Cu2+对日本沼虾幼虾的急性致毒研究

Cu2+浓度为0.000 5 mg/L、0.005 mg/L、0.05 mg/L时,日本沼虾幼体在54 h内均能够正常存活;Cu2+浓度为0.1 mg/L时,只有部分沼虾幼体中毒致死.而当Cu2+浓度超过0.25 mg/L时,日本沼虾幼虾在48 h内致死,并出现鳃变兰、肝脏变黑的现象.随着Cu2+浓度增大,日本沼虾幼虾存活的时间变短,肝脏和鳃的中毒颜色变深.日本沼虾幼虾48 h的半致死浓度为0.268 mg/L,其安全浓度为0.026 8 mg/L.     

莠去津对雌性日本沼虾的毒性作用

研究莠去津对雌性日本沼虾的生殖毒性,为其养殖水体水质管理提供依据.以概率作图法计算日本沼虾24,48,72和96 h的半致死质量浓度,并观察各暴露组卵巢组织结构的变化.通过胁迫实验,研究莠去津对暴露4 d和8 d的日本沼虾卵巢乳酸脱氢酶(LDH)比活力的影响.结果表明:22℃时,莠去津对雌性日本沼虾24,48,72和96 h的半致死质量浓度分别为134.23,90.24,52.57和46.36 mg/L,安全质量浓度为4.64 mg/L;卵巢急性毒性实验切片显示,随莠去津质量浓度的增大,卵母细胞间隙增大,胞体膨大、变形.胁迫实验表明,低质量浓度莠去津在短时间内对卵巢LDH活力有诱导作用,当质量浓度高于0.46 mg/L时,LDH活力明显受到抑制.本研究提示,莠去津对雌性日本沼虾具有生殖毒性作用.     

铜、锌离子对汤匙华哲水蚤的急性毒性和联合毒性效应

通过单因子静态急性毒性试验法和等毒性溶液法分别研究了重金属离子铜、锌对汤匙华哲水蚤的急性毒性和联合毒性效应.急性毒性试验结果表明:铜、锌离子对汤匙华哲水蚤24 h半致死浓度(LC50)分别为0.481、3.221 mg/L;48h LC50分别为0.383、1.573 mg/L;72h LC50分别为0.315、0.471 mg/L.铜、锌联合毒性致毒特征表明:高强度的锌离子对铜离子有拮抗作用,高强度的铜离子对锌离子有协同作用.     

铜、锌离子对汤匙华哲水蚤的急性毒性和联合毒性效应

通过单因子静态急性毒性试验法和等毒性溶液法分别研究了重金属离子铜、锌对汤匙华哲水蚤的急性毒性和联合毒性效应.急性毒性试验结果表明:铜、锌离子对汤匙华哲水蚤24 h半致死浓度(LC50)分别为0.481、3.221 mg/L;48h LC50分别为0.383、1.573 mg/L;72h LC50分别为0.315、0.471 mg/L.铜、锌联合毒性致毒特征表明:高强度的锌离子对铜离子有拮抗作用,高强度的铜离子对锌离子有协同作用.     

铅和铬对鱼类联毒性的研究

采用斑马鱼研究铅和铬共存的联合毒性.二价铅对斑马鱼的24,48,96h的半致死浓度分别为171,155,146mg/L,六价铬对斑马鱼的24,48,96h的半致死浓度分别为112,67,50mg/L,在浓度1∶1的情况下,铅和铬共存对斑马鱼24,48,96h的半致死浓度分别为35,29,26mg/L,根据Marking的指数法求得24,48,96h的相加指数AI分别为0.89,0.61,0.43,皆大于零,表现为协同作用.     

氨氮对锯缘青蟹的急性毒性和温度对其耗氧率、窒息点的影响

通过急性毒性实验确定了体重（43.5±2.13）g的锯缘青蟹24 h、48 h氨氮半致死浓度和安全浓度分别为179.99 mg/L、129.99 mg/L和20.34 mg/L。体重（20.8±1.55）g的锯缘青蟹24 h、48 h氨氮半致死浓度和安全浓度分别为175.55 mg/L、131.35 mg/L和20.06 mg/L。锯缘青蟹耗氧率随温度的而增大,在30℃左右达到最大值。体重为（31.6±2.23）g的青蟹,窒息点在15℃时最低为0.17 mg/L,25℃时最高为0.34 mg/L。     

