氢化物发生原子荧光法测定土壤中铅镉砷3种有害重金属

应用氢化物发生-原子荧光法对土壤中铅镉砷含量进行测定。研究了分析测定条件;测定铅、镉、砷的线性范围分别为:0～40μg/L,0～5μg/L,0～40μg/L;相关系数分别为:0.9999,0.9999,0.9994。应用于样品测定,测定结果的相对偏差小于2.6%;加标回收率为96.8%～104%。     

微波消解氢化物原子荧光法测定海水蔬菜中的砷、汞

建立了一种微波消解处理样品,氢化物发生原子荧光光谱法同时测定海水蔬菜中微量砷、汞的方法.在优化的实验条件下,海水蔬菜中砷、汞回收率分别为96.0%、103.2%;检出限分别为0.24μg/L和0.17μg/L.并对方法的精密度和准确度进行评估,结果表明该方法用于海水蔬菜中砷和汞的同时测定是可行的.     

原子荧光光谱法测定烟草中的砷和汞

研究了用原子荧光光谱法同时测定烟草中的砷和汞,烟草样品采用HNO3-H2O2消化体系微波消化,然后用原子荧光光谱法测定.在最佳微波消化条件和测定条件下,线性范围为:Hg 0.1~150μg/L、As 0.1~200μg/L,检出限均为0.035μg/L,汞测定的相对标准偏差为2.8%,砷测定的相对标准偏差为2.5%,汞的标准回收率为93%,砷的标准回收率为96%,结果令人满意.     

氢化物-原子荧光法测定酱油中的砷

本法采用自动回流消化仪处理样品,在标准溶液中加入相同量的氯化钠以消除盐份基体效应,氢化物-原子荧光法测定酱油中的微量砷。方法简单,结果可靠,方法的测定线性范围3.0～100μg/L,检出限为1.6μg/L,相对标准偏差为3.62%。     

流动注射在线浓缩分光光度法测定海水中痕量的铜

采用一种新型浓缩柱,选用草酸-柠檬酸混合液作为解吸液,乙基紫作为显色剂,建立了在线浓缩-流动注射分光光度法测定海水中痕量铜的新方法,并对实验条件进行了优化.在最佳实验条件下,该方法的线性范围为0.5~20μg/L和20~40μg/L,检出限达0.2μg/L,相对标准偏差(RSD)为1.08%(5μg/L Cu,n=8)和1.30%(40μg/L Cu,n=8).将该方法应用于实际海水中Cu(Ⅱ)的测定,结果满意.     

氢化物发生原子荧光法测定饮用水中的砷和硒

建立饮用水中砷和硒同测的氢化物发生-原子荧光法测定方法。选择最佳的仪器条件,在体积分数为10%的盐酸介质中,砷和硒线性范围为0~40.00μg/L,砷和硒的检出限分别为0.06μg/L和0.04μg/L,加标回收率为97.8%~106.6%,RSD(n=10)2.9%。此方法操作简便,灵敏度高,适用于饮用水中砷和硒的测定。     

固相萃取-超高压液相色谱-串联质谱法分析海水中9种磺胺类抗生素

应用固相萃取及液相色谱-质谱联用技术,建立了海水中9种磺胺类抗生素的分析方法.海水样品经HLB固相萃取柱富集、净化后用甲醇洗脱浓缩定容,利用超高压液相色谱-串联质谱仪多反应监测（MRM）离子模式对目标物进行定性、定量分析.9种磺胺测定的线性范围为0.2～1000μg/L,方法检测限在0.2～0.4 ng/L之间（S/N=10,1 000倍浓缩）.以海水为基底,磺胺甲基嘧啶为替代物,加标浓度分别为5.0 ng/L和20.0 ng/L时,9种磺胺的回收率在86.4%～150.4%之间,相对标准偏差0.5%～8.4%（n=4）,方法成功应用于厦门近岸海域海水样品中抗生素残留的分析.     

原子荧光法测定浙江近岸养殖海水中的微量元素硒

采用氢化物发生-原子荧光法定养殖海水中硒含量。通过实验条件选择,对消解样品的酸浓度和硒还原方式等条件进行了优化。在优化后的最佳测定方法下,硒测定的标准曲线线性范围为0~10.0μg/L,养殖海水样品加标回收率在84.4%~102%,相对标准偏差在0.13%~5.27%之间(n=6),方法检出限为0.15μg/L。该方法简便快速、结果准确、灵敏度高、易于普及,适用于养殖海水中硒的快速检测。     

微波消解-氢化物发生原子荧光法连续测定砷、硒、锑的研究

建立了氢化物发生原子荧光法连续测定食品中砷、硒和锑的方法.采用微波消解的方法处理样品,研究了在酸性介质下,砷、硒、锑与硼氢化钾生成氢化物的反应行为,并对影响荧光强度的诸因素进行了试验和探讨.该法砷、硒、锑的线性范围分别为0~250,0~200,0~200μg/L,检出限分别为0.36,0.42,0.31μg/L,相对标准偏差为1.23%~4.85%.该法灵敏度高,检出限低,应用于实际样品的测定,结果满意.     

氢化物原-子-荧光光谱法测定食品中微量砷

采用氢化物原子荧光光谱法研究了用砷化钾－硫脲作为预还原剂对测定砷的影响，讨论和确定了最佳检测条件，结果表明：该方法线性范围广，线性关系良好，r=0.9998,检出限为0.219μg/L，标准偏差为0.63%-0.85%，回收率为94．22－100.60%，该方法准确，简便，可广泛用于食品中砷的检测。     

Markedness and its Interpretation in Language Use

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.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

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.     

低渗透非均质砂岩油藏启动压力梯度研究

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。     

On Tragic Consciousness In The Works By Ernest Hemingway

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.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

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.     

Achieving Unusual States of Matter Under High Pressure

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-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

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-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

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