共查询到19条相似文献，搜索用时 218 毫秒
1.
《常熟理工学院学报》2016,(2)
采用MnSO_4和KMnO_4制备前驱体MnOOH,将MnOOH、LiOH、(NH_4)_2S_2O_8与氧化石墨烯复合,用传统水热法制备Li_2MnO_3/氧化石墨及Li_2MnO_3/石墨烯的复合材料.氧化石墨、石墨烯的存在对Li_2MnO_3的晶体形貌和结构具有明显的影响.氧化石墨和石墨烯具有优良的导电性,显著提高了Li_2MnO_3材料的导电性和电化学性能. 相似文献
2.
《赤峰学院学报(自然科学版)》2017,(7)
采用高锰酸钾与葡萄糖为原料,通过氧化还原反应将葡萄糖碳化,从而一步法制备纳米MnO_2-C催化剂.对高锰酸钾与葡萄糖用量做梯度分析来确定实验的最佳条件.通过灼烧法对MnO_2-C催化剂中碳含量进行分析.论文采用傅里叶红外光谱仪对MnO_2-C纳米颗粒进行表征.实验结果表明:通过灼烧法对MnO_2-C催化剂进行分析,说明催化剂中有大量的碳;从红外光谱图中可得出,在1340cm~(-1)处有碳的特征吸收峰;在534.58cm~(-1)出现一个二氧化锰特征吸收峰. 相似文献
3.
本文发现对Coats Redfern积分式进行适当修改后,可用于MnO_2与KClO_3催化反应的动力学研究,并找出了MnO_2与KClO_3催化反应中MnO_2的最佳用量。 相似文献
4.
(1)取33厘米长粗玻管一枝,配上孔偏一 旁的寒子导管,粗玻管内装2/3红色水。(2)具支试管配一带滴管的塞子,具支试管内放少量KClO_3,滴管内装少量MnO_2,滴紫嘴尖粘一点胶水防MnO_2流下。 (3)连接粗玻管和具支试管后加热KClO_3,直至熔化沸腾,见都是不连续的气泡,捏滴管吹下MnO_2,可见大量连续气泡产生。 相似文献
5.
本文报导的高锰酸根半导体传感器(简称MnO_4~-—ISFET)是以乙基紫—MnO_4~-缔合物为电活性物质的化学半导体传感器。它是我们在研制钾离子敏感半导体传感器的基础上发展起来的又一化学半导体传感器,是传统的离子选择性电极和场效应晶体管相结合的产物。不仅工艺简单,并且具有半导体传感器的固有特点,如微型化、 相似文献
6.
在《无机化学》和《无机化学实验》教材中,鉴定Mn~(2 )离子的存在都是利用NaBiO_3~(?)氧化法将Mn~(2 )氧化为MnO_4成为紫色溶液,反应式:2Mn~(2 ) 5NaBiO_3~- 14H~ =2MnO_4~- 5Bi~(3 ) 7H_2O 5Na~ 这一反应灵敏度高,效果好,是一个很理想的方法.应用氧化还原反应理论解释也能得到满意的结论,电极反应:Mn0_4~- 8H~ 5e~-(?)Mn~(2 ) 4H_2O (?)~0=1.491VNaBiO_3~(?) 6H~ 2e~-(?)Bi~(3 ) 3H_2O Na~ 1 (?)_A(?)=1.80V,故在酸性条件下,上述反应能进行.但在实验时,若不控制反应条件,反应后,往往得到棕黑色浑浊液而不是澄清的MnO_4~-紫色溶液.初步分析其原因可能是NaBiO_3~-的量少,未能将Mn~(2 )全部氧化为MnO_4~-或溶液的酸度不够.因此实验时增加了NaBiO_3的用量,提高了溶液的酸度.但实验结果.并没有改变.针对此现象笔者经过反复实验发现掌握好适当的Mn~(2 )浓度和溶液的酸度对Mn~(2 )转化为MnO_4~-的反应是成功的关键,因此该实验取得良好效果. 相似文献
7.
