共查询到20条相似文献,搜索用时 15 毫秒
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Life history evolution: successes, limitations, and prospects 总被引:1,自引:0,他引:1
Stearns SC 《Die Naturwissenschaften》2000,87(11):476-486
Life history theory tries to explain how evolution designs organisms to achieve reproductive success. The design is a solution to an ecological problem posed by the environment and subject to constraints intrinsic to the organism. Work on life histories has expanded the role of phenotypes in evolutionary theory, extending the range of predictions from genetic patterns to whole-organism traits directly connected to fitness. Among the questions answered are the following: Why are organisms small or large? Why do they mature early or late? Why do they have few or many offspring? Why do they have a short or a long life? Why must they grow old and die? The classical approach to life histories was optimization; it has had some convincing empirical success. Recently non-equilibrium approaches involving frequency-dependence, density-dependence, evolutionary game theory, adaptive dynamics, and explicit population dynamics have supplanted optimization as the preferred approach. They have not yet had as much empirical success, but there are logical reasons to prefer them, and they may soon extend the impact of life history theory into population dynamics and interspecific interactions in coevolving communities. 相似文献
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生物多样性的干扰、生活史及优化管理 总被引:3,自引:0,他引:3
Qinfeng Guo 《Ambio-人类环境杂志》2003,32(6):428-430
在许多生态系统中,日益增长的人类活动已经加剧了干扰的频度和强度.结果,在地球上,短命物种(包括许多外来的物种)在丰富度上可能会有巨大的提高;同时长寿命的物种又可能消失.这个结论可以通过对理论和经验研究中大量演替循环的观察得到.这篇文章主要讨论现有生态管理政策和保护中两个受到忽视的问题①生活史的限制因素;②未来全球变暖趋势.同时也强调了这两个因素在平衡干扰的频度和强度以优化生物多样性保持和生态系统管理方面的重要性. 相似文献
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生物炭对三氯生的吸附热动力学研究 总被引:1,自引:0,他引:1
以玉米秸秆、皇竹草和花生壳为原料制备成玉米秸秆生物炭(BCcs)、皇竹草生物炭(BCn)、花生壳生物炭(BCps),采用CEC、等电点滴定,表面官能团分析,元素分析、FT-IR、扫描电镜等方法对3种生物炭进行表征,采用单因素静态吸附实验方法考察了生物炭吸附三氯生的主要影响因素.结果表明:CEC和表面官能团数量排序为BCcsBCnBCps,BCcs极性和亲水性更强,孔结构发育更加完善,其次是BCn,BCps的极性和亲水性最弱,孔隙极少.3种生物炭对三氯生的吸附去除率均随着三氯生初始浓度的升高而升高,随着温度的升高而降低,酸性更有利于吸附实验的进行.低离子强度有利于BCcs和BCn吸附三氯生,BCps则相反.在10、25、40℃3种温度下,3种生物炭对三氯生的吸附均更符合准二级反应动力学,Freundilich等温方程和Langmuir等温方程都能描述这3种生物炭对三氯生的吸附行为,吸附反应属于自发、放热反应.吸附机制主要为物理吸附,生物炭与三氯生之间无化学键、配位基交换等强作用力. 相似文献
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以泰乐菌素(TYL)为目标有机污染物,系统研究了两种微塑料聚乙烯(PE)和聚氯乙烯(PVC)对泰乐菌素的吸附动力学与热力学.结果表明:PVC对泰乐菌素的吸附大于PE;吸附在36h可完全达到平衡,吸附动力学可以用二级动力学较好的拟合;颗粒扩散模型表明表面吸附和颗粒扩散是PE和PVC对TYL吸附的主要机理;吸附等温线可以用Henry模型较好拟合,说明泰乐菌素在PE和PVC上的吸附存在明显的线性分配规律,吸附热力学表明吸附过程是自发进行的;本研究可以为科学合理的评价微塑料在环境中的行为及其对环境中污染物的迁移转化的影响提供理论依据. 相似文献
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Dietrich von Holst Hans Hutzelmeyer Paul Kaetzke Martin Khaschei Ronald Schönheiter 《Die Naturwissenschaften》1999,86(8):388-393
Wild rabbits of the two sexes have separate linear rank orders, which are established and maintained by intensive fights.
