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1.
本试验用鼠伤寒沙门氏菌组氨酸缺陷型—哺乳动物肝微粒体酶测试系统(Ames Test),对扬州五泉矿泉水的非极性树脂XAD-2吸附物进行检测。结果表明,在矿泉水剂量50ml/皿—2500ml/皿时,对TA98、TA100、TA97a和TA102四个突变株;在加或不加S9活化系统情况下,均为致突变阴性。因此就致癌作用而言,扬州平山五采矿泉水用于食品工业上的原材料是安全的。  相似文献   

2.
从海水养殖场的生物膜,逛荡河口淤泥,烟大三元湖底泥中分离筛选出8株异养硝化细菌和8株好氧反硝化细菌.分别对16株细菌的异养硝化性能和好氧反硝化性能进行测定,结果表明,异养硝化细菌Y-3、Y-6、Y-7的72 h NH4+-N去除率分别为95.65%、96.60%、96.09%,好氧反硝化细菌F-3、F-5、F-7的72 h NO3--N去除率分别为76.20%、75.87%、76.00%.选择性能较高的3株异养硝化细菌和3株好氧反硝化细菌进行传统生理生化鉴定,并对各菌株的16S r DNA序列进行测定及分析,结果表明,Y-3和F-3为除烃海杆菌(Marinobacter hydrocarbonoclasticus),Y-6为溶藻孤菌(Vibrio alginolyticus),Y-7和F-7为恶臭假单胞菌(Pseudomonas putida),F-5为海洋单胞菌属(Oceanimonas sp.).  相似文献   

3.
微生物在生物栅植物根系和填料生物膜上的数量分布差异   总被引:2,自引:0,他引:2  
实验中以组合填料、美人蕉和水生动物为要素构建生物栅,以上海市苏州河支流绥宁河河水为实验用水,测定分析了功能微生物和微型动物在植物根系和填料生物膜上的数量分布差异,以研究生物栅强化处理污染景观水体的作用机理.结果表明,生物栅中有机物的矿化分解、氨化作用、硝化作用和反硝化作用可以在填料和植物根系上同时进行,有机物的矿化分解、氨化作用和硝化作用场所以植物根系为主,而反硝化作用主要在填料上进行.生物栅内植物根系和填料所具有的不同生境为异养细菌、硝化细菌和反硝化细菌的生长提供了各自适宜的场所,单位质量根系异养细菌数量比单位质量填料上异养细菌数量高出一个数量级,植物根系的泌氧作用提高了根系局部的溶解氧水平,硝化细菌对生境的选择结果使得单位质量根系或填料的硝化细菌数量表现为:实验组根系实验组填料对照组填料,而反硝化细菌对生境选择表现为:对照组填料实验组填料实验组根系.同时单位质量根系微型动物的数量和种类都要大于填料,根系和填料上微型动物的多样性指数值分别为2.16和2.08.  相似文献   

4.
低温下曝气生物滤池内生物量变化   总被引:3,自引:0,他引:3  
低温下(甚至低于1℃)异养细菌生物量仍能大量增加,但生物量的增加受生物可利用有机基质浓度的限制。虽然氨氮浓度不是曝气生物滤池内硝化细菌生物量增加的限制因子,但硝化细菌生物量的增加仍受低温的严重限制。低温对硝化细菌生物量增加比异养细菌生物量增加的限制作用更显著。  相似文献   

5.
通过田间试验、采用平板表面涂抹法和稀释法对稻-鱼(泥鳅)复合体系的水田土壤微生物生理群进行了定位定量研究。结果表明,底栖鱼类对水田土壤特殊微生物生理群具有重要影响,促进了土壤固氮菌、纤维素分解菌、硝化细菌、硫化细菌和氨化细菌的生长,抑制了反硝化细菌和反硫化细菌的繁殖,有助于增加土壤N、P、S等养分元素的供给能力、土壤肥力和生化活性,提高水田的养分利用效率。  相似文献   

6.
稻-鱼复合生态系统对水田土壤微生物生理群的影响   总被引:1,自引:0,他引:1  
通过田间试验、采用平板表面涂抹法和稀释法对稻一鱼(泥鳅)复合体系的水田土壤微生物生理群进行了定位定量研究。结果表明,底栖鱼类对水田土壤特殊微生物生理群具有重要影响,促进了土壤固氮菌、纤维素分解菌、硝化细菌、硫化细菌和氨化细菌的生长,抑制了反硝化细菌和反硫化细菌的繁殖,有助于增加土壤N、P、S等养分元素的供给能力、土壤肥力和生化活性,提高水田的养分利用效率。  相似文献   

