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1.
Glaser R 《Science (New York, N.Y.)》1958,128(3338):1577-1578
The number of movements of matched groups of night lizards in a photothermal gradient was recorded over periods of weeks. The placement of an aluminum foil shield over the parietal eye in one group was followed by an increase in activity over the control group. 相似文献
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Technology standard alliance, as vectors of research, development and circulation for technology standard, has already become an important transformation form from laboratory standard to fact standard for all countries. However, during the process of forming the technology standard alliance, it is a focus for members in the alliance to take control over others. How to construct a scientific and reasonable decision model of control over technology standard alliance is closely related to each enterprise member＇s interest. Under the condition that the risk is neutral, the paper explored necessary and sufficient conditions of knowledge sharing and the most endeavor among enterprise members through constructing a decision model of control over technology standard alliance, and put forward that the joint control model was the best decision model for constructing the technology standard alliance. 相似文献
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Levinton JS 《Science (New York, N.Y.)》1979,204(4390):335-336
If the world can only support a finite amount of biomass, species might be added over time, with a decrease in population size of an average species. Population sizes of species will decrease to the extent that stochastic events eliminate species as fast as others appear, yielding an equilibrium. A resource diversity control of niche subdivision is therefore not needed to generate an equilibrium number of species. Morphological evolution may decelerate over time for similar reasons. 相似文献
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针对外浮顶油罐密封装置在生产运行中出现的密封不严或密封压缩过紧的现象进行了现场调查,分析了产生这一问题的原因,提出油罐基础沉降,罐壁的垂直度和椭圆度超差等是造成密封不严或密封压缩过紧的主要原因,提出了施工控制方法,特别是要加强油罐壁板预制质量控制,提高底圈壁板的安装质量,对第二圈以上壁板垂直度逐圈控制,把总体垂直度的控制误差分解到各圈壁板中,建议在大型储罐施工中,除提高技术水平外,还应加强人员质量 相似文献
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Atom transfer radical polymerization is a versatile technique for exerting precise control over polymer molecular weights, molecular weight distributions, and complex architectures. Here, we show that an externally applied electrochemical potential can reversibly activate the copper catalyst for this process by a one-electron reduction of an initially added air-stable cupric species (Cu(II)/Ligand). Modulation of polymerization kinetics is thereby tunable in real time by varying the magnitude of applied potential. Application of multistep intermittent potentials successfully triggers initiation of polymerization and subsequently toggles the polymerization between dormant and active states in a living manner. Catalyst concentrations down to 50 parts per million are demonstrated to maintain polymerization control manifested in linear first-order kinetics, a linear increase in polymer molecular weight with monomer conversion, and narrow polymer molecular weight distributions over a range of applied potentials. 相似文献
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番茄黄化曲叶病毒病 (TYLCD)是由烟粉虱作为唯一传播途径传播的具有暴发性、毁灭性病毒病害。在陕西渭南、西安、咸阳、延安发生严重,平均发病株率 78.2%,产量平均降低32.5%。以越夏茬栽培为害造成损失最大,发病株率平均94.8%,产量平均降低74.0%。通过多年试验示范,总结提出番茄黄化曲叶病毒病防治策略。集成适合陕西省不同种植茬口防控技术体系,即早春茬番茄采取调整播期,越夏茬番茄采取选、阻、诱、遮、避技术组合,秋延茬采取选、阻、诱、避技术组合,越冬茬采取阻、诱、避技术组合,均能有效控制不同茬口番茄黄化曲叶病毒病的为害,实现了番茄黄化曲叶病毒病可防可控的目标。 相似文献
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杨张利 《西南大学学报(自然科学版)》2018,40(8):172-176
