排序方式: 共有51条查询结果,搜索用时 46 毫秒
41.
冯泳兰 《衡阳师范学院学报》1994,(6)
研究了铜(Ⅱ)与邻羟基萘基荧光酮,在阳离子表面活性剂溴化十六烷基三甲铵存在下,NH4Cl-NH3·H2O缓冲介质中在形成紫红色配合物,其最大吸收波长在560nm处,表观摩尔吸光系数为1.06×105l·mol-1·cm-1。Cu(Ⅱ)含量在0~4μg/25ml符合比尔定律。配合物组成:Cu(Ⅱ):0-HNF为1:2。研究的新方法应用于标准岩石样品中微量铜的测定,结果满意。 相似文献
42.
Ezequiel M. Gonçalves Catarina N. Matias Diana A. Santos Luis B. Sardinha Analiza M. Silva 《Journal of sports sciences》2015,33(6):634-640
Bioelectrical impedance spectroscopy (BIS) is an inexpensive and non-invasive technique to measure total body water (TBW), extracellular water (ECW), and intracellular water (ICW). The purpose of this study was to validate TBW, ECW and ICW assessed by BIS, using dilution techniques as the reference method (REF) in elite judo athletes. Thirty-two Portuguese elite male judo athletes were evaluated during a period of weight stability. TBW, ECW and ICW were assessed by BIS (Xitron 4000). Deuterium and bromide dilution techniques were used as the criterion method for measuring TBW and ECW, while ICW was calculated as the difference between the two. BIS explained 96%, 77% and 94% of the total variability from REFs for TBW, ECW and ICW, respectively. BIS also demonstrated high precision (ρ ≥ 0.88) and accuracy (Cb = 0.98), with a minimum concordance coefficient correlation of 0.87 for ECW. The mean bias demonstrated that BIS slightly overestimated the REF in 1.1 kg (2.3%), 0.3 kg (1.6%) and 0.8 kg (2.7%) for TBW, ECW and ICW, respectively. The 95% limits of agreement ranged from ?1.2 to 3.3 kg in TBW, from ?1.8 to 2.4 kg in ECW and from ?1.0 to 2.6 kg in ICW. A non-significant trend was found between the difference and the mean of reference and alternative methods. These findings highlight the efficacy of BIS as a valid non-biased tool for the assessment of TBW and its compartments in elite male judo athletes, during a period of weight stability. 相似文献
43.
本文介绍了以甲苯为原料 ,以易购医用的新洁尔灭为催化剂的相转移催化法制备苯甲酸的实验过程 ,并讨论了新洁尔灭溶液的浓度对催化速度的影响 相似文献
44.
俞善信 《江西教育学院学报》1999,20(6):45-46
在相转移催化剂溴化四下基铵存在下,正了醇、正丁基溴和氢氧化钠在90℃反应二小时,合成了正丁基醚,收率79%以上。 相似文献
45.
王艳 《武汉工程职业技术学院学报》1999,(1)
利用溴化锂溶液的物理性能和热力学性能,对溴化锂吸收式制冷机结晶问题、蒸发器冷剂水过多的故障等进行分析、判断,提出处理故障的具体办法.此外,文章还简要地指出了处理各种故障的快速反应对策. 相似文献
46.
合成了一个新颖的离子对化合物[TBA][Ni(dddt)2](1)(TBA=tetra-N-butylammonium,dddt^2-=5,6-dihydro-1,4-dithiin-2,3-dithiolate),单晶衍射结果表明化合物1属于单斜晶系,空间群为P21/c,晶体不对称单元含1个[Ni(dddt)2]^-阴离子以及1个[TBA]^+阳离子.在[Ni(dddt)2]^-阴离子中,Ni离子呈现平面正方形配位几何构型,相邻阴离子间存在弱的S…S相互作用.在化合物1晶体中,阴、阳离子间弱的堆积作用以及静电作用将化合物1连接形成三维分子固体. 相似文献
47.
在pH=7.40的Tris-HCl缓冲溶液中,采用荧光光谱法和粘度法研究了8-羟基喹啉(HQ)与鲱鱼精DNA的作用方式.用摩尔比法确定了HQ与DNA的结合比为12∶1.通过热力学研究得出,在27℃时HQ与DNA之间相互作用的Kφ27℃=3.844×105L/mol,热力学函数ΔrHφm=-5.08×104J/mol,ΔrGφm 300.15K=-3.2×104J/mol,ΔrSφm=-62.6 J/(mol.K).结果显示该反应为焓驱动.实验表明HQ与DNA的作用方式为部分嵌插与静电作用方式. 相似文献
48.
16Mn钢在含H2S的薄层液膜下的缓蚀研究 总被引:1,自引:0,他引:1
用极化曲线和交流阻抗技术研究了硫脲和溴化十六烷基毗啶在复配前后对含H2S薄层液膜下的16Mn钢的缓蚀行为,得到了一些重要结论,并对其进行解释和讨论。 相似文献
49.
热力学分析溴化浸金体系 总被引:1,自引:0,他引:1
王京芳 《南阳师范学院学报》2008,7(9):47-49
依据氧化剂和络合剂,分析溴化物浸金体系。在标准条件下,只要氧化剂的标准电极电位大于0.88V,金将以三价金溴络合物的形态浸出;当氧化剂的标准电极电位高于0.94V,金将以一价金溴络合物的形态浸出。热力学上更有利于金以三价金溴络合物的形态浸出。通过选择非溴水氧化剂,有可能避免溴化物浸金过程中溴的挥发。 相似文献
50.
Arbutin was synthesized from glucose by two-step reaction below: (a) 2,3,4,6-tetra-O-acetyl-α-D-glucosyl chloride or bromide was prepared by glucose and acetyl halide (chloride or bromide). (b) 2,3,4,6-tetra-O-ace tyl-α-D-glucosyl halide (Cl, Br) reacted with hydroquinone, methanol as solvent at pH=9.5~10.0. 相似文献