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排序方式: 共有151条查询结果,搜索用时 15 毫秒
31.
In this paper, we prove some fixed point results for multivalued mappings in bounded metric spaces via symmetric spaces. Moreover an application to an integral inclusion is given.
相似文献32.
Computational Management Science - Motivated by a model introduced by Moiseev, we consider a problem of optimal investment into agricultural infrastructure (irrigation, storage) under uncertainty... 相似文献
33.
We study the concepts of the 𝒫C-projective and the ?C-injective dimensions of a module in the noncommutative case, weakening the condition of C being semidualizing. We give the relations between these dimensions and the C-relative Gorenstein dimensions (GC-projective and GC-injective dimensions) of the module. Finally, we compare, in some circumstances, the global 𝒫C-projective dimension of a ring and the global dimension of the endomorphisms ring of C. 相似文献
34.
35.
Headspace solid-phase microextraction combined with gas chromatography-ion trap tandem mass spectrometry (HS-SPME-GC-ITMS-MS) method has been developed and studied for the simultaneous determination of 15 organochlorine pesticides (OCPs) and 20 polychlorinated biphenyls (PCBs) in aqueous samples. To perform the HS-SPME polydimethylsiloxane (PDMS) (7, 30 and 100 microm film thickness) and polydimethylsiloxane-divinylbenzene (PDMS-DVB) fibers were initially compared on the basis of their absorption capacities for the selected compounds, and PDMS 100 microm film thickness was selected to accomplish the rests of essays. The influence of various parameters on OCPs and PCBs extraction efficiency by HS-SPME was thoroughly studied using GC-electron capture detector (ECD). Parameters such as collision induced dissociation (CID) resonant excitation amplitude and RF storage level were optimized to increase specificity and sensibility for ITMS-MS analysis. The performance of proposed HS-SPME-GC-ITMS-MS methodology with respect to linearity, reproducibility and limit of detection (LOD) was evaluated by water spiked with target compounds. The linear range of most compounds was found to be between 0.01 and 1 ng mL(-1) and the limits of detection were between 0.4 and 26 pg mL(-1). The reproducibility of the method (n = 6), expressed as relative standard deviation (RSD), was between 5 and 21%. Finally, developed procedure was applied to determine selected OCPs and PCBs in river water samples in concentration below 0.1 ng mL(-1) can be easily carried out with ultra-selectivity and precision. 相似文献
36.
Fatma Chaari Lilia Belghith-Fendri Soumaya Zaouri-Ellouzi Dorra Driss Monia Blibech Fatma Kallel 《Natural product research》2016,30(12):1353-1359
The aim of this study was first to ascertain the chemical composition and the physicochemical properties of cereal extracted β-glucan from barley flour. Secondly, to assess the antioxidant properties and the antibacterial properties of extracted β-glucan hydrolysates. The proximate composition, FT-IR and scanning electron microscopy of extracted β-Glucan were studied. Hydrolysates from extracted β-glucan, obtained by lichenase EGL from Penicillium occitanis, were a mixed linkage beta-oligosaccharides (MLBO) of trisaccharides and tetrasaccharides. MLBO showed a DPPH radical scavenger with IC50 about 1.8 ± 0.01 mg/mL whereas the IC50 of extracted β-glucan was about 5 ± 0.01 mg/mL. MLBO showed a high antioxidative capacity (175 μmol/mL α-tocopherol equivalents) at 5 mg/mL. The antimicrobial activity was confirmed against all tested bacteria especially at 20 mg/mL of MLBO while no inhibition was observed for all the strains used after the addition of either EGL or extracted β-glucan. 相似文献
37.
Sergio Amat Concepción Bermúdez Sonia Busquier Driss Mestiri 《Journal of Computational and Applied Mathematics》2009
A modification of some classical third order methods is studied. The main advantage of these methods is that they do not need evaluate any Fréchet derivative. A convergence theorem in Banach spaces, just assuming that the second divided difference is bounded by a nondecreasing function and a punctual condition, is presented. Fréchet differentiability is not required. Finally, a particular example is analyzed where our conditions are fulfilled and the classical ones fail. 相似文献
38.
Stanisław Boryczka Kinga Suwińska Georges Le Guillanton Quang Tho Do Driss Elothmani 《Journal of chemical crystallography》1998,28(7):555-560
The title compound (C14H11NO2) is monoclinic with a = 13.579(2), b = 5.297(1), c = 16.455(2) Å, = 98.11(2)°, Z = 4, and space group P21/n. The significant structural features lie in the two carbonyl groups of the glyoxamide which are oriented antiperiplanar to each other [–163.6(3)°]. The central bond C(1)–C(2) is 1.545(4) Å. The observed conformation is stabilized by intramolecular hydrogen bonds. 相似文献
39.
Mehrzia Krimi Ammar Tahar Jouini Ahmed Driss 《Journal of chemical crystallography》2000,30(4):265-268
The synthesis and crystal structure of a new three dimensional cobalt(II) complex [Co(C6H12N4)2(H2O)4Co(H2O)6][SO4]2.6H2O are reported. It crystallizes in the triclinic space group P-1 with a = 13.394(3), b = 16.077(3), c = 9.282(2) Å, = 89.71(2), = 90.42(2), = 114.02(2)°, V = 1825.6(7)Å3 and Z = 2. The structure is comprised of [Co(C6H12N4)2 (H2O)4Co(H2O)6][SO4]2 units and H2O molecules. Two molecules of ligand and four molecules of water chelate one type of CoII in an octahedral fashion through two N and four O atoms: the four O atoms form the equatorial plane and the two N atoms occupy the apical positions. The other type of CoII cation is chelated by six water molecules. 相似文献
40.
Using the phase transfer catalysis technique, a series of fluorinated acetals has been prepared, in basic medium, by action of dicholromethane on 2-mononfluorinated alcohols or 1-F-alkyl 2-fluoroethanols. The identification of these new acetals has been achived by the study cf their 1H, 19F NMR and their mass spectra. 相似文献