我国城乡居民肉类消费的碳排放特征分析——基于过程生命周期理论

基于过程生命周期理论,将肉类消费分解为生产、运输和消费3个阶段,量化了2000～2010年城乡居民肉类消费生命周期的碳排放,并分析其潜在影响因素.结果表明：①城乡居民肉类生命周期碳排总量呈现增长趋势,且城镇居民大于农村居民.肉类生产阶段碳排放量占全生命周期比重最大,运输阶段碳排量增长迅速,消费阶段排放较少;②肉类消费总量和消费结构变化、农村生活能源利用结构不合理以及高耗能低效率的肉类物流现状均是造成我国居民肉类生命周期温室气体排放增长的主要原因;③加强饲养环节的技术革新、建立节能环保畜产品运输流通模式、提倡地产地销以及优化农村地区生活能源利用结构是现阶段肉类消费生命周期各阶段减排的有效措施.     

拟南芥突变体lls糖信号响应异常

拟南芥突变体lls(long life span)是生活周期很长的单基因突变体.为了研究该突变对糖信号途径的影响,本文通过形态和生理学分析,结果发现lls突变体具有一些糖相关的表型特征,如:植株矮小,叶色深绿,生长缓慢等.通过测定植株的可溶性糖含量及叶绿素和花青素含量,结果显示lls植株的叶绿素和可溶性糖水平升高,可能由此引起花青素含量升高.施加外源的葡萄糖和蔗糖的实验结果表明lls突变体对外源糖信号敏感,这说明LLS突变可能严重影响了糖代谢或糖响应的某一途径.     

人口年龄结构对农村居民消费的影响研究

在生命周期理论、预防性储蓄理论和家庭储蓄需求理论的基础上,运用农村居民实地调研消费数据对人口年龄结构与居民消费的关系进行实证分析。结果表明:少儿抚养系数和老年抚养系数对农村居民的消费均具有显著的影响,少儿抚养比对农村居民消费有显著的正向影响,老年抚养比对农村居民消费有显著的负向影响。     

Living with the past: evolution, development, and patterns of disease

Epidemiological observations have led to the hypothesis that the risk of developing some chronic noncommunicable diseases in adulthood is influenced not only by genetic and adult life-style factors but also by environmental factors acting in early life. Research in evolutionary biology, developmental biology, and animal and human physiology provides support for this idea and suggests that environmental processes influencing the propensity to disease in adulthood operate during the periconceptual, fetal, and infant phases of life. This "developmental origins of health and disease" concept may have important biological, medical, and socioeconomic implications.     

基于旅游地生命周期理论的旅游产品开发研究——以武夷山为例

旅游地生命周期是研究旅游地发展演化的重要理论基石。本文在分析武夷山旅游地发展阶段的基础上,有针对性地提出旅游产品开发建议,以期获得较长的生命周期。     

河北省农业综合生产能力评价与提升对策

从农业生产投入、农业产出水平、农业生产潜力三部分考虑选取了15个单项指标,构建了河北省农业综合生产能力评价指标体系。运用变异系数法确定指标权重,对2000～2009年河北省农业综合生产能力进行了综合评价,发现存在的问题,并在此基础上提出加强农业科研投入与技术推广体系建设、加大农田水利基础设施建设、构建资源节约型农业等提升对策。     

Macronuclear Subunits of Tetrahymena thermophila Are Functionally Haploid

In Tetrahymena thermophila the major argument for the existence of diploid subunits has been that some loci show a delay in the accumulation of stable subclones during macronuclear assortment. This delay is based on the assumption that throughout the life cycle there are 45 subunits. We find that for at least 50 fissions after conjugation there is sufficient DNA for 66 haploid subunits. These additional subunits early in the life cycle are sufficient to explain the observed accumulation of stable subclones in all instances. This removes the need to invoke diploidy to explain assortment, thus resolving the question of subunit ploidy in favor of haploidy.     

