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61.
Chen D Albuquerque IF Baublis VV Bondar NF Carrigan RA Cooper PS Lisheng D Denisov AS Dobrovolsky AV Dubbs T Endler AM Escobar CO Foucher M Golovtsov VL Goritchev PA Gottschalk H Gouffon P Grachev VT Khanzadeev AV Kubantsev MA Kuropatkin NP Lach J Lang Pengfei Lebedenko VN Li Chengze Li Yunshan Mahon JR McCliment E Morelos A Newsom C Pommot Maia MC Samsonov VM Schegelsky VA Shi Huanzhang Smith VJ Sun CR Tang Fukun Terentyev NK Timm S Tkatch II Uvarov LN Vorobyov AA Yan Jie Zhao Wenheng 《Physical review letters》1992,69(23):3286-3289
62.
Foucher M Albuquerque IF Bondar NF Carrigan R Chen D Li Chengze Cooper PS Denisov AS Dobrovolsky AV Dubbs T Endler AM Escobar CO Tang Fukun Golovtsov VL Goritchev PA Gottschalk H Gouffon P Grachev VT Shi Huanzhang Yan Jie Khanzadeev AV Kubantsev MA Kuropatkin NP Lach J Luksys M Lebedenko VN Dai Lisheng Mahon JR McCliment E Morelos A Newsom C Lang Pengfei Pommot Maia MC Samsonov VM Zheng Shuchen Smith VJ Terentyev NK Timm S Tkatch II Uvarov LN Vorobyov AA Zhao Wenheng Zhong Yuanyuan 《Physical review letters》1992,68(20):3004-3007
63.
Ponraj Prabakaran Jebamony Justin Robert Packianathan Thomas Muthiah Gabriele Bocelli Lara Righi 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):459-461
In the title cocrystal, trimethoprim maleate [2,4‐diamino‐5‐(3,4,5‐trimethoxybenzyl)pyrimidin‐1‐ium maleate], C14H19N4O3+·C4H3O4?, the trimethoprim molecule is protonated at N1. The carboxyl group of the maleate ion makes a specific double hydrogen bond of type N—H?O with the 2‐amino group and the protonated N1 atom of the trimethoprim cation which is similar to the carboxylate–trimethoprim cation interaction observed in the complex of dihydrofolate reductase with trimethoprim. The pyrimidine moieties of trimethoprim cations are centrosymmetrically paired through a pair of N—H?N hydrogen bonds involving the 4‐amino group and the pyridinium N3 atom of a symmetry‐related molecule. One of the O atoms at the maleate carboxylate group bridges the 2‐amino and 4‐amino groups on either side of the paired trimethoprim cations. The other O atom of the carboxylate group forms an intramolecular O—H?O hydrogen bond with the carboxyl group. These characteristic hydrogen bonds result in infinite two‐dimensional aggregation of rings into a supramolecular ladder, which is further crosslinked through weak C—H?O interactions with methoxy groups of neighbouring trimethoprim molecules to form a layered structure. 相似文献
64.
Sylvian Cretton Alejandra Oyarzún Davide Righi Lamia Sahib Marcel Kaiser 《Natural product research》2018,32(6):695-701
A new bibenzyl derivative (4), together with two glycosylated flavonoids (1 and 2), batatasin III (3) and the phenanthrene isohircinol (5) were isolated from the aerial parts of Gavilea lutea. Their structures were elucidated on the basis of spectroscopic studies including 1D and 2D NMR, UV, IR and HRESIMS. All isolated compounds were evaluated for their antifungal activity towards Candida albicans. The new compound 4 showed inhibitory activity with a MIQ of 50 μg. In addition, compound 4 exhibited a selective activity (IC50 = 2.3 μg/mL) against Leishmania donovani. 相似文献
65.
Giuliana Righi Emanuela Mandic’ Gaia Clara Mercedes Naponiello Paolo Bovicelli Ilaria Tirotta 《Tetrahedron》2012,68(14):2984-2992
The results obtained from a study on the stereochemical control in the dihydroxylation of the double bond of vinyl epoxides and their derivatives (bromo derivatives, azido derivatives and vinyl aziridines) are presented herein. A significant diastereoselectivity was observed for the bromo derivatives, azido derivatives and N-protected vinyl aziridines, whereas vinyl epoxides and unprotected vinyl aziridines showed no diastereoselectivity. The results obtained are generally consistent with the Kishi model. 相似文献
66.
Righi M Topi F Bartolucci S Bedini A Piersanti G Spadoni G 《The Journal of organic chemistry》2012,77(14):6351-6357
An efficient, one-pot reductive alkylation of indoles with N-protected aminoethyl acetals in the presence of TES/TFA is reported. It represents the first general method for the direct synthesis of tryptamine derivatives from indoles and nitrogen-functionalized acetals. This convergent and versatile approach employs safe and inexpensive reagents, proceeds under mild conditions, and tolerates several functional groups. The new procedure was efficiently applied to a gram-scale synthesis of both luzindole, a reference MT2-selective melatonin receptor antagonist, and melatonin. 相似文献
67.
