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971.
The fixation capacity of mixtures of acrolein, glutaraldehyde, and tannic acid, was investigated to arrive at a fixative for small and delicate marine plankton that is more universal than the current selective fixatives. A mixture containing 4% acrolein, 4% glutaraldehyde and 2% tannic acid added 1:1 to the cell suspension proved to be satisfactory. Mounting of the material in euparal before staining is recommended. Of several dyes tried, fuchsin acid proved suitable for observation of flagella and cell shapes. Delafield haematoxylin staining gave the best results for internal details. Fuchsin base staining, requiring a complex procedure, is recommended when it is necessary to search for flagellar hairs as found in Ochromonas spp. Schedules for the fixation, mounting and staining are given.  相似文献   
972.
973.
974.
OLAND生物脱氮系统运行及其硝化菌群的分子生物学检测   总被引:5,自引:0,他引:5  
采用两阶段限氧自养硝化 -反硝化生物脱氮系统 (oxygen limitedautotrophicnitrificationanddenitrificationsystem ,以下简称OLAND)处理高氨氮、低COD的废水 .应用内浸式多聚醚砜中空膜 ,实现了污泥的完全截留 ,阻止了生物量的大量洗脱 ,并通过控制溶氧在 0 .1~ 0 .3mgL-1之间 ,实现了硝化阶段出水中氨氮与亚硝态氮浓度的比例达到最适值〔1 (1.2± 0 .2 )〕 ,从而为第二阶段的厌氧氨氧化提供理想的进水 ,进而获得较高的脱氮率 .同时应用荧光原位杂交技术对硝化阶段不同时期硝化菌群的变化进行分子生物学检测 ,揭示了随溶氧浓度的降低 ,氨氧化菌的数量基本保持恒定、亚硝酸氧化菌的数量略有减少的变化规律 ,并且发现 ,在两阶段限氧自养硝化 -反硝化生物脱氮系统中氨氮的氧化主要是由Nitrosomonassp .完成 ,亚硝酸的氧化主要由Nitrobactersp .完成 .图 4表 2参 2 2  相似文献   
975.
We present a simple model of within-group leveling coalitions among male primates. The model assumes that the value of the coalition is the sum of the payoffs of its members, that the individuals payoff is monotonically decreasing with its rank and that coalitions do not cause rank changes. It predicts that mainly mid- to low rankers engage in leveling coalitions, and that most coalition partners are of adjacent ranks. These predictions agree reasonably well with observations in nature. The model also makes the novel predictions that leveling coalitions are found where male mating competition has only a moderate contest component, and that male dominance ranks will become poorly differentiated where leveling coalitions are frequent. Both these predictions are consistent with observations on groups of macaques and baboons. The model also may account for leveling coalitions among egalitarian human foragers, without making additional assumptions about special human capabilities.
Carel P. van SchaikEmail:
  相似文献   
976.
A short outline is given of the floristic composition, structure and distribution of coastal dune vegetation found at Malindi Bay, Kenya. The area was studied by air photo interpretation and field sampling to determine the relationship of plants to aeolian features. TWINSPAN classification was used to distinguish geomorphological units on the basis of their species composition. In this paper, an inventory and first quantitative analysis of vegetation distribution is presented. We identified 174 plant species from 62 families in the sand dunes and several plant communities are distinguished based on the species content and the connection with morphological units.Papilionaceae with 18 species andPoaceae with 17 species were the most represented families. A distinct zonal distribution of the plant communities was found. The most important plant species are the pioneer vegetation consisting ofHalopyrum mucronatum, Ipomoea pescaprae andScaevola plumieri. The woody shrub species which have colonized the established primary dunes and hummock dunes areCordia somaliensis, Pluchea discoridis, Tephrosia purpurea (dunensis). Succulent herbs were identified in the dune slacks and salt marsh that are moist and damp environments.  相似文献   
977.
A comprehensive list of 1068 typical littoral plant species and subspecies has been composed. They are considered endemic in a wide sense and are subdivided into widespread, transregional, regional and local endemics, the latter three categories being considered as endemics s.s. For each taxon the distribution, habitat preference, endemic status and conservation status are given. The list, which is available upon request, is summarized in a number of figures and tables, from which it appears that 61% of all species are endemics s.s., that ca. 30% of all species are dune and beach species and another nearly 30% are maritime rock species. Species of wet habitats are concentrated in northern and northwestern Europe, dune species in western and southwestern Europe, western Mediterranean and Black Sea. The conservation status of most species is indicated; 37% is considered threatened. It is concluded that the Bern Convention and the European Habitat Directive offer an entirely insufficient framework for effective conservation action. It is suggested to take the present list as a starting point for a geographical/taxonomical/ecological data base of European coastal endemics.  相似文献   
978.
This article provides information about a Series dealing with Integrated environmental assessment’ (IEA). We describe the development and the structure of a ‘Graduiertenkolleg’ (interdisciplinary course of study) which has been established in two phases at the University of Kiel from 1996–2002. The central terms ‘integration’, ‘environment’, and ‘assessment’ are discussed. Here, we take a special look at the chances and problems of interdisciplinary cooperation and communication (ecosystem research, jurisprudence, economics, social sciences) with regard to the general subject of IEA as a subject of research and schooling. Finally, we give a short review about the articles in the series.  相似文献   
979.
Perfluorooctanesulfonyl fluoride (POSF, C8F17SO2F) related-materials have been used as surfactants, paper and packaging treatments, and surface (e.g., carpet, textile, upholstery) protectants. A metabolite, perfluorooctanesulfonate (PFOS, C8F17SO3), has been identified in the serum and liver of non-occupationally exposed humans and wildlife. Because of its persistence, an important question was whether elderly humans might have higher PFOS concentrations. From a prospective study designed to examine cognitive function in the Seattle (WA) metropolitan area, blood samples were collected from 238 dementia-free subjects (ages 65–96). High-pressure liquid chromatography-electrospray tandem mass spectrometry determined seven fluorochemicals: PFOS; N-ethyl perfluorooctanesulfonamidoacetate; N-methyl perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamidoacetate; perfluorooctanesulfonamide; perfluorooctanoate; and perfluorohexanesulfonate. Serum PFOS concentrations ranged from less than the lower limit of quantitation (3.4 ppb) to 175.0 ppb (geometric mean 31.0 ppb; 95% CI 28.8–33.4). An estimate of the 95% tolerance limit was 84.1 ppb (upper 95% confidence limit 104.0 ppb). Serum PFOS concentrations were slightly lower among the most elderly. There were no significant differences by sex or years residence in Seattle. The distributions of the other fluorochemicals were approximately an order of magnitude lower. Similar to other reported findings of younger adults, the geometric mean serum PFOS concentration in non-occupational adult populations likely approximates 30–40 ppb with 95% of the population’s serum PFOS concentrations below 100 ppb.  相似文献   
980.
The substituent chlorine is generally considered to be an agent which reduces the reactivity of organic molecules with regard to the indirect photodegradation by OH radicals. A systematic study of selected, representative classes of compounds, however, reveals that the deactivating influence of chlorine on the OH radical reactivity is actually rather moderate. In individual cases, for instance, chlorine substitution can even lead to an increase in this reactivity. This study is based on both experimental data and on the molecular orbital calculations of OH radical reactivity.  相似文献   
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