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61.
Manoel Lemos 《Discrete Mathematics》2006,306(7):680-687
In [On Mills's conjecture on matroids with many common bases, Discrete Math. 240 (2001) 271-276], Lemos proved a conjecture of Mills [On matroids with many common bases, Discrete Math. 203 (1999) 195-205]: for two (k+1)-connected matroids whose symmetric difference between their collections of bases has size at most k, there is a matroid that is obtained from one of these matroids by relaxing n1 circuit-hyperplanes and from the other by relaxing n2 circuit-hyperplanes, where n1 and n2 are non-negative integers such that n1+n2≤k. In [Matroids with many common bases, Discrete Math. 270 (2003) 193-205], Lemos proved a similar result, where the hypothesis of the matroids being k-connected is replaced by the weaker hypothesis of being vertically k-connected. In this paper, we extend these results. 相似文献
62.
63.
F. Lemos J. M. Lopes F. Ramôa Ribeiro M. Guisnet 《Reaction Kinetics and Catalysis Letters》1990,41(2):351-355
The influence of neodymium content on the catalytic properties of a HNaY zeolite was investigated using the cracking of n-heptane as model reaction. Neodymium zeolites were found to be more active for cracking and hydrogen transfer reactions than zeolites containing lanthanum, cerium or praseodymium.
HnaY . , , , .相似文献
64.
F. C. D. Lemos M. Muraro J. Zukerman-Schpector É. T. G. Cavalheiro E. R. Dockal 《Journal of Thermal Analysis and Calorimetry》2004,75(2):599-606
The iron(II) complex of the Schiff bases trans-N,N'-bis(salicylidene)-1,2-cyclohexanediamine (Salcn), manganese(II) and vanadyl complexes of the Schiff bases cis- andtrans-N,N'-bis(salicylidene)-1,2-cyclohexanediamine (Salcn) were prepared and characterized by IR spectroscopy, and elemental analysis.
These new complexes were submitted to thermal analysis (TG and DSC) under dynamic air atmosphere. The differences in the decomposition
profiles were related to the structure of isomers and decomposition intermediates were characterized according to their X-ray
diffraction pattern and by their infrared spectrum.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
65.
66.
Lemos Paulo Vitor França Barbosa Leandro Santos Ramos Ingrid Graça Coelho Rodrigo Estevam Druzian Janice Izabel 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2555-2567
Journal of Thermal Analysis and Calorimetry - The thermal features of potato, banana, corn and cassava starches were correlated with structural properties. These starches were characterized by SEM,... 相似文献
67.
Lemos Maurício Ferrapontoff Mendes Luis Claudio Bohn Manfred Keicher Thomas 《Journal of Thermal Analysis and Calorimetry》2019,137(2):411-419
Journal of Thermal Analysis and Calorimetry - Hydroxyl-terminated polybutadiene (HTPB) has been widely modified and copolymerized with azide substances to be applicable as an elastomer binder in a... 相似文献
68.
69.
A procedure for preconcentration and determination of lead in water is described. The method is based on the sorption of Pb(II) in a minicolumn packed with a functionalized sorbent and subsequent elution with acidic solution. The determination of lead content in the eluate was carried out using flame atomic absorption spectrometry. The sorbent was prepared by immobilization of the ligand 4-(5'-bromo-2'-thiazolylazo)orcinol on polystyrene-divinylbenzene through an azo spacer. Diazotization and coupling reactions were used for synthesis of the sorbent. Some variables affecting the preconcentration were optimized using a full factorial design. Under optimized conditions, the method presented a detection limit of 0.5 microg/L and enrichment factor of 36 for a sample volume of 25 mL. The accuracy of the method was tested by the determination of lead in a standard reference material (National Institute of Standards and Technology 1643d Fresh Water). The proposed procedure was applied to the determination of lead in samples of natural and drinking waters. 相似文献
70.
We introduce the notion of k-hyperclique complexes, i.e., the largest simplicial complexes on the set [n] with a fixed k-skeleton. These simplicial complexes are a higher-dimensional analogue of clique (or flag) complexes (case k = 2) and they are a rich new class of simplicial complexes. We show that Dirac’s theorem on chordal graphs has a higher-dimensional
analogue in which graphs and clique complexes get replaced, respectively, by simplicial matroids and k-hyperclique complexes. We prove also a higher-dimensional analogue of Stanley’s reformulation of Dirac’s theorem on chordal
graphs.
相似文献