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Search Results: 1 - 10 of 250351 matches for " 刘汉勇 "
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冻融循环后粉煤灰陶粒混凝土定侧压下的强度和变形性能试验研究
王立成,
工程力学 , 2007,
Abstract: 利用混凝土静、动三轴试验系统,完成了粉煤灰陶粒混凝土立方体试件在4组不同冻融循环次数、4种恒定侧压下的双轴压压强度和变形性能试验。考察了不同侧压应力水平下试件的破坏形态和试件表面裂缝分布及走向特征。测量了4种侧压应力水平下的极限抗压强度及两个加载方向的应变值,并根据试验结果系统分析了定侧压下粉煤灰陶粒混凝土双轴压压极限强度和变形性能(包括峰值应变、应力-应变关系曲线、弹性模量)随冻融循环次数和侧压应力水平的变化规律,建立了考虑冻融循环次数和侧压应力水平的主应力空间的双轴压压强度准则,为寒冷海洋环境条件下粉煤灰陶粒混凝土结构在经受双轴压压荷载作用时的强度分析提供试验和理论依据。
研究催化剂内表面特性的新工具-正电子寿命谱
戚盛,
催化学报 , 1987,
Abstract: ?
钢纤维轻骨料混凝土抗冲击性能试验研究与统计分析
王立成,王海涛,
大连理工大学学报 , 2010, DOI: 10.7511/dllgxb201004015
Abstract: 对5组钢纤维体积掺量分别为0、0.5%、1.0%、1.5%、2.0%的钢纤维轻骨料混凝土圆饼试件进行了自由落锤冲击试验.试验结果表明钢纤维的掺入可以提高轻骨料混凝土的抗冲击性能,而且钢纤维的体积掺量越多,提高效果越明显.由于试验结果具有较大的离散性,借助数理统计的方法对试验结果进行分析,研究随着钢纤维掺量的改变,钢纤维轻骨料混凝土抗冲击性能的变化规律.采用对数正态分布和两参数的威布尔分布分别对5组钢纤维轻骨料混凝土的抗冲击性能进行概率分布拟合,拟合结果表明,对数正态分布和两参数威布尔分布均能很好地描述不同掺量钢纤维轻骨料混凝土的抗冲击性能.最后,采用两种分布拟合了钢纤维轻骨料混凝土的抗冲击性能方程.
鬼鮋人工育苗技术研究

上海海洋大学学报 , 2005,
Abstract: 研究了鬼人工催产、受精卵孵化、饵料系列的选择以及仔、稚、幼鱼的生态习性,并对其胚胎发育进行了连续观察。使用激素lrha3和hcg的人工催产、人为条件下的受精卵孵化和仔、稚、幼鱼培育,经35d的人工育苗共获得了平均全长2.1cm左右的鬼幼鱼11.025万尾,受精卵平均孵化率为62.9%,育苗平均成活率达30.2%。结果表明提高海水盐度能提高鬼受精卵的孵化率,轮虫、卤虫、桡足类是鬼仔、稚、幼鱼的优质饵料,仔、稚、幼鱼有两个死亡高峰期,水质好坏是影响育苗成活率高低的主要因素。
麦长管蚜和禾谷缢管蚜对小麦挥发物的触角电位反应
,,陈巨莲,
昆虫学报 , 2003,
Abstract: 采用活体蚜虫测定法,利用EAG技术比较分析了麦长管蚜Sitobionavenae和禾谷缢管蚜Rhopalosiphumpadi有翅及无翅成蚜对小麦挥发物及麦蚜取食诱导挥发物组分的嗅觉反应,揭示了两种麦蚜的嗅觉变异特点。结果表明:麦长管蚜对水杨酸甲酯、反-2-己烯醛、反-2-己烯醇、-6-甲基-5-庚烯-2-酮和-6-甲基-5-庚烯-2醇的反应较强,禾谷缢管蚜对水杨酸甲酯、反-3-己烯乙酸酯、-6-甲基-5-庚烯-2-酮和-6-甲基-5-庚烯-2-醇的反应较强,并得到了剂量反应曲线。麦长管蚜的有翅和无翅成蚜对6-甲基-5-庚烯-2-酮、反-2-己烯醇和水杨酸甲酯的反应差异显著;禾谷缢管蚜的有翅和无翅成蚜对反-2-己烯醇、辛醛、里那醇、水杨酸甲酯和反-3-己烯乙酸酯的EAG反应差异显著,其原因与禾谷缢管蚜迁移及转主为害的生物学特性有关。
Q345高周疲劳失效机理及固有耗散能研究
,黄志,王清远
- , 2017, DOI: 10.15961/j.jsuese.201700303
Abstract: 中文摘要: 双相钢Q345多用于建筑或机械结构的承力构件,循环载荷的长期作用使得构件在低于其静强度的载荷条件下发生疲劳断裂,经济可靠的强度设计需要对材料的疲劳失效进行研究。作者利用电磁谐振高频疲劳试验机,在载荷频率140 Hz、应力比为-1条件下,得到不同失效概率时材料高周疲劳(10 4周次< 疲劳寿命< 10 7周次)应力-寿命( S-N)曲线。利用扫描电子显微镜观察材料受到循环载荷作用后的显微结构的变化和疲劳失效后试样的断面微观形貌,研究材料疲劳裂纹的萌生和扩展。同时,利用红外热像仪记录Q345试样表面的温度场随循环载荷作用周次的变化,研究材料在高频循环载荷作用下的固有耗散能。双相钢Q345在高频循环载荷作用下的疲劳失效主要是由于铁素体-珠光体双相结构在循环载荷作用下的微观强度差异使得微观裂纹首先萌生于相对薄弱的铁素体晶粒,且随循环载荷周次的增加而裂纹逐渐扩展。珠光体晶粒对疲劳裂纹的扩展起阻碍作用,使得疲劳裂纹沿铁素体或铁素体与珠光体之间的晶界向前扩展。当载荷幅值低于其高周疲劳极限时,试样表面温升不明显;有限寿命的载荷条件下,试样表面温度场的变化受到材料微观变形的影响,基于试样表面温度场的变化,能快速确定材料的高周疲劳强度极限。高频循环载荷作用下,单位体积材料的固有耗散能与载荷之间呈非线性关系,在热力学框架内建立了材料的固有耗散能表征模型。
