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排序方式: 共有113条查询结果,搜索用时 46 毫秒
21.
Aymen Bensouf Hichem Chtioui 《Calculus of Variations and Partial Differential Equations》2011,41(3-4):455-481
In this paper we prescribe a fourth order conformal invariant on the standard n-sphere, with n????5, and study the related fourth order elliptic equation. We prove new existence results based on a new type of Euler?CHopf type formula. Our argument gives an upper bound on the Morse index of the obtained solution. We also give a lower bound on the number of conformal metrics having the same Q-curvature. 相似文献
22.
Implementation of a continuation method for normal maps 总被引:2,自引:0,他引:2
This paper presents an implementation of a nonsmooth continuation method of which the idea was originally put forward by Alexander
et al. We show how the method can be computationally implemented and present numerical results for variational inequality
problems in up to 96 variables.
The research reported here was sponsored by the Air Force Office of Scientific Research, Air Force Materiel Command, USAF,
under grant numbers F49620-93-1-0068 and F49620-95-1-0222, by the U.S. Army Research Office under grant number DAAH04-95-1-0149,
and by the National Science Foundation under grant number CCR-9109345. The U.S. Government has certain rights in this material,
and is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon.
The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing
the official policies or endorsements, either expressed or implied, of the sponsoring agencies or the U.S. Government. 相似文献
23.
Souheil Behij Ahmed Hichem Hamzaoui Ridha Rokbani Adel M’nif 《Russian Journal of Inorganic Chemistry》2011,56(6):991-998
Solubility of sodium, potassium and calcium sulfates and chlorides in 28% ammonia solution was determined through monitoring
conductivity measurements and kinetics of solids dissolution as a function of temperature and stirring time. The major findings
of the present study show that Na2SO4 and K2SO4 solutions conductivity follow straight linear segments with different slopes. However, in case of NaCl, KC1, CaCl2 and CaSO4 · 2H2O, conductivity curves were continuous, monotonous and reach constants maximum values. The hypothesis of complex formation
or dissolution via intermediaries such as NaNH4SO4 and KNH4SO4 salts seams to be true, through X-ray diffraction study of resulting deposits. Furthermore, the dissolution rates at 25°C
of potassium and calcium chlorides in ammonia solution are higher than that reported in the literature for water. In fact,
ammonia significantly reduces the solubility of K2SO4; conversely, a slight increase in this parameter was observed for CaSO4. 相似文献
24.
Hichem Elamari Faouzi MeganemJean Herscovici Christian Girard 《Tetrahedron letters》2011,52(6):658-660
Best of both worlds, molecules bearing two alkyne groups, activated and unactivated, can selectively react on the activated one in a copper-free version of Huisgen’s reaction to form a first triazole ring, with a good selectivity toward the 1,4-isomer, which is solely isolated by a simple trituration procedure. The other alkyne function is then submitted to the selective reaction using a polymer-supported copper(I) catalyst to form a second triazole ring. This gave access to disymmetric bistriazoles without the need of protection using simple, easy, and fast procedures. 相似文献
25.
Jabrane A Ben Jannet H Miyamoto T Tanaka C Mirjolet JF Duchamp O Harzallah-Skhiri F Lacaille-Dubois MA 《Magnetic resonance in chemistry : MRC》2011,49(2):83-89
From the roots of Atriplex glauca L. var. ifiniensis (Caball) Maire (syn. of Atriplex parvifolia Lowe var. genuina Maire), three new saikosaponins designated as glaucasides A-C (1-3) were isolated together with the known 3-O-β-D-glucopyranosyl-(1 → 2)-β-D-galactopyranosyl-saikogenin F (4). The structures of the new compounds were elucidated by extensive analysis of one-dimensional and two-dimensional NMR spectroscopy, FABMS, HR-ESIMS and chemical evidence as 13β,28-epoxy-16β,21β-dihydroxyolean-11-en-3β-yl O-β-D-[2-O-sulfate]-glucopyranosyl-(1 → 2)-α-L-arabinopyranoside (1), 13β,28-epoxy-16β,21β-dihydroxyolean-11-en-3β-yl O-β-D-[2-O-sulfate]-glucopyranosyl-(1 → 2)-α-L-arabinopyranosyl 21-O-{4-(secbutylamido)-butanoyl ester} (2) and 3-O-β-D-glucopyranosyl-(1 → 2)-β-D-galactopyranosyl saikogenin G (3). The cytotoxic activities of these compounds were evaluated against the HT-29 and HCT 116 human colon cancer cell lines. 相似文献
26.
27.
A non lipschitzian nonlinear elliptic equation is reviewed and results of existence, uniqueness, positivity and classification are proved using direct methods derived from the equation. 相似文献
28.
Med Habib Oueslati Jalloul Bouajila Med Amine Belkacem Abdel Halim Harrath Saleh H. Alwasel Hichem Ben Jannet 《Natural product research》2019,33(5):708-714
Two new monoterpene Ducrosin A (1) and sesquiterpene Ducrosin B (2) were isolated along with three known compounds, stigmasterol (3) and two furanocoumarins (4 and 5), from the dichloromethane extract of the seeds of Ducrosia anethifolia (DC.) Boiss. Their structures were determined using extensive 1D and 2D NMR, (ES)-HRMS and IR spectroscopic analyses and by comparison with literature data. Gas chromatography analysis of the fatty acids (FAs) of D. anethifolia seed oils (DAOs) showed high percentages of elaidic acid (C18:1 Δ9t) 65% and oleic acid (C18:1 Δ9c) 15%. The total tocopherol (tocols) content in DAOs was found to be 164 mg/100 g. The cytotoxic effect of the isolates was also evaluated using the MTT assay against the HCT-116 and SKOV-3 cell lines. The results showed that compound 2 was the most cytotoxic agent followed by compounds 1 and 4, which has an epoxide moiety that most likely contributes to its activity. 相似文献
29.
30.
A novel O-heteroside, (3RS,4RS)-3,4-dihydroxy-4-(2-hydroxy-5-acetylphenyl)-2-[(beta-O-glucopyranosyl)methyl]-but-1-ene (1), named nauplathizine, and a previously known compound, acetophenone-4-O-glucoside (2), were isolated from the antibacterial acetone extract of the aerial parts of Nauplius aquaticus (L) (Asteraceae, Inulae). The structure of 1 was established via its acetylated derivative by means of spectroscopic and chemical data. 相似文献