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141.
在浓度场基础上,利用总磷、总氮和COD三项指标的综合指数法,结合管理部门提供的资料,划分了滇不不环境保护功能区,给出了划分指标值及功能区划分图。  相似文献   
142.
Many methods that study the diversity within hierarchically structured populations have been developed in genetics. Among them, the analysis of molecular variance (AMOVA) (Excoffier et al., 1992) has the advantage of including evolutionary distances between individuals. AMOVA is a special case of a far more general statistical scheme produced by Rao (1982a; 1986) and called the apportionment of quadratic entropy (APQE). It links diversity and dissimilarity and allows the decomposition of diversity according to a given hierarchy. We apply this framework to ecological data showing that APQE may be very useful for studying diversity at various spatial scales. Moreover, the quadratic entropy has a critical advantage over usual diversity indices because it takes into account differences between species. Finally, the differences that can be incorporated in APQE may be either taxonomic or functional (biological traits), which may be of critical interest for ecologists.  相似文献   
143.
Abstract:  We compared the species diversity of copronecrophagous beetles (Scarabaeinae) , bats, and frogs in tropical montane cloud forest (original vegetation) and shaded coffee plantations (an agroecosystem common to the region) for a landscape in central Veracruz, Mexico. We sampled in three tropical montane cloud forest fragments and in three coffee plantations with traditional polyculture shade between 1998 and 2001. The three indicator groups responded differently to the transformation of tropical montane cloud forest into shaded coffee plantations. The species richness of frogs was one-fifth less in coffee plantations than in forest fragments, and only one-third of the frog species occurred in both forest fragments and coffee plantations. The number of beetle species and their abundance was significantly greater in coffee plantations than in the forest fragments, whereas species richness and species composition of bats were virtually the same in both habitats. The majority of the abundant species remained as such in both communities, but species that were less abundant were not scarce in both habitats. We attributed differences in the species assemblages to the differing degrees of penetrability of the borders of the two habitat types (especially for the coffee plantations) and to the differences in life-history traits among species. Shaded coffee plantations form a matrix that envelops the remaining fragments of cloud forest. Together they connect the forest fragments with the other habitats of the landscape and represent a highly functional resource for the preservation of biodiversity that serves as a complement to but not a substitute for cloud forest in this notably modified landscape.  相似文献   
144.
Mixed-species associations have been described in many vertebrate species, but few behavioral studies have investigated associations between species from different mammalian orders. Cape ground squirrels (Xerus inauris) are highly social rodents that inhabit burrows with two species of mongoose, but the benefits of these interspecific associations to ground squirrels remain unresolved. We compared the behavior of squirrels while solitary, with conspecifics, and in the presence of suricates (Suricata suricatta) and yellow mongooses (Cynictis pencillatus). Squirrels spent less time alert and more time feeding when suricates were present, but increased vigilance in the presence of yellow mongooses. In a series of mobbing trials with a puff adder (Bitis arietans), a common predator of all three species, Cape ground squirrels were the most active in mobbing the snake. Our results suggest that Cape ground squirrels benefit from associating with suricates, but not necessarily with yellow mongooses. Both mongoose species benefit from the burrowing activities of the squirrels for thermoregulation and escape from predators, and a suite of other organisms may similarly benefit from the habitat modifications by Cape ground squirrels, suggesting they could be considered ecosystem engineers of the arid and semi-arid regions of southern Africa. Thus, the association between Cape ground squirrels and suricates appears mutually beneficial, whereas yellow mongooses may merely be commensals of the squirrels.  相似文献   
145.
以自制PAN-基聚丙烯腈活性碳纤维ACF-PAN(ACF-活性碳纤维、PAN-聚丙烯腈)和改性处理的ACF-PAN吸附SO_2,借助IR、x-光电子能谱分析等研究ACF-PAN改性处理及吸附SO_2前后表面结构变化。结果表明:各型ACF-PAN吸附SO_2的活性中心为表面结构中的含氮官能团以及引入的金属氧化物,其吸附机理是活性氮催化或电子传递。  相似文献   
146.
微波加热对活性炭表面基团及其对SO2吸附性能的影响   总被引:8,自引:0,他引:8  
采用了微波加热技术,通过在不同微波功率和辐射时间条件下对不同粒径活性炭进行改性,研究了改性前后活性炭的表面化学基团、元素组成的变化,以及对SO2吸附性能的影响.结果表明,经过微波改性后活性炭的SO2吸附性能大为提高,微波功率是影响改性活性炭脱硫性能的主要因素.活性炭经微波热处理后,酸性基团发生分解,表面含氧量减少,碱性特征增强,是吸附性能增加的主要原因之一.  相似文献   
147.
This paper presents a digitized version of a thermodynamic sorption database, implemented as a relational database with MS Access. It is mineral-specific and can therefore be used for additive models of complex solid phases such as rocks or soils. An integrated user interface helps users to access selected mineral and sorption data, to extract internally consistent data sets for sorption modeling, and to export them in formats suitable for other modeling software. Data records comprise mineral properties, specific surface area values, surface binding sites' characteristics, sorption ligand information, and surface complexation reactions. An extensive bibliography is included, providing links not only to the above listed data, but also to background information concerning surface complexation model theories, evidence for surface species, and sorption experimental techniques.  相似文献   
148.
Shen YH 《Chemosphere》2002,48(10):1075-1079
This study investigates the feasibility of using ethylene oxide chain adsorption to determine the surface area of an expandable clay, montmorillonite. Experimental results indicate that high molecular weight poly(ethylene oxide) or nonionic surfactant with long ethylene oxide chain should be used to provide reasonable estimations for monolayer capacity. The method has advantages over Brunauer, Emmett, and Teller method in that it is readily applicable to a wide range of areas, particularly to 2:1 layer silicates under aqueous conditions.  相似文献   
149.
利用水泥处理垃圾渗滤液生物处理出水的研究   总被引:4,自引:0,他引:4  
利用水泥的表面吸附和水化反应性质处理垃圾渗滤液生物处理出水可以取得很好的效果,COD的去除率可达69.5%.处理效果与水灰比、反应时间密切相关,低水灰比和较长反应时间对COD的去除更为有利.对处理前后水样的COD和TOC分析表明,水泥对非TOC贡献的COD有很强的去除效果.  相似文献   
150.
Sorption and desorption of Yb(III) were studied on hematite and on alumina using a surface complexation model. The experimental methodology was conceived to allow an analysis of the data using a constant capacitance model. The FITEQL code was used for the calculations.The experimental results tend to show reversibility of sorption when the surface loading is small, and irreversibility when the surface loading is high. Surface complexation modeling gives a good interpretation of these two phenomena, taking into account hydroxylation of the surface complexes. In these two cases, it is possible to describe sorption and desorption curves with the same surface stoichiometries and the same surface complexation constants. The existence of these surface complexes depends on the pH of the solution, surface loading, and reaction direction.  相似文献   
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