The social rank of individuals strongly influence their fitness: males and females that gain a high social rank, at least
at the outset of their second breeding season, have a much higher lifetime fitness than subordinate individuals. This is because
of two separate factors: a much higher fecundity and annual reproductive success and a 50% longer reproductive life span.
These results are in contrast to the view in evolutionary biology that current reproduction can be increased only at the expense
of future survival and/or fecundity. These concepts entail higher physiological costs in high-ranking mammals, which is not
supported by our data: In wild rabbits the physiological costs of social positions are caused predominantly by differential
psychosocial stress responses that are much lower in high-ranking than in low-ranking individuals.
Received: 23 February 1999 / Accepted: 17 March 1999 相似文献
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对硝基苯酚在沉积物上的吸附特征---吸附等温线和吸附热力学 总被引:17,自引:2,他引:17
研究了对硝基苯酚在不同沉积物上的吸附等温线,比较分析了Linear方程、Freundlich方程和Langmuir方程描述吸附等温线的准确性和稳定性结果表明,Iinear方程更适合描述沉积物吸附对硝基苯酚的等温线对硝基苯酚在沉积物上的吸附主要是溶质在沉积物有机质中的分配,其吸附热为-7 8 kJ@mol-1,主要的吸附作用力为疏水键力.对硝基苯酚在18个沉积物有机质上吸附自由能改变量为-5 4--7.2kJ@mol-1.标准自由能的变小是对硝基苯酚在沉积物有机质上吸附的推动力. 相似文献
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生命周期评价法(Life Cycle Assessment)在国际上广泛应用于工业企业部门、政府管理部门和服务行业,但最突出的贡献是在环境管理方面的应用.LCA的技术框架分为确定目的与范围、生命周期清单分析、生命周期影响评价(LCIA)和结果解释4个部分.LCIA的方法可归纳为中点法和终点法.LCA存在数据获取、清单分配、边界选择、评价模型、时空限制,以及结果不确定性等方面的局限性.为适应环境管理和评价技术本身的要求,LCA评价技术朝系统化方向发展,目前主要有IO-LCA、ALCA、CLCA、LCC、S-LCA和LCSA等评价技术.不同的评价技术从不同侧面拓展了LCA的应用领域和回避LCA评价的局限性,使得LCA越来越成为环境管理不可或缺的工具. 相似文献
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Adsorption of lead on multi-walled carbon nanotubes with different outer diameters and oxygen contents: Kinetics, isotherms and thermodynamics 总被引:2,自引:0,他引:2
The effects of different outer diameters and surface oxygen contents on the adsorption of heavy metals onto six types of multi-walled carbon nanotubes (MWCNTs) were investigated in an aqueous solution and lead was chosen as a model metal ion. The results indicated that the percentage removal and adsorption capacity of lead remarkably increased with decreasing outer diameter due to larger specific surface area (SSA). The SSA-normalized maximum adsorption capacity (qm /SSA) and SSA-normalized adsorption coefficient (Kd /SSA) were strongly positively correlated with surface oxygen content, implying that lead adsorption onto MWCNTs significantly increases with the rise of oxygen content and decreases with decreasing SSA. The calculated thermodynamic parameters indicated that adsorption of lead on MWCNTs was endothermic and spontaneous. When the oxygen content of MWCNTs increased from 2.0% to 5.9%, the standard free energy (△ G0 ) became more negative, which implied