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971.
A practicable and selective liquid chromatography-mass spectrometry assay for the determination of two cyclooxygenase-2 inhibitors, etoricoxib and valdecoxib, in human plasma is presented. The analytical technique is based on reversed-phase high-performance liquid chromatography (HPLC) coupled to atmospheric pressure chemical ionisation (APCI) mass spectrometry (Finnigan Mat LCQ ion trap). Mass analysis was performed in the positive ion mode. The ion trap was operated in the tandem MS mode (MS2) and the transitions of etoricoxib (m/z 359.2 --> 280.3) and valdecoxib (m/z 315.1 --> 235.1) were followed by selected reaction monitoring. Retention times of etoricoxib and valdecoxib were 1.05 and 1.08 min, respectively. The method was validated over a linear range 10-2500 and 5-1000 microg/L using the other substrate as internal standard. After validation, the method was used to study the pharmacokinetic pro fi le of etoricoxib or valdecoxib in a healthy volunteer after administration of a single oral dose (valdecoxib, 20 mg; etoricoxib, 90 mg). The presented method was suf fi cient to cover more than 90% of the area under the plasma concentration time curve. 相似文献
972.
973.
研究了4个偶氮染料在酸性介质中的电还原性质。偶氮基在酸性介质中的还原均为不可逆四电子一步全还原。邻、对位上有吸电子基(如—CO_2Bu-n)的偶氮基较间位有吸电子基时更易被还原。分子中同时含有偶氮基和硝基时,偶氮基先被还原。 相似文献
974.
1 INTRODUCTION Coordination chemistry has been playing an important role in nonlinear optical (NLO) materi- als [1~3] in recent years. It has been found that tetrahedral or square pyramidal molecular configurations are useful for designing transparent second-harmonic generation (SHG) materials from coordination compounds[4]. It has also been reported that the pyridyl-based metal complexes can exhibit SHG effects[5]. Recently, we have successfully synthesized a new coordination compoun… 相似文献
975.
This paper reported the research results concerning the surface characterization ofpolystyrene-graft-w-stearyl poly(ethylene oxide) (PS-g-SPEO) by means of XPS,contactangle measurement and TEM, and its in vitro blood compatibility assessment by measuringthe plasma recalcification time (RT) and partial thromboplastin time (PTT). The XPSresults demonstrated that the surface and bulk composition of the PS-g-SPEO graftcopolymers differ remarkably from each other,and that SPEO component was constantlyenriched at the copolymer/air interface. Contact angle studies indicated that the surfacewater wettability can be adjusted effectively by changing the composition of the copolymer.PS-g-SPEO graft copolymers can undergo microphase separation as clearly illustrated byTEM photographs. The relationship between the surface properties of PS-g-SPEO graftcopolymer and its blood compatibility was also discussed. 相似文献
976.
J. G. Liu M. H. He H. W. Zhou Z. G. Qian F. S. Wang S. Y. Yang 《Journal of polymer science. Part A, Polymer chemistry》2002,40(1):110-119
Organosoluble polyimides were synthesized with the alicyclic dianhydride 1,8‐dimethylbicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride and aromatic diamines. The polyimides possessed good solubility both in strong dipolar solvents and in common solvents; the thermal decomposition temperature of the polyimides exceeded 420 °C. Strong and flexible films of the polyimides, with the cutoff of ultraviolet–visible absorption lower than 310–320 nm, exhibited good features as the alignment layers for nematic liquid crystals with pretilt angles of 1.5–2.9°. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 110–119, 2002 相似文献
977.
Robert Liska 《Journal of polymer science. Part A, Polymer chemistry》2002,40(10):1504-1518
The synthesis of new water‐soluble photoinitiators (PIs) based on hydroxyalkylphenones, benzophenones, and thioxanthones with carbohydrate residues such as glucose, cellobiose, and 1‐amino‐1‐deoxy‐D ‐glucitol (glucamine) is described. In addition, selected initiators were reacted with methacryloyl chloride to obtain copolymerizable initiators with improved migration stability. Results from photo differential scanning calorimetry and gel‐content measurements in commercially available water‐thinnable and emulsion‐type resins as well as 2‐hydroxyethyl acrylate are included. Glucose‐modified PIs gave the best results with respect to compatibility with the resin, reactivity, and gel content. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1504–1518, 2002 相似文献
978.
979.
Thermally induced phase separation technique was utilized to fabricate biodegradable poly(l ‐lactic acid) (PLLA) macrocellular foams which were capable of being applied in tissue engineering. The block copolymer Pluronic F127 composed of (polyethyleneoxide)‐(polypropyleneoxide)‐(polyethyleneoxide) [(PEO)‐(PPO)‐(PEO)] was used as a porogen. Water/dioxane mixtures with different volume ratios were used as solvents. The addition of Pluronic F127 could induce an appearance of large pores (50–200 μm) besides small pores (10–20 μm) or a change from a solid–liquid phase separation to a liquid–liquid phase separation. The role of Pluronic F127 depends on the water/dioxane ratios in the PLLA/dioxane/water system. The X‐ray diffraction patterns and porosity measurement results showed that Pluronic F127 was crystallized and existed on the pore wall. The effect of Pluronic F127 on changing pore structure is attributed to the occurrence of the interaction of the lipophilic PPO blocks in Pluronic F127 with PLLA clews, consequently, this results in PLLA aggregation and early phase separation on cooling. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
980.
Hans‐Peter Kormann Günter Schmid Katrin Pelzer K. Philippot Bruno Chaudret 《无机化学与普通化学杂志》2004,630(12):1913-1918
Nanoporous alumina membranes, loaded with palladium and ruthenium nanoparticles of various size, were used for gas phase hydrogenation of 1, 3‐butadiene and for oxidation of carbon monoxide, respectively. Those membranes contain 109 ‐ 1011 pores per cm2, all running perpendicular to the surface. Membrane discs of 20 mm in diameter and only 60 μm thick, incorporated in a reactor in which the reactants can be pumped in a closed circuit through the pores, turned out to very actively catalyze hydrogenation of butadiene (Pd) and oxidation of CO (Ru). The activity of the Pd catalysts depends characteristically on the particles size, the gas flow, and of the educts ratio. As could be expected, larger particles are less active than smaller ones, whereas increasing gas flows in case of hydrogenation accelerates the reactions. Excessive hydrogen reduces selectivity with respect to the various butenes, but favours formation of butane. 相似文献