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101.
Alkaline phosphatase activity (APA) was determined in bulk particulate material and in a single-cell (ELF) assay at station L4 in the western English Channel during the summer of 2007. Throughout this period, the UK experienced its heaviest summertime rainfall since records began in 1914; with the result that riverine run-off into coastal waters was also elevated relative to long-term averages. Between May and August 2007, three distinct periods of elevated river run-off were observed which resulted in salinity minima at L4 on days 141, 190 and 232. An extended period of high river run-off between days 170 and 210 was responsible for decreases in near-surface salinity at L4 from 35.2068 to a minimum on day 190 of 34.7422. This contributed to the development of haline stratification which supported the development of an intense bloom of the centric diatom Chaetoceros debelis, with maximum observed chlorophyll a concentration of 8.69 μg l−1. Minima in salinity, and maxima in chlorophyll concentration on day 190 were coincident with a peak in river-derived dissolved inorganic nitrogen (DIN) of 1.9 μmol l−1 which was >5 times greater than the summertime mean and 24 times the concentrations experienced at L4 on weeks immediately before and after. There was no accompanying increase in dissolved inorganic phosphorus (DIP), and the DIN:DIP ratio increased to 49. With the inherent phosphorus stress that this caused, rates of APA increased from <4 to 42.4 nmolP l−1 h−1. ELF analysis on day 197 identified two taxa actively expressing alkaline phosphatase: the dinoflagellate Prorocentrum micans and ciliate Tiarana sp.  相似文献   
102.
从构词法 ,语义学的角度对英汉两种语言在词的构成和主义方面进行探讨 ,使教师注意到英汉两种语言在某些方面的规律 ,以促进英语教学工作。  相似文献   
103.
The fish assemblage structure was analyzed along an estuarine gradient of a small macrotidal estuary (the Canche, France). Fishes were collected every two months between May 2006 and July 2007 from 12 sampling stations using a 1.5-m beam trawl with a 5 mm mesh size in the cod end. To complement this information, sampling was also performed using 15-m fyke nets (8 mm mesh size in the cod end). For each sample, abiotic (temperature, salinity, pH, oxygen, turbidity, river flow, wind speed and depth) and biotic (macro crustacean species abundances) were recorded. Throughout the study, 28 fish species belonging to 20 families were collected. Fish catches were dominated by juveniles, especially Young-Of-the-Year (YOY) for the majority of the species. According to the Index of Relative Importance (IRI), common goby Pomatoschistus microps, flounder Platichtys flesus, sprat Sprattus sprattus, sea-bass Dicentrarchus labrax and plaice Pleuronectes platessa were the most abundant species, together accounting for 99.2% of the total IRI. Estuarine residents (ER = 66.2%) and marine juvenile migrants species (MJ = 31.4%) were the most important ecological guilds. The structure of the fish assemblage and its relationship to environmental variables was examined using multivariate techniques. Cluster and non-metric multidimensional scaling (nMDS) analysis defined six distinct groups in the Canche estuary, which are discriminated by specific species (SIMPER). Spatio-temporal variations in fish assemblage structure reflect the density peaks of the most abundant species. Spearman rank correlations and canonical correspondence analysis (CCA) showed that among the ten environmental variables examined, temperature, salinity and Crangon crangon (a potential predator for YOY fish or prey for older ones) are the three most important factors influencing fish species richness and abundances. Our observations reinforce the idea that certain fish species may have different life history styles in different geographic areas. The present study highlights the necessity of a better knowledge of the connectivity between estuaries and adjacent marine areas. The Canche constitutes an important ecosystem for fishes and as it is subject to little anthropogenic disturbance; its ichthyofauna can be viewed as a reference or normal assemblage for small temperate macrotidal estuaries.  相似文献   
104.
The short-term dynamics (time scale of a few days) of phytoplankton communities in coastal ecosystems, particularly those of toxic species, are often neglected. Such phenomena can be important, especially since these very species can endanger the sustainability of shellfish farming. In this study, we investigated the short-term changes in phytoplankton community structure (species succession) in two coastal zones in parallel with physical and chemical conditions. Mixing events with allochtonous waters could thus be distinguished from local processes associated with population growth when it was associated with a change in light or nutrient limitation. Mixing events and water advection influenced fluctuations in total phytoplankton biomass and concentration of dominant species, while local processes influenced delayed changes in community structure. The estuarine species Asterionellopsis glacialis increased in concentration when the water mass mixed with the nearest estuarine water masses. The biological response, measured as photosynthetic capacity, occurred after a time-lag of a few hours, while the changes in community structure occurred after a time-lag of a few days. Finally, the coastal water mass was constantly mixed with both the nearest estuarine and marine water masses, leading in turn to delayed changes in phytoplankton community structure. These changes in species composition and dominance were observed on a time scale of a few days, which means that some toxic species may be missed with a bi-weekly sampling strategy.  相似文献   
105.
