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基于交通流特性分析的高速公路复杂路段改扩建方案研究

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公路 2024年第7期69卷 262-268页

作者：谢可李锋利中交第二公路勘察设计研究院有限公司武汉市430056

交通流是公路设计的重要参数和服务对象,当前部分公路通车后出现局部拥堵、事故频发的现象,究其原因就是公路供给能力与交通需求不匹配。提出基于交通流特性分析的高速公路复杂路段改扩建方案研究思路,重点分析拟建道路交通流的总量特... 详细信息

交通流是公路设计的重要参数和服务对象,当前部分公路通车后出现局部拥堵、事故频发的现象,究其原因就是公路供给能力与交通需求不匹配。提出基于交通流特性分析的高速公路复杂路段改扩建方案研究思路,重点分析拟建道路交通流的总量特性、时间特性、OD特性、车型构成特性和速度特性等,并针对性应用于改扩建方案研究,以期提供高效、安全、匹配的交通服务。以广深高速改扩建工程太平立交至五点梅立交段为例,逐项分析了路段交通流特性,提出了针对性的改扩建方案。相较以往主要依靠控制因素来确定扩建方案的方法相比,基于交通流特性分析确立的改扩建方案能更好地适应交通需求,减少交通事故发生率,提高道路通行质量和通行能力。

关键词：高速公路交通流特性改扩建方案复杂路段分车道与分车型组合限速广深高速改扩建项目

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互通式立体交叉与土地综合开发融合方案研究

公路 2024年第7期69卷 252-255页

作者：李锋利唐登科中交第二公路勘察设计研究院有限公司武汉市430056

广深高速沿线互通密集,大部分互通占地面积大,深挖潜力巨大。以道滘互通为例,通过方案研究,实施交通优化、改善提升出行条件、提高土地使用效率,实现集约节约用地和综合开发。

关键词：高速公路改扩建项目互通立交土地释放综合开发

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预应力超高性能混凝土工字形梁抗剪性能试验

科学技术与工程 2024年第3期24卷 1242-1250页

作者：李伟东邹德强潘泽宇李立峰齐瑞中国建筑第五工程局有限公司长沙410004 湖南大学土木工程学院长沙410082

为了研究预应力超高性能混凝土(ultra-high performance concrete,UHPC)工字形梁的抗剪性能和抗剪承载力计算方法,设计并完成了3片预应力UHPC工字形梁的单点加载试验,获得了试验梁的荷载-位移曲线、破坏模式和裂缝分布特征等关键结果;... 详细信息

为了研究预应力超高性能混凝土(ultra-high performance concrete,UHPC)工字形梁的抗剪性能和抗剪承载力计算方法,设计并完成了3片预应力UHPC工字形梁的单点加载试验,获得了试验梁的荷载-位移曲线、破坏模式和裂缝分布特征等关键结果;基于试验结果,结合法国UHPC规范、瑞士UHPC规范、中国公路桥梁规范及公路桥涵超高性能混凝土应用规范意见稿计算了试验梁的抗剪承载力,分析了各个规范的适用性。此外,基于修正压力场理论(modified compression filed theory,MCFT),分别采用Mohr-Coulomb准则和Rankine准则,计算了试验梁的抗剪承载力,并进行了分析讨论。研究表明:预应力UHPC工字梁的抗剪承载力随着剪跨比的增加而减小,箍筋对于抗剪承载力影响较大;各国规范对UHPC梁的抗剪承载能力的计算较为保守。采用Mohr-Coulomb准则的计算结果较Rankine准则的计算结果与试验值更为接近;特别是小剪跨比的试验梁,处于弯剪复合状态,Mohr-Coulomb准则考虑了受压区UHPC法向和切向应力的影响,更为接近实际状况。

关键词：桥梁工程超高性能混凝土工字梁 MCFT 抗剪承载力

牛奶蛋白过敏婴儿肠道菌群特异性变化及短链脂肪酸水平分析

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中国当代儿科杂志 2024年第3期26卷 236-243页

