多菌灵在加工番茄农田土壤中的残留动态

为评价多菌灵在新疆干旱区农田土壤中的残留动态和安全性,在加工番茄农田进行了多菌灵施用的田间试验,采用高效液相色谱法测定了多菌灵在土壤中的残留降解动态。结果表明:高效液相色谱法具有较高的检测精度,添加回收率为87.3%～94.5%,最低检测浓度为0.03mg/kg,符合农药残留分析的要求。多菌灵施用后7d,其在土壤中的残留率为30%～46%,28d时残留率低于10%,60d后多菌灵残留量均低于最低检测限(≤0.03mg/kg)。多菌灵在土壤中的残留量随着多菌灵浓度增加而增加,半衰期却随着多菌灵浓度的增加而减小,多菌灵在加工番茄农田土壤中的半衰期为6.48～10.27d。     

稻田中扑草净的消解规律及最终残留量研究

为评价扑草净的环境安全性,以制定安全、合理的使用准则,选择吉林、黑龙江和湖南的三个试验区域,研究了稻田中扑草净的消解规律及最终残留量.结果表明,扑草净在稻田水和水稻植株中的降解速率较快,半衰期相对较短(稻田水中扑草净半衰期为0.7~1.9d,水稻植株为2.0~2.2d);而在土壤中的降解速率较慢,半衰期较长(4.9~17.4d).收获期,对土壤、植株、糙米及稻壳样品进行了最终残留量的测定,均未检出扑草净.由此可见,扑草净较易降解,在推荐施用剂量(25%扑草净(WP),2.250kg/hm2)下,环境和水稻中残留量较低,对环境和作物安全.     

丁硫克百威对棉花根际土壤酶活的影响及其在土壤中残留降解的规律

为了评价丁硫克百威在土壤中的安全性,采用室内盆栽法研究了丁硫克百威2、8、20和50 mg/kg 4个浓度处理对棉花根际土壤酶活性的影响及其在土壤中的残留降解规律。结果表明:(1)低浓度丁硫克百威残留对土壤蔗糖酶的影响主要表现为"抑制-恢复"的变化趋势,50 mg/kg处理以抑制作用为主;对土壤脲酶表现为"抑制-促进-恢复"的变化趋势;各浓度残留在整个试验期内对碱性磷酸酶有轻微抑制作用,但差异不显著;8 mg/kg处理浓度对过氧化氢酶活性表现为先促进后抑制的变化趋势,2、20和50 mg/kg处理浓度对过氧化氢酶活性以抑制作用为主。(2)高效液相色谱法测定丁硫克百威在土壤中的残留,添加回收率为84.6%-87.4%,最低检测浓度为0.01 mg/kg,符合农残分析的要求,结果可靠。7 d测得降解率达到50%左右,30 d时降解率达到90%以上,丁硫克百威在土壤中的残留量随着浓度的增大而增加,但是半衰期却随之减小,为6.05-8.53 d。本研究结果说明不同浓度丁硫克百威残留会影响棉花根际土壤酶的活性,但是这种影响是暂时的,随着施药时间延长有些会恢复至对照水平。在土壤环境中丁硫克百威会被降解,降解半衰期较短。     

高效液相色谱法测定砂土和壤土中敌草隆残留消解动态

为了研究敌草隆在砂土和壤土中的残留消解动态,明确土壤中不同敌草隆浓度对敌草隆消解的影响,采用高效液相色谱法(HPLC)建立快速准确的敌草隆在土壤中的残留分析方法,对比砂土和壤土在不同时间的敌草隆残留量。建立的敌草隆在砂土及壤土中的残留分析方法表明:敌草隆在0. 01～5 mg/L内有良好的线性关系,且灵敏度、准确度均符合要求,相关系数为0. 99,且目标峰分离效果较好;敌草隆的添加回收率为94. 9%～95. 7%,相对标准偏差为0. 93%～1. 64%,最少检出量为0. 01 mg/kg敌草隆在砂土和壤土中的消解动态均符合一级动力学方程;敌草隆在砂土中的半衰期为14. 7～16. 5 d,在壤土中的半衰期为20. 4～22. 4 d; 0、90、180、360 m L/hm~2 540 g/L噻苯·敌草隆悬浮剂施用于砂土及壤土中,浓度越大,敌草隆消散越慢。本试验利用高效液相色谱法测定了砂土和壤土中敌草隆残留消解动态,为敌草隆在田间的合理使用提供依据。     