A novel methodology for the monitoring of the agricultural production process based on wireless sensor networks

Precision agriculture is a field which provides one of the most suitable scenarios for the deployment of wireless sensor networks (WSNs). The particular characteristics of agricultural environments - which may vary significantly with location - make WSNs a key technology able to provide accurate knowledge to farmers. This knowledge represents a valuable resource because it enables real-time decision making with regard to issues such as establishing water saving policies while providing adequate irrigation and choosing the right time to harvest the fruit based on its maturity.This article proposes a methodology consisting of a set of well-defined phases that cover the complete life cycle of WSN applications for agricultural monitoring. We have studied different existing real-world scenarios where WSNs are being applied. Based on this study we have discovered that there exist significant commonalities but no methodology that specifies the best practices that should be used in the general, crop-independent case. The lack of a general methodology negatively impacts the amount of effort, development time, and cost of developing applications.     

基于生命周期模型的科技文献数据管理体系研究

[目的/意义]科技文献数据资源具有覆盖广、数量大、类型多、更新快、时效强等特点,为提高科技文献数据管理效果和数据安全,本文基于数据生命周期模型对科技文献管理体系进行研究。[方法/过程]对科技文献管理模式进行探索,基于数据管理流程,构建了科技文献的生命周期体系,并从数据创建、数据存储、数据预处理、数据计算、数据服务、数据归档、数据销毁等7个阶段对数据管理工具和数据管理方法进行阐述。[结果/结论]本文对科瑞唯安核心数据集WOS BP数据进行了基于科技文献生命周期的管理和实践,同时基于DAMA数据质量的6个评估维度对数据管理效果进行综合评价。     

栾多态毛蚜生活周期的研究

蚜虫的生活周期十分复杂,可以分为不全周期和全周期。全年孤雌生殖,不发生性蚜世代的,称为不全周期。在1～2年内,一般在一年内有孤雌生殖与两性生殖世代交替的,称为全周期。全周期还可以根据转移情况分为几个类型。了解这些类型,可以对蚜虫的生活习性有一简明概念,有利于进行观察研究和防治。该试验着重对栾多态毛蚜(Periphyllus koelreuteriae)的生活周期进行了详尽研究。栾多态毛蚜生活周期属于全周期类型。它有其自身的特殊性,尤其是越夏小型蚜的出现,更是对不良外界环境的一种适应表现。     

家庭生命周期、社会资本与农户生计策略研究

基于家庭生命周期视角,采用农户实地调查数据,运用Mlogit回归模型,分析社会资本对农户生计策略产生的影响。结果表明:湖北农村家庭的兼业化程度较高,家庭结构呈现"纺锤形"分布,社会资本积累会促使农户选择偏非农型的生计策略。通过检验社会资本的影响机制,发现社会资本在家庭生命周期对生计策略的影响中既存在调节作用,又存在部分中介作用,其中介效应的大小为35.2%。为促进农户生计多样化,加强农户抗风险能力,防止生命周期阶段两端的家庭遭受生计风险,建议政府通过职业教育或者技能培训提高农户的人力资本,加强对农户资金、贷款方面的支持,扩大农户的社会网络。     

变频技术在长输管道输油泵机组上的应用

传统工频定速电机在管道输量较低时,既浪费电能,又缩短了输油泵机组的维护周期和使用寿命。针对该问题,提出了对泵机组采用变频调速改造的方法进行节能控制。输油泵节能原理：保持离心泵输送流量不变,减小离心泵扬程。以某实际运行长输管道为例,详细介绍了高压变频改造项目在长输管道输油泵机组上的节能测试过程,对比分析了输油泵机组加装变频装置前后的节能效果。结果表明：加装变频装置后,节流率、功率因数和机组效率均满足评价标准SY/T 6275-2007限定值和节能评价值的要求,管道2008-2009年度节省电费304.5×104元。     

关联数据研究的主题结构和研究进展解析

[目的/意义]通过调研关联数据的研究文献,分析关联数据的研究的主题结构与研究进展。[方法/过程]综合采用文献综述方法、文献计量方法与可视化工具对Web of Science中的关联数据研究进行分析。其中,利用Citespace可视化软件分析了关联数据研究主体,利用VOSviewer将构建的关键词矩阵可视化。以关联数据的生命周期阶段为线索,结合关键词共现图谱,探寻了关联数据研究的主题结构与研究进展。[结果/结论]分析结果显示欧洲为关联数据研究的主阵地,Tim Berners-Lee等人在关联数据领域具备深厚的影响力。目前关联数据的研究覆盖了发布、优化、评价、应用等生命周期各个方面,但也存在一些薄弱环节,如在研究推动关联数据发布的进一步规范、实现实体自动丰富与链接、构建全面的质量评价体系与工具等方面存在挑战。     

