300 research outputs found
Status of Mud Crabs(Scylla spp.) Farming and Studies on the Population Biology of S. paramamosain
综述了国内外青蟹养殖的基本情况,包括养殖模式、养殖历史、人工育苗的现状,我国青蟹养殖在海水养殖中的地位及其特点,以及我国拟穴青蟹种群生物学研究现状及其在养殖中的重要性.This paper summarized the internationally general situation of mud crabs( Scylla spp.) farming,including cultivation pattern,cultural history,the situation of artificial mass larvae culturing,study progresses of population biology of S. paramamosain and its significance in its farming in China,as well as the status and characteristics of China mud crab farming.国家自然科学基金(31472294
JIT Production Sequencing Based on Blended Genetic Algorithms
JIT管理方式是实施CIMS工程中的一种重要的生产管理方式 ,以消除制造过程中的一切浪费为宗旨 ,消除和降低企业生产经营中的各种浪费 ,降低产品的成本 ,从而给企业带来了巨大的效益。JIT管理方式近来被广泛地应用于企业的生产经营管理中。在JIT生产方式中如何设计最佳的投产顺序计划问题一直是一个难题。在前人研究成果的基础上 ,使用把原有算法和自调整参数遗传算法相结合的混合遗传算法来求解这个问题。仿真结果表明这种算法是行之有效的。JIT is an important way for a CIMS project. Aiming to eliminate all wastes in the process of manufacture, it is effective to eliminate and reduce all kinds of wastes in production management, and cut down the cost of products, thus bringing the manufacturer to great benefits. So JIT has been widely used during the pastyears. In JIT mode of production, it is a difficult problem on how to design the optimal sequence. In this paper, Blended genetic algorithms (BGA) combining the proximal solution with genetic algorithms (GA) is used to solve the problem. The simulations show that the BGA is effective.厦门大学工科专项经费资助课题 (3 0 0 3
ISR@bucknell
isr@bucknell was a newsletter published by Bucknell University\u27s Information Services and Resources department (later Library and Information Technology). The publication served the community by providing software, project, and service updates. Regular features included a letter from the Associate Vice President for Information Services and Resources, the Ask ISR column, and featured ISR web pages. This issue includes the following articles: Blackboard Rocks, Faculty Focus, The Company We Keep, Appletree Alley, Citation Searching is Here, Bucknell Banner Web, Ask ISR
低温季节不同种群拟穴青蟹线粒体呼吸速率和酶活性的差异
已有研究显示分布于我国东南沿海的拟穴青蟹(Scylla paramamosain)可能已分化为南、北2个种群.在低温季节从不同纬度的3个海域采集拟穴青蟹的野生个体,比较其南、北种群线粒体呼吸速率和酶活性的差异.结果如下:除了乳酸脱氢酶、丙酮酸激酶以及肝胰腺细胞色素C氧化酶外,无论是北方种群还是南方种群,生活在纬度较高的宁波海域的拟穴青蟹的线粒体呼吸速率和酶活性都显著高于生活在纬度较低的儋州海域的个体;同一海域的南、北种群间,鳃、肌肉和肝胰腺线粒体呼吸速率和细胞色素C氧化酶活性总体上都是北方种群高于南方种群,纬度越高的海域的南、北种群间差异越显著;南、北种群肌肉的乳酸脱氢酶、丙酮酸激酶和己糖激酶活性相比,宁波海域北方种群的己糖激酶活性显著高于该海域的南方种群.上述结果表明,分布于我国东南沿海的拟穴青蟹的北方种群比南方种群对温度有更有效的代谢补偿能力,且纬度越高,二者的差异越显著,由此可见分布于我国东南沿海的拟穴青蟹的北方种群比南方种群更能适应低温环境.国家自然科学基金(31472294
Analysis of genetic variability of Castanopsis hystrix by rbcL gene sequences
通过PCR扩增得到10个红锥品系的rbcL基因全序列,均为1.513 kb.核苷酸序列比对结果表明,在256-1 455 bp区间10个红锥品系共有16处碱基发生变异,变异率为1%,其中在306 bp和634 bp处10个红锥品系较同属对照castanopsis lucida均发生相同的变异,可以看作属内进化信息碱基.对表达的氨基酸序列进行比对分析,发现16处碱基变异共引起8处氨基酸序列变异.The rbcL gene sequences of 10 assassin of Castanopsis lucida were analyzed by PCR,and sixteen mutations in 256-1 455 bp were found,the mutation ratio was 1 %.Compared to Castanopsis lucida,between 306 bp and 634 bp,they had two characteristic mutations of their own,so it was different from Castanopsis lucida.Compared to Castanopsis lucida,8 amino acid variations were found,caused by 16 point mutations.广西林业科学研究院国家林业局中南速生材繁育重点实验室开放基金课题;; 兰州理工大学博士基金(SB08200602);; 甘肃省教育厅研究生导师基金( 0703-11)
Applications of stable isotope techniques in aquatic ecological studies
