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农村劳动力转移对县域劳动生产率的影响

安徽农业科学 2024年第16期52卷 173-177页

作者：欧阳博强刘浩韶关学院商学院广东韶关512005 韶关学院粤北乡村振兴研究中心广东韶关512005

县域经济增长的关键在于生产要素的积累及其效率提升。农村劳动力的乡县转移会促进劳动要素在各部门重新配置,有助于转变发展方式和调整经济结构,是县域要素生产率提升的重要推手。分析了农村劳动力转移对县域劳动生产率的影响,并利用... 详细信息

县域经济增长的关键在于生产要素的积累及其效率提升。农村劳动力的乡县转移会促进劳动要素在各部门重新配置,有助于转变发展方式和调整经济结构,是县域要素生产率提升的重要推手。分析了农村劳动力转移对县域劳动生产率的影响,并利用粤东西北县区的统计数据,建立计量模型对其进行了实证检验。结果表明:农村劳动力转移对县域劳动生产率具有显著的积极影响,且对非农部门劳动生产率的影响程度大于农业部门,同时根据县级市和非县级市进行分组检验的结果依然稳健。为进一步促进县域经济发展,从增强县域经济发展动能、积极推进农业转型发展、持续提高要素生产效率等方面给出了具体建议。

关键词：农村劳动力转移劳动生产率县域经济

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LHAASO discovery of highest-energy photons towards new physics

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Science Bulletin 2021年第22期66卷 2254-2256,M0003页

作者： Chengyi Li bo-qiang Ma School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China Center for High Energy Physics Peking UniversityBeijing 100871China Collaborative Innovation Center of Quantum Matter Beijing 100871China

Ultrahigh-energy(UHE)photons up to 1.4 peta-electronvolts have been observed by new cosmic-ray telescope in China[1]–a hint that Lorentz invariance might break down at the Planck-scale level[2].As one of the most sensitive gamma-ray detector arrays currently operating in the UHE band,the Large High Altitude Air Shower Observatory(LHAASO)recently reported large numbers of gamma-ray photons with energies larger than 100 TeV from twelve cosmic accelerators within the Milky Way[1],including the most high-energetic c-ray detected at about 1:4 *** observation of such high-energy lights from space can be used not only to investigate the long-lasting puzzle of the origin of UHE cosmic rays and their acceleration mechanism in the extreme regions of the Universe,but can provide also the unique and crucial opportunity in testing fundamental concepts of physics,such as one basic symmetry underlying Einstein’s relativity–Lorentz invariance[2].

关键词： Lorentz invariance symmetry

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土质边坡数值模型稳定性的求解精度研究

公路交通科技 2024年第1期41卷 71-78页

作者：武博强王勇张葆永程振全杨德宏中交第一公路勘察设计研究院有限公司陕西西安710065 中铁第一勘察设计院集团有限公司陕西西安710043

为尽可能提高土质边坡模型在数值模拟求解过程中的精度,在前人研究的基础上引申了3个影响边坡模型稳定性精度的主要问题,一是模型边界尺寸应该如何确定,二是初始应力场的求解方法应该如何选择,三是边坡模型的网格划分应遵循什么原则可... 详细信息

为尽可能提高土质边坡模型在数值模拟求解过程中的精度,在前人研究的基础上引申了3个影响边坡模型稳定性精度的主要问题,一是模型边界尺寸应该如何确定,二是初始应力场的求解方法应该如何选择,三是边坡模型的网格划分应遵循什么原则可以满足模型的计算精度。基于此,以多个学者研究的典型边坡案例为研究对象,采用FLAC3D对以上3个问题进行了分析并解决。首先,讨论了目前模型边界尺寸确定存在的问题,引入数值模型的复合位移作为判据之一与边坡稳定系数共同确定新的模型边界尺寸原则,在前人基础成果上对边界尺寸原则进行了局部优化,精简了计算模型,并通过实例验证其正确性;其次,讨论了目前初始应力场搭建存在的问题,通过模型稳定系数云图、塑性区应变增量、坡顶位移综合分析弹性求解与弹塑性求解初始应力场的区别,确定了不同的适用情况;最后,分析了目前网格尺寸划分存在的问题,建立不同高度不同网格密度的边坡模型,确定了一种较为合理的网格划分原则。以上3种情况均采用大量边坡模型进行了准确性验证,并采用极限平衡法中的Corps of Engieers#1法及Bishop法作为校核,结果显示,边坡模型计算结果与极限平衡法计算结果极为接近,并且复合位移、最大剪应变增量等判据均满足应力应变分布规律,在一定程度上提高了土质边坡模型在数值模拟求解过程中的精度,具有普遍适用性。

关键词：道路工程精度研究 FLAC3D 土质边坡边界尺寸初始应力场

Preparation of Exfoliated Low-density Polyethylene/Montmorillonite Nanocomposites Through Melt Extrusion

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Chemical Research in Chinese Universities 2006年第3期22卷 383-387页

作者： YANG Hong-mei SONG Yi-hu XU bo ZHENG qiang Department of Polymer Science ＆ Engineering Key Laboratory of Macromolecule Synthesis and Functionalization of MOE Zhejiang University Hangzhou 310027 P. R. China

The effects of ethylene vinyl acetate copelymer （EVA） as a compatibilizer on the dispersion of organically modified montmorillonite（org-MMT） into low-density polyethylene（LDPE） during melt extrusion compounding were studied. The X-ray diffraction patterns reveal that as compared with LDPE, EVA can intercalate more easily into the interlay gallery of org-MMT when the composites contain a low org-MMT content. Exfoliated LDPE/org-MMT nanocompesites in the presence of an EVA compatibilizer could be prepared by using a two-step melt compounding technique with a twin-screw extruder.

