of information systems analysts associated with present trends in computer-based information systems and, by concentrating on the decision support systems area, argues that O.R. workers and systems analysts may find themselves competing for new roles in ways which make if difficult to set out the contribution of each in terms of what they do at present. A modest proposal is made for a new form of team for the development of decision support systems. This incorporates a division of skills which cuts across existing lines of differentiation and foresees an increased contribution on the part of user-managers. 相似文献