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921.
NdFeB合金选择氢爆的研究   总被引:3,自引:0,他引:3  
对NdFeB合金的选择氢爆进行了研究。研究表明,在较低的环境温度和氢气压力下,通过事先对合金中富Nd相的吸氢量进行理论计算并对放人容器内的NdFeB合金量进行定量控制,NdFeB合金在吸氢过程中完全可以实现良好的选择氢爆。SEM观察表明,选择氢爆时其碎裂的方式均为沿晶断裂,爆裂后粉末中的主相晶粒均是单晶粒子,Nd2Fe14B主相晶粒内均无裂纹形成。与完全氢爆相比,选择氢爆后的晶粒较粗大,且较均匀,但细小晶粒较少。  相似文献   
922.
六神丸中砷的研究   总被引:10,自引:0,他引:10  
六神丸是临床常用的消炎止痛中成药之一。但因含有雄黄致使砷含量相对增高,为研究砷的有关毒性反应,本文进行了六神丸物相分析和兔血浆砷含量的分析,并对有关毒性问题进行了研究,效果满意。  相似文献   
923.
报导了一种新拟除虫菊酯的设计和合成。标题化合物是由二氯菊酰氯与新自制的2-甲基-3-(2-呋喃基)-2-丙烯-1-醇酯化合成。  相似文献   
924.
A new Acidithiobacillus ferrooxidans cell immobilization technique utilizing the complex of PVA solution and sodium alginate solution crosslinked by Ca(NO3)2 as entrapment medium is reported. The mixture of A. ferrooxidans suspension and the entrapment complex were extruded into a solution of Ca(NO3)2 (1-5%) to form beads, then the beads were frozen at −20 °C for 1-2 days and thawed at room temperature. The forming mechanism, characteristic of this immobilized beads and the factors affecting activity of immobilized cells were also discussed. A maximum oxidation rate of 4.6 g Fe2+/(L h) was achieved in batch cultures by these immobilized cells. Precipitation formed during culture process was analyzed. The forming mechanism of this precipitation and how this precipitation affects the whole system were also discussed. In addition, the immobilization technique is operated simply, and the gel beads have high stability even under non-sterile conditions. So its application on an industrial scale would be more practicable.  相似文献   
925.
Quinolinic acid is an intermediate in the biosynthesis of nicotinamide-containing redox cofactors. The ultimate step in the formation of quinolinic acid in prokaryotes is the condensation of iminosuccinate and dihydroxyacetone phosphate, which is catalyzed by the product of the nadA gene in Escherichia coli. A combination of UV-vis, M?ssbauer, and EPR spectroscopies, along with analytical methods for the determination of iron and sulfide, demonstrates for the first time that anaerobically purified quinolinate synthetase (NadA) from E. coli contains one [4Fe-4S] cluster per polypeptide. The protein is active, catalyzing the formation of quinolinic acid with a Vmax [ET]-1 of 0.01 s-1.  相似文献   
926.
报道了空气乙炔火焰中SmO蒸气的发射光谱行为,试验了La、Nd、Eu、Y对SmO发射强度增强作用,在大量La存在下,SmO的发射强度与其浓度成正比关系。用大量La作增感剂和干扰抑制剂,借助双波长测定法克服光谱干扰,实现了直接测定高Y混合稀土浓集物中的Sm,方法准确,快速  相似文献   
927.
生物电极是生物传感器最重要的一个分支,本文对近年来国内外有关生物电极的最新研究成果作一综述,并按生物膜材料、固定方法、换能器、应用及理论研究五部分加以分类。  相似文献   
928.
Tu H  Xue J  Cao X  Zhang W  Jin L 《The Analyst》2000,125(1):163-167
A novel electrochemical microsensor for the determination of NO based on an electropolymerized film of tetraaminophthalocyaninecopper [Cu(TAPc)] was prepared. Its response to NO and its application to the study of an NO donor (S-nitrosoglutathione; GSNO) are also described. The microsensor exhibited an electrocatalytic effect on NO oxidation and showed a low detection limit, high sensitivity and selectivity for NO determination. The oxidation current (measured by differential pulse amperometry) was linear for NO concentrations ranging from 6.2 x 10(-9) to 3.0 x 10(-5) mol L-1 with a calculated detection limit of 4.0 x 10(-9) mol L-1 (S/N = 3) and a linear coefficient of 0.9984. Some endogenous electroactive substances in biological tissues, such as dopamine, 5-hydroxytryptamine and nitrite, at concentrations higher than those in biological systems did not interfere with NO determination. The sensor shows promise for the possible in vivo determination of NO. Using the microsensor, the NO release from the NO donor (GSNO) was successfully monitored. This work sets a foundation for the study of the pharmacology and the biological effects in vivo of S-nitrosothiols.  相似文献   
929.
A novel reaction to synthesis a series new N‐hydroxyldecahydroacridine derivatives by a one‐pot condensation of aldehyde, 1,3‐dicarbonyl compound and NH2OH in glycol under microwave irradiation is described. N‐hydroxyldecahydroacridine was obtained in excellent yields (81–95%) within short reaction time (4–7 min)  相似文献   
930.
A new type of composite microporous gel polymer electrolyte was prepared by directly coating the hydrolyzed prepolymers onto PVdF microporous membrane, and then polymerizing and cross-linking with ultra-violet (UV). Their chemical, thermal, surface microscopic configuration, swelling ability and electrochemical properties have been investigated for various prepolymer’s solution concentrations. The swelling ability and ionic conductivity of the membrane supporting hybrid gel electrolyte (MSHGE) could reach an extreme point at 0.15 g/ml of the prepolymer’s solution. It is thought that their performance can be affected by the surface microscopic configuration and the quality of coated copolymer. The Arrhenius-type relationship was observed in the temperature dependence of ionic conductivity. The ionic conductivity of MSHGE (PVdF-15) at room temperature can reach 6.18 × 10−3 S cm−1, and its electrochemical stability window is about 4.9 V.  相似文献   
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