Abstract:Q345 is a kind of ferrite and pearlite dual phase steel that is widely used on bearing force components in architectural structures and mechanical systems,the long term dynamic loading during their service life induces the fatigue fracture under the stress amplitude that far below the tensile strength of the material,which require the study of the fatigue failure of the material.The conventional fatigue test was carried out with the help of electromagnetic resonance fatigue test machine (140 Hz) to study the fatigue failure of Q345,the stress-life ( S-N) curve of Q345 was collected in high cycle fatigue regime.The initiation and propagation of the cracks of Q345 under cyclic loading was studied by the scanning electron microscope (SEM),and the intrinsic dissipation energy during the fatigue failure of the material was investigated with the help of infrared camera additionally.The fatigue failure of low carbon steel Q345 under high frequency cyclic loading was induced by the micro cracks initiated from ferrites grains.The propagation of the micro cracks was influenced by the micro structure of the material,and apt to propagate along the ferrite grains and the grain boundaries,but could be easily hampered by the presents of pearlite grains in the crack tip.The presence of pearlite grains helped retard crack propagation,which made the fatigue crack tortuous.The variation of the temperature field was not distinct until the stress amplitude was higher than the fatigue limit in the high cycle fatigue regime,therefor,the fatigue limit can be quickly determined based on the temperature variation of the specimen surface under the cyclic loading.Furthermore,a model was established in thermodynamics framework to characterize the intrinsic dissipation energy of the material under high frequency cyclic loading, and the result showed that the relation between intrinsic dissipation energy of unit volume material and limited fatigue life loading presented to be nonlinearly.
