食品中重金属铅、镉电化学检测的前处理技术

以湿法消解为食品中重金属电化学检测的前处理技术,通过电化学实验确定湿法消解的最佳条件,使得食品样品在前处理过程中能够消解完全。结果表明,采用硝酸-过氧化氢湿法消解体系,加入10 m L硝酸后无需放置预消解,在120~140℃范围内加热,加入10~15 m L过氧化氢,样品可以消解完全。湿法消解食品样品,电化学检测消解液的相关系数为0.99,加标回收率为82%~115%。湿法消解作为食品样品前处理技术,能够消解完全,满足电化学检测的要求。     

土壤中有机质含量测定方法研究

通过对土壤中有机质含量测定方法要点消解温度、消解时间、试液酸度的研究,得出在测定土壤中有机质含量时,试样消解温度、试样消解时间、试样消解酸度对试样测定结果影响较大,影响顺序为试样消解温度试样消解时间试样消解酸度;若消解温度控制在170～180℃、试样酸度约为9.2 mol/L、消解时间≥5 min时,试样中的有机碳将全部被氧化,测定结果稳定可靠.     

不同消解法对土样中汞的测定对比分析

采用微波消解、水浴加热、电热板加热方法消解土壤标准样品,以氢化物发生-原子荧光法测定消解液中汞的含量,比较了几种消解方式的精密度与准确度。结果表明:微波消解法可达到较高的精密度与准确性,其相对标准偏差为1.6%~5.5%;水浴加热法相对标准偏差为2.3%~8.9%,适用于大量样品的消解;电热板法相对标准偏差为1.8%~12.4%,精确度差且酸耗大。水浴加热消解法因其酸耗小、操作简便、测定结果准确度较高等特点更适用于环境监测工作中大批量土壤样品中汞含量的测定。     

微波技术消解芦荟样品研究

利用微波等离子体炬原子发射光谱法(MPT-AES)测定了芦荟样品中Ca、Mg、Fe、Zn、Pb元素的含量,对微波消解技术消解芦荟时的最佳消解体系与最佳操作条件进行了研究.实验结果表明:6.0 mL硝酸、1.5 mL过氧化氢、0.4g样品为最佳的微波消解体系;微波消解操作参数设置为:微波功率为360 W,恒压值为0.4 MPa,恒压时间为10 min,并分3步消解.微波消解后的芦荟样品中Ca、Mg、Fe、Zn、Pb的RSD均小于5.10%,回收率在99.7%～102.5%之间,与常规消解法测定结果基本一致.但微波消解方法称样量要比常规法少,溶样时间远少于常规消解法,并且消解过程中不引入杂质,安全、环保.     

专家PID温度控制算法在智能石墨消解仪中的应用

智能石墨消解仪是一种新型的湿法消解设备,能满足控温消解的要求。本文以智能石墨消解仪为研究对象,根据控温消解的特点,采用专家控制和增量式PID相结合的方法,并引入智能积分,设计了一种温度控制算法。MATLAB仿真和实际应用表明,该算法完全适用于石墨消解仪的温度控制,并取得了良好的控制效果。     

不同消解方法测定土壤中重金属含量的研究

影响土壤重金属测定结果准确性的关键是消解。以两种土壤标准样品为试材,比较研究微波消解、高压消解、石墨消解和电热板消解四种不同消解条件,同时对不同类型土壤中Cr、 Ni、 Cu、 Pb、 Cd、 Zn六种重金属测定结果进行对比分析。结果表明:四种消解方法的测定值均在标准值范围内,但不同酸体系及消解时间会对结果的稳定性有一定的影响。在实际的消解过程中应根据土壤中待测金属元素的理化特性、种类、含量以及样品的数量来选择消解方法。     

两种不同消解方法测定近海沉积物氮磷含量的比较

采用两种不同的消解方法—微波消解法和高压消解法,对近海沉积物中的总氮、总磷进行同时消解,并比较了测定结果.结果表明:高压消解条件下测定样品1和样品2总氮的相对标准偏差分别为7.7%和7.4%,总磷的标准偏差分别为3.9%和7.8%;微波消解条件下测定样品1和样品2总氮的相对标准偏差分别为9.4%和10.1%,总磷的相对标准偏差分别为6.9%和8.1%;两种消解条件下的总磷含量相差不大(样品1分别为0.460 mg/kg和0.454 mg/kg,样品2分别为0.449 mg/kg和0.439 mg/kg),但高压消解条件下的总氮含量(样品1为0.114 mg/kg,样品2为0.122 mg/kg)明显高于微波消解(样品1为0.088 mg/kg,样品2为0.092 mg/kg),且相对标准偏差较小.因此可以认为高压消解方法的精密度高于微波消解方法.     

多晶硅材料消解方法的探究

探究了多晶硅样品的酸溶消解法.优化了氢氟酸、硝酸建立的酸解体系,并针对多晶硅粉末状样品给出了最优消解V（H2O）〖KG-1.5mm〗∶〖KG-1mm〗V（HF）〖KG-1.5mm〗∶〖KG-1mm〗V（HNO3）约为20〖KG-0.7mm〗∶〖KG-1mm〗28〖KG-1mm〗∶〖KG-1mm〗10.比较了室温密闭消解、超声辅助消解、水浴加热辅助消解和微波消解对消解效果的影响,结果表明,对于多晶硅粉末样品室温密闭消解1 h为最简便有效的消解方式.     

污泥重金属组分测定中微波消解与常压消解的方法比对

本文通过一系列的实验操作及数据比对,系统的研究了对于测定污泥重金属组分中微波消解与常压消解的方法比对,确定了最佳的微波消解实验条件,填补了这一项目的空白。实验基于将相同组分的污泥样本,分别通过常压消解和微波消解两种不同的方式进行预处理后,用相同的原子吸收仪测定其重金属组分(试验中以镉为代表),使两种预处理方式进行比较,发现微波消解能更快更好更完全的完成消解任务,并通过平行数据分析,找到最佳的实验条件。     

离子色谱法测定米糠中植酸含量

采用微波消解技术将植酸转化为磷酸盐,然后用离子色谱法测定磷酸盐,从而获得米糠中植酸含量.实验中比较了米糠直接消解、提取液直接消解和提取液经阴离子交换处理消解的测定结果.离子色谱定量工作曲线方程为y=0.116 1x+0.650 9,相关系数为R2=0.998 0,测定结果相对标准偏差为0.68%,回收率为97.0%～102.3%,结果令人满意.     

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.     

Lower Paleozoic oil relationships within Williston Basin, Canada

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

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.     

Features of Women's language

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.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

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.