互文研究在文学批评、翻译等领域得到了长足的发展,近年来也越来越多地用于语篇分析理论,而在实用语篇的互文性分析方面还有待进一步研究,运用语篇的互文分析理论,对大学英语阅读语篇中的体裁互文现象进行分析,重点研究大学英语阅读语篇中体裁互文性及其表现形式,以及对教学的相关启示.  相似文献   
106.
在大学英语翻译教学现状分析的基础上,对在大学英语教学中如何提高学生的翻译能力的教学进行了探讨,提出对现行教学大纲进行必要的修订,对教学内容和方法作出进一步的改革,注重对学生的跨文化交际能力的培养等建议。  相似文献   
107.
通过对全球化语境下英语教学范式正由"正统"到"非正统"、由"一元"到"多元"的发展变化的探讨,提出在全球英语教学多元化格局下我国高校英语教学应选择适合中国本土特征的英语教学模式、将本土文化的内容融入英语教材的编写中,实施双向互动的交流方式,以培养学生本土文化意识。  相似文献   
108.
We examined plankton responses to climate variance by using high temporal resolution data from 1988 to 2007 in the Western English Channel. Climate variability modified both the magnitude and length of the seasonal signal of sea surface temperature, as well as the timing and depth of the thermocline. These changes permeated the pelagic system yielding conspicuous modifications in the phenology of autotroph communities and zooplankton. The climate variance envelope, thus far little considered in climate-plankton studies, is closely coupled with the non-stationary dynamics of plankton, and sheds light on impending ecological shifts and plankton structural changes. Our study calls for the integration of the non-stationary relationship between climate and plankton in prognostic models on the productivity of marine ecosystems.  相似文献   
109.
Traditional rural homegarden agroforestry systems in the Chengdu Plain of China are often referred to as “Linpan” in Chinese, which integrates the landscape of ecological functions and human production activities. In recent years, due to the influences of urbanization and the aging population, the Linpan landscape has changed dramatically. Clarifying the factors which influence Linpan landscape evolution is a critical way to improve rural landscape renovation. Through oral history interviews, the deep-seated factors driving the evolution of the Linpan landscape form from 1949 to 2020 are explored using the grounded theory. The results show that in the process of Linpan landscape evolution, beneficiary groups, the material basis, and cultural characteristics are the prerequisites for changing the Linpan settlement landscape. The demand of production and life and government-led behavior are the two main influencing factors, and landscape change is the final result. The demand of production and life from the residents is the primary internal driving force of landscape change, while government-led behavior is the main external driving force of settlement development and evolution. The nature of the main driving forces behind the evolution of the Linpan landscape in the Chengdu Plain can be divided into three stages. (1) From 1949 to 1980, it was characterized as a balancing of government forces and social forces. (2) From 1981 to 1993, it was characterized by social forces suppressing government forces. (3) From 1994 to 2020, it was characterized as a stalemate between the government and social forces. From the perspective of the evolution of the Linpan settlement landscape, the traditional Linpan form and settlement layout have been unable to meet the new requirements of the rural social and economic transition period. They are facing the challenges of rural reconstruction and rural revitalization. In the future, village and town planning and the design of new settlements need to comprehensively consider the demands of different interest groups.  相似文献   
110.
目的:利用网络药理学及分子对接探讨重连口服液治疗流行性感冒的作用机制。方法:通过TCMSP、PubChem、Swiss Target Prediction平台以及相关文献获取重连口服液所含中药的活性成分及对应靶点;通过DisGeNET、DrugBank、Herb数据平台获得流感相关靶点;将有效成分的靶点映射到流感靶点,得到交集靶点即为重连口服液抗流感的潜在靶点;利用Cytoscape软件和String数据库建立化合物-靶点网络及靶蛋白互作(PPI)网络;通过R语言clusterProfiler工具包对核心靶点进行基因本体(GO)功能及京都基因与基因组百科全书(KEGG)通路富集分析。结果:根据筛选条件获取160个活性成分,59个潜在靶点;经网络拓扑分析筛选出重连口服液前5位重要成分为:槲皮素、木犀草素、山柰酚、汉黄芩素、β-谷甾醇,2个重要靶蛋白转录因子P65(RELA)、丝裂原活化蛋白激酶14(MAPK14)。通过分子对接显示5个重要成分与RELA、MAPK14结合能均<-5.0 kcal/mol。GO富集分析发现重连口服液作用的生物途径与调节脂多糖、细菌源分子等有关系;KEGG通路富集分析表明重连口服液治疗流感涉及IL-17信号通路、TNF信号通路等。结论:重连口服液以多种成分通过调控RELA、MAPK14等靶蛋白,作用于多种生物途径以抑制病毒的复制,减轻炎症反应,调节机体免疫,调控氧化应激等,从而起到抗流感的治疗作用。  相似文献   
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