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991.
992.
993.
S. I. Dikhtyarev M. M. Yanina R. G. Kuznetsova B. I. Kurganov V. T. Chernobai 《Chemistry of Natural Compounds》1984,19(5):587-591
The enzyme urease has been isolated from the seeds of the watermelon of the Ogonek variety and has been characterized. The molecular weight of a rechromatographed sample of the enzyme has been determined as 480,000. The pH dependence of the activity of the urease and the kinetic parameters of the enzyme have been studied.All-Union Scientific-Research Institute of the Chemistry and Technology of Drugs, Khar'kov. Vitaminy Scientific-Production Amalgamation, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 624–628, September–October, 1983. 相似文献
994.
锂离子电池正极材料LiMn2O4的合成与晶体结构(英) 总被引:2,自引:0,他引:2
Spinel LiMn2O4 powders were prepared using two-step synthesis method consisting of solid-state reaction method and citrate modified sol-gel method. The effects of the calcination temperature and the Li/Mn ratio of raw materials were studied on the physicochemical and electrochemical properties of the spinel LiMn2O4 powders, such as crystallinity, lattice constant and density. The title compound was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Polycrystalline LiMn2O4 powers calcined at 750 ℃ were found to be composed of very uniformly-sized microcrystal with an average particle size of 300 nm. The improvement in electrochemical properties was mainly attributed to the process of re-grinding by absolute alcohol. 相似文献
995.
龋病人牙釉质表面硬度及抗磨损性能测试 总被引:1,自引:0,他引:1
采用人工方法制成人牙釉质浅龋及使用抗龋措施的龋损釉质样本,分别测量各组釉质表面显微硬度,并以微动摩擦磨损试验机测试其抗磨性能,试验结果表明:各组实验组釉质较对照组表面硬度都有不同程度下降,氟化钠前处理会使釉质表达硬度显著下降,人工浅龋牙釉质的抗磨损性能不如正常釉质,使用两种抗龋措施对其抗磨性能没有明显改善。 相似文献
996.
0IntroductionRareearthsarenowappliedwidelyinChina,whichcanimprovecropsyieldsandthetheirqualit-ies犤1犦.Thebeneficialeffectsmaybeduetothestimu-latoryeffectsoftheseelementsonthenutrientuptakebyplantsorontheincreasingofchlorophyllsynthesisintheplants犤2犦.Whilealotofresearcheshavebeendoneontheimprovednutritionofcropsafterapplica-tionofrareearths,muchlessattentionhasbeenpaidtothedeteriorationofsoilqualityduetotheapplicationofrareearthsforyears犤3犦.Scientistshavediscoveredthataccumula… 相似文献
997.
2,6-O-diethyl-β-cyclodextrins were prepared and immobilized onto silica gel to develop a fluorosensor for dipyridamole. The
analytical performance characteristics of the proposed sensor for analysis of dipyridamole were as follows: the detection
limit was 0.8 nmol/L with a relative standard deviation of 1.4% for 10 determinations of 50 nmol/L of dipyridamole. The modification
of β-CD improved the sensitivity and selectivity for measuring dipyridamole. The recommended method has been successfully
tested for the determination of dipyridamole in clinical samples (urine and pharmaceutical preparations).
Received: 23 January 1997 / Revised: 14 April 1997 / Accepted: 21 April 1997 相似文献
998.
Hyoung Sik Kim Min Kang Min Woo Song Jin Won Park Byoung Ryul Min 《Reaction Kinetics and Catalysis Letters》2004,81(2):251-257
Pt-Pd bimetallic catalysts were prepared in order to develop and investigate catalysts having excellent activity and stability
for benzene destruction. The effect of Pt addition to Pd catalysts is studied by XPS analysis.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
999.
邻苯二胺合钴氧合反应的研究Ⅰ 水溶液中配合物及其氧合配合物稳定常数的测定 总被引:2,自引:0,他引:2
自1938年Tsumaki报道犤1犦氧载体以来,这方面的研究已有很大进展犤2犦,只是理论研究居多。氧载体的氧合常数是氧载体研究中的一个重要参数,它的测定是氧载体研究中的一项重要内容,用pH电位法测定氧载体的氧合常数已有研究报道犤2~4犦,作者在研究中发现,邻苯二胺合钴(o-Phdn-Co)配合物在固相和水溶液中与O2反应时表现出很大差异,其反应产物的组成比分别为液相配合物Co∶O2=2∶1,而固相配合物Co∶O2=1∶2,为究其成因和进行理论探讨,有必要先测定其氧合常数。由于o-Phdn-Co配合物的配位常数也未见文献… 相似文献
1000.
Wataru Ueda Kenzo Oshihara Damien Vitry Tokio Hisano Youhei Kayashima 《Catalysis Surveys from Japan》2002,6(1-2):33-44
Mo-V-M(=Al, Ga, Bi, Sb and Te)–O mixed oxide catalysts were synthesized hydrothermally for the first time, characterized structurally, and tested for ethane and propane oxidation after activation by various ways. These catalysts were black solids of rod-shaped (fiber like) crystals, which had a layer structure in the direction of fiber axis and a high dimensional arrangement of metal octahedra in the cross-section plane. These fresh crystalline materials became active for catalytic oxidation of alkanes after heat-treatment at 600 °C and subsequent grinding in order to increase exposed plane of the cross-section. The resulting catalysts were very active for an oxidative dehydrogenation of ethane with 80% of the ethylene selectivity in the reaction temperature range of 300 to 400 °C and also showed about 50% selectivity to acrylic acid in the propane oxidation. Multi-functional character which derived from the high dimensional structure of the catalysts and mechanism of the selective alkane oxidation were discussed. 相似文献