关键词： Polyethylene Montmorillonite Nanocompesite Intercalation Exfoliation

SU(3) Breaking from Baryon-Meson Fluctuation in Baryon Magnetic Moments

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Chinese Physics Letters 2001年第2期18卷 190-192页

作者： CHEN Xiao-Lin MA bo-qiang ZU Dong-Lin Department of Physics Peking UniversityBeijing 100871 Department of Technical Physics Peking UniversityBeijing 100871

We investigate the effect of intrinsic sea quark-antiquark pairs on the magnetic moments of the SU(3)octet *** intrinsic quark-antiquark pairs are introduced by a model of energetically-favoured non-perturbative baryon-meson *** is shown that the baryon-meson fluctuation model provides a mechanism of SU(3)symmetry breaking in the baryon sea and is related to the violations of Gell-Mann-Okubo and Coleman-Glashow sum rules for the baryon magnetic *** a model is also consistent with its explanation of the violations of Gottfried and Ellis-Jaffe sum rules in deep inelastic scattering.

关键词： scattering SU(3) quark

Detection of Structural Damage Through Changes in Frequency

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Wuhan University Journal of Natural Sciences 2005年第6期10卷 1069-1073页

作者： ZHU Hong-ping HE bo CHEN Xiao-qiang School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 Hubei China

Among all the structural vibration characteristics, natural frequencies are relatively simple and accurate to measure, and provide the structural global damage informalion. In this paper, the feasibility of using only natural frequencies to identify structural damage is exploited by adopting two usual approaches, namely, sensitivity analysis and neural networks. S, ome aspects of damage detection such as the problem of incomplete modal test data and robustness of detection are considered. A laboratory tested 3 storey frame is used to demonstrate the possibility of frequency-based damage detection techniques. The numerical results show that the damaged element can be correctly localized and the content of damage can be identified with relatively high degree of accuracy by using the changes in frequencies.

关键词： damage detection changes in frequency sensitivity analysis neural network

Effect of chlorpyrifos on soil microbial populations and enzyme activities

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Journal of Environmental Sciences 2006年第1期18卷 4-5页

作者： SHAN Min FANG Hua WANG Xiao FENG bo CHU Xiao-qiang YU Yun-long Department of Plant Protection College of Agriculture and Biotechnology Zhejiang University Hangzhou 310029 China

Chlorpyrifos is an organophosphate pesticide that acts as an insecticide-acaricide by ingestion, contact, and inhalation, and is now widely used in greenhouse for the control of pests. The dissipation of chlorpyrifos in crops such as orange fruit （Martinez-Vidal et al., 1998）, tomatoes（Aysal et al., 1999）, soil and its effects on soil microbial characteristics （Singh et al., 2002） has been reported frequently. However, little information is available to describe impacts of chlorpyrifos on soil microbial population and enzyme activity in greenhouse. In this study, the effect of chlorpyrifos on soil bacteria, fungi, actinomycetes, and soil enzyme activity was investigated.

关键词： chlorpyrifos microorganism soil enzyme

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氧化铝晶型变化

广州化工 2024年第1期52卷 30-32页

作者：胡博强侯焕焕王建立中铝郑州有色金属研究院有限公司河南郑州450041

综述了铝酸钠溶液分解过程中氢氧化铝的各种晶型变化以及高温焙烧后生成的氧化铝的晶型及应用。工业上铝酸钠溶液的分解方式有种分和碳分,其中溶液的pH值、沉淀试剂的种类、添加剂、溶液的组成、温度等因素都会对氢氧化铝的性质有影响... 详细信息

综述了铝酸钠溶液分解过程中氢氧化铝的各种晶型变化以及高温焙烧后生成的氧化铝的晶型及应用。工业上铝酸钠溶液的分解方式有种分和碳分,其中溶液的pH值、沉淀试剂的种类、添加剂、溶液的组成、温度等因素都会对氢氧化铝的性质有影响。氧化铝的晶型分为九种,其中过渡相具有比表面积大、多孔隙结构等特点。α-Al_(2)O_(3)是氧化铝形态中最稳定的,通过控制不同的煅烧温度、加入不同的种类的添加剂、研磨方式等,生产出不同形貌的α-Al_(2)O_(3)。

关键词：铝酸钠溶液氢氧化铝机理氧化铝

Geochemical Forms of Phosphorus in Sediments of Three Large, Shallow Lakes of China

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Pedosphere 2006年第6期16卷 726-734页

作者： ZHU Guang-Wei QIN bo-qiang ZHANG Lu LUO Lian-Cong Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China

A sequential extraction method for the fractionation of phosphorus （P） in lake sediments was used to analyze phos- phorus fractions of sediments taken from three large, shallow. eutrophic freshwater lakes of China-Talhu Lake. Chaohu Lake, and *** Lake. All three lakes are located in the lower reaches of the Changjiang River （Yangtze River）. In Taihu Lake and Chaohu Lake, algae blooms occurred every year, while Longgan Lake was a macrophyte-dominated lake. Results showed that exchangeable phosphorus fractions were much higher in the eutrophic lake sediments than in the macrophyte-flourishing lake sediment. Also, the ratio of Fe：P in the sediments of the algae-predomlnant lakes was generally much lower than that in the macrophyte-predominant lakes. Thus, the geochemical fractions of phosphorus in sediments had a closer relationship with the type of aquatic vegetation.

关键词： algal bloom macrophyte phosphorus sediment shallow lakes