Céline Righi 《Journal of Algebra》2008,319(4):1555-1584
We extend the results of Cellini and Papi [P. Cellini, P. Papi, Ad-nilpotent ideals of a Borel subalgebra, J. Algebra 225 (2000) 130–140; P. Cellini, P. Papi, Ad-nilpotent ideals of a Borel subalgebra II, J. Algebra 258 (2002) 112–121] on the characterizations of ad-nilpotent and abelian ideals of a Borel subalgebra to parabolic subalgebras of a simple Lie algebra. These characterizations are given in terms of elements of the affine Weyl group and faces of alcoves. In the case of a parabolic subalgebra of a classical simple Lie algebra, we give formulas for the number of these ideals. 相似文献
68.
Global air quality and climate 总被引:1,自引:0,他引:1
AM Fiore V Naik DV Spracklen A Steiner N Unger M Prather D Bergmann PJ Cameron-Smith I Cionni WJ Collins S Dalsøren V Eyring GA Folberth P Ginoux LW Horowitz B Josse JF Lamarque IA Mackenzie T Nagashima FM O'Connor M Righi ST Rumbold DT Shindell RB Skeie K Sudo S Szopa T Takemura G Zeng 《Chemical Society reviews》2012,41(19):6663-6683
Emissions of air pollutants and their precursors determine regional air quality and can alter climate. Climate change can perturb the long-range transport, chemical processing, and local meteorology that influence air pollution. We review the implications of projected changes in methane (CH(4)), ozone precursors (O(3)), and aerosols for climate (expressed in terms of the radiative forcing metric or changes in global surface temperature) and hemispheric-to-continental scale air quality. Reducing the O(3) precursor CH(4) would slow near-term warming by decreasing both CH(4) and tropospheric O(3). Uncertainty remains as to the net climate forcing from anthropogenic nitrogen oxide (NO(x)) emissions, which increase tropospheric O(3) (warming) but also increase aerosols and decrease CH(4) (both cooling). Anthropogenic emissions of carbon monoxide (CO) and non-CH(4) volatile organic compounds (NMVOC) warm by increasing both O(3) and CH(4). Radiative impacts from secondary organic aerosols (SOA) are poorly understood. Black carbon emission controls, by reducing the absorption of sunlight in the atmosphere and on snow and ice, have the potential to slow near-term warming, but uncertainties in coincident emissions of reflective (cooling) aerosols and poorly constrained cloud indirect effects confound robust estimates of net climate impacts. Reducing sulfate and nitrate aerosols would improve air quality and lessen interference with the hydrologic cycle, but lead to warming. A holistic and balanced view is thus needed to assess how air pollution controls influence climate; a first step towards this goal involves estimating net climate impacts from individual emission sectors. Modeling and observational analyses suggest a warming climate degrades air quality (increasing surface O(3) and particulate matter) in many populated regions, including during pollution episodes. Prior Intergovernmental Panel on Climate Change (IPCC) scenarios (SRES) allowed unconstrained growth, whereas the Representative Concentration Pathway (RCP) scenarios assume uniformly an aggressive reduction, of air pollutant emissions. New estimates from the current generation of chemistry-climate models with RCP emissions thus project improved air quality over the next century relative to those using the IPCC SRES scenarios. These two sets of projections likely bracket possible futures. We find that uncertainty in emission-driven changes in air quality is generally greater than uncertainty in climate-driven changes. Confidence in air quality projections is limited by the reliability of anthropogenic emission trajectories and the uncertainties in regional climate responses, feedbacks with the terrestrial biosphere, and oxidation pathways affecting O(3) and SOA. 相似文献
69.
Sergio Bonora Michele Di Foggia Vitaliano Tugnoli Valeria Righi Enrico Benassi Assimo Maris 《Journal of Raman spectroscopy : JRS》2011,42(4):612-620
Cimetidine (cim) is one of the most potent histamine H2‐receptor antagonists for inhibiting excessive acid secretion caused by histamine; it has been hypothesized that the therapeutic effects can be related to its interactions with metal ions. Raman spectra of the solid cim with Co(II), Cu(II), Ni(II) and Zn(II) metal complexes show that they can adopt two different structures: one is octahedral and the other, with Zn(II), is probably tetrahedral. The octahedral structure appears to be distorted both by the different metal ions as well as by the different anion present. The study was extended to very dilute solutions (ppm range) by using the surface‐enhanced Raman scattering (SERS) technique, mimicking the physiological concentrations of cim and its metal complexes. SERS spectra suggest that, upon the binding of cim to silver colloids, the formation of stable 1:2 cim–metal complexes is excluded, the formation of 1:1 adduct appearing more probable; in this product the metal reaches its total coordination shell by complexion with water molecules. To better explain the binding mechanism of cim to a metal (Ag) surface, we performed theoretical B3LYP calculations on cim alone as well as on cim bonded to an Ag2 metal cluster in presence of water, observing a sufficiently good agreement between experimental and theoretical wavenumbers. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
70.
Righi G Silvestri IP Barontini M Crisante F Di Manno A Pelagalli R Bovicelli P 《Natural product research》2012,26(14):1278-1284
Scutellarein is a component of Scutellaria, recently known as a potent cytotoxic agent on human leukaemia cells. The aim of this study was the synthesis of scutellarein and its methylated derivative. The new features are the innovating method to afford flavones from flavanones and the A-ring regioselective bromination step that lead to the target molecule by a facile and high-yielding pathway. 相似文献