共查询到20条相似文献,搜索用时 31 毫秒
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J Regan J Bruno D McGarry G Poli B Hanney S Bower J Travis D Sweeney B Miller J Souness S Djuric 《Canadian Metallurgical Quarterly》1998,8(19):2737-2742
A new family of PDE4 inhibitors based on a benzimidazole framework is described. Several of these compounds are orally bioavailable and show efficacy in in vivo models of inflammatory disease. 相似文献
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ES Lazer R Sorcek CL Cywin D Thome GJ Possanza AG Graham L Churchill 《Canadian Metallurgical Quarterly》1998,8(10):1181-1186
A series of 2-benzyl-4-sulfonyl-4H-isoquinoline-1,3-diones was prepared. Members of this series are potent and selective inhibitors of cyclooxygenase-2 (COX-2) in both microsomal and cellular assays. Two representatives demonstrated activity in the carrageenan-induced paw edema model in rats upon oral administration. 相似文献
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MK Ellis AC Whitfield LA Gowans TR Auton WM Provan EA Lock LL Smith 《Canadian Metallurgical Quarterly》1995,133(1):12-19
The administration of the compound 2-(2-nitro-4-trifluoromethylbenzoyl)-cyclohexane-1,3-dione (NTBC) to rats (10 mg/kg body wt) caused an elevation in the concentration of plasma tyrosine and gave products in urine that were identified as 4-hydroxyphenylpyruvate (HPPA) and 4-hydroxyphenyllactate (HPLA). This observed chemically induced tyrosinemia established that this compound perturbs tyrosine catabolism and suggested that the causal effect is the inhibition of 4-hydroxyphenylpyruvate dioxygenase (HPPD). This was confirmed when rat liver HPPD was found to be markedly inhibited by NTBC when the enzyme and chemical were incubated, in vitro, for 3 min at 37 degrees C prior to the initiation of the enzyme reaction by the addition of substrate. At 100 nM NTBC, approximately 90% of the enzyme activity was lost and an IC50 was calculated at approximately 40 nM. The inhibition of HPPD by NTBC (50 nM) is time-dependent; the enzyme activity was reduced by > 50% within 30 sec. Progress curve data of loss of enzyme activity with time gave a rate constant for the inactivation of rat liver HPPD [k*, formation of an HPPD-inhibitor (EI) complex] by NTBC of 9.9 +/- 2.5 x 10(-5) sec-1 nM-1. It was established that NTBC is not irreversibly bound in the EI complex but slowly dissociates with a recovery of enzyme activity of 13.7 +/- 1.0% over a 7-hr period (t1/2, 25 degrees C estimated at 63 hours). In comparison, the compound 2-(2-chloro-4-methanesulfonylbenzoyl)-cyclohexane-1,3-dione (CMBC), an analog of NTBC, gave a similar rate for the inactivation of HPPD (k*, 3.3 +/- 0.8 x 10(-5) sec-1 nM-1), whereas 45 +/- 8% of the enzyme activity was recovered over a 7-hr period (t1/2, 25 degrees C approximately 10 hr). These studies establish that NTBC and CMBC are potent, time-dependent (tight-binding) reversible inhibitors of HPPD. The inhibition is characterized by a rapid inactivation of the enzyme by the formation of an HPPD-inhibitor complex that dissociates with recovery of enzyme activity. In vivo, the inhibition of HPPD causes a tyrosinemia that abates with the recovery of enzyme activity. The understanding of the mechanism by which NTBC perturbs tyrosine catabolism has led to the clinical use of this chemical as the first effective pharmacological therapy for the hereditary disorder tyrosinemia I. 相似文献
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Sung-Kook Park Yasuhiro A. Wakura Hiroshi Majima 《Metallurgical and Materials Transactions B》1989,20(1):13-20