炔螨特在桑树及土壤中的残留特性

为科学指导安全用药,确定炔螨特在桑树上的安全用药准则,研究了农药炔螨特在桑树不同部位的降解动态和最终残留特性。采用液质联用检测技术,研究炔螨特施用后不同时间的残留量,以及不同施药方式处理下炔螨特的最终残留特性。结果表明,炔螨特在桑树不同部位的残留规律均符合一级反应动力学方程C=C0e-kt。由该方程求出炔螨特在桑叶、土壤和桑葚中的半衰期分别为6.78～10.42、9.21～12.46和7.91～10.85 d。最终残留结果显示,桑叶、桑葚和土壤施药后10 d残留量分别下降到施药后3 d的16.7%～30.40%、29.0%～31.1%和37.1%～34.7%。距最后一次施药10 d后,桑叶和桑葚部位炔螨特最终残留量检测结果低于10.0mg/kg。因此,建议炔螨特在桑树上最大残留限量(maximum residue limit,MRL)值暂定为10.0mg/kg,最多使用2次,安全间隔期为10 d。     

除草剂硝磺草酮在环境中残留的液相色谱分析

分别采用不同的前处理方法处理土壤、植株和玉米样品.土壤样品以水为提取剂,振荡提取,液液分配净化;玉米植株样品和玉米样品以乙腈为提取剂,振荡提取,氨基柱净化.样品中硝磺草酮的残留量采用高效液相色谱-紫外检测器测定.硝磺草酮在0.05~0.4 mg/L范围内线性良好,相关系数为0.999 9.土壤、玉米植株以及玉米样品的平均加标回收率分别为88.8%~100.0%、94.0%~109.0%、103.2%~109.0%,相对标准偏差在2.2%~10.6%之间.     

噻虫嗪在水稻中的消解动态及风险评估

为评价20%噻虫嗪悬浮剂在水稻上使用的安全性,于安徽、吉林两地进行田间试验,采用高效液相色谱-紫外分析法研究噻虫嗪在水稻植株、稻秆、稻壳和糙米中的消解动态和最终残留.结果表明:所建立的甲醇-二氯甲烷(1∶1,v∶v)混合液具有良好的洗脱效果;噻虫嗪在植株中的消解规律符合一级动力学模型,其在安徽、吉林两地间水稻植株中的半衰期分别为2.1 d和5.6 d;按推荐剂量施药,糙米中噻虫嗪的最终残留量最高为1.0 mg.kg-1;推算每人经水稻摄入噻虫嗪日均仅为0.4 mg,风险商值(RQ)为0.32,处于安全水平.     

噻虫嗪在水稻中的消解动态及风险评估

为评价20%噻虫嗪悬浮剂在水稻上使用的安全性,于安徽、吉林两地进行田间试验,采用高效液相色谱-紫外分析法研究噻虫嗪在水稻植株、稻秆、稻壳和糙米中的消解动态和最终残留.结果表明:所建立的甲醇-二氯甲烷(1∶1,v∶v)混合液具有良好的洗脱效果;噻虫嗪在植株中的消解规律符合一级动力学模型,其在安徽、吉林两地间水稻植株中的半衰期分别为2.1 d和5.6 d;按推荐剂量施药,糙米中噻虫嗪的最终残留量最高为1.0 mg.kg-1;推算每人经水稻摄入噻虫嗪日均仅为0.4 mg,风险商值(RQ)为0.32,处于安全水平.     

接种AM真菌对利用冰草降解土壤石油污染的效果研究

为研究冰草作为修复陕北石油污染土壤生物材料的潜力,以及接种丛枝菌根(AM)真菌后冰草对石油烃降解力的增效效果,实验设定了不同浓度的石油烃污染土壤,测定接种丛枝菌根真菌60 d后的冰草株高差异及不同接种量时冰草对石油烃的降解力。结果表明,高浓度石油烃污染的土壤对冰草的株高有明显抑制作用,但接种丛枝菌根真菌可缓解抑制,最高能使冰草株高提高14.90%。接种AM真菌的冰草对石油烃的降解率明显提高,最佳的接种量为150个/盆。此外,接种AM真菌的冰草在高浓度石油烃污染土壤环境中仍有较高的降解力,在土壤中石油烃浓度为20000 mg/kg环境下,60 d降解石油烃15624 mg。     

几种长残留除草剂对甜菜苗期的影响

本文选用喷施除草剂豆磺隆、阔草清、广灭灵3年的土壤育苗种植甜菜,考察其后茬种植甜菜的安全性,结果表明：在喷施豆磺隆、阔草清、广灭灵三年后土壤中种植甜菜,均可以出苗,其中甜菜对广灭灵不敏感,其出苗率、保苗率及苗期各项生长指标与对照相近可以安全种植甜菜。阔草清残留土壤后茬种植甜菜,出苗率降低9.4%,保苗率降低11.5%,其与对照相比株高降低0.9cm,根长降低1.2cm,株鲜重降低0.41g;可以种植甜菜。豆磺隆残留土壤后茬种植甜菜苗期药害较严重,苗期死苗现象严重,不能安全种植。     

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.     

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.     

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.     

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.     

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.     

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