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31.
Moreau A Couture A Deniau E Grandclaudon P Lebrun S 《Organic & biomolecular chemistry》2005,3(12):2305-2309
The first total synthesis of the phytotoxins cichorine and zinnimidine is described. The synthetic tactics involve the sequential connection of the dense and diverse functionalities on the aromatic nucleus followed by a Parham cyclization process, giving rise to the lactam unit embedded in the title compound framework. 相似文献
32.
G. Bizard R. Brou H. Doubre A. Drouet F. Guilbault F. Hanappe J. M. Harasse J. L. Laville C. Lebrun A. Oubahadou J. P. Patry J. Péter G. Ployart J. C. Steckmeyer B. Tamain 《Zeitschrift für Physik A Hadrons and Nuclei》1986,323(4):459-464
Heavy residues created in the reaction Ar + Ag at 35 MeV/u have been detected at various forward angles. Their velocity spectra (quite different from the corresponding spectra measured at 27 MeV/u) show that these events result both from central and peripheral reactions and that the fusion component has dramatically decreased. Coincident light charged particles spectra have been obtained in a large solid angle forward hodoscope. The analysis of these spectra allows to differentiate peripheral and central collisions. The proton spectra are analysed in terms of emitting sources. There is no need for a participant zone in peripheral reactions. Instead protons are emitted either from the target like or from the projectile like fragments. However projectile sequential emission is not sufficient to explain all the high energy protons. 相似文献
33.
D. Dalili P. Lhenoret R. Lucas C. Mazur C. Ngô M. Ribrag T. Suomijarvi E. Tomasi B. Boishu A. Genoux Lubin C. Lebrun J. F. Lecolley F. Lefebvres M. Louvel R. Regimbart J. C. Adloff A. Kamili G. Rudolf F. Scheibling 《Zeitschrift für Physik A Hadrons and Nuclei》1984,318(3):371-372
The Qβ-values of99Rb,99,100Sr and100Y have been measured for the first time at the mass separator OSTIS of the ILL; for99Y,99,100Zr and100Nb, the results of earlier experiments were confirmed with reduced experimental errors. The two-neutron binding energies derived from the experimental Qβ-values clearly indicate that the nuclei100Sr and100Y are strongly deformed. 相似文献
34.
A. Litnovsky C. Boucher P. Sicard G. Lebrun J.-P. St-Germain G. Van Oost 《Czechoslovak Journal of Physics》2003,53(10):903-910
Electrical probes are an excellent tool for local measurements of basic plasma parameters, fluctuations and plasma flow studies. However, the application of a probe diagnostics is usually accompanied by theoretical restrictions, practical limitations and problems. In this paper we describe the new probe system recently developed for the TOMAS toroidal device (Forschungszentrum Jülich, Germany). This system comprises multi-collector Gundestrup probe for flow measurements and Langmuir probe for plasma characterization. During development of such a system, several physical and technical issues, which are common for probe applications, were solved or essentially suppressed. 相似文献
35.
J. Julien M. Boloré H. Dabrowski J. M. Hisleur V. Bellini A. S. Figuera R. Fonte A. Insolia G. F. Palama G. V. Russo M. L. Sperduto J. Chauvin P. De Saintignon D. Lebrun D. Rebreyend 《Zeitschrift für Physik A Hadrons and Nuclei》1988,330(1):83-86
Inclusive production of neutral pions has been studied in16O +27Al,197Au reactions at 38 MeV/u and20Ne +27Al reaction at 200 MeV/u. A setup of 10 Pb glass Cherenkov detector telescopes was used to detect the twoγ rays from theπ 0 decay. 相似文献
36.
37.
