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1.
采用双波长β修正光度法研究铜 (II) -二溴邻羧基偶氮氯膦 (DBOK -CPA)显色体系 ,在中性条件下所生成络合物组成比Cu∶DBOK -CPA为 1∶2。配合物的各级真实吸光系数和稳定常数均被测得 ,在 630nm下络合物真实摩尔吸光系数ε=1 .49× 1 0 4 L·mol·cm- 1 ,络合物累积稳定常数K =8.58× 1 0 9( 1 5℃和离子强度 0 .0 1 )。  相似文献   

2.
在Triton X-100存在下,钨(Ⅵ)-与4,5-二溴邻硝基苯基萤光酮(Br-ONPF)形成络合物。络合物可在0.5~2.8mol·1~(-1)的盐酸介质中分光光度法测定。波长为534nm处得摩尔吸光系数ε=9.2×10~4l·mol~(-1)·cm~(-1)。钨(Ⅵ)浓度在2~45μg/25ml的范围内服从比耳定律。络合物显色极快,瞬间达到平衡且在2小时内吸光度值稳定不变。大多数常见阳离子不干扰本法对微量钨的测定。样品测定结果满意。在本实验条件下,测定络合物的组成为钨(Ⅵ):Br-ONPF=1:2。  相似文献   

3.
铜(Ⅱ)-二溴邻羧基偶氮氯膦显色体系性质研究   总被引:1,自引:0,他引:1  
采用双波长β修正光度法研究铜(II)-二溴邻羧基偶氮氯膦(DBOK-CPA)显色体系,在中性条件下所生成络合物组成比Cu∶DBOK-CPA为1∶2.配合物的各级真实吸光系数和稳定常数均被测得,在630nm下络合物真实摩尔吸光系数ε=1.49×104L.mol.cm-1,络合物累积稳定常数K=8.58×109(15℃和离子强度0.01).  相似文献   

4.
4,5-二溴邻硝基苯基萤光酮(BrONPF)分光光度法测定钨   总被引:1,自引:1,他引:1  
在Triton X-100存在下,钨(Ⅵ)-与4,5-二溴邻硝基苯基萤光酮(Br-ONPF)形成络合物.络合物可在0.5~2.8mol·1~(-1)的盐酸介质中分光光度法测定.波长为534nm处得摩尔吸光系数ε=9.2×10~41·mol~(-1)·cm~(-1).钨(Ⅵ)浓度在2~45μg/25ml的范围内服从比耳定律.络合物显色极快,瞬间达到平衡且在2小时内吸光度值稳定不变.大多数常见阳离子不干扰本法对微量钨的测定.样品测定结果满意.在本实验条件下,测定络合物的组成为钨(Ⅵ):Br-ONPF=1∶2.  相似文献   

5.
详细研究了9-(3,5-二溴)水杨基荧光酮(简称DBSAF) 溴代十四烷基吡啶(TPB)与钴形成三元络合物的显色反应条件和光度性质.结果表明在pH=9.50的Na2B-4O-7-NaOH缓冲溶液中,钴与试剂形成三元络合物,其最大吸收波长在610 nm,表观摩尔吸光系数为2.30×105 L@mol-1@cm-1, 钴(Ⅱ)含量0~6 μg/25ml范围内符合比耳定律.用本法测定了维生素B12中的钴,结果较好.  相似文献   

6.
研究了在大量钨存在下,钼与溴邻苯三酚红、溴化十四烷基吡啶的显色反应,最佳显色酸度为PH4.0,加入EDTA等络合剂,可有效地消除干扰元素的影响,钨含量即使高达1mg,也不干扰20ugM_o的测定,加入tritonX-100,具有增溶、增稳作用,但不改变吸收峰的位置,不改变络合物的组成,在0~40ugMo/25mL范围内符合比尔定律。应用于矿石及钨精矿(WO_3%=63.80%)中钼的测定,与硫氰酸盐-硫脲光度法测定钼的结果作了对照,互相符合。  相似文献   

7.
拟定了一种微量镓(Ⅲ)的测定方法:当有聚乙烯醇存在时,在pH3.6的醋酸一醋酸钠缓冲溶液中,镓(Ⅲ)能与溴邻苯三酚红及邻菲啰啉形成蓝紫色的三元络合物,λmax=615 nm,25 ml溶液中镓(Ⅲ)量为1.0×10-~35μg范围内符合比尔定律,表观摩尔吸光系数ε=3.69×10 4,络合物组成比:镓(Ⅲ):溴邻苯三酚红:邻菲啰啉=1:2:1.大量铝(Ⅲ)可用氟化钠掩蔽,此法可用于大量铝中微量镓的测定.  相似文献   

8.
以异戊醇和氢溴酸为原料 ,改性镍钼粉为催化剂 ,催化合成 3,1-溴代异戊烷。探索出适于合成 1-溴代异戊烷的工艺控制条件 ,由异戊烷与氢溴酸物质的量比为n(异戊烷 ) :n(氢溴烷 ) =1 0 :2 5 ,催化剂用量为m(异戊烷 ) :m(催化剂 ) =1 0 0 0 :0 12 5 ,反应温度为 10 0~ 110℃ ,反应时间为 2h ,1-溴代异戊烷的收率为 :90 %。  相似文献   

9.
在 p H4.5的醋酸盐缓冲底液中 ,用单扫示波极谱法可获得灵敏的 Mo( ) -5 -溴水杨基荧光酮络合吸附波 ,钼浓度在 1 .0× 1 0 - 8~ 1 .0× 1 0 - 6mol/ L范围内与二阶导数波峰高成正比关系 ,检测限为 7.0× 1 0 - 9mol/ L,测得电活性络合物组成为Mo( )∶ 5 - Br SAF=1∶ 2 ,条件稳定常数为β=5 .4× 1 0 1 0 .  相似文献   

10.
以1,3-二溴-5,5-二甲基海因(DBDMH)和液溴作为溴化剂,研究了异香草醛在不同溶剂、不同温度下的选择性溴化反应,探讨了影响溴化反应的主要因素。在25℃条件,以氯仿为溶剂,液溴为溴化剂,制得6-溴异香草醛,其选择性达到85.8%,以DBDMH为溴化剂,氯仿为溶剂,制2-溴异香草醛的选择性达到99.8%。目标产物经HPLC、1H NMR分析与表征。  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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