敌百虫对九孔鲍稚鲍和真猛水蚤的毒性作用

不同温度下 ,敌百虫对稚鲍的毒性作用不同 ,在水温 2 1～ 2 2℃下 ,2 4h、 4 8h、72h、96h的半致死浓度分别为 182mg/L、 4 6mg/L、10 6mg/L ,6 6mg/L ,安全浓度为 4 6mg/L ;水温 2 6～ 2 7℃ ,在相同时间内的半致死浓度分别降至 12 9mg/L、 11 1mg/L、 8 2 5mg/L和5 1mg/L ,安全浓度为 1 11mg/L ;敌百虫对真猛水蚤的毒性也是随着水温升高而增强 ,水温2 1～ 2 2℃ ,2 4h、 4 8h、 72h的半致死浓度分别为 2 7× 10 - 1mg/L、 3 5× 10 - 2 mg/L、 2 0×10 - 2 mg/L ,安全浓度为 3 5× 10 - 2 mg/L ;当水温升至 2 6～ 2 7℃时 ,半致死浓度分别为 8 3× 10 - 2mg/L、8 3× 10 - 3mg/L、3 6× 10 - 3mg/L ,安全浓度为 8 3× 10 - 4mg/L 敌百虫对稚鲍的亚急性作用结果是 :在 0 4～ 2 0mg/L下生活 2 0d ,稚鲍的壳长、体重、摄食及存活率随其浓度的增大而降低 本文对九孔鲍工厂化育苗中如何正确使用敌百虫防治底栖桡足类提供了科学依据     

3种酚类化学物质对林蛙蝌蚪的急性毒性效应

目的探讨中国林蛙(Rana chensinensis)蝌蚪暴露在不同浓度的2,4-D丁酯、2,4-D和2,4—二氯苯酚中急性毒性效应,为农业环境保护和治理以及两栖动物资源保护提供基础资料。方法采用单因子急性毒性实验法统计半数致死浓度(LC50)和安全浓度(SC)。结果常温下,2,4-D丁酯对中国林蛙蝌蚪24,48,72,96 h的LC50分别为5.28,4.53,4.79,4.90 mg/L,SC为1.27 mg/L。2,4-D对林蛙蝌蚪24,48,72,96 h的LC50分别为276.89,268.62,273.50,267.55 mg/L,SC为79.37mg/L。2,4—二氯苯酚对林蛙蝌蚪24,48,72,96 h的LC50分别为17.06,15.82,14.11,11.48 mg/L,SC为4.57 mg/L。结论使用除草剂2,4-D丁酯对稻田中蝌蚪具有毒性作用,而植物激素2,4-D对蝌蚪毒性微弱。     

3种常见有机磷农药对麦瑞加拉鲮鱼幼鱼的急性毒性

开展了三唑磷、乙酰甲胺磷、增效水胺硫磷对麦瑞加拉鲮鱼幼鱼的急性毒性试验,结果表明:三唑磷对麦瑞加拉鲮鱼幼鱼24h,48h,72h,96h的半致死浓度分别为0.080mg/L,0.065mg/L,0.060mg/L,0.050mg/L;乙酰甲胺磷对麦瑞加拉鲮鱼幼鱼24h,48h,72h,96h的半致死浓度分别为113.783mg/L,114.451mg/L,113.366mg/L,113.214mg/L;增效水胺硫磷对麦瑞加拉鲮鱼幼鱼24h,48h,72h,96h的半致死浓度分别为0.736mg/L,0.549mg/L,0.469mg/L,0.280mg/L。麦瑞加拉鲮鱼幼鱼对三唑磷、乙酰甲胺磷、增效水胺硫磷96h安全质量浓度分别为0.005mg/L、0.028mg/L和11.321mg/L,3种有机磷农药的毒性大小依次为三唑磷、乙酰甲胺磷、增效水胺硫磷。最后,还就三唑磷、乙酰甲胺磷、增效水胺硫磷对麦瑞加拉鲮鱼幼鱼的急性致毒效应特征以及麦瑞加拉鲮鱼幼鱼对三唑磷、乙酰甲胺磷、增效水胺硫磷的安全浓度进行了评价。     

Cu2+和Cr6+对中国林蛙蝌蚪的急性毒性

采用中国林蛙(Rana chensinensis)出膜后一周的蝌蚪为实验对象,研究了Cu2 和Cr6 对中国林蛙蝌蚪的急性毒性.实验结果表明,在水温22℃～24℃条件下,Cu2 对中国林蛙蝌蚪24 h,48 h,72 h的半致死浓度(LC50)分别为0.131,0.105,0.038 mg/ L;Cu2 对蝌蚪的安全浓度为0.02 mg/ L.Cr6 对中国林蛙蝌蚪24 h,48 h,72 h的半致死浓度(LC50)分别为4.16,4.48,4.57 mg/ L;Cr6 对蝌蚪的安全浓度为1.55 mg/ L.同时讨论了中国林蛙与其他两栖类蝌蚪相比对Cu2 和Cr6 耐受性的差异.     

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.     

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