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991.
Heitz MC Durand G Spiegelman F Meier C Mitrić R Bonacić-Koutecký V 《The Journal of chemical physics》2004,121(20):9906-9916
Short-time, excited-state dynamics of the lowest isomer of the Na(3)F cluster is studied theoretically in order to interpret the features of recent time-resolved pump-probe ionization experiments [J. M. L'Hermite, V. Blanchet, A. Le Padellec, B. Lamory, and P. Labastie, Eur. Phys. J. D 28, 361 (2004)]. In the present paper, we propose an identification of the vibrational motion responsible for the oscillations in the ion signal, on the basis of quantum mechanical wave packet propagations and classical trajectory calculations. The good agreement between experiment and theory allows for a clear interpretation of the detected dynamics. 相似文献
992.
Jrme Durand Alessandro Scarel Barbara Milani Roberta Seraglia Serafino Gladiali Carla Carfagna Barbara Binotti 《Helvetica chimica acta》2006,89(8):1752-1771
The catalytic behavior of dicationic bis‐chelated PdII complexes, [Pd(N? N)2][PF6]2, in the CO/ethylene/styrene terpolymerization reaction is studied in detail. The bidentate N‐donor ligands were chosen among 2,2′‐bipyridine ( 1 ), 1,10‐phenanthroline ( 3 ), their symmetrically substituted derivatives 2, 4 , and 5 , and 3‐alkyl‐substituted 1,10‐phenanthrolines 6 – 10 . The effect of several parameters (like temperature, CO/ethylene pressure, styrene content, reaction time) was investigated and related to the productivity of the catalytic system, to the relative content of the two olefins in the polymeric chains, and to the molecular mass of the synthesized polyketones. The presence of 1,4‐benzoquinone was necessary to reach productivities as high as 16 kg of terpolymer (TP) per gram of Pd. 13C‐NMR spectroscopy was useful to characterize the distribution of the two repetitive units along the polymer chain. Terpolymers with prevailingly isolated CO/styrene units in CO/ethylene blocks as well as terpolymers with CO/styrene and CO/ethylene blocks were obtained by varying the reaction conditions. Detailed MALDI‐TOF‐MS analysis was performed on the CO/ethylene/styrene terpolymers for the first time, and it allowed us to characterize the end groups of the terpolymer chains. The presence of different chain end groups was found to be related to the initial amount of the two alkenes, thus suggesting that different reactions are involved in the initiation and termination steps of the terpolymerization catalytic cycle. 相似文献
993.
H. Umesha Shetty Eileen M. Daly Nigel H. Greig Stanley I. Rapoport Timothy T. Soncrant 《Journal of the American Society for Mass Spectrometry》1991,2(2):168-173
An automatic reaction control chemical ionization technique in an ion trap detector (lTD) was used to quantitate the levels of the cholinergic drug, arecoline, in plasma of treated patients with Alzheimer’s disease. The chemical ionization reaction was carried out with acetonitrile. The protonated molecules of arecoline (m I z 156) and the internal standard, homoarecoline (m / z 170), were monitored. Human plasma samples were extracted with a readily evaporable solvent mixture, the residues reconstituted and injected along with a tertiary amine-carrier into a capillary gas chromatograph interfaced with the ITD. Standard curves for plasma-extracted arecoline between 20-ng/mL and 156-pg/mL levels were linear (r> 0.9980). Satisfactory precision (relative standard deviation < 20%) and accuracy (relative error < 15%) at the limit of quantitation, 156 pg/mL arecoline, were achieved. Optimal conditions for handling of blood samples obtained by venipuncture were determined. The assay was successfully applied for the therapeutic monitoring of Alzheimer patients treated intravenously with arecoline. 相似文献
994.
Dieter H. Klaubert Stanley C. Bell Thomas W. Pattison 《Journal of heterocyclic chemistry》1985,22(2):333-336
A three step synthesis of 5H-tetrazolo[5,1-c][1,4]benzodiazepin-11-ones 8a-d via the reaction of a substituted benzyl azide and ethyl cyanoformate is described. The derived lactams are converted to the corresponding 11-thiones 9a-d and, through the S-methylated derivatives, to the 11-amino analogs 11a-f. All of the described compounds are representatives of a novel ring system. 相似文献
995.