Federico Cisnetti Dr. Christelle Gateau Dr. Colette Lebrun Pascale Delangle Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(30):7456-7469
Unnatural metal‐chelating amino acids bearing aminodiacetate side‐chains have been introduced into two hexapeptides to obtain efficient lanthanide‐binding peptides. The synthesis of the enantiopure Fmoc‐Adan(tBu)2‐OH synthons is described with overall yields of 32 and 50 % for n=2 and n=3 side‐chain carbon atoms, respectively. The two peptides AcWAdanPGAdanGNH2 ( P n ) were synthesized from the protected synthons by standard solid‐phase peptide synthesis. Studies of the lanthanide complexes of the two peptides P n by luminescence titrations, mass spectrometry, circular dichroism, and solution NMR spectroscopy demonstrate that the Adan chain length has a dramatic effect on the complexation properties. Indeed, the flexible compound P3 forms a mononuclear complex of moderate stability (β11=109.9), which tends to transform into a binuclear species in the presence of excess of the metal ion. Interestingly, the more compact peptide P2 provides stable Ln3+ complexes with the exclusive formation of the mononuclear Ln P2 adduct. The stability constant of Tb P2 is two orders of magnitude higher (β11=1012.1) than that measured for P3 . The 800 MHz NMR spectrum of the La3+ complex of P2 evidences a well‐defined type II β‐turn as well as a hydrophobic Trp(indole)–Pro interaction. These interactions exemplify the non‐innocent character of the peptide spacer in the complex La P2 as well as the role of a peptide secondary structure in the stabilization of metal complexes. 相似文献
38.
Phosphoester Hydrolysis: The Incoming Substrate Turns the Bridging Hydroxido Nucleophile into a Terminal One 下载免费PDF全文
Dr. Eric Gouré Dr. Michaël Carboni Angélique Troussier Colette Lebrun Dr. Jacques Pécaut Jean‐François Jacquot Patrick Dubourdeaux Dr. Martin Clémancey Dr. Geneviève Blondin Dr. Jean‐Marc Latour 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8064-8068
Identifying the active nucleophile in hydrolysis reactions catalyzed by binuclear hydrolases is a recurrent problem and a matter of intense debate. We report on the phosphate ester hydrolysis by a FeIIIFeII complex of a binucleating ligand. This complex presents activities in the range of those observed for similar biomimetic compounds in the literature. The specific electronic properties of the FeIIIFeII complex allowed us to use 1H NMR and Mössbauer spectroscopies to investigate the nature of the various species present in the solution in the pH range of 5–10. Both techniques showed that the hydrolysis activity is associated to a μ‐hydroxido FeIIIFeII species. Further 1H NMR experiments show that binding of anions or the substrate changes this bonding mode suggesting that a terminal hydroxide is the likely nucleophile in these hydrolysis reactions. This view is further supported by the structure determination of the hydrolysis product. 相似文献
39.
40.
Thiazole‐Based γ‐Building Blocks as Reverse‐Turn Mimetic to Design a Gramicidin S Analogue: Conformational and Biological Evaluation 下载免费PDF全文
Dr. Baptiste Legrand Loïc Mathieu Aurélien Lebrun Soahary Andriamanarivo Prof. Vincent Lisowski Dr. Nicolas Masurier Dr. Séverine Zirah Prof. Young Kee Kang Prof. Jean Martinez Dr. Ludovic T. Maillard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6713-6720
This paper describes the ability of a new class of heterocyclic γ‐amino acids named ATCs (4‐amino(methyl)‐1,3‐thiazole‐5‐carboxylic acids) to induce turns when included in a tetrapeptide template. Both hybrid Ac‐Val‐(R or S)‐ATC‐Ile‐Ala‐NH2 sequences were synthesized and their conformations were studied by circular dichroism, NMR spectroscopy, MD simulations, and DFT calculations. It was demonstrated that the ATCs induced highly stable C9 pseudocycles in both compounds promoting a twist turn and a reverse turn conformation depending on their absolute configurations. As a proof of concept, a bioactive analogue of gramicidin S was successfully designed using an ATC building block as a turn inducer. The NMR solution structure of the analogue adopted an antiparallel β‐pleated sheet conformation similar to that of the natural compound. The hybrid α,γ‐cyclopeptide exhibited significant reduced haemotoxicity compared to gramicidin S, while maintaining strong antibacterial activity. 相似文献