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1.
城市大气重金属(Pb,Cd,Cu,Zn)污染及其在植物中的富积   总被引:17,自引:0,他引:17  
通过对烟台市区不同大气污染区域绿化植物叶片中重金属Pb ,Cd ,Cu ,Zn 富积量和大气与土壤中相应重金属的含量研究分析发现,植物叶片中重金属Pb ,Cu 和Zn 的富积量与大气中Pb ,Cu 和Zn 的相对含量呈显著的正相关,而植物叶片中Cd 的富积量与大气中重金属的相对含量相关不显著.所研究的4 种重金属在植物叶片中的富积量与其生长土壤中的重金属的含量无相关性.研究证明,在所调查的5 种市区绿化植物中以园柏( Sabina chinesis) 叶片对大气中Pb 和Cd 的富积能力最强,对Pb 的富积依次为侧柏( Platycladusorientalis) 、冬青卫茅( Euonymusjaponicus) 、悬玲木( Platanus acerifolia) 和樱桃李( Prunuscerasifera) ,而对Cd 则依次为侧柏、冬青卫茅、樱桃李、悬玲木.悬玲木叶片对Cu 和Zn 的富积量最高,对Cu 的富积能力依次为悬玲木> 园柏> 侧柏> 冬青卫茅> 樱桃李,对Zn 则为悬玲木> 园柏> 侧柏> 樱桃李> 冬青卫茅.市区大气重金属污染物主要为Pb ,Cu 和Zn .市区大气重金属污染的总态势依次为发电厂> 汽车站> 市府区> 奇山小区>  相似文献   

2.
钙,锌对玉米幼苗吸收镉,铅的影响   总被引:9,自引:0,他引:9  
本试验以玉米幼苗为材料,研究了在溶液培养条件下,Ca.Zn对玉米幼苗吸收Cd、Pb的影响及其特点。当在0~50mg/L及0~30mg/L范围内逐步增大Cd和Pb的浓度时,玉米幼苗对Cd、Pb的啄收随之增大。向上述体系中加入Ca或Zn后,玉米幼苗对Cd、Pb的吸收减弱,其中Ca的作用更为明显。从结果还可以看出,Ca和Zn对玉米幼苗Cd、Pb的吸收和运输的抑制作用,并不随着Cd、Pb浓度在一定范围内的增大而减弱。  相似文献   

3.
HarmonicACsusceptibilitiesasafunctionoftemperature(T),ACfieldfrequency(f),amplitude(Bac)inDCfiedld(Bdc)havebeenstudiednumerically.Thenumericalcalculationisbasedonnonlinearvortexdiffusion.Theresultshowsthatthereexistssecondharmonicalthoughveryweakwh…  相似文献   

4.
菌种储藏对一株头孢霉菌产DHA的影响   总被引:2,自引:0,他引:2  
将一株头孢霉菌(Cephalosporium.sp.)斜面菌种分别在20.4和-20℃d,将菌种分别经活化和不活化后转接入液本PDA培养基中发酵发现DHA(Docosahex-aenoic acid.22:6)产量和储藏时间、储藏温度、发酵前菌种是否转接活化有关系,在-20℃储藏的菌种,DHA最高产量可达27.86mg/L,此时每克干菌丝中DHA含量为4.26mg,生物量为6.54g/L;在4℃储  相似文献   

5.
本文通过原子吸收分光光度法,对主治血管性头痛的一种方剂及其6种中药成分─—蒺藜TribulusterrestrisL.北细辛AsarumheteropoidesFr.Schmidtvar.mandshuricum(Maxim)Kitagawa,地龙PheretimaasitaticaMichaelsen,川芎LiguaticumwallichiiFranch,牛膝AchyranthesbidentataBlume和当归Angelicasinensis(Oliv)Diels进行了镉Cd、钴Co、锶Sr、铬Cr、铜Cu、锰Mn、镍Mi、铅Pb、锌Zn和铁Fe10种元素含量的测定,并就10种微量元素对方剂药性的影响进行了分析和探讨  相似文献   

6.
施用城市污泥的土壤重金属生物有效性   总被引:4,自引:0,他引:4  
对盆栽试验的植物和土壤样品的分析测定表明,施用城市污泥对植物生长发育有明显的促进作用,生长量随污泥施用量增加而增加;施用污泥的土壤重金属(Cd、Cr、Ni、Zn)有效态含量和植物重金属含量也随污泥施用量增加而提高.施用污泥的土壤加施石灰(CaO)将pH调节到65和75后,土壤有效态Ni、Zn的含量明显减少,但有效态Cr含量升高;植物对Ni、Zn、Cd的吸收大幅度降低,表现出加施石灰提高土壤pH值对随污泥进入土壤的Ni、Zn、Cd的生物有效性有明显的抑制作用  相似文献   

7.
IntroductionCase Based ReasoningCase based Reasoning (CBR)isa processof“rememberand adapt”or“memberand compare”[1] .Casesare usedtohelpin understandingand assessingsituationsandtohelpinsolving problems. CBRistoretrievethe“mostsimilar”caseorsetofcases,itscyc…  相似文献   

8.
发表了广西苏铁5个新种.①长球果苏铁CycaslongiconiferaChang,Y.C.ZhongetY.Y.Huang以雄球果狭长,羽叶疏远为特征;②尖尾苏铁CycasacuminatisimaChang,Y.C.ZhongetZ.F.Lu以羽片先端尖长,大孢子叶短小为特征;③掌裂苏铁CycaspalmatifidaChang,Y.Y.HuangetY.C.Zhong以大孢子叶掌状深裂、裂片圆锥状,刺特长为特征;④七籽苏铁CycasseptemspermaChang,Y.Y.HuangetH.X.Zheng以羽片及刺均极短,胚珠7个为特征;⑤短叶苏铁CycasbrevipinnataChang,Y.Y.HuangetY.C.Zhong以羽叶和羽片均短小,刺亦极短为特征  相似文献   

9.
施有城市污泥的土壤重金属生物有效性   总被引:2,自引:1,他引:1  
对盆栽试验的植物和土壤样品的分析测定表明,施用城市污泥对植物生长发育有明显的促进作用,生长是随访泥施用量增加而增国;施用污泥的土壤重金属有效态含量植物重金属含量也随污泥施用量增另而提高,施用污泥的土壤加施石灰(CaO)将PH调节到6.5和7.5后,土壤有效态Ni、Zn的含量明显减少,但有效态Cr含量升高;植物对Ni、Zn、Cd的吸收大幅度降低,表现出加施石灰提高土壤P至随污泥进入土壤的Ni、Zn、  相似文献   

10.
报道了《河南植物志》中未记录的堇菜属植物4种1变种:细齿堇菜(Viola microdonta Chang)、长萼堇菜(V.inconspicua BL.)、白花堇菜(V.lactifora Nakai)、犁头叶堇菜(V。magnifica C.J Wang et X.D.Wang)各短毛七星莲(V.diffusa ging var.brevibarbata C.J.Wang),订正了一些分类群的学  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.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
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   

15.
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   

16.
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.  相似文献   

17.
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   

18.
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   

19.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

20.
The non-orthogonal localized molecular orbital(NOLMO)is the most localized representation of electronic degrees of freedom.As such,NOLMOs are thus potentially the most efficient for linear scaling calculations of electronic structures for large systems.However,direct ab initio calculations with NOLMO have not been fully implemented and widely used,partly because of the slow convergence issue in the optimization of NOLMO.We devel-  相似文献   

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