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排序方式: 共有919条查询结果,搜索用时 15 毫秒
1.
Khalid KOUFANY 《数学学报(英文版)》2006,22(5):1467-1472
Let Ω be a symmetric cone. In this note, we introduce Hilbert's projective metric on Ω in terms of Jordan algebras and we apply it to prove that, given a linear invertible transformation g such that g(Ω) = Ω and a real number p, |p| 〉 1, there exists a unique element x ∈ Ω satisfying g(x) = x^p. 相似文献
2.
N-Substituted oxazolidin-2,4-diones have been synthesized in a novel one-pot reaction by reacting cyanohydrins stepwise with 1,1′-carbonyldiimidazole and primary amines followed by acidic hydrolysis of the intermediate 4-imino-oxazolidin-2-ones. Their microwave-assisted conversion into α-hydroxyamides was accomplished by treatment with catalytic amounts of sodium methoxide in methanol. 相似文献
3.
Tawarah Khalid M. Jibril Ibrahim Bani-Fwaz Mutasem Z. 《Transition Metal Chemistry》2000,25(6):659-663
The kinetics of the photolytic CO-substitution of CpFe(CO)2SCOR [Cp = C5H5, Bu
t
C5H4, 1,3-Bu2
t
C5H3; R = Me, Bu
t
, Ph, 2-(O2N)C6H4, 3-(O2N)C6H4, 4-(O2N)C6H4, 3,5-(O2N)2C6H3] with PPh3 were studied in CH2Cl2 at 0 °C by i.r. spectroscopy. The reactions yielded exclusively the mono-CO-substituted derivatives, CpFe-(CO)(PPh3) SCOR, and were found to follow second order kinetics with first order dependence on the concentration of each reactant. The differences in rates are discussed in terms of current knowledge pertaining to such reactions. An associative mechanism is proposed to account for the kinetic data of the reactions described. 相似文献
4.
Saify ZS Mushtaq N Khan KM Perveen S Shah ST Abdel-Jalil RJ Fecker M Voelter W 《Chemical & pharmaceutical bulletin》2005,53(1):64-66
A new series of 4-(4'-chlorophenyl)-4-hydroxypiperidine derivatives (2-5), substituted at nitrogen, were synthesized and tested as potential analgesic compounds as well as evaluated for their effect on hypotensive activity. Results showed that all the derivatives exhibit significant analgesic activity in male Wistar rats at a dose of 50 mg/kg of body weight after intramuscular injection, when tested by thermal stimuli (tail flick test). Pethidine was used as reference drug. Compounds 2, 3 and 5 produced reduction in blood pressure in normotensive rat. 相似文献
5.
Todd B. Kreutzian Khalid S. A. Seraj Larry G. Anderson Donald C. Zapien 《Electroanalysis》2007,19(23):2479-2482
In this work, long optical path length thin‐layer electrochemical cell was constructed using indium‐tin oxide on glass as the electrode material. Iron release from ferritin adsorbed on the electrode was induced by applying a negative potential sweep in the presence of 1,10‐phenanthroline. The usefulness of spectroelectrochemistry as a means of determining the quantity of iron released from an adsorbed layer of ferritin is demonstrated. 相似文献
6.
A novel zirconia-based hybrid organic-inorganic sol-gel coating was developed for capillary microextraction (CME) (in-tube SPME). High degree of chemical inertness inherent in zirconia makes it very difficult to covalently bind a suitable organic ligand to its surface. In the present work, this problem was addressed from a sol-gel chemistry point of view. Principles of sol-gel chemistry were employed to chemically bind a hydroxy-terminated silicone polymer (polydimethyldiphenylsiloxane, PDMDPS) to a sol-gel zirconia network in the course of its evolution from a highly reactive alkoxide precursor undergoing controlled hydrolytic polycondensation reactions. A fused silica capillary was filled with a properly designed sol solution to allow for the sol-gel reactions to take place within the capillary for a predetermined period of time (typically 15-30 min). In the course of this process, a layer of the evolving hybrid organic-inorganic sol-gel polymer got chemically anchored to the silanol groups on the capillary inner walls via condensation reaction. At the end of this in-capillary residence time, the unbonded part of the sol solution was expelled from the capillary under helium pressure, leaving behind a chemically bonded sol-gel zirconia-PDMDPS coating on the inner walls. Polycyclic aromatic hydrocarbons, ketones, and aldehydes were efficiently extracted and preconcentrated from dilute aqueous samples using sol-gel zirconia-PDMDPS coated capillaries followed by thermal desorption and GC analysis of the extracted solutes. The newly developed sol-gel hybrid zirconia coatings demonstrated excellent pH stability, and retained the extraction characteristics intact even after continuous rinsing with a 0.1 M NaOH solution for 24 h. To our knowledge, this is the first report on the use of a sol-gel zirconia-based hybrid organic-inorganic coating as an extraction medium in solid phase microextraction (SPME). 相似文献
7.
