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211.
Summary. In the past decades, several studies have focused on the identification of feeding stimulants for specialists that feed on
solanaceous plants, especially potato (Solanum tuberosum). In the 1950's, a phagostimulant was isolated from potato and tomato for Manduca sexta and characterised as a glycoside. It was suggested that the phagostimulant for M. sexta and Leptinotarsa decemlineata is identical. We tested whether these insects indeed share the same recognition factor. Previous bioassays for L. decemlineata larvae and adults were found to be unsatisfactory, so a new assay system was developed, using starch and wheat flour-based
wafers as a neutral substrate. An aqueous extract of potato foliage that was highly active as a stimulant was fractionated
by reverse phase medium pressure liquid chromatography (MPLC). Both insects were stimulated by a MPLC fraction that eluted
with 25% methanol in water. Further separation of this and the following fraction (35% methanol, stimulatory for the beetle
only) by semi-preparative high performance liquid chromatography (HPLC), using gradients of water and acetonitrile, resulted
in the isolation of two distinct fractions that stimulated feeding by L. decemlineata. None of the HPLC fractions was active for M. sexta. However, fractions of the flash chromatography with less polarity (45–75% methanol) had a stimulatory effect only on M. sexta. Thus, the two insects do not use a common feeding stimulant, and for both at least two compounds of different polarity are
active.
Received 3 July 2000; accepted 24 October 2000 相似文献
212.
阐释了长江经济带港口代际识别的意义和UNCTAD框架下港口代际识别的标准。运用模糊模式识别的方法对长江经济带主要港口进行代际识别测度,并对初步识别结果做进一步分析和修正。研究表明:①长江经济带港口代际等级总体上较低,大多数处于UNCTAD框架下的第一代港和第二代港水平;②不同代际港口在空间上呈现出明显的东西分异特征,港口代际等级和港口分布密度由东向西均表现出显著的下降趋势;③从局部空间看,不同等级的港口在地理分布上呈现出一定的"省域化"特征,即在省域范围内形成以一两个高等级港为中心、其他低等级港为支线港、喂给港的港口群形态。根据研究结论,提出长江经济带建设下的港口战略转向:充分认识港口在长江综合运输体系中的作用;有序推进长江经济带港口代际更替;以港口群的形式推进港口建设和适时推进长江沿岸自贸区建设。 相似文献
213.
阐述了评价环境空气质量的属性识别法,介绍了属性识别理论模型和属性权重的确定,通过将熵值法与属性识别理论相结合,建立了基于熵权的属性识别理论模型,并依据《环境空气质量标准》(GB 3095-2012),对郑州市城区2009年至2013年的环境空气质量进行了综合评价.结果表明:2009年至2013年郑州市城区的环境空气质量均为Ⅱ级.属性识别理论概念清晰,计算简单,评价结果比较客观.评价结果表明运用属性识别理论应用于环境空气质量综合评价是合理可信的. 相似文献
214.
基于复杂网络的城市湖库藻类水华形成识别研究 总被引:1,自引:0,他引:1
在对城市湖库藻类水华形成机理深入研究的基础上,将提取的影响水华暴发的关键因子总磷(TP)、总氮(TN)、温度(T)、pH值、溶解氧(DO)、光照(I)、叶绿素a浓度(chl_a)作为网络节点,将影响因素间的关系抽象成网络的边,构建了藻类水华形成的有向网络模型.同时,计算了复杂网络的统计特征参数,构建了节点的关键度模型,并进行修正,进而构建了水华形成的复杂网络统计特征参数模型G,对其进行半定量分级,从而实现对水华暴发的有效识别,最后采用北京城市河湖水质的实验数据对模型进行了验证.结果表明,复杂网络统计特征参数G与叶绿素a浓度有显著的相关性,能够较好地表征水华形成过程. 相似文献
215.
216.
