共查询到19条相似文献，搜索用时 357 毫秒
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以磷硫混酸对铬矿石样品分解试样,在银盐存在条件下,用过硫酸铵氧化,以N-苯基代邻氨基苯甲酸作指示剂,用硫酸亚铁铵标准溶液滴定。不仅操作简单,分析速度快,分析结果准确,且分析成本低,更适合大批量样品的高效分析。 相似文献
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通过对巴西铁矿中主成分全铁含量分析方法的试验,采用硫磷混酸处理样品,三氯化钛还原Fe^3＋至Fe^2＋,重铬酸钾容量法测定全铁,精密度（RSD,n=12）为0．25％一0．29％,方法经国家标准物质验证,测定值与标准值基本一致。 相似文献
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试样经硫-磷混合酸、高锰酸钾分解,以硝酸银为催化剂用过硫酸铵将铬全部氧化至六价,加热煮沸破坏过量的氧化剂,加入氯化钠加热煮沸将七价锰还原。以二苯胺磺酸钠为指示剂,用硫酸亚铁铵标准溶液滴定。 相似文献
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Joseph W. Richards 《Journal of The Franklin Institute》1910,169(2):131-142
The application of the electric current as a source of heat energy in the reduction of iron ores would but a short time ago have scarcely been seriously considered. Its possibility has however been more than demonstrated. In this paper, Dr. Richards describes the work of several investigators in the development and operation of this method of manufacturing pig-iron on a practical commercial scale. 相似文献
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Iron deficiency evolves, slowly through several stages. Early iron deficiency caused a depletion in iron stores as shown by
a reduction in the levels of hepatic non heme iron (44%) in the 7 days old pups born to iron deficient mothers. The hemoglobin
levels and PCV (packed cell volume) were significantly reduced only after the age of three weeks. The activities of GABA (γ-amino
butyric acid) shunt enzymes viz. GDH, GAD and GABA-T (glutamate dehydrogenase, glutamate decarboxylase and GABA-transaminase,
respectively) and GABA content were found to decrease during gestation and/or lactation iron deficiency at 1 week (wk), 2wk,
3wk and 4wk of age in the developing rat brains. However GABA binding showed a significant increase at different age groups.
The iron deficiency during lactational exposure showed significant alteration in most of the parameters only at the age of
3 weeks onwards. On rehabilitation with iron supplemented diet for 2 weeks, these altered parameters could not attain corresponding
control values. A prolonged iron deficiency causing alterations in GABA may lead to neurological and behavioral alterations. 相似文献
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Shalini Gupta Smiti Nanda Uma Singh Sadhna Bansal Harbans Lal 《Indian journal of clinical biochemistry : IJCB》1997,12(1):91-94
Serum iron levels were studied in 50 patients with pre-eclampsia and the results were compared with 50 control cases. Their
serum iron levels were found to be higher than the controls. Increase in serum iron was directly proportional to the increased
levels of uric acid, urea and creatinine. Mean reticulocyte counts, plasma free haemoglobin and unconjugated bilirubin levels
were also higher in these patients. It is suggested that haemolysis may be a major contributory factor for the increased levels
of serum iron in pre-eclampsia. 相似文献
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I. Rabias H. Pratsinis G. Drossopoulou M. Fardis T. Maris N. Boukos N. Tsotakos D. Kletsas E. Tsilibary G. Papavassiliou 《Biomicrofluidics》2007,1(4)
Ultrasmall superparamagnetic iron oxide nanoparticles coated with gummic acid have been investigated as possible constituents of aqueous ferrofluids for biomedical applications and especially for MRI contrast agent. The structural characteristics and the size of the nanoparticles have been analyzed as well as the magnetic properties. In order to evaluate any possible capabilities as a contrast agent, the relaxation time, T2, of hydrogen protons in the colloidal solutions of nanoparticles have been measured in order to gain information on the relaxation behavior compared to other MRI contrast agents. The in vitro cytotoxicity of the obtained magnetic nanoparticles of iron oxide coated with gummic acid was investigated by two separate methods (MTT and FACS analysis) and by using three different normal and transformed cell lines. Our results showed that the synthesized nanoparticles had no toxic effect on any of the cell lines used. 相似文献