Ayoub Mourjane Hafida Hanine El Mustapha El Adnany Mourad Ouhammou Nadia Hidar Bouchra Nabil Ahcne Boumendjel Khalid Bitar Mostafa Mahrouz 《Molecules (Basel, Switzerland)》2022,27(10)
Argania spinosa L. Skeels is an emblematic tree in Morocco, known worldwide for its medicinal and nutritional value. Its fruits contain kernels used to prepare an edible oil, the leaves are used to feed livestock, and its wood is used as fuel. If the oil acquires high importance, the other components of the fruit of the argan are undervalued. Our objective is to invest the waste of the argan industry. Particularly, our study aimed to assess the effect of thermal activation of argan pulp on its therapeutic value, its phenolic profile and its functional and physicochemical properties. After heat treatment, the HPLC analysis for the average total phenolic content varied from 2% to 37%, depending on temperature. The antioxidant activity was increased with heat treatment. Higher values of antioxidant activity, polyphenol and pigment content were recorded at 70 °C. Functional properties analysis indicated that water solubility index and water absorption capacity were significantly affected by heat stress. Physicochemical analysis showed that moisture content, titratable acidity and soluble solids were affected. 相似文献
8.
Asaad Khalid Mohnad Abdalla Maria Saeed Muhammad Nabeel Ghayur Surya Kant Kalauni Mohammed Albratty Hassan A. Alhazmi Mohammed Ahmed Mesaik Anwarul Hassan Gilani Zaheer Ul-Haq 《Molecules (Basel, Switzerland)》2022,27(11)
Acetylcholinesterase (AChE) inhibitors and calcium channel blockers are considered effective therapies for Alzheimer’s disease. AChE plays an essential role in the nervous system by catalyzing the hydrolysis of the neurotransmitter acetylcholine. In this study, the inhibition of the enzyme AChE by Sarcorucinine-D, a pregnane type steroidal alkaloid, was investigated with experimental enzyme kinetics and molecular dynamics (MD) simulation techniques. Kinetics studies showed that Sarcorucinine-D inhibits two cholinesterases—AChE and butyrylcholinesterase (BChE)—noncompetitively, with Ki values of 103.3 and 4.66 µM, respectively. In silico ligand-protein docking and MD simulation studies conducted on AChE predicted that Sarcorucinine-D interacted via hydrophobic interactions and hydrogen bonds with the residues of the active-site gorge of AChE. Sarcorucinine-D was able to relax contractility concentration-dependently in the intestinal smooth muscles of jejunum obtained from rabbits. Not only was the spontaneous spasmogenicity inhibited, but it also suppressed K+-mediated spasmogenicity, indicating an effect via the inhibition of voltage-dependent Ca2+ channels. Sarcorucinine-D could be considered a potential lead molecule based on its properties as a noncompetitive AChE inhibitor and a Ca2+ channel blocker. 相似文献
9.
10.
An efficient three-step synthesis of COX-2 inhibitor inotilone from acetaldoxime is described. The structure of inotilone was elucidated via an aldol reaction between 5-methyl-3(2H)-furanone and 3,4-dihydroxybenzaldehyde. This approach describes a convenient pathway to 5-alkyl-3-furanones through isoxazole chemistry. 相似文献