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排序方式: 共有443条查询结果,搜索用时 31 毫秒
371.
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373.
We discuss the explicit formulation of the transcendental constraints defining spectral curves of SU(2) BPS monopoles in the twistor approach of Hitchin, following Ercolani and Sinha. We obtain an improved version of the Ercolani-Sinha constraints, and show that the Corrigan-Goddard conditions for constructing monopoles of arbitrary charge can be regarded as a special case of these. As an application, we study the spectral curve of the tetrahedrally symmetric 3-monopole, an example where the Corrigan-Goddard conditions need to be modified. A particular 1-cycle on the spectral curve plays an important rôle in our analysis. 相似文献
374.
The dispersion of pollutants in the environment is an issue of great interest as it directly affects air quality, mainly in large cities. Experimental and numerical tools have been used to predict the behavior of pollutant species dispersion in the atmosphere. A software has been developed based on the control‐volume based on the finite element method in order to obtain two‐dimensional simulations of Navier–Stokes equations and heat or mass transportation in regions with obstacles, varying position of the pollutant source. Numeric results of some applications were obtained and, whenever possible, compared with literature results showing satisfactory accordance. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
375.
Rom Harré 《Foundations of Chemistry》2009,11(2):93-103
The traditional ontology within which chemistry has developed involved various versions of a general substance/attribute scheme.
Recently this has been challenged by two versions of Dynamism. One version is derived from the writings of A. N. Whitehead
and the other from several sources, including G. Leibniz and I. Kant. Both involve the idea of flux of actual occasions. Unlike
the former scheme, the latter involves a foundation of causal powers and the energetics of field theory. The situation has
been made more interesting because of the revival of trope theory, based on an ontology of particularized attributes. This
notion is claimed to resolve philosophical problems about the nature of universals and of substances through the introduction
of spatial and temporal sequences of tropes. While trope theory seems, at first sight, to work as an attractive alternative
to substance/attribute close inspection shows that it is beset with difficulties that are more problematic that the dynamist
ontology based on casual powers, dispositions and affordances.
相似文献
Rom HarréEmail: |
376.
Santos-Silva T Mukhopadhyay A Seixas JD Bernardes GJ Romão CC Romão MJ 《Journal of the American Chemical Society》2011,133(5):1192-1195
CORM-3, [fac-Ru(CO)(3)Cl(κ(2)-H(2)NCH(2)CO(2))], is a well-known carbon monoxide releasing molecule (CORM) capable of delivering CO in vivo. Herein we show for the first time that the interactions of CORM-3 with proteins result in the loss of a chloride ion, glycinate, and one CO ligand. The rapid formation of stable adducts between the protein and the remaining cis-Ru(II)(CO)(2) fragments was confirmed by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Liquid-Chromatography Mass Spectrometry (LC-MS), Infrared Spectroscopy (IR), and X-ray crystallography. Three Ru coordination sites are observed in the structure of hen egg white lysozyme crystals soaked with CORM-3. The site with highest Ru occupancy (80%) shows a fac-[(His15)Ru(CO)(2)(H(2)O)(3)] structure. 相似文献
377.
Pérez-Yáñez S Beobide G Castillo O Cepeda J Fröba M Hoffmann F Luque A Román P 《Chemical communications (Cambridge, England)》2012,48(6):907-909
The presence of butanoic acid excess in the reaction media employed for the synthesis of a MOF with formula [Cu(2)(μ(3)-ade)(2)(μ(2)-OOC(CH(2))(2)CH(3))(2)](n) (ade: adeninate) leads to the formation of micelles that exert a template effect and provide a pronounced increase of its microporosity, doubling the intrinsic adsorption capacity of the pristine crystal network. 相似文献
378.
M Lanchas D Vallejo-Sánchez G Beobide O Castillo AT Aguayo A Luque P Román 《Chemical communications (Cambridge, England)》2012,48(79):9930-9932
The direct acid-base reaction between ZnO/CoO/Co(OH)(2) and imidazolic ligands under moderate heating (100-160 °C), in a closed vessel, leads to the generation of the corresponding zinc/cobalt-imidazolates in a high yield (87-97%) in which network topology is controlled by the addition of small amounts of structure directing agents. Moreover, the fine tuning of the thermal process at the synthetic stage permits us to increase the crystal size, and even to grow X-ray quality single crystals. 相似文献
379.
380.
Simó C Pérez P Neusüss C Pelzing M San Román J Gallardo A Cifuentes A 《Electrophoresis》2006,27(11):2250-2258
Analytical characterization of dimethacrylate-tyrosine-lysine-tyrosine (DMTLT, a new biodegradable acrylic cross-linker synthesized at our laboratory) is carried out using CE-MS. DMTLT is a pseudopeptide composed by tyrosine-lysine-tyrosine amino acids linked through urea bonds with two methacrylic groups, one at each end of the molecule, making this compound an excellent cross-linker for polymerization reactions and for obtaining new biodegradable materials. A new CE-MS method is developed for the characterization of DMTLT and its products of degradation after basic hydrolysis. In order to carry out an exhaustive examination of such degradation products methods based on CE coupled to IT and TOF-MS are employed. Based on CE-IT-MS results and the elemental composition of the degradation products obtained by CE-TOF-MS, conclusions on the mechanism and kinetic of hydrolysis of DMTLT are obtained confirming both the usefulness of CE-MS to characterize new biomaterials and the applicability of DMTLT for preparing new biodegradable polymers. These results are corroborated through the CE-MS detection of the identified products of degradation in a dimethyl acrylamide polymer cross-linked with DMTLT. 相似文献