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91.
Rosaria Conte Bruce Edmonds Scott Moss R. Keith Sawyer 《Computational & Mathematical Organization Theory》2001,7(3):183-205
A lengthy and intensive debate about the role of sociology in agent based social simulation dominated the email list simsoc@jiscmail.ac.uk during the autumn of 2000. The debate turned on the importance of models being devised to capture the properties of whole social systems and whether those properties should determine agent behaviour or, conversely, whether the properties of social systems should emerge from the behaviour and interaction of the agents and, if so, how that emergence should be represented. The positions of four of the main protagonists concerned specifically with the modelling issues are reprised and extended in this symposium. 相似文献
92.
Compliant multistable structures are presented which exhibit a large geometric change when actuated between their stable states. It is demonstrated how asymmetric-bistability is achieved through the combination of linear and nonlinear springs. Finite element analytical techniques are provided which enable the design of such structures, and which illustrate how the presence of imperfections can substantially alter their structural performance. A multistable structure is developed which consists of four connected bistable tetrahedral units. The validity of the analytical techniques is confirmed through observation of several physical models. 相似文献
93.
Electrochemical fluorination of tripropylamine in anhydrous hydrogen fluoride was studied in order to verify the correlation between the operating conditions and the yield of the corresponding perfluoroamine. The parameters tested were: temperature, voltage, initial concentration of amine in the bath, constant concentration of amine in the bath and stirring effect. Experimental data show that temperature is the parameter exerting the most remarkable influence over perfluoroamine yield and by-products formation. 相似文献
94.
95.
In this work we present a detailed numerical analysis of the interplay between symmetry breaking, integrability, and chaos in the two- and three-spin Heisenberg models. The results suggest that a very simple and powerful tool to convey such information are the plots of the energy level spacings Delta(n) versus the energy level index n, together with the correlation plots Delta(n+1)xDelta(n). When integrability is broken, these plots are shown to identify very sharply an energy below which one has chaotic behavior. The particularly strong point in favor of such analysis is that it can be useful in partially chaotic regimes. (c) 1995 American Institute of Physics. 相似文献
96.
[reaction: see text]. Room-temperature ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium chloride, are used as "green" recyclable alternative to chlorinated solvents for the stereoselective halogenation of alkenes and alkynes. 相似文献
97.
L. Conte G. P. Gambaretto M. Napoli C. Fraccaro E. Legnaro 《Journal of fluorine chemistry》1995,70(2):175-179
The fluorination of aromatic compounds (benzene, toluene, phenol and benzoic acid) by elemental fluorine diluted with nitrogen has been investigated in various solvents (Freon 11, chloroform, methanol, trifluoroacetic acid, 2,2,2-trifluoroethanol, water) in order to define the influence of the experimental conditions on the reaction. Experiments have been carried out by varying the temperature, the substrate concentration in solution, the molar ratio of fluorine to substrate, and the concentration of fluorine in the fluorine/nitrogen mixture. In all cases, the effects on the yield of fluorinated products were studied. Monofluorinated compounds were mainly found in the reaction mixture, the isomers formed being in accord with the mechanism for electrophilic substitution. The highest yield of monofluorinated products was obtained with polar solvents and the following order was found: CFCl3 < CHCl3 < CH3OH < CF3CH2OH < CF3COOH. Interesting results were also found using particular additives (for instance, KOH or C4F9SO3Na in methanol) or water as the solvent. A direct relationship was observed between the yield of monofluorinated compounds and the molar ratio of fluorine to substrate, which has to be less than one in order to obtain high yields. In contrast, low selectivity, expressed as the yield ratio of ortho to para (or meta) isomers, was found. 相似文献
98.
A technique is presented for the measurement of rifampin in humans by reversed-phase column chromatography and postcolumn photo irradiation. The assay employs diazepam as an internal standard and provides specific, rapid, and reliable determinations for drug concentration in plasma, bronchoalveolar lavage (BAL), and alveolar cells (AC). The preparation of plasma and AC samples utilizes a simple deproteinization step, whereas BAL supernatants require a solid-phase extraction. The assay produces sharp peaks with retention times of 6.2 and 15 min for rifampin and diazepam, respectively. The detection limits for rifampin were 0.5 microgram/mL for plasma, 0.015 microgram/mL for BAL supernatants, and 0.03 microgram/mL for AC suspensions. The assay has excellent performance characteristics, making it suitable for pharmacological studies in humans, and it is being used to support a study of the intrapulmonary pharmacokinetics of rifampin. 相似文献
99.
Gabriella Butera Claudio De Pasquale Antonella Maccotta Giuseppe Alonzo Pellegrino Conte 《Cellulose (London, England)》2011,18(6):1499-1507
Use of crude oil derivatives such as diesel and gasoline is becoming unsuitable due to their detriment to environment and
to the increasing worldwide energy demand which is driving crude oil reservoirs towards exhaustion. Replacement of diesel
and gasoline with biofuels (i.e. biodiesel and bioethanol, respectively) is very desirable. In fact, biofuels are not only
environmentally sustainable, but also potentially inexhaustible due to the large amounts of waste biomasses from which they
can be retrieved. In the present study, a model compound (micro-crystalline cellulose) was dissolved in phosphoric acid and
converted at 80 °C to glucose, thereby providing the possible substrate for fermentation to bioethanol. Results revealed that
after 1 h heating, the reaction had the largest glucose yield as compared to similar studies done by using other acid catalysts.
In addition, the temperature applied here was from 40 to 60 °C lower than those already reported in literature for acid-driven
cellulose degradations. Phosphoric acid allowed both glucose and levulinic acid achievement. The latter is usually used to
synthesize fuel additives, catalysts, solvents and herbicides, thereby enhancing the added value of the conversion of cellulose
to glucose in phosphoric acid. Finally, 1H T1 NMR relaxometry showed its suitability to monitor cellulose degradation. The advantages of relaxomety are its quickness since
only few minutes are needed to obtain relaxograms, and the possibility to use raw mixtures without the needing of sample preparation. 相似文献
100.
Dr. Andrea Bonetti Prof. Egle Beccalli Dr. Alessandro Caselli Prof. Francesca Clerici Dr. Sara Pellegrino Prof. Maria Luisa Gelmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(4):1692-1703
The reactivity of various α‐diazocarbonyl piperidine scaffolds, characterised by an increased molecular complexity, was tested with various RhII catalysts. The structure of the starting reagent is of relevance to the synthetic results. An unexpected dimerisation took place, starting from the simple piperidine scaffold, to give the hexahydrotetrazine ring system. Products derived from a nitrogen ylide intermediate or aromatic substitution (1,3,4,5‐tetrahydro‐2,5‐methanobenzo[c]azepine and 1,2,3,3a‐tetrahydrocyclopenta[de]isoquinolin‐4(5 H)‐one rings, respectively) were obtained from tetrahydroisoquinoline derivatives. The chemoselectivity of the reaction could be controlled by the choice of starting reagent, RhII catalyst and the reaction conditions. Finally, it was found that the azepino heterocycle could coordinate to the catalyst to give new RhII complexes. 相似文献