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1.
采用Fe(phen)32 光度法测定了辉光放电电解过程中产生的羟基自由基(.OH),考察了本方法的可行性及工作电压、溶液电导率和初始pH对.OH生成浓度的影响.结果表明,在电压为560 V,溶液电导率为4.500 mS/cm,初始pH=3.20的情况下,在盐桥装置中60 min内捕获到.OH的浓度约为1.01×10-4mol/L.  相似文献   

2.
采用Fe(phen)23+光度法测定了辉光放电电解过程中产生的羟基自由基(·OH),考察了本方法的可行性及工作电压、溶液电导率和初始pH对·OH生成浓度的影响. 结果表明,在电压为560 V,溶液电导率为 4.500 mS/cm,初始pH=3.20的情况下,在盐桥装置中60 min内捕获到·OH的浓度约为 1.01×10-4 mol/L.  相似文献   

3.
针对高浓度柠檬酸酸洗废水的光降解过程,以水杨酸为羟基自由基(·OH)捕获剂,通过紫外分光光度法检测产物2,3-二羟基苯甲酸在510 nm处的吸光度,以证实·OH的存在。以对苯二甲酸为·OH捕获剂,315 nm为激发波长,利用荧光分光光度法测定2-羟基对苯二甲酸在425 nm处的荧光强度,间接测定柠檬酸酸洗废水中·OH的浓度。检测结果表明:利用1stopt v1.5软件中的拟牛顿法和通用全局优化法对试验结果进行拟合,得出决定因数DC=0.993 2,说明水杨酸的光解过程较好地符合两步一级反应模型,证实光降解过程中有·OH产生。对苯二甲酸浓度为4×10~(-5)mol/L时,荧光强度与反应时间线性关系较好(R~2=0.999 8),即光照过程中·OH的浓度约为4×10~(-5)mol/L。  相似文献   

4.
分光光度法测定Fenton反应产生的羟基自由基   总被引:6,自引:0,他引:6  
基于水杨酸可以捕获羟基自由基(·OH)生成2,3-二羟基苯甲酸和2,5-二羟基苯甲酸,在波长510nm处有最大吸收的原理,建立一种用分光光度法检测Fenton反应产生的羟基自由基(·OH)的方法.通过对反应体系影响条件的优化,筛选出最佳反应物配比和最佳实验条件,并对其稳定性进行检测.在此基础上。测定抗氧化剂对羟基自由基(·OH)的清除率.结果表明:该体系反应灵敏、稳定性高,可作为抗氧化剂的筛选方法之一.  相似文献   

5.
毛细管电泳同时测定酚类系列化合物的表观离解常数   总被引:2,自引:0,他引:2  
毛细管电泳提供了一种简单、迅速、精确的pKa值的测定方法,可以适用于很宽的pH范围内.采用电流突跃来标记电渗流,并利用Boltzmann形式的函数进行非线性拟合,同时测定了9种酚类系列化合物的pKa值.9种酚类化合物包括焦儿茶酚、水杨酸、2,3-,2,6-和2,5-二羟基苯甲酸、2-氨基-3-羟基苯甲酸、2-氨基-5-羟基苯甲酸、2-氨基苯酚以及邻氨基苯甲酸,共得到11个pKa值并对其进行了讨论.  相似文献   

6.
在基体辅助激光解吸电离飞行时间质谱(Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry,MALDI-TOF MS)分析中,使用合适的基体或基体添加剂,可以改善样品结晶的形状、颗粒大小和分布的均匀性、提高样品分子解吸电离的效率、增强质谱信号、延长样品出峰时间、增加样品出峰的重复性、提高分辨率、扩大质量测定范围,从而提高分析的灵敏度、谱图质量以及分析的速度和效率.研究结果表明,与MALDI-TOF MS分析葡聚糖的常用一元基体2,5-二羟基苯甲酸(2,5-dihydroxybenzoic acid,DHB)相比,在2,5-二羟基苯甲酸中加入3-氨基-4-羟基苯甲酸(3-amino-4-hydroxybenzoic acid,AHB)组成的DHB AHB二元新基体测定相对分子质量为10 000、未经进一步分级的高聚合度葡聚糖样品,不仅能使样品形成均匀的结晶、易于解吸电离;而且还可使检测的质量范围比用DHB HIQ二元基体有所扩大,达到21 000以上.  相似文献   

7.
以丙烯酸(AA)和凹凸棒土(ATP)为原料,N,N′-亚甲基双丙烯酰胺为交联剂,采用辉光放电等离子体引发聚合法在水溶液中一步制得了聚丙烯酸/凹凸棒(PAA/ATP)高吸水性复合材料.考察了放电电压、交联剂用量、单体浓度及凹凸棒土含量对树脂吸水率的影响,并用红外光谱(FT-IR)、扫描电镜(SEM)、原子吸收光谱(AAS)和热重分析(TGA)表征了复合材料的结构、形态和性能.结果表明,在最佳条件下,复合材料性能良好,吸水率达1 281 g·g-1,对Cu2+的吸附量达到98.93 mg·g-1.  相似文献   

8.
用水杨酸浸渍膜捕集-高效液相色谱(HPLC)法测定介质阻挡放电降解甲苯中羟基自由基(·OH)的生成量.考察了能量密度(S1E)、相对湿度(RH)、背景气氛、催化剂对·OH产生量的影响.实验表明,·OH量随能量密度的增大而增加,能量密度从140J·L-1增至320J·L-1时,·OH量从5.9×1013个·cm-3增加到...  相似文献   

9.
石松黄酮类化合物的抗氧化作用研究   总被引:1,自引:0,他引:1  
以贵州省六盘水野生的石松为原料,利用70%乙醇作为提取介质,对石松黄酮类化合物进行了提取.采用邻苯三酚自氧化法、水杨酸比色法分别测定了石松黄酮提取物清除超氧阴离子自由基(O2)以及羟基自由基(—OH)的效果.结果表明,不同浓度的石松黄酮类化合物能显著地清除超氧阴离子自由基和羟基自由基,随着石松种子黄酮类化合物浓度的升高其抗氧化性作用逐渐增强.  相似文献   

10.
为深入了解接触辉光放电等离子体降解水中有机污染物的机理,用紫外-可见吸收光谱法研究了放电过程中染料结构的变化,考察了pH值、自由基清除剂等实验条件对艳红B脱色的影响.结果表明:加入羟基自由基清除剂可增强艳红B的脱色效果,加入氢自由基清除剂对艳红B的脱色有轻微的阻碍作用.溶液初始pH值在7.0~11.0之间时对脱色影响不大.随着反应的进行,溶液的化学需氧量逐渐升高.紫外-可见吸收光谱分析表明,等离子体产生的活性氢原子对偶氮键的破坏是艳红B脱色的主要原因.  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.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

16.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

17.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

20.
1 Rise of studies on climate change's effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America's annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].  相似文献   

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