运用未确知测度理论,建立煤矿奥灰岩岩溶水类底板突水评价模型。选取煤层底板的地质构造(断裂构造密度、褶皱、断层导水性、岩体的裂隙发育情况)、水文地质条件(水压、含水性、岩溶含水层发育情况、强水源补给情况)、底板隔水层条件(隔水层厚度、岩石力学强度以及隔水岩层的完整性)、开采条件(采厚和采深)4个一级指标、13项二级指标作为未确知测度模型的判别指标;根据指标值的类型采用定量或定性的方法对其进行分级和赋值,建立评判集,进而构建单指标测度函数。将13个突水评价指标值代入单指标测度函数计算得到单指标测度评价矩阵。利用信息熵理论获得各判别指标的权重,依照置信度识别准则进行等级判定,最后得出煤层底板突水危险性评价结果。利用该方法对肥城矿区14个地质块段的煤层底板突水危险性进行评价,结果表明,该评价结果与矿山实际情况相符。 相似文献
217.
Foundresses of the social wasp Polistes biglumis were tested to see whether they were able to recognize alien eggs experimentally introduced into their own nests. Foundresses
removed alien conspecific reproductive-destined eggs while they accepted worker-destined eggs. The results indicate that social
wasps discriminate among eggs and that they discriminate against alien eggs destined to produce unrelated reproductives. P. biglumis is a strictly solitary founding species, with no reproductive competition within colonies; thus, brood discrimination abilities
could have evolved as a counteradaptation against intra- and inter-specific brood parasitism.
Received: 12 May 2000 / Revised: 15 July 2000 / Accepted 20 July 2000 相似文献
218.
A conflict over male production arises in social insects where workers are able to lay unfertilized male eggs. This happens
because each female (queen or worker) is most closely related to her own sons and is thus predicted to reproduce. The conflict
is modulated by worker policing where workers prevent each other from reproducing by aggression or egg cannibalism. In this
study, we show that in the ant Formica fusca, worker policing occurs by egg cannibalism rather than by overt aggression among workers. Furthermore, we show that, contrary
to bees, wasps and other ant species, egg discrimination in F. fusca is not based only on a universal queen signature chemical and that nest mate recognition of eggs occurs. 相似文献
219.
基于差异进化算法的爆破震速参数识别与优化 总被引:1,自引:1,他引:0
爆破震动衰减特性研究通常采用经典的萨道夫斯基公式实现。如何根据不同爆破条件合理选择公式中的场地系数K和衰减指数α是确定爆破控制参数的关键。实际工程分析中,通常采用可监测参数反演识别方法获取K和α值。以大连地铁2号线201标段接收井横通道爆破作业为背景,基于差异进化(DE)算法中缩放因子F和交叉概率Cr贡献值的合理选择,研究萨道夫斯基公式K和α的反演问题。首先,通过对算法中F和Cr不同取值对萨道夫斯基公式计算结果的影响分析,得到各向震速条件下收敛最小的F和Cr值;然后,根据F和Cr取值反演K和α参数。工程实践表明,基于DE算法反演识别得到的K和α值代入萨道夫斯基公式,计算得到的垂向、纬向、经向速度及合速度与实测速度变化趋势一致,并处在合理误差范围之内。 相似文献
220.
Amer Obeidi Keith W. Hipel D. Marc Kilgour 《Journal of the American Water Resources Association》2006,42(6):1629-1645
Abstract: A systematic technique is proposed for assisting in the design and implementation of policy and addressing the need to minimize or resolve disputes that may arise in the enforcement of regulations. The Graph Model for Conflict Resolution is a methodology that facilitates the modeling and analysis of interactive multiple participant-multiple objective decision problems. In the problems considered here, decision makers and policy planners engaged in capacity building typically have different viewpoints over appropriate ways of developing options and enforcing policy choices. Incompatible understandings of resource potentials and limits, and disparities in utilization of these resources, exasperate stakeholders and make the capacity building process counterproductive and even conducive to conflict. A systematic conflict resolution technique is invaluable to policy makers and practitioners in defusing confrontations and reaching out for consensus among participants. In support of current approaches to policy planning and regulation, the Graph Model provides accurate predictions and strategic insights into shortand long-term opportunities in multiple participant-multiple objective decision situations. A conflict among the government of Canada, the Mi'kmaq First Nation, and commercial fishermen over the sharing of a natural resource in New Brunswick, Canada, is used to illustrate the advantages of this technique in practical problems. 相似文献