作者：于志丹岳玲玲王梓潓王睿孜李利锋张万存李小芹郑州大学附属儿童医院/河南省儿童医院郑州儿童医院消化内科/郑州市儿童消化疾病重点实验室河南郑州450018

目的探索牛奶蛋白过敏(cow's milk protein allergy,CMPA)患儿肠道菌群及短链脂肪酸水平的变化,明确其在CMPA中的作用。方法纳入2019年8月—2020年8月在郑州大学附属儿童医院就诊的25例CMPA婴儿作为CMPA组,同时选取25例正常婴儿作为对... 详细信息

目的探索牛奶蛋白过敏(cow's milk protein allergy,CMPA)患儿肠道菌群及短链脂肪酸水平的变化,明确其在CMPA中的作用。方法纳入2019年8月—2020年8月在郑州大学附属儿童医院就诊的25例CMPA婴儿作为CMPA组,同时选取25例正常婴儿作为对照组。收集两组婴儿粪便200mg,采用16SrDNA高通量检测技术和液相色谱质谱联用技术分别检测肠道微生物组成及其代谢产物的变化,并将微生物多样性与代谢产物进行联合分析。结果与对照组相比,CMPA组患儿肠道菌群结构发生变化,且α-多样性显著增加(P<0.001)。与对照组相比,CMPA组患儿肠道内厚壁菌门、梭状芽孢杆菌目、拟杆菌丰度显著降低,而梭菌科、支原体科、鞘脂单胞菌科丰度显著增加(P<0.001)。代谢组学检测发现,与对照组相比,CMPA组菌群代谢产物乙酸、丁酸和异戊酸水平显著下降,并与短链脂肪酸产生菌粪杆菌属、罗氏菌属等丰度呈正相关(P<0.05)。结论CMPA患儿肠道内菌群结构发生改变,微生物多样性增加,短链脂肪酸水平降低,可能导致肠道炎症反应增加。

关键词：牛奶蛋白过敏肠道菌群多样性短链脂肪酸婴儿

Preparation and anti atomic oxygen erosion properties of OPPOSS/PI composites

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International Journal of Minerals,Metallurgy and Materials 2013年第10期20卷 994-1000页

作者： Wei-ping li Hui-cong liu li-li feng School of Materials Science and Engineering Beihang University Key Laboratory of Urban Stormwater System and Water Environment (Ministry of Education) Beijing University of CivilEngineering and Architecture

Atomic oxygen （AO） found in low earth orbit can cause serious erosion to polyimide （PI） materials, which greatly limits their lifetime. 8-phenyl silsesquioxane （OPPOSS） was synthesized, and OPPOSS/PI composites were pre- pared by physical blending, followed by thermal imidization to enhance the AO erosion resistance of PI materials. The morphology, composition, and structure of the composites were analyzed before and after AO exposure in a ground sim- ulated facility of atomic oxygen. After 16 h AO exposure, the OPPOSS/PI composite with 5wt% OPPOSS addition shows an erosion rate of about 1.4×10-24 cm3/atom with only 48% mass loss of that of PI without OPPOSS addition. The mixture of OPPOSS nano molecules is assembled into a kind of regular square structure and distributed evenly in OPPOSS/PI composites. Some SiO2 particles are formed in the composites during AO exposure, which can act as ＂inert points＂ to reduce the AO erosion rate of OPPOSS/PI composites.

关键词： composite materials polyimides silsesquioxanes atomic oxygen erosion

The Effects of Metal Ions and Secondary ligands on the Formation of Structures Resulted from Flexible Building Blocks

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Chinese Journal of Structural Chemistry 2005年第12期24卷 1462-1467页

作者： li feng li Tao-Hai CAO Rong State Key Laboratory of Structural Chemistr3 Fujian Institute of Research on the Structure of Matter The Chinese Academy of Sciences Fujian Fuzhou 350002 China

Two coordination polymers have been synthesized from cpg/4,4＇-bipy/metal ions reaction system, [Zn（cpg）（4,4＇-bipy）0.5（H2O）]·H2O 1 and [Cd（cpg）（4,4＇-bipy）0.5（H2O）2]·H2O 2. X- ray analyses show that different coordination geometries of zinc and cadmium ions lead to similar ladder structures （tetra-for zinc ion and hexa- for cadmium ion）, in which all the flexible cpg molecules exist as single conformations of anti-form.