稳定同位素作为一种天然的示踪物,应用十分广泛,其在水域生态学中的应用也日益受到重视。生物同位素组成总是与其食物同位素组成相一致,能随食物的改变而相应地发生改变,是生物生存状况的理想指示物,为水域生态系统食物网结构与功能、物质流与能量流的研究提供了有力的技术支撑。在综评稳定同位素技术原理与方法的基础上,较为详细地对其应用于水域生态研究的理论基础与进展进行了总结。该方法的应用以水域中生产者同位素组成差异为前提,主要涉及确定食物来源、食物的贡献比例、营养级的确定、食物网结构的构建及鱼类等水生生物的洄游及迁移路线等方面,这些研究对了解生态系统的动态变化与外界环境对其影响具有重要意义。并对我国此类研究的前景和存在问题进行了探讨。Stable isotopes have been used in many research areas as natural labels and are becoming an important tool in aquatic ecological research.The theoretical basis and application of stable isotope analysis in aquatic ecology as well as its principle and method are reviewed in this paper.An organism's stable isotope ratios(δ()~(15)N and δ()~(13)C etc.) are an integration of the isotopic signatures of prey items that have been assimilated through time,the organism will come into isotopic equilibrium with its diet with the time to equilibrium depending on growth and tissue turnover rates.Stable nitrogen isotope ratios increase with trophic level by approximately 3‰ to 4‰;this provides a powerful analytical tool to quantify relative trophic position.In contrast,stable carbon isotope ratio changes very little with trophic level(0 to 1‰ enrichment per trophic level).Instead,stable carbon isotope values of organisms reflect the average δ()~(13)C of their diets.When an organism moves to a different habitat,its stable isotope ratios will change.From the stable ratios of the different habitats and the organism,we can judge the migration routine of the organism.Stable isotopes are often used to quantify the contributions of multiple sources to an organism.In general,the proportional contributions of n+1 different sources can be uniquely determined by the use of n isotope groups with linear mixing models based on mass balance equations.When there are n isotope groups and >n+1 sources,all possible combinations of each sources contribution can be obtained by a computer program(IsoSource),but the proportional contributions aren't unique.The above two cases presume that the proportional contribution of a source to an organism is the same for all isotope elements,while not all cases are so.An isotope element concentration-weighted linear mixing model was developed,whose quantified results are more reasonable,but only determined the proportional contributions of n+1 sources with n isotope groups.Prey sources,trophic level and prey proportional contributions etc.are basic information needed to construct aquatic ecosystem food web patterns and functions and material and energy flows,which are fundamental to understand the dynamic of ecosystems and effects of environment to the ecosystems.The prospect of such studies in China and some existing problems are also discussed国家自然科学基金重大资助项目(30490233)~
STUDY ON ADSORPTION OF A BACILLUS STRAIN TO CADMIUM AND COPPER
从土壤中分离并纯化获得1株芽孢杆菌(Bacillus)。通过该菌菌液对Cd2+和Cu2+的吸附实验,探讨了该菌株对上述2种重金属离子的吸附特性。结果表明:该菌株对2种重金属离子都有较强的吸附能力,但对Cu2+的吸附能力比对Cd2+强;其吸附行为可以用Langmu ir和Freund lich吸附方程描述,但更符合Freund lich吸附方程。与此同时,研究还考察了吸附条件的影响,并获得了最佳的吸附实验条件。A bacteria strain was separated and purified from the soil and identified as Bacillus.In an adsorption experiment,its biosorption characteristics to Cd~(2+) and Cu~(2+) were studied.The strain was shown to have a strong adsorptive capacity to the above two metal ions,with a stronger adsorptive capacity to copper ions than to cadmium ions.Its adsorption behavior could be described by either the Langmuir adsorption equation or the Freundlich adsorption equation,the latter equation being the better.The effect of experimental conditions on adsorption was examined and the optimum experimental conditions were identified
塔里木沙漠公路防护林生态工程的综合生态环境效应
为了探讨重大工程的生态环境效应,从风沙环境、土壤环境、小气候、生物多样性和地下水环境5个方面对塔里木沙漠公路防护林工程的综合生态环境效应进行了研究.结果表明:(1)防护林改变了近地表风沙运动过程,防沙体系内风速、输沙率降低幅度分别达64%~80%和87.45%~99.02%,风沙流结构、沙物质粒度、地表蚀积状况也发生了明显变化;(2)与自然流沙地相比,防护林土壤容重减小,全盐含量、总孔隙度和含水量增大,土壤肥力质量明显提高,其变化基本呈现"先快后慢"的规律;(3)防护林对于小环境改善作用明显,距地面6m范围内,林地不同高度的空气温度普遍低于自然流沙地,而空气湿度则高于自然流沙地,林地土壤温度也低于自然流沙地;(4)随着防护林内生境的变化,土壤微生物种类显著增加,但不同种类微生物的种群分布并不均匀;(5)目前防护林灌溉抽水对地下水位、地下水矿化度的影响不大,水位在厘米级范围波动,矿化度的变化幅度在±1g·L-1左右,且没有明显的变化趋势
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