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精细分选高炉除尘灰中的铁粉的工艺研究 总被引：1，自引：0，他引：1
利用控制变量法精细分选技术分离高炉除尘灰,以便获得铁精粉。通过分析原料的含碳量和全铁含量,测定磁选机、一重、二重选铁粉产量,检测各过程的全铁量数据,确定分选铁粉的最佳的工艺参数,利用该工艺可以获得更高品质的铁精粉。 相似文献
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Edwin Michael Guyer 《Journal of The Franklin Institute》1932,213(1):75-88
The relative magnetic permeability of iron, nickel and permalloy was measured over the range of wave-lengths from 70 to 200 meters by the heterodyne balance method and by the resonance method. Nothing suggestive of the anomalous dispersion of the magnetic permeability reported in this region by Wwedensky and Theodortschik was found when certain precautions were observed in carrying out the measurements. When these precautions were neglected irregular breaks resulted in the curves of permeability as a function of wavelength which varied in position with the conditions of the circuit.The high frequency resistance of iron, nickel and permalloy wires was measured over the range of approximately fifty thousand kilocycles from two to three meter wave-lengths. What appeared to be anomalous variations at certain frequencies were found not to exist when the proper precautions were observed in making the measurements. 相似文献
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Ralph Bown 《Journal of The Franklin Institute》1917,183(1):41-60
Not many years ago it was quite generally believed that iron was unable to follow rapid magnetic changes. Experiments which showed an apparent decrease in the permeability of the iron with an increase in the frequency of the magnetic cycle furnished a basis for a theory that iron was magnetically sluggish. Further and more accurate experiments proved, however, that the effects which had previously been ascribed to a peculiarity of the material were in reality caused by eddy currents in the sample. Theoretical calculations were made which demostrated that eddy currents in an iron test piece increased as the square of the frequency and that for even the lower frequencies it was necessary to use quite thin laminations in magnetic circuits in order to eliminate deleterious effects. Furthermore, it was found that due to eddy currents and the magnetic properties of iron, the magnetization in high frequency fields was confined to a thin surface layer of the piece. This “Magnetic Skin Effect” reduced the cross section of the iron which was magnetically active even though the laminations were extremely thin. Careful experimental measurements compared with theoretical calculations proved that the real permeability of iron remained unchanged at frequencies up to about 106 and that previous results had been is serious error due to neglect of the factors mentioned. This fact having been established, efforts were made to see what practical use could be made of iron in high frequency work and to that end some extensive experimental investigations of the saturation curves and core losses were made upon specimens laminated as thinly as was commercially practicable. The resulting data have furnished a basis for design.It is a demostrated fact that the permeability of all metals is unity for the magnetic cycles imposed upon them by heat and light waves. In the region between frequencies of about 106, where the true permeability of iron is practically the same as at zero frequency, and frequencies of about 1010 where the true permeability of iron approaches unity, the experimental values of μ decrease smoothly with the frequency. What happens to μ in the range of frequencies between the lingest heat waves and the shortest Hertzian waves which have yet been made is a question which has many interesting features but which has not yet yielded to the experimenter. 相似文献
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中国铁矿石资源供应风险评价与治理研究 总被引：1，自引：0，他引：1
由于中国国内铁矿资源禀赋的约束,中国高度依赖进口铁矿的局面将长期存在。为了保证中国铁矿资源的供应安全,已有研究重点从中国铁矿石资源供需、贸易或定价的某一维度深入分析铁矿石资源供应风险,较少同时考虑供需、贸易和定价的综合性供应风险,相应地缺乏多维主体的铁矿石供应风险综合治理措施。本研究采用BGR-VW方法,基于2000—2015年中国铁矿石时间序列数据,从当前市场风险、资源风险、政治风险、市场权力、未来供需趋势等5个方面对中国铁矿石供应资源供应风险进行了综合评价。结果表明,中国铁矿石资源供应风险主要存在于资源和政治风险,综合风险等级处于紧张状态。最后,本文以实现铁矿石资源可持续供给为最终目标,从全球层面、区域层面和国家层面的多维主体分别提出相应治理措施。 相似文献