that the oxygenated functional groups increased the adsorption affinity of MWCNTs for lead. Through calculation of enthalpy (△ H0 ), G0 and free energy of adsorption (Ea ), lead adsorption onto MWCNTs was recognized as a chemisorption process. The chemical interaction between lead and the phenolic groups of MWCNTs could be one of the main adsorption mechanisms due to highly positive correlations between the phenolic groups and K d /SSA or q m /SSA. 相似文献
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保护和改善生态环境,拥有绿色生活,是全人类紧迫而艰巨的任务。通过环境保护与治理,环境质量恶化的趋势基本得到控制,局部地区环境质量逐步得到改善,但环境保护依然面临诸多问题与挑战。本文从如何拥有绿色生活的角度阐述了当前面临的环境问题,及加强环境保护的对策,从而实现人与自然的和谐发展,拥抱绿色生活。 相似文献
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DMF在大孔吸附树脂上的吸附热力学及动力学研究 总被引:5,自引:0,他引:5
研究了大孔吸附树脂吸附N,N-二甲基甲酰胺(DMF)的热力学与动力学特性.经过初步筛选,发现NKA-Ⅱ型大孔吸附树脂对DMF具有良好的吸附与再生性能.在温度为298、和318K条件下分别测定了吸附平衡数据并应用Freundlich和Langmiur等温吸附方程进行拟合,结308果表明,DMF在NKA-Ⅱ型大孔吸附树脂上的吸附平衡符合Freundlich等温吸附方程.在此基础上,通过热力学分析发现ΔH>0、ΔG<0、ΔS>0,表明DMF在大孔吸附树脂上的吸附属于可自发进行的物理吸附,吸附过程吸热,但吸附热较小,温度对吸附过程的影响较小.吸附动力学研究中分别采用一级速率方程、准二级速率方程和二级速率方程对吸附过程进行模拟,结果表明,准二级动力学方程的计算值与实验值吻合良好,适合描述NKA-Ⅱ型大孔吸附树脂对DMF的吸附过程. 相似文献
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<正> 该书为《矿物学评论》第14卷,由S.W.Kie-ffer和A.Navrotsky合编,1985年由美国矿物学会出版,计428页。该书旨在研究矿物的微观结构与它们的宏观热力学性质的关系。对这种微观—宏观关系的了解,可为能量关系式提供严格的理论依据,有了这种依据,就能比仅仅使用经验关系更有把握地外推并预测出测量范围以外的热力学性质。 相似文献
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有机地球化学是研究有机化合物在当前和化石环境中的形成、变化和分布的一门高度综合性的学科.为了加强瑞典与其它国家之间就这一学科的科学合作,2003年5月在瑞典斯德哥尔摩召开了一次研讨会,从观察、理论和实验等多方面对无机、有机及生物学物质之间的相互作用进行了探讨研究.会议的目的是探索这些物质在影响地球环境的进化和形成过程中它们的性能和过程.有机地球化学具有重要的经济学意义,因为它涉及到石油、天然气和煤炭的形成;同时有机地球化学也因为其对生命起源以及其它天体生命存在的假设而吸引着广泛的兴趣.并非所有的有机化合物都具有生物学的渊源.科学家也正在寻找真正的非生物学化合物,它们直接关系到生命起源问题以及外星物质的研究. 相似文献
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WANG Hai-ling FEI Zheng-hao CHEN Jin-long ZHANG Quan-xing XU Yan-hua 《环境科学学报(英文版)》2007,19(11):1298-1304
The adsorption behavior of p-aminobenzoic acid and o-aminobenzoic acid onto the different polymeric adsorbents was systematically investigated as a function of the solution concentration and temperature.Experimental results indicated that the equilibrium adsorption data of the four polymeric adsorbents fitted well in the Freundlich isotherm.The adsorption capacity of multi-functional polymeric adsorbent NJ-99 was the highest,which might be attributed to the strong hydrogen-bonding interaction between the amino groups on the resin and the carboxyl group of aminobenzoic acid.The adsorption capacity of o-aminobenzoic acid onto any adsorbent was higher than p-aminobenzoic acid.Thermodynamic studies suggested the exothermic,spontaneous physical adsorption process.Adsorption kinetics results showed that the adsorption followed the pseudo-second-order kinetics model and the intraparticle mass transfer process was the rate-controlling step. 相似文献