学习了氧气和化学方程式的初步知识后,为巩固氧气性质、实验室制法,使学生初步学会称量、加热、过滤、仪器组装等基本操作技术,初步培养学生实验方法、观察和分析能力,我结合课本“化学实验基本操作”的内容,组织了“用实验证明KMnO_4热分解产物是K_2MnO_4、MnO_2和O_2”的综合性课外活动,在教师的指导下进行。做法是: 1.布置讨论题 (1)查阅 KClO_3、KMnO_4、MnO_2、O_2、K_2MnO_4的重要性质(教师提示有关资料)。 (2)根据哪些性质证明O_2、MnO_2、K_2MnO_4的存在? 相似文献
8.
9.
《天津大学学报(英文版)》2020,(5)
Anisotropic MnO_2 nanostructures,including α-phase nanowire,α-phase nanorod,δ-phase nanosheet,α+δ-phase nanowire,and amorphous floccule,were synthesized by a simple hydrothermal method through adjusting the pH of the precursor solution and using different counterions.The catalytic properties of the as-synthesized MnO_2 nanomaterials in the selective oxidation of benzyl alcohol(BA) and 5-hydroxymethylfurfural(HMF) were evaluated.The effects of micromorphology,phase structure,and redox state on the catalytic activity of Mn02 nanomaterials were investigated.The results showed that the intrinsic catalytic oxidation activity was mainly influenced by the unique anisotropic structure and surface chemical property of MnO_2.With one-dimensional and 2 D structures exposing highly active surfaces,unique crystal forms,and high oxidation state of Mn,the intrinsic activities for MnO_2,catalysts synthesized in pH 1,5,and 10 solutions(denoted as MnO_2-pH1,MnO_2-pH5,and Mn_2-pH10,respectively) were twice higher than those of other MnO_2 catalysts in oxidation of BA and HMF.With a moderate aspect ratio,the α+δ nanowire of MnO_2-pH10 exhibited the highest average oxidation state,most abundant active sites,and the best catalytic oxidation activity. 相似文献
10.
对高二课本中氨的催化氧化实验,我们用MnO_2代替铂丝作催化剂,并对装置作了一些改进,实验现象非常明显。实验操作如下: 1.用塑料食品袋制作一个空气袋。 2.取一根约10厘米长的干燥的玻璃导管,在中间平铺一层MnO_2粉末。玻管两端用少量石棉绒疏松地塞住(防止鼓入空气时带走MnO_2)。 3.按右图装置好: 4.先点燃酒精灯,将MnO_2加热至红热后,再轻轻挤压空气袋,慢慢地向浓氨水中鼓入空气(以每秒 相似文献
11.
利用标准的固相反应法制备了(La0.7Y0.3)2/3Ca1/3MnO3和La空位(La0.62Y0.3)2/3Ca1/3MnO3锰氧化物粉末样品。X射线衍射(XRD)测量分析表明样品均为单相,并且在300K到30K温度范围内结构没有发生改变,单胞仍然具有正交对称性(Pnma)。并用Rietveld全谱拟合法对X射线衍射测量所得的晶体结构衍射谱进行了拟合。结果表明,晶体结构参数(a,b,c)和晶胞体积(v)随温度发生了明显变化,Mn-O键长随温度减小单调增大,而Mn-O-Mn键角呈单调减小,这也说明存在静态的Jahn-Teller效应。 相似文献
12.
邝代治 《衡阳师范学院学报》1990,(3)
本文利用DDMBAB作为相转移催化剂运用在苯甲酸的合成中进行了实验探讨。寻找到了优化条件:(1)中性介质进行反应;(2)相转移催化剂与KMnO_4等摩尔比时可一次性定量萃取MnO_4-进入反应底物相中;(3)本实验条件下相转移催化剂用量nDDMBAB与底物甲苯n甲苯比为0.08,在反应中足以反复运载MnO_4-进行相转移;(4)KMnO_4的量与甲苯量比为n=2配原料;(5)反应2～2.5hr.。PTC氧化合成苯甲酸简便,产率70％。 相似文献
13.
蔡宏灵 《常熟理工学院学报》2006,20(2):58-61
用标准的固态反应方法制备了Cu掺杂的La0.67Ca0.33Mn1-xCuxO3样品。所有样品的X射线衍射结果用Rietveld全谱拟合的方法来分析。结果表明所有Cu掺杂的样品均表现为单相,空间群为Pnma。当x 0.25时,晶格对称性由正交对称性变为四方对称性。所有样品的电输运性质用小极化子模型和渗流模型来分析。 相似文献
14.
