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1.
Ignasi Mundet i Riera 《Topology》2003,42(3):525-553
In this paper we introduce invariants of semi-free Hamiltonian actions of S1 on compact symplectic manifolds using the space of solutions to certain gauge theoretical equations. These equations generalise both the vortex equations and the holomorphicity equation used in Gromov-Witten theory. In the definition of the invariants we combine ideas coming from gauge theory and the ideas underlying the construction of Gromov-Witten invariants. 相似文献
2.
Tutusaus O Viñas C Núñez R Teixidor F Demonceau A Delfosse S Noels AF Mata I Molins E 《Journal of the American Chemical Society》2003,125(39):11830-11831
exo-Cluster dicarbollides substitution has allowed tuning of the E degrees (Ru(II)/Ru(III)) potential to obtain the best-performing Kharasch catalyst. We postulate that this is possible through the to-and-fro electron movement between the boron cluster and the sulfonium moieties. 相似文献
3.
Anna Vallverdú‐Queralt Olga Jáuregui Alexander Medina‐Remón Cristina Andrés‐Lacueva Rosa M. Lamuela‐Raventós 《Rapid communications in mass spectrometry : RCM》2010,24(20):2986-2992
Tomato (Lycopersicon esculentum Mill.) is the second most important fruit crop worldwide. Tomatoes are a key component in the Mediterranean diet, which is strongly associated with a reduced risk of chronic degenerative diseases. In this work, we use a combination of mass spectrometry (MS) techniques with negative ion detection, liquid chromatography/electrospray ionization linear ion trap quadrupole‐Orbitrap‐mass spectrometry (LC/ESI‐LTQ‐Orbitrap‐MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) on a triple quadrupole, for the identification of the constituents of tomato samples. First, we tested for the presence of polyphenolic compounds through generic MS/MS experiments such as neutral loss and precursor ion scans on the triple quadrupole system. Confirmation of the compounds previously identified was accomplished by injection into the high‐resolution system (LTQ‐Orbitrap) using accurate mass measurements in MS, MS2 and MS3 modes. In this way, 38 compounds were identified in tomato samples with very good mass accuracy (<2 mDa), three of them, as far as we know, not previously reported in tomato samples. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
4.
Jose DA Mon I Fernández-Pérez H Escudero-Adán EC Benet-Buchholz J Vidal-Ferran A 《Organic letters》2011,13(14):3632-3635
The synthesis of new P═O-disubstituted receptors with appended crown ethers and their properties as receptors for dicarboxylic acids have been studied. High affinities have been observed (oxalic and malonic acids with 4-, 5-, 6-, or 8-crown ethers). Binding of a cationic effector within the crown ether unit resulted in a positive "allosteric" effect, which has been determined to be K(rel) = 7 in the best case (binding of malonic acid with Li(+) @ rac-3b). 相似文献
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6.
Eva Marguí Clàudia Fontàs Manuela Hidalgo Ignacio Queralt 《Spectrochimica Acta Part B: Atomic Spectroscopy》2008
This work was aimed at improving the instrumental sensitivity and detection limits for Cd determination in liquid samples by using conventional Wavelength Dispersive X-ray Fluorescence (WDXRF) instrumentation equipped with Rh-anode X-ray sources. 相似文献
7.
Pitarch A Ramón A Álvarez-Pérez A Queralt I 《Analytical and bioanalytical chemistry》2012,402(4):1481-1492
Energy dispersive X-ray fluorescence is a common analytical tool for layer thickness measurements in quality control processes
in the coating industry, but there are scarce microanalytical applications in order to ascertain semi-quantitative or quantitative
information of painted layers. “Oil on copper” painting becomes a suitable material to be analysed by means of X-ray fluorescence
spectrometry, due to the metallic nature of substrate and the possibility of applying layered models as used in coating industry.
The aim of this work is to study the suitability of a quantitative energy dispersive X-ray fluorescence methodology for the
assessment of the areal distribution of pigments and the characterization of painting methods on such kind of pictorial artworks.
The method was calibrated using standard reference materials: dried droplets of monoelemental standard solutions laid on a
metallic plate of copper. As an example of application, we estimated pigment mass distribution of two “oil on copper” paintings
from the sixteenth and eighteenth centuries. Pictorial layers have been complementarily analysed by X-ray diffraction. Apart
of the supporting media made of copper or brass, we could identify two different superimposed layers: (a) a preparation layer
mainly composed by white lead and (b) the pictorial layer of variable composition depending on the pigments used by the artist
on small areas of the painting surface. The areal mass distribution of the different elements identified in the painting pigments
(Ca, Cr, Mn, Fe, Zn, Cd, Hg and Pb) have been determined by elemental mapping of some parts of the artworks. 相似文献
8.
Héctor Gómez Ignasi Colominas Fermín Navarrina Manuel Casteleiro 《Heat and Mass Transfer》2008,45(2):219-226
A number of contributions have been made during the last decades to model pure-diffusive transport problems by using the so-called hyperbolic diffusion equations. These equations are used for both mass and heat transport. The hyperbolic diffusion equations are obtained by substituting the classic constitutive equation (Fick’s and Fourier’s law, respectively), by a more general differential equation, due to Cattaneo (C R Acad Sci Ser I Math 247:431–433, 1958). In some applications the use of a parabolic model for diffusive processes is assumed to be accurate enough in spite of predicting an infinite speed of propagation (Cattaneo, C R Acad Sci Ser I Math 247:431–433, 1958). However, the use of a wave-like equation that predicts a finite velocity of propagation is necessary in many other calculations. The studies of heat or mass transport with finite velocity of propagation have been traditionally limited to pure-diffusive situations. However, the authors have recently proposed a generalization of Cattaneo’s law that can also be used in convective-diffusive problems (Gómez, Technical Report (in Spanish), University of A Coruña, 2003; Gómez et al., in An alternative formulation for the advective-diffusive transport problem. 7th Congress on computational methods in engineering. Lisbon, Portugal, 2004a; Gómez et al., in On the intrinsic instability of the advection–diffusion equation. Proc. of the 4th European congress on computational methods in applied sciences and engineering (CDROM). Jyväskylä, Finland, 2004b) (see also Christov and Jordan, Phys Rev Lett 94:4301–4304, 2005). This constitutive equation has been applied to engineering problems in the context of mass transport within an incompressible fluid (Gómez et al., Comput Methods Appl Mech Eng, doi: 10.1016/j.cma.2006.09.016, 2006). In this paper we extend the model to compressible flow problems. A discontinuous Galerkin method is also proposed to numerically solve the equations. Finally, we present some examples to test out the performance of the numerical and the mathematical model. 相似文献
9.
Relative Hitchin-Kobayashi Correspondences for Principal Pairs 总被引:1,自引:0,他引:1
10.
[structure: see text] Crystals of a disecondary squaramide covalently linked to a crown ether presents a great variety of inter- and intramolecular nonbonded interactions including C-H/pi contacts, C-H...O and N-H...O hydrogen bonds, and pi-pi stacking between squaramide rings. Latter interaction, the stacking between squaramide rings, can be considered as an experimental evidence for the proposed aromaticity of squaramide when it is forming hydrogen bonds, either as acceptor or donor. 相似文献