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101.
Mosbah Habib Chahdoura Hassiba Mannai Asma Snoussi Mejdi Aouadi Kaïss Abreu Rui M. V. Bouslama Ali Achour Lotfi Selmi Boulbaba 《Applied biochemistry and biotechnology》2019,187(3):1113-1130
Applied Biochemistry and Biotechnology - A series of enantiopure isoxazolidines (3a–c) were synthesized by 1,3-dipolar cycloaddition between a (−)-menthone-derived nitrone and various... 相似文献
102.
103.
In this Letter we construct non-Abelian field theories employing the Faddeev-Jackiw symplectic formalism. The original Abelian fields were modified in order to introduce the non-Abelian algebra. We construct the SU(2) and SU(2)⊗U(1) Yang-Mills theories having as starting point the U(1) Maxwell electromagnetic theory. 相似文献
104.
In this paper we study existence and properties of solutions of the problem Δw=0 on the half-space with nonlinear boundary condition ∂w/∂η+w=|w|p−2w where 2<p<2(N−1)/(N−2) and N?3. We obtain a ground state solution w=w(x1,…,xN−1,t) which is radial and has exponential decay in the first N−1 variables. Moreover, w has sharp polynomial decay in the variable t. 相似文献
105.
In the first part of this paper, we share and elucidate the way we mobilize histories in some disciplines that are part of the undergraduate courses in mathematics teacher education offered by State University of Campinas and Federal University of Rio Grande do Norte in Brazil. This way of mobilization can be featured as a set of collective indisciplinary problematizations occurring in a series of student investigations. Mobilizing practices of mathematics culture are the object of these investigations. These practices are performed by different communities both constituted by and constituent of different human activities. In the second part of this paper, we will discuss our way of mobilizing histories, contrasting it with the theoretical perspective of expansive learning, just as it has been defended by Yrjö Engeström, in his article Non scolae sed vitae discimus—towards overcoming the encapsulation of school learning. We will also attempt to highlight the role which this researcher has attributed to history in his model of expansive learning, a perspective based on the current research on activity theory. 相似文献
106.
Lucas M. Abreu Richard K. Phipps Charlotte H. Gotfredsen Thomas O. Larsen 《Tetrahedron letters》2010,51(13):1803-3363
Cytosporones O, P and Q, together with the known compounds cytosporones B, C, D, E and dothiorelones A, B, C, and H were isolated from the ascomycete fungus Cytospora sp. during a chemotaxonomic study of fungal endophytes belonging to the related genera Cytospora and Phomopsis from Brazil. The structures were determined by NMR spectroscopy and mass spectrometry. With exception of cytosporones D, E, Q, and dothiorelone B, all compounds were consistently detected in the metabolite profiles of eight Cytospora isolates investigated; and were also produced by a distinct chemotype of Phomopsis. 相似文献
107.
Ribeiro Nde C da Camara CA Born Fde S de Siqueira HA 《Natural product communications》2010,5(11):1819-1822
The fumigant action of peel essential oils of Citrus sinensis var. pear (pear orange = PO) and C. aurantium (bitter orange = BO) from the northeast of Brazil were evaluated against Bemisia tabaci biotype B and compared with eugenol as a positive control. The oil concentration in the PO at 8.5 microL/L of air caused 97% mortality, while the oil concentration of BO at 9.5 microL/L of air caused 99% mortality. However, the LC50 estimates for both oils (LC50 = 3.80 microL/L of air for PO and LC50 = 5.80 microL/L of air for BO) did not differ from each other, but they did when compared with eugenol (LC50 = 0.20 microL/L of air). Regarding their effects on oviposition, the Citrus oils showed concentration-response dependence, reducing the number of eggs as the concentration increased, which was not observed for eugenol. The minimum concentrations of the oils that caused a significant reduction in the egg lay were 3.5 and 7.0 microL/L of air for BO and PO, respectively. These results suggest that oils from PO and BO peels may be promising as models to develop new insecticides that might be applied into the integrated management of whiteflies. 相似文献
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109.
Alejandro Peixoto de Abreu Lima Natali Graziano 《Green Chemistry Letters and Reviews》2016,9(4):210-215
Herein, we describe an efficient, green, and lithium salt-free synthesis of 2-substituted 1,4-benzenediol in water/ethanol as solvent and potassium carbonate as a base. Optimized reaction time, the required equivalent of base and the observed solvent effect are reported. 相似文献
110.
Nanomaterials have been demonstrated to possess novel characteristics that can be applied in developing new packaging with better properties than packaging produced with micromaterials. Such developments include the production of packaging with improved barrier properties, which applied to the food industry will extend the shelf life of a food, thereby expanding its marketing potential. The present study entailed the optimization of experimental variables (pressure, temperature, processing time, feed position, etc.) involved in the elaboration of polypropylene and polyethylene films with nanoparticles, to obtain a film with good exfoliation, barrier and mechanical properties. SEM, TEM and XRD were also evaluated as tools for determining the degree of exfoliation of nanoparticles. Optimization of the technology involved in production of an exfoliated nanocompound is a complex process in which multiple variables and parameters are involved. The results of the study showed that the feed position of the nanoparticle in the double screw extruder is of vital importance in obtaining an exfoliated film. The maximum temperatures used in the extruder were 170 °C and 130 °C, for polypropylene and polyethylene respectively. 相似文献