侯占忠 《河北北方学院学报(社会科学版)》2003,19(6):65-71
根据SO42-与Ba2+反应生成BaSO4沉淀,用原子吸收法测定溶液中剩余的Ba2+,进而间接求出水中的SO42-含量.在5ml水样中加入1.75mlBa2+(1mg/ml),经一定时间的陈化后,用原子吸收法测定水样中的Ba2+,利用先作好的标准曲线,得到水样中的SO42-的量.用于不同类型的水样分析,对于河水中的硫酸根的测定标准偏差为0.0012,相对标准偏差为2.87％. 相似文献
15.
Infants who failed to complete a 2-day operant-conditioning task were compared with a stratified random sample of those who did on measures of infant temperament and several demographic characteristics. A discriminant-function analysis revealed that female infants who cried differed from female infants who did not cry on measures of duration of orienting and latency to approach sudden or novel stimuli. Reliable prediction of crying and noncrying could not, however, be made for males. No sex differences emerged in the incidence of crying or in the number of sessions completed. Partially successful females (i.e., those completing 1 of the 2 sessions) could reliably be discriminated from those who cried during the first session on measures of age at testing and maternal ratings of smiling behavior. The results of this study suggest that, as with habituation studies, subject loss in operant-conditioning studies is influenced by individual differences among the infants which may or may not adversely affect external validity. 相似文献
16.
Neuropsychological stability and prognosis of subgroups of children with learning disabilities 总被引：1，自引：0，他引：1
T T Korhonen 《Journal of learning disabilities》1991,24(1):48-57
A sample of 74 Finnish children with mild learning disabilities (LD) and 57 controls was followed from the third grade (Study 1) to the sixth grade (Study 2). In the initial study, the sample had been grouped into five valid subgroups (Normal, General Language, Visuo-Motor, General Deficiency, Naming) utilizing a cluster analysis. In both studies a battery of 12 neuropsychological, reading, and writing tests was administered, and teacher ratings were obtained. The results indicated that the general neuropsychological profiles of the subgroups were maintained, but some changes, consistent with the progress in reading, were noted. The developmental rate of some neuropsychological functions from Study 1 to Study 2 in the subgroups of children with learning disabilities more closely approached that of the Normal subgroup. At follow-up, 64% of the original LD sample continued to have marked reading and/or writing problems. The Naming subgroup had a more unfavorable prognosis than the other subgroups, especially in reading, and the General Deficiency subgroup in writing (spelling), respectively. Some possibilities for using the results to improve remedial teaching are discussed. 相似文献
17.
介绍了纳米MnO2的制备和表征的综合实验的方法和原理,通过本实验有利于学生综合能力和创新能力的培养。 相似文献
18.
何英 《蒙自师范高等专科学校学报》1999,1(2):49-52
用稀硫酸和盐酸处理天然二氧化锰制备活化二氧化锰．经XRD、ICP分析,确定了活化二氧化锰的晶型与天然二氧化锰相同,仍为β型,但锰和二氧化锰含量增加．经恒流放电、电位扫描测试,发现活化二氧化锰的电性能较天然二氧化标有所改善：开路电压、工作电压提高,放电容量增大．对此进行了初步的理论探讨． 相似文献
19.
Empirical studies demonstrated Type-I error (TIE) inflation (especially for highly discriminating easy items) of the Mantel-Haenszel chi-square test for differential item functioning (DIF), when data conformed to item response theory (IRT) models more complex than Rasch, and when IRT proficiency distributions differed only in means. However, no published study manipulated proficiency variance ratio (VR). Data were generated with the three-parameter logistic (3PL) IRT model. Proficiency VRs were 1, 2, 3, and 4. The present study suggests inflation may be greater, and may affect all highly discriminating items (low, moderate, and high difficulty), when IRT proficiency distributions of reference and focal groups differ also in variances. Inflation was greatest on the 21-item test (vs. 41) and 2,000 total sample size (vs. 1,000). Previous studies had not systematically examined sample size ratio. Sample size ratio of 1:1 produced greater TIE inflation than 3:1, but primarily for total sample size of 2,000. 相似文献