Theoretical study of global and local reactivities of coumarin and its hydroxylated derivatives 下载免费PDF全文
Francisco J. Melendez J. Sergio Durand‐Niconoff Miguel A. Domínguez‐Ortiz Oscar García‐Barradas Norma A. Caballero Enrique González 《International journal of quantum chemistry》2016,116(9):663-669
Coumarins are bioactive substances of the benzo‐α‐pyrone family, which have shown antioxidant, antiviral, anti‐inflammatory and antitumor activities, among others. 7‐Hydroxycoumarin and 6,7‐dihydroxycoumarin (esculetin) are two coumarin derivatives that have been reported to exhibit antitumor activity, but the action mechanism underlying this activity remains unknown. In this work, to elucidate this mechanism, a theoretical study of the local and global electronic reactivity properties of a series of hydroxylated and dihydroxylated coumarin derivatives with possible antitumor action is performed using Density Functional Theory in aqueous solution. The substitution by one or two hydroxyl groups in the benzene ring of coumarin produces better charge‐donor than charge‐acceptor compounds. All the studied compounds are generally stable in water and exhibit permanent polarization in the solvent. With one hydroxyl substitution, 7‐hydroxycoumarin is the most polar and polarizable derivative, whereas 5,7‐dihydroxycoumarin is the most polar and polarizable compound with two hydroxyl substitutions. 5,7‐Dihydroxycoumarin is suggested to possess antitumor activity. © 2016 Wiley Periodicals, Inc. 相似文献
996.
Bioanalysis, a key supporting function for generating data for pre‐clinical and clinical studies in drug development, is under the regulation of local agencies as well as global organizations to ensure the data integrity and quality in submission. As major regulatory agencies and organizations, the US Food and Drug Administration, the European Medicines Agency and the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use have been updating their industry guidance for bioanalytical method validation, to keep up with the development new modalities, technologies and regulations. This article summarizes the recent updates and any clarifications and controversies triggered by those updates. Perspectives and recommendations are given based on our own experience as well as commonly accepted practice in the bioanalytical community. 相似文献
997.
Nicholas Stanley Georgiana Bucataru Yong Miao Audrey Favrelle Marc Bria Francois Stoffelbach Patrice Woisel Philippe Zinck 《Journal of polymer science. Part A, Polymer chemistry》2014,52(15):2139-2145
The polymerization of ε‐caprolactone (ε‐CL) has been assessed in water using various Brønsted acids as catalysts. The reaction was found to be quantitative at 100 °C, leading to number–average molecular weights up to 5000 g mol?1. The Brønsted acid‐catalyzed polymerization of ε‐CL in water was further conducted in the presence of water‐soluble polysaccharides thereby affording graft copolymers. The approach enables an easy, mild access to dextran hydroxyesters. For low degree of substitution, the latter self‐assembles in water to form nanoparticles. Poly(ε‐CL)‐graft‐methylcellulose copolymers can also be obtained via a similar approach. It is noteworthy that the methodology reported herein is a one‐step route to poly(ε‐CL)‐graft‐water‐soluble polysaccharides, operating in mild conditions, that is, at low temperatures, using readily available metal‐free catalysts and water as a solvent. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2139–2145 相似文献
998.
999.
Abstract We present a simple dynamical model which describes the time dependence of the threshold electric field for breaking the surface anchoring of nematics. This model includes a surface friction, resulting from volume hydrodynamic dissipation. Experimental data with AC and DC pulsed fields are explained by this model. For DC, the threshold difference versus the field polarity is well-described by the flexo-electric effects in a uniform field for short times and in a non-uniform field for long times. 相似文献
1000.
Jonas Croissant Dr. Marie Maynadier Audrey Gallud Dr. Harmel Peindy N'Dongo Dr. Jeff L. Nyalosaso Dr. Gaëlle Derrien Dr. Clarence Charnay Dr. Jean‐Olivier Durand Dr. Laurence Raehm Prof. Françoise Serein‐Spirau Dr. Nathalie Cheminet Dr. Thibaut Jarrosson Dr. Olivier Mongin Dr. Mireille Blanchard‐Desce Dr. Magali Gary‐Bobo Dr. Marcel Garcia Dr. Jie Lu Prof. Fuyuhiko Tamanoi Dr. Derrick Tarn Tania M. Guardado‐Alvarez Prof. Jeffrey I. Zink 《Angewandte Chemie (International ed. in English)》2013,52(51):13813-13817