The activities of water in H2SO4-(NH4)2SO4-H2O solutions, the concentrations of which ranged from 0.1 to 4.0 mol kg-1 H2SO4 and 0.1 to 5.0 mol kg-1 (NH4)2SO4, were determined by an isopiestic method at 298 K. The experimentally determined water activities showed considerable deviation
from the Zdanovskii rule. The activities of water were not in agreement with those calculated from the Robinson-Bower equation,
even though the formation of sulfato-complexes of NH4(I) and the dissociation of sulfuric acid were taken into consideration. The behavior of H2SO4-(NH4)2SO4 solu-tions is quite different from other systems. Water activities of aqueous solutions of H2SO4-Li2SO4 and H2SO4-Na2SO4 can be calculated from the Robinson-Bower equation with satisfactory accuracy. The interesting behavior of (NH4)2SO4 can be attributed to the water structure-breaking property of NH4
+ ions. An additivity equation for estimating the water activity of aqueous H2SO4 solutions con-taining (NH4)2SO4 was proposed by considering the contributing effects of solutes on the structure of water. The proposed equation satisfactorily
described the solution system under investigation. The mean activity coefficients of H2SO4 and (NH4)2SO4 in the solution system, H2SO4-(NH4)2SO4-H2O, at 298 K, were calculated by the McKay-Perring method using the water activities experimentally determined. It is believed
that the calculated values for concentrated solutions of more than one sol-ute are sufficiently accurate since the mean activity
coefficients of H2SO4 agree with the values measured by the emf method. 相似文献
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本文研究了从选择性电溶WC-Co废合金得到的氯化钴溶液中回收草酸钴的工艺条件。结果表明:酸效应、同离子效应均影响草酸钴的转化率。在适当的条件下,草酸钴的转化率可达99%。 相似文献
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Bajorek A. Berger C. Dulski M. Zubko M. Lewińska S. Prusik K. Ślawska-Waniewska A. Grasset F. Randrianantoandro N. 《Metallurgical and Materials Transactions A》2022,53(4):1208-1230
Metallurgical and Materials Transactions A - The comparison between NiFe2O4 (co-precipitation) and NiFe2O4@SiO2 (co-precipitation and microemulsion) ferrite nanoparticles in their as-received and... 相似文献
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以H_2O_2和Fe_2(SO_4)_3为氧化剂、NaCl为助浸剂,在H_2SO_4溶液中浸出辉铜矿中的铜。结果表明,在反应温度85℃,反应时间180 min,H_2O_2、Fe_2(SO_4)_3、NaCl、H_2SO_4浓度分别为0.2、0.25、0.5、0.5mol/L的条件下,铜浸出率可达94.33%。采用XRD和EDS等手段对不同反应时间浸出残渣进行了表征与分析,初步揭示了辉铜矿浸取反应历程。 相似文献
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Zhu Ling Wang Xuezhong Liang Cunzhen 《中国稀土学报(英文版)》2006,24(5):528-528
The K2NiF4 type oxides, La2-x KxCuO4 complex oxides with nanometric size were prepared by sol-gel method. The characters of these samples were analyzed by H2-TPR, XRD, FT-IR and SEM. The catalytic activity for soot combustion was evaluated by temperature-programmed reaction (TPO) technique. The results demonstrate that the substitution of K^+ for La^3+ at A-site will increase the catalytic activities of La2-xKxCuO4 to soot combustion greatly, and the substitution quantity affects the structure and catalytic activity obviously. The La1.8 K0.2 CuO4 complex oxides with tetrahedral structure has the best catalytic activity for soot removal reaction, the ignition temperature of soot combustion is decreased from 490 to 320℃. 相似文献
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用LiMn2O4和碳酸锂制备了锂改性的锰酸锂产物,循环性能和比容量测试结果表明随着碳酸锂加入量的增加,循环稳定性逐渐增强,而比容量有逐渐下降的趋势。循环伏安测试结果表明,LiMn2O4及其改性产物具有两对氧化还原峰。随着碳酸锂加入量的增加,两对氧化峰和还原峰峰电位差呈逐渐下降趋势,说明了锂脱嵌的可逆性越来越好;氧化(或还原)峰之间的分形变得不明显,峰形逐渐宽化,说明锂离子两步脱嵌过程变得越来越不明显。研究表明锂离子脱出和嵌入的总量随着碳酸锂量的增加而减少。XRD结果显示,随着碳酸锂加入量的增大,晶格常数逐渐降低,晶格逐渐收缩,结构稳定性增强。 相似文献
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