蜘蛛生活史及其分类

本文在综述有关蜘蛛生活史大量文献的基础上,讨论了蜘蛛个体发育中所涉及的形态学、发育学、生理学和生态学的诸方面,论述了蜘蛛生活史的组成成分及各组成的多样性与生活史分类的关系;蜘蛛生活史的发生类型;蜘蛛生活史与季节性气候的适应关系。分析了环境因素对生活史各阶段的影响,其中环境因素如温度、光周期、湿度和食物是影响生活史各阶段的重要因素,从而决定了蜘蛛的生活史类型。     

柑桔木虱生物学研究

柑桔木虱在浙南平阳一年发生6～7代,以成虫在寄主叶背越冬,翌年3月中、下旬产卵于芽缝间,4月上、中旬出现若虫;第一代成虫始见于5月上旬.世代重叠,7～8月柑桔秋稍期为成虫发生高峰期.卵期2～11天;若虫5龄,若虫期11～36天;世代历或共20～67天.成虫寿命13～246天,产卵前期6～30天.产卵期1～72天,一般连续一个月左右;每雌产卵量3～762粒,每代平均172～277粒.性比为1.06:1.     

Studying adolescence

Young people in their teens constitute the largest age group in the world, in a special stage recognized across the globe as the link in the life cycle between childhood and adulthood. Longitudinal studies in both developed and developing countries and better measurements of adolescent behavior are producing new insights. The physical and psychosocial changes that occur during puberty make manifest generational and early-childhood risks to development, in the form of individual differences in aspects such as growth, educational attainment, self-esteem, peer influences, and closeness to family. They also anticipate threats to adult health and well-being. Multidisciplinary approaches, especially links between the biological and the social sciences, as well as studies of socioeconomic and cultural diversity and determinants of positive outcomes, are needed to advance knowledge about this stage of development.     

林学对口招生本科学生学习成绩分析

通过对河北农业大学林学院近年来对口单独招生的学生与普通高中毕业生成绩进行比对,分析了对口单独招生生源学习成绩的特点。对口招生生源学生必修课成绩与普招生没有明显差别;部分基础课成绩与普招生存在差距;专业课、专业基础课及专业实践课成绩比普招生有明显优势。并在此基础上,着重对培养计划编制、教学改革等方面进行了认真的思考。     

使用减阻剂提高管道节能效果

减少管路阻力,提高管路效率是泵站节能的重要举措施。提高管路效率有两种基本途径,即添加减阻剂和改善流体运动边界条件。重点介绍了新型减阻剂的性能,特点及其应用,分析了影响其性能的基本因素及主要优点,并对管路节能与泵站节能的关系进行了讨论。     

Integration of environmental, agronomic, and economic aspects of fertilizer management

Nitrogen fertilization is a substantial source of nitrogen-containing trace gases that have both regional and global consequences. In the intensive wheat systems of Mexico, typical fertilization practices lead to extremely high fluxes of nitrous oxide (N2O) and nitric oxide (NO). In experiments, lower rates of nitrogen fertilizer, applied later in the crop cycle, reduced the loss of nitrogen without affecting yield and grain quality. Economic analyses projected this alternative practice to save 12 to 17 percent of after-tax profits. A knowledge-intensive approach to fertilizer management can substitute for higher levels of inputs, saving farmers money and reducing environmental costs.     

The rise of the angiosperms: a genecological factor

In the primitive angiosperms, closed carpels are believed to have evolved as protection for ovules, which would otherwise be injured by animal pollinators. The hypothesis is presented that, whatever the origin and other functions of angiosperms, insect pollination and closed carpels may, in combination, reduce the influence of random variation on pollen tube competition, thus enhancing the ability of natural selection to act on the gametophytic phase of the life cycle. The microgametophytic phase represented by vast numbers of haploid individuals can then serve, by insect pollination and closed carpels, as a screen against any genome not functioning with a high degree of metabolic vigor. Poorly balanced genomes could thus be eliminated at relatively little cost. Insect-pollinated angiosperms would therefore benefit from positive aspects of sexual recombination. Such a system may have allowed the angiosperms to undergo their rise to dominance.