7.
黑河水库水源的微生物区系考察   总被引:2,自引:0,他引:2  
以黑河水系的陈河(地名)和黑河大桥上侧坝内作断面采水样。分离得36株异养细菌和13株霉菌,并对以上菌株按常规方法进行了鉴定.还发现有与水质有关的紫色细菌、绿硫细菌、反硝化细菌、磷细菌、铁细菌、氨细菌和大肠杆菌。没有检测到氧化硫硫杆菌和氧化亚铁硫杆菌。反硝化细菌、氨细菌和大肠杆菌群的最大可能数(MPN)分别是273个/g,300个/g,75个/l。水体内的细菌总数是3.79×10~2个/ml.本文还对黑河水系的微生物区系与水质的关系进行了评估和未来预测.  相似文献   

8.
反硝化细菌Klebsiella sp.DB-1的分离鉴定与活性研究   总被引:1,自引:0,他引:1  
从巢湖芦苇湿地分离筛选出一株异养反硝化细菌,对其进行鉴定,并进行了反硝化活性研究,目的是为了研究地下水硝酸盐污染的生物修复机理.用酒石酸钾钠培养基从湿地土壤中富集并分离出反硝化细菌,对该菌株进行了16SrDNA鉴定及系统发育分析,并研究了单一碳源、碳氮比对其反硝化活性的影响,以及其对水中硝酸盐氮含量的适应性.分离出了一株异养反硝化细菌,具有较高的反硝化活性,命名为Klebsiellasp.DB-1,革兰氏阴性球形,兼性厌氧,16SrDNA序列分析表明,该菌株与Klebsiella sp.的相似性为99.6%以上;该菌株利用乙酸钠为碳源,采用碳氮比(C/N)为3,水中初始硝酸盐氮含量在100mg/L以内,120h几乎完全去除水中硝酸盐氮.菌株Klebsiellasp.DB-1为异养反硝化细菌,具有较广的碳源谱,能够有效地去除水中硝酸盐氮.  相似文献   

9.
SBR是序批式活性污泥法的简称, SBR系统行运行模式不同,脱氮除磷效果会发生变化。SBR系统氨氮硝化过程在好氧阶段进行,脱氮过程主要在缺氧阶段进行。除少数细菌能进行自养反硝化,大部分反硝化细菌进行反硝化都是进行异养反硝化。经研究发现SBR运行过程中TN浓度和COD浓度具有相关性,COD和TN浓度之间存在三阶函数关系,本实验反硝化速率为1.2mg/L。  相似文献   

10.
在大田条件下,以超级稻"II优航2号"为试验材料,水稻拔节期至始穗期设置55%和85%两个遮光强度,以全生育期正常自然光为对照,研究花前光照亏缺对水稻根际土壤微生物生态效应的影响,为光贫乏区土壤良性生态循环和超级稻栽培技术研究提供依据.结果表明,水稻拔节期至始穗期弱光胁迫条件下,在水稻生长的孕穗期、始穗期、灌浆期、收获期,显著降低了水稻根际土壤微生物细菌、放线菌、氨化细菌、硝酸细菌、好气性自生固氯菌数量,增加了真菌、反硝化细菌、反硫化细菌数量,从而导致土壤微生物生物量C和N含量减少,抑制了根际土壤中脲酶、磷酸酶的活性.而且,随着弱光胁迫强度和时间的增加,水稻根际土壤微生物细菌、放线菌、氨化细菌、硝酸细菌、好气性自生固氮菌的生长和土壤微生物生物量C、N的含量和土壤中脲酶、磷酸酶的活性受抑制程度加重,真菌、反硝化细菌、反硫化细菌生长的促进作用增强.说明花前光照亏缺降低了稻田根际微生物生物量和土壤酶活性,改变了根际微生物群落结构,破坏了稻株生长的根际微生态环境.  相似文献   

11.
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.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
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.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
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.  相似文献   

14.
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.  相似文献   

15.
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。  相似文献   

16.
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.  相似文献   

17.
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-  相似文献   

18.
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-  相似文献   

19.
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  相似文献   

20.
<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  相似文献   

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