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1.
利用葡萄糖和果糖与 2,4二硝基酚在强碱性介质中反应生成红色化合物的反应速度差,建立了光度法同时测定葡萄糖和果糖的速差动力学法.当 Na O H 浓度为 16×10- 3 m ol/ L,2,4二硝基酚浓度为 12×10- 3 m ol/ L,分别在 50℃下反应 8m in 和 55℃下反应 6 m in 时,同时测定葡萄糖的线性范围为 0~960×10- 3 m ol/ L,果糖的线性范围为0~200×10- 3 m ol/ L.对葡萄糖与果糖浓度比为15∶1~1∶1 的混合液进行回收试验,回收率为963% ~1053% .该方法已用于果葡糖浆的分析  相似文献   

2.
研究了阳离子表面活性剂及非离子表面活性剂对镉-5-Br-DMPAP的增溶作用.结果表明,阳离子表面活性剂对该体系增溶增敏作用显著,ε可达1.21×105Lmol-1cm-1.同时,利用S2-对该体系的褪色作用可间接测定S2-,建立的方法用于啤酒及工业污水中水溶性S2-的测定,结果令人满意.  相似文献   

3.
提出用4-(对-重氮氨基苯甲酸)偶氮苯进行镍的光度方面研究,并探讨了混合表面活性剂存在时对显色反应的增敏情况.研究结果表明:镍与显色剂可形成1∶2的络合物,在pH=10.70~11.10范围内,其表观摩尔吸光系数为1.45×105L·mol-1·cm-1,若采用双波长法测定摩尔吸光系数可提高至1.96×105L·mol-1·cm-1,在0~8μgNi2+/25mL内,服从比尔定律,大多数外来离子不干扰,用于环境样品和铝合金中镍的测定,回收率在96%~110%之间,结果令人满意  相似文献   

4.
新型板翅式冷凝蒸发器的传热特性研究   总被引:3,自引:0,他引:3  
采用1m长的新型板翅式单元作为工业用冷凝蒸发器的结构单元,对此单元试样进行了冷凝与沸腾传热特性的实验研究.实验结果表明:当热流密度达到6000W/m2时,其总的传热温差仅为1.1K,比通常结构的冷凝蒸发器的传热温差减小0.3~0.8K.根据单元试样的试验结果,选用优化结构尺寸,设计制造了用于150m3/h制氧机的新型板翅式冷凝蒸发器正式产品,对其进行了工业性试验.测试结果表明:传热系数达到754W/(m2K),与原有产品相比,其重量减轻了36%,体积减小了40%.  相似文献   

5.
在聚乙烯酸(PVA)存在下,锇与铅酸铵和碱性染料(罗丹明B,了基罗丹明B,耐尔蓝)形成离子缔合物,不同碱性染料所形成的缔合物服从比耳定律的浓度范围和摩尔吸光系数分别是:0 ̄1.2μg/25ml和ε570nm=2.62×106L·mol-1·cm-1(罗丹明B体系),0 ̄1.0μg/25ml和ε570nm=2.86×106L·Cm-1(丁基罗丹明B体系);0~1.8μg/25ml和ε585nm=2.81×106L·mol-1·cm-1(耐尔蓝体系)研究了三个显色体系的光度特性和30多种共存离子的影响,方法用于一些催化剂和冶金产品中锇的测定,结果满意.  相似文献   

6.
本文制作了K+,Na+液态膜离子敏感微电极(K+,Na+—ISME),并稳定了其制作条件,经测试,K+—ISME线性范围为1—10-4mol/L,检测下限为3.0×10-6mol/L。对Na+选择系数为2.68×10-4。电位飘移为±0.1mV/h。Na+—ISME线性范围为1—2.0×10-mol/L,检测下限为5.0×1.0-4mol/L。对K+的选择系数为1.85×10-2,对Ca2+的选择系数为1.46。上述参数均满足生理实验要求,离子敏感微电极技术可做为生理学研究的重要手段。  相似文献   

7.
本文用8-羟基喹啉修饰的铅笔芯电极研究了铜的阶梯阳极溶出伏安特性,并将此法用于人发中微量铜的测定。实验指出,在此修饰电极上,铜的阶梯溶出峰有两个,1#峰电位在-0.03V,2#峰电位在0.27V处。同样的试液和条件下,1#峰总比2#峰的峰电流大。实验研究了测定铜的最佳条件,并测得铜的浓度在4.0×10-8~1.6×10-6mol·L-1范围内,1#峰的峰高与浓度呈良好的线性关系,最低检测限为2×10-8mol·L-1。2#峰高与铜的浓度在6.0×10-8~1.6×10-6mol·L-1范围内也有较好的线性关系,也可用于测定铜。本文还分析了铜在修饰电极上的反应机理  相似文献   

8.
患者女,36岁,住院号31947,子宫下段剖腹产手术史8年。腰痛、尿急、尿频、尿病月经期上述症状加重伴血尿1年。于1995年5月16日入院。体检;腹软、腹部未触及包块、双肾未触及、无叩击病。B超检查子宫下段前壁内膜回声显示不清、膀胱三角区见3.82cm×3.12cm×1.70cm低回声团,表面不规则,周边可见动脉回流,后方与子宫颈前壁密切相贴。子宫被膜显示不清。B超诊断:膀胱子宫之间异常低回声包块。膀胱镜检见膀胱右后壁距输尿管口1.2cm可见2.0cm×2.0cm肿物,表面囊泡状,基底宽大,钳取…  相似文献   

9.
研究了1-[(2-吡啶)]偶氮-2-萘酚-磺酸(简称PAN-S)与锰显色反应的最佳条件。在pH9硼砂-HC1介质中,锰与PAN-S形成1:2红色配合物,λmax=535um,ε535=2.66×104L·mol-1·cm-1.0~50μgMn/25mL符合比尔定律。本法可满意地用于测定碳素比色钢、低合金钢和碳素钢。  相似文献   

10.
香港草地和芒萁群落生物量收获的最佳样方选择   总被引:4,自引:0,他引:4  
利用Wiegert的方法,结合边界效应分析,根据估算及以往热带草地的研究,讨论了香港草地和芒萁群落选择最佳的样方大小和样方数目问题.表明1.0m×1.0m是最佳的样方尺寸,需要大约8~16个1.0m2样方才可达到标准误差小于(或等于)生物量平均值10%的标准.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

14.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

15.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

16.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

17.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

18.
For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the  相似文献   

19.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

20.
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