针对车用燃气发动机空燃比难于实时精确控制,探讨了一种最优空燃比融合控制策略.首先分析了燃烧室的控制论特性,研究了优化的控制策略,基于HSIC动静态特性与误差特征识别模型,构造了基于HSIC控制算法.在Matlab环境下,分别采用基于仿人智能融合控制与Smith最优PID控制的算法作了仿真对比研究,系统响应验证了融合控制算法优于Smith最优PID控制策略.仿真结果表明,采用融合控制算法实现对燃气发动机的最优空燃比控制是合理与可取的. 相似文献
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Observations of tidal flow over a sill show that upstream solitary wave generation occurred in conjunction with the downstream movement of a streamline bifurcation over the obstacle crest. Solitary waves appeared upstream of the bifurcation, riding on the surface stratification. Shear flow instabilities on the plunging interface were also evident and may contribute to wave generation through subharmonic interaction. Nonlinear waves generated downstream of an internal control became trapped in the supercritical flow. 相似文献
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热媒——水换热器水侧的腐蚀与缓蚀剂 总被引：2，自引：0，他引：2
输油站热媒－－水换热器的循环水因含氯离子、高溶解氧及高度和流速等的作用，引起民循环管网严重的腐蚀和结垢。根据实地调查分析，研制出缓蚀阻垢剂ＩＭＣ－５０－Ｓ。该水质缓剂选用了在水介质中缓蚀性能优良的无机缓蚀组分和有机膦酸盐为主要缓蚀阻垢成为，可在表面形成保护膜，有效地抑制金属的腐蚀。同时，ＩＭＣ－５０－Ｓ还具有较镐的热稳定怀和适应ＰＨ值的能力，在高温和较宽ＰＨ范围均有良好的阻垢效果，分析了输油站循环 相似文献
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We present an analysis of the current foot-and-mouth disease epidemic in Great Britain over the first 2 months of the spread of the virus. The net transmission potential of the pathogen and the increasing impact of control measures are estimated over the course of the epidemic to date. These results are used to parameterize a mathematical model of disease transmission that captures the differing spatial contact patterns between farms before and after the imposition of movement restrictions. The model is used to make predictions of future incidence and to simulate the impact of additional control strategies. Hastening the slaughter of animals with suspected infection is predicted to slow the epidemic, but more drastic action, such as "ring" culling or vaccination around infection foci, is necessary for more rapid control. Culling is predicted to be more effective than vaccination. 相似文献
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佳多频振式杀虫灯对水稻害虫的控制作用研究 总被引：6，自引：0，他引：6
应用佳多频振式杀虫灯对水稻害虫进行诱集,结果表明该杀虫灯可诱集到30种左右的昆虫,对主要水稻害虫均有诱集作用。通过将灯控施药区、灯控不施药区、非灯控施药区、非灯控不施药区4种处理防治效果进行对比,发现灯控施药区与灯控不施药区防效差异不显著,防效均达80％以上,而与非灯控不施药区差异显著。此杀虫灯虽对天敌有一定诱集作用,但对害虫的综合防治效果明显。通过对4个处理地的水稻产量比较及灯诱与化防成本计算,该杀虫灯具有成本低、无污染的优势,可用于水稻害虫的防治。 相似文献
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闽豆6号是以浙2818为母本、闽豆1号为父本进行有性杂交,经系选而成的菜用大豆新品种;在福建省2010-2011年的多点区域试验中,该品种表现高产、稳产,适应性广,抗逆性强,鲜荚平均产量达9 568.20kg·hm~(-2),比对照增产8.85%,标准荚平均产量达5 497.50kg·hm~(-2),比对照增产4.31%;在2012年生产试验中鲜荚平均产量达10 742.55kg·hm~(-2),比对照增产15.86%;2013年4月通过福建省农作物品种审定委员会审定(闽审豆2013001),适合在福建省大部分地区种植。 相似文献
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2013年广东省花生品种区域试验 总被引：1，自引：0，他引：1
2013年广东省花生品种区域试验由广东省种子管理总站、广东省农作物技术推广总站组织指导,广东省农科院作物研究所主持实施.共有10个新品种参试,设汕油523为对照种,全省共10个试验点承担本年度试验.10个参试品种有7个品种比对照种汕油523增产,3个品种比对照种减产.其中,汕油诱1号、仲恺花44、汕油辐1号、仲恺花99、粤油18、粤油390比对照种增产均达到极显著水平,湛油53增产不显著,仲恺花332、粤油410两个品种减产未达显著水平,花育33号比对照种减产达到极显著水平.推荐粤油390、汕油辐1号、汕油诱1号和仲恺花99共4个品种参加广东省农作物品种审定. 相似文献
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禽流感是重要的人畜共患性疾病，威胁着全世界人和动物的健康。世界卫生组织预测该病在未来可能会引起大流行。本文综述了近年来禽流感发生和流行的特点和动态，并对防控对策进行了讨论，提出对该病防控的未来方向。 相似文献
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2013年广东省花生品种区域试验由广东省种子管理总站、广东省农作物技术推广总站组织指导,广东省农科院作物研究所主持实施。共有10个新品种参试,设汕油523为对照种,全省共10个试验点承担本年度试验。10个参试品种有7个品种比对照种汕油523增产,3个品种比对照种减产。其中,汕油诱1号、仲恺花44、汕油辐1号、仲恺花99、粤油18、粤油390比对照种增产均达到极显著水平,湛油53增产不显著,仲恺花332、粤油410两个品种减产未达显著水平,花育33号比对照种减产达到极显著水平。推荐粤油390、汕油辐1号、汕油诱1号和仲恺花99共4个品种参加广东省农作物品种审定。 相似文献
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为明确迷向处理对梨小食心虫的防治效果,为生产中的合理使用提供理论依据,选用澳大利亚BioGlobal公司产梨小食心虫迷向丝和中国科学院动物所产梨小食心虫迷向诱芯在陕西省梅县桃园进行了迷向防治试验。结果表明,迷向丝和迷向诱芯对梨小食心虫均有明显的迷向和防治效果。迷向处理96 d后,各处理的迷向率都在90%以上,防效均在64%以上,且迷向丝和迷向诱芯不同处理间迷向和防效均无显著差异。据此建议生产上使用255条.hm-2迷向丝或450只.hm-2迷向诱芯更为经济。 相似文献