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981.
铟(Ⅲ)-芦丁极谱络合吸附波的研究 总被引:3,自引:0,他引:3
在pH6.0的乙酸盐缓冲底液中,用单扫极谱法可获得高灵敏度的铟(Ⅲ)-芦丁的络合吸附波,其检测下限达3.0×10~(-10)mol/L。成功地用于纯金属锌中10~(-5)%铟的测定。测得吸附电活性络合物的组成为:In(Ⅲ):芦丁=1∶2,条件稳定常数为1.8×10~(10)。电极反应是吸附络合物中的In(Ⅲ)还原为In(Hg)。测得电极反应的转移系数α=0.51,表面电化学反应的标准速率常数k_s=0.43/s 相似文献
982.
983.
Hydrogen species in both SiO2 and Rh/SiO2 catalysts pretreated in different atmospheres (H2, O2, helium or air) at different temperatures (773 or 973 K) were investigated by means of 1H MAS NMR. In SiO2 and O2-pretreated catalysts, a series of downfield signals at -7.0, 3.8-4.0, 2.0 and 1.5-1.0 were detected. The first two signals can be attributed to strongly adsorbed and physisorbed water and the others to terminal silanol (SiOH) and SiOH under the screening of oxygen vacancies in SiO2 lattice, respectively. Besides the above signals, both upfield signal at -110 and downfield signals at 3.0 and 0.0 were also detected in H2-pretreated catalyst, respectively. The upfield signal at -110 originated from the dissociative adsorption of H2 over rhodium and was found to consist of both the contributions of reversible and irreversible hydrogen. There also probably existed another dissociatively adsorbed hydrogen over rhodium, which was known to be p hydrogen and in a unique form of "delocalized hydrogen". It wa 相似文献
984.
A New Technique of Synthesizing 10—Hydroxy—5—methyl—5,10—dihydrophenophosphazine 10—Oxide 总被引:1,自引:0,他引:1
ZhiGangYIN DeFengZHAO 《中国化学快报》2003,14(4):347-350
10-Hydroxy-5-methyl-5,10-dihydrophenophosphazine 10-oxide(1)was prepared by a new technique of treating 10-methoxy-5,10-dihydrophenophosphazine 10-oxide(2)with an equivalent of NaH in anhydrous DMF,and then at 120℃ for 3-4h,which not only avoided poisonous and expensive methyl iodide used in literature,but made the consumption of NaH greatly decrease as well.The possible reaction mechanism was also described.The chemical structure of 1 was confiremed by IR,NMR,and mass spectroscopy. 相似文献
985.
Two Novel Myrinsol Diterpenes from Euphorbia prolifera 总被引:1,自引:1,他引:1
Two novel diterpenes,Euphorprolitherin A(1) and Euphorprolitherin B(2), were isolated from the roots of Euphorbia prolifera. Their structures were elucidated on the basis of spectroscopic methods. 相似文献
986.
987.
报道了一种抗真菌治疗新药酮康唑的吸附行为及其测定。该药物在玻碳电极上预富集后,用示差脉冲伏安法测定,其响应电流与药物浓度在2.0×10^-10-1.0×10^--5mol/L范围内呈线性关系;检屈限为4.0×10^-11mol/L。可用于尿和血清样品中药物含量的测定。 相似文献
988.
989.
T. C. E. Cheng 《The Journal of the Operational Research Society》1984,35(5):433-437
Given a set of n jobs with deterministic processing times and the same ready times, the problem is to find the optimal processing-time multiple k* for the T.W.K. due-date assignment method, and the optimal sequence σ* to minimize the total amount of missed due-dates. It is found that k* is a constant for a given job set and σ* should be in S.P.T. sequence. After the theoretical treatment, a numerical example is given for discussion. The optimal results can readily be extended to situations in which the processing times are random variables with known means and having the same coefficient of variation. From a practical point of view, the main merit of this paper is that it demonstrates how, under certain production environments in which completion times of the jobs can be anticipated, to determine the optimal due-dates and obtain the optimal sequence. 相似文献
990.
1—苯乙酰基—4—芳酰基氨基硫脲的合成及其在碱催化下的环化反应 总被引:1,自引:0,他引:1
1-酰基-4-芳基氨基硫脲类化合物在碱性条件下环化为具有广泛生物活性的3-取代基-4-芳基-1,2,4-三唑啉-5-硫酮的反应报道甚多,但1,4-位都含羰基的酰氨基硫脲在碱性条件下环化反应迄今报道较少。我们曾研究了1-[5-(α-萘)-2H-四唑-2-乙酰基]-4-芳酰基氨基硫脲和1-(α-萘乙酰基)-4-芳酰基氨基硫脲在碱催化下环化为3-取代基-4-芳酰基-1,2,4-三唑啉-5-硫酮的反应,它们在低浓度下均有一定的生物活性。本文研究了1-苯乙酰基-4-芳酰基氨基硫脲1_(a~m)在1mol/L K_2CO_3溶液催化下的环化反应,得到环化产物3-苄基-4-芳酰基-1,2, 相似文献