中国表层土壤汞和硒分布空间异质性的因素分析

在大尺度(中国)范围内,季风和降水等因素可能对土壤中挥发性元素汞和硒的含量具有显著影响,但影响表层土壤中汞和硒差异的关键因子及其贡献率仍未知.分析了干、湿沉降,微生物挥发作用对土壤中汞和硒积累的贡献,结果显示表层土壤汞和硒的积累是一个动态的过程.在全国尺度上,湿沉降对表层土壤中硒的贡献率达到91.5％,对汞的贡献率为4...     

硒对蛭石培养大豆生理生化特性的影响

采用蛭石培养大豆,并施以不同浓度的硒处理,对大豆的表观性状、生物学性状、生理性状进行了研究.结果表明,蛭石中补以适宜浓度的硒,能够促进大豆植株生长,硒浓度过高,大豆的生长会受到抑制;可溶性蛋白和可溶性糖的含量均较对照组有所提高,一定浓度的硒能够增强大豆的抗逆性能;蛭石中硒浓度高于5μg.mL-1时,脯氨酸含量上升,提高了大豆的抗逆性,而硒浓度在0.1～5μg.mL-1范围内时,MDA含量均低于对照,补硒浓度达到10μg.mL-1时,MDA的含量高于对照和低浓度硒处理,所以低浓度的硒(补硒浓度小于10μg.mL-1)有利于降低过氧化产物MDA的生成,对大豆有一定的抗氧化作用;当硒浓度低于10μg.mL-1时,叶绿素含量均高于对照组,说明适量的硒有利于促进光合作用,从而利于大豆的生长.     

叶面喷施硒肥对红小豆品质及硒含量的影响

为研究红小豆的富硒能力,以不同质量浓度的硒肥叶面喷施,研究硒对红小豆产量、品质及硒含量的影响.结果表明,随着硒质量浓度的增加,红小豆快速生长,产量增加;但质量浓度过高则抑制红小豆生长,产量下降;红小豆的蛋白质含量随硒肥质量浓度的增加而逐步增大,脂肪含量的变化较小;红小豆籽粒硒含量和籽粒硒积累量随硒质量浓度增加而增大,但是籽粒硒利用率却逐步下降.综合红小豆的富硒规律和生长发育规律得出,叶面喷施30g/hm2为红小豆的最佳喷施质量浓度.     

湘西地区土壤硒含量及其分布的调查

以湖南湘西地区土壤为对象,研究了湘西地区土壤中硒元素的含量及其分布．结果表明,湘西地区土壤中硒的质量分数高,其含量远高于全国土壤硒的质量分数,属富硒地区;硒在土壤中的分布也存在差异,总体趋势是由北向南和由西向东逐渐下降．     

硒在土壤—水稻系统中的迁移转化规律

通过研究江门市都斛、牛江、宅梧3个优质稻产地土壤Se的空间分布规律及其与指示不同物质来源的特征元素组合的相互关系,得出土壤Se来源于陆相沉积,其中基性物源对土壤硒的贡献率大于花岗岩物源.Se的7种形态中,强有机态Se和腐殖酸态Se均占全量的一半以上,且此2种形态与全量间相关系数高,说明土壤中Se的富集与有机质的活动密切相关.硒在水稻植株根、茎、叶、谷壳、米粒中的分布、迁移和总量传输,是一个动态过程.从土壤和根部传输上来的硒会逐渐在各器官内积累,浓集系数大小顺序表现为C茎-谷壳,C土-根,C茎-米,C根 -茎的特点.水稻在地面以上部分的硒量不足植株总硒量的50％.高硒区土壤总硒与土壤有机态硒和残渣态硒有关,硒的含量、形态明显受土壤pH、Eh和有机质含量影响.     

不同价态硒对小白菜生长及土壤硒形态的影响

采用田间小区试验,研究不同价态硒对小白菜生长、硒吸收和土壤硒形态的影响.结果表明,适当含量(2.5mg/株)的两种价态硒对小白菜生物量增加有促进效果,而高含量(5 mg/株)则有明显的抑制作用.两种价态硒处理显著增加了小白菜硒含量,在7.5 mg/株处理达最大值,分别为0.401 mg/kg和2.207 mg/kg,较对照增加了2.0倍和15.5倍.相同浓度条件下,六价态硒处理的小白菜硒积累量和硒的有效利用率均显著大于四价硒处理.两种价态硒处理可有效提高土壤各形态硒含量,且四价态硒效果好于六价态硒.小白菜硒含量受土壤中交换态硒含量的影响最大,其次为水溶态硒含量.     

兰州市土壤及重点农产品硒形态分析

农产品中的硒含量与其生长环境中的硒含量密切相关,但是,研究发现,产品中的硒含量往往不与土壤中的总硒含量出现关系,而是与土壤中的有效态硒有一定的正相关关系.而土壤中有效态硒的含量又与土壤的类型,理化性质及其所处地区的气候条件密切相关.兰州市土壤的大地质区域背景及其所处地理条件有利于土壤中的硒向有效形态的转化,这也是虽然兰州市的表层土壤硒含量平均值仅为0.177 mg/kg,处于全国中等水平,但是还有少数品种的蔬菜达到富硒标准,具备成为该市天然的富硒农产品的条件.     

江西于都县盘古山地区土壤中硒的分布特征及其影响因素

为研究于都县盘古山地区土壤中硒的分布特征及其影响因素,在该地区采集 1255件表层土壤样品和10件土壤剖面样品,并对其进行化学元素测试分析和物性分析.结果表明,本区富硒土壤资源丰富,平面上硒元素含量高值区与低值区沿北东方向呈条带状分布,垂向上土壤硒含量总体随深度增加呈"先增后减"的变化趋势.研究亦发现,土壤中硒主要富集...     

红香米硒含量与土壤中硒含量相关性研究

目的:通过研究测定土壤中全硒、有效硒和红香米中硒的含量,利用统计学的方法来分析土壤中全硒、有效硒与红香米中硒含量的相关性,从而达到指导选择合适地块种植红香米的实际目的。方法:采集土壤和红香米样品,用原子荧光光度计分别对红香米中硒、土壤中全硒和有效硒含量进行测定,以研究其相关性。结果:红香米中硒含量与土壤中全硒、有效硒含量呈正相关关系。结论:在富硒的土壤中种植的红香米其硒含量也较高,在种植时可以选择在富硒量较高的土壤中种植红香米,得到很有价值的富硒红香米。     

大豆蛋白中硒分布的研究

用分级盐析法将高硒土壤上栽培的大豆蛋白质分为A、B、C、D、E五组，进而测定了各组中蛋白质的分布及其硒含量，结果表明大豆吸收的硒主要贮存结合于蛋白质中。     

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.     

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.     

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.     

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     

Call for Papers

<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     

Journal of Donghua University ( English Edition) Contents of Volume 31

正~~