关键词： hydrothermal synthesis flexible ligand prediction

Study on the Urban and Rural Cultural Conflict and Fusion in Novels

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学术界 2014年第8期 259-264页

作者： li li feng Wenlou College of Humanities Xi' an International University Xi' an shaanxi 710077

From the distinct boundary consciousness contrast between rural and urban areas as two fields,the social life portrayals in Chinese novels are *** Chinese novels,however,great importance is attached to the rural novels,while urban novels are thought lightly;the mainstream is rural novel,while urban novel is turned into only a *** the long development period of the novels,the conflict between the urban and rural different cultures is *** expression to different fields in rural and urban novels and the conflict between the rural and urban cultures in novels are analyzed,and finally the fusion of the urban and rural relationship in the novels during this period is introduced.

关键词：文化冲突城乡关系小说城市地区社会生活城市文化农村中国

Novel Kinetic Method for Expressing the Ability of Antioxidant to Scavenge Radicals

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Chemical Research in Chinese Universities 2013年第5期29卷 947-951页

作者： li Yan-feng li Pei-ze liU Zai-qun Department of Organic Chemistry College of Chemistry Jilin University Changehun 130012 t~ R. China

A method was developed to treat the result from an antioxidant trapping radicals including 2,2＇-azinobis （3-ethylbenzothiazoline-6-sulfonate） cationic radieal（ABTS＋＇）, 2,2＇-diphenyl-l-picrylhydrazyl radical（DPPH）, and galvinoxyl radical. In the presence of a certain concentration of an antioxidant, the decrease of the concentration of a kind of radicals follows the second order exponential function with the increase of the reaction time（t）, v＆., [radical]=Ae-t/a＋Be rib＋c, the derivation operation of which obtains the differential style, -d[radical]/dt= （A/a）e t/a＋（B/b）e-t/b, revealing the relationship between the reaction rate（r=-d[radical]/dt） and the reaction time（t）. Thus, the reaction rate at the beginning of the reaction@0） can be calculated by assigning t=-0 in the equation of -d[radical]/dt-t. Based on the concept of the reaction rate, r=k[radical][antioxidant], the rate constant（k） can be calculated based on r0 and the initial concentrations of radical and antioxidant, k=-r0/（[radieal]o[antioxidant]0）. The k means the rate of a fresh antioxidant molecule to trap a fresh radical. This method was used to treat the interactions of ABTS＋＇, DPPH, and galvinoxyl radicals with three homoisoflavonoids, four pyrazoles, and three ferrocenyl Schiff bases. It was found that ferrocenyl group is beneficial for antioxidants to reduce ABTS＋＇, and ortho-hydroxyl group is beneficial for antioxidants to donate hydrogen atom in phenolic hydroxyl group to DPPH and galvinoxyl radicals.

关键词： Rate constant Radical-scavenging ability Antioxidant capacity Chemical kinetics

An efficient synthesis of 3-(guaiazulene-1-yl)succinimides by addition of guaiazulene to maleimides

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Chinese Chemical Letters 2011年第7期22卷 789-792页

作者： Dao lin Wang Shao Fei li Wei li Yuan feng li li Nan lin Key Laboratory of Synthesis & Application of Functional Compound College of Chemistry & Chemical Engineering Bohai University Jinzhou 121001 China

A facile, efficient synthesis of 3-（guaiazulen-l-yl）succinimides was developed by Michael-type addition of guaiazulene to maleimides in the presence of p-toluenesulfonic acid under mild reaction conditions.

关键词： Guaiazulene Succinimidcs Michael-type addition p-Toluenesulfonic acid