用离子色谱法测定丙烯中痕量碱性氮化物
,樊立民,,吴志
分析化学 , 1995,
Abstract: 采用化学反应浓缩技术,将丙烯中痕量碱性氮化物转变为水溶性的阳离子,用离子色谱法进行测定.该法准确度高,操作简便,可测定丙烯中10-9g/L的碱性氮化物,也可用于炼油厂及其它环境气氛中碱性氮化物的测定.
我国非营利组织营利活动的税收优惠问题浅探
On the Problem of Preferential Tax on NGO’s Prof-it-Making Activities in China
 [PDF]


Open Journal of Legal Science (OJLS) , 2013, DOI: 10.12677/OJLS.2013.13003
Abstract:
非营利组织是社团革命、社会管理民主化的产物。但因为我国法律上没有明确划分“营利组织”与“非营利组织”的界限,在实践中非营利组织有各种名称,为维持运营,非营利组织也会从事营利性活动,对此,法律并无禁止性规定。因此,主张加大非营利组织的优惠力度,不论其从事营利性还是非营利性活动都给与税收优惠,可能违背税收优惠政策的初衷。本文提出应从静态的资格优惠转向动态的行为优惠,以营利活动是否体现组织的非营利目的为标准来确定税收优惠政策在非营利组织营利性活动方面的适用。
The non-profit organization (hereinafter referred to as NGO) is a product of society revolution and social democratic management. However, being no clear division of “for-profit organization” and “non-profit organization” in laws, NGOs have a variety of names in practice. In reality, non-profit organization engages in profit-making activities in order to maintain its operation. However, there are no legal provisions for that. Therefore, the opinion that NGOs should be given preferential tax regardless of its engaging in for-profit or non-profit activities may violate the intention of preferential tax policy intention. This paper believes that the preferential tax policy for NGOs should be turned from static qualification concessions to dynamic behavior of preferential, and as far as profit-making activities of NGOs are concerned, the application of preferential tax policy should depend on whether their profit-making activities reflect the aim of non-profit organizations.
三苯基锡4-吡啶甲酸酯的合成、性质和晶体结构有机化学
,王传华,,马春林,国富
有机化学 , 2002,
Abstract: 用三苯基氯化锡与4-吡啶甲酸钠反应,合成了三苯基锡4-吡啶甲酸酯,并进行了红外光谱、核磁共振氢谱及质谱表征。X射线单晶衍射表明,化合物属单斜晶系,空间群P21,晶胞参数:a=1.6629(3)nm,b=104987(4)nm,c=2.4318(7)nm,β=90.040(5)°,Z=8,Dc=1.1529g/cm^3,R1=0.0543,wR2=0.1086。化合物的晶体是由两个结构相似但键长和键角不同的独立分子所组成,且每个分子含有两种化学环境不同的锡原子。它们通过4-吡啶甲酸配体的氮原子桥联,形成五配位三角双锥构型的一维无限链聚合物。
三苯基锡2-噻吩甲酸酯的合成、性质和晶体结构有机化学
,朱德忠,,马春林,国富
有机化学 , 2002,
Abstract: 用三苯基氯化锡与2-噻吩甲酸钠反应,合成了三苯基锡2-噻吩甲酸酯,并进行了红外光谱、核磁共振氢谱及质谱表征。X射线单晶衍射表明,化合物属单斜晶系,空间群P21/n,晶胞参数:a=1.3429(7)nm,b=1.11773(6)nm,c=1.4241(8)nmβ=116.519(6)°,V=2.0146(18)nm^3,Z=4,Dc=1.573g/cm^3,R1=0.0391,Wr2=0.0943。该化合物的晶体是由孤立的分子所组成,四配位的锡原子呈畸变的四面体构型,配体噻吩环上的硫原子和锡原子之间存在弱的配位作用。
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