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超级中学垄断与城市内顶尖大学入学机会区域差异——基于北京市的实证研究

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北京社会科学 2024年第8期 103-114页

作者：吴宇川郭丛斌北京大学教育学院北京大学教育经济研究所

超级中学的发展壮大可能加剧城市内部顶尖大学入学机会的区域差异,不利于大型城市引导人口向郊区流动。基于对某顶尖大学A北京生源调查数据(2001—2021年)的分析发现,顶尖大学入学机会在北京市存在着明显的城郊差异,位于城区的超级中学... 详细信息

超级中学的发展壮大可能加剧城市内部顶尖大学入学机会的区域差异,不利于大型城市引导人口向郊区流动。基于对某顶尖大学A北京生源调查数据(2001—2021年)的分析发现,顶尖大学入学机会在北京市存在着明显的城郊差异,位于城区的超级中学与首位中学近年来分别垄断了A大学约40%与超过20%的生源;超级中学垄断降低了北京市一般高中学生的顶尖大学入学机会,但这种负面影响主要表现为对郊区一般高中学生顶尖大学入学可能性、顶尖大学生源密度及相对录取排名的冲击,城区一般高中所受影响并不明显。因此应该增加郊区优质教育资源投入,强化市级政府的资源统筹力度,同时也需要扩大优质高中的资源覆盖、加强郊区教师队伍建设、优化高中学校规划布局。

关键词：超级中学顶尖大学入学机会城郊差异

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Enhancing Na^(+) diffusion dynamics and structural stability of O3-NaMn_(0.5)Ni_(0.5)O_(2)cathode by Sc and Zn dual-substitution

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Transactions of Nonferrous Metals Society of China 2024年第10期34卷 3344-3357页

作者： bin-bin WANG Yi-ming FENG Xin LUO Qun HUANG Zi-xing HOU Ya-qin wu Peng-yu WANG yu-yang QI Qing-fei MENG Wei-feng WEI Liang-jun ZHOU State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Vital Material Co. Ltd.Guangzhou 510623China The 48th Research Institute of China Electronics Technology Group Corporation Changsha 410111China wuhan Zhongyuan Changjiang Technology Development Co. Ltd.Wuhan 430090China

Sc and Zn were introduced into O3-NaMn_(0.5)Ni_(0.5)O_(2)(NaMN)using the combination of solution combustion and solid-state *** effect of Sc and Zn dual-substitution on Na^(+) diffusion dynamics and structural stability of NaMN was *** physicochemical characterizations suggest that the introduction of Sc and Zn broaden Na^(+) diffusion channels and weaken the Na—O bonds,thereby facilitating the diffusion of sodium *** indicate that the Sc and Zn dual-substitution decreases the diffusion barrier of Na-ions and improves the conductivity of the *** dual-substituted NaMn_(0.5)Ni_(0.4)Sc_(0.04)Zn_(0.04)O_(2)(Na MNSZ44)cathode delivers impressive cycle stability with capacity retention of 71.2%after 200 cycles at 1C and 54.8%after 400 cycles at ***,the full cell paired with hard carbon anode exhibits a remarkable long-term cycling stability,showing capacity retention of 64.1%after 250 cycles at *** results demonstrate that Sc and Zn dual-substitution is an effective strategy to improve the Na^(+) diffusion dynamics and structural stability of NaMN.

关键词： layered oxide cathode Sc and Zn dual-substitution structural stability Na^(+)diffusion dynamics

Effect of integration of mechanical ball milling and flue gas desulfurization gypsum on dealkalization of bauxite residue

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Transactions of Nonferrous Metals Society of China 2024年第8期34卷 2702-2713页

作者： Feng ZHU Xu-yao GUO Jun JIANG Kai-bin CHEN Xuan-zhi ZHU Dan-dan DENG yu-jun wu yu-wei HUANG Sheng-guo XUE School of Metallurgy and Environment Central South UniversityChangsha 410083China Zhengzhou Non-ferrous Metals Research Institute Co. Ltd.of CHALCOZhengzhou 450041China College of Environment and Resources Xiangtan UniversityXiangtan 411105China School of Resources and Safety Engineering Central South UniversityChangsha 410083China

The synergistic impact of mechanical ball milling and flue gas desulfurization(FGD)gypsum on the dealkalization of bauxite residue was investigated through integrated analyses of solution chemistry,mineralogy,and *** results showed a significant decrease in Na_(2)O content(>30 wt.%)of FGD gypsum-treated bauxite residue after 30 min of mechanical ball *** ball milling resulted in differentiation of the elemental distribution,modification of the minerals in crystalline structure,and promotion in the dissolution of alkaline minerals,thus enhancing the acid neutralization capacity of bauxite residue.5 wt.%FGD gypsum combined with 30 min mechanical ball milling was optimal for the dealkalization of bauxite residue.

关键词： bauxite residue alkalinity regulation flue gas desulfurization gypsum mechanical activation soil formation of bauxite residue

随机干扰下拓扑时变Kuramoto网络事件触发固定时间同步

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控制理论与应用 2024年第1期41卷 1-10页

作者：孙佳贾玉斌武永宝董璐刘剑东南大学自动化学院江苏南京210096 东南大学网络空间安全学院江苏南京210096

本文针对一类网络拓扑时变且耦合通道存在随机干扰的Kuramoto型振子网络的同步问题,设计了事件触发机制下的固定时间控制算法.针对耦合网络的拓扑在切换中保持连通的假设,给出了一种具有多层结构的事件触发分布式控制策略,并能够抵消随... 详细信息

本文针对一类网络拓扑时变且耦合通道存在随机干扰的Kuramoto型振子网络的同步问题,设计了事件触发机制下的固定时间控制算法.针对耦合网络的拓扑在切换中保持连通的假设,给出了一种具有多层结构的事件触发分布式控制策略,并能够抵消随机干扰对同步性能带来的负面影响.利用随机Lyapunov稳定理论和固定时间稳定性理论给出了达到实际固定时间相位同步的控制参数条件和同步调节时间的上界.另外,证明了所使用的事件触发机制在引入双曲正切函数之后不会产生Zeno现象,并给出了触发间隔的下界.同时,在推论中给出了本文提出的控制方法也可以应对振子耦合拓扑图不连通情况的结论.最后,通过两组具有不同噪声强度的仿真实验验证了理论分析结果.

关键词： Kuramoto模型网络控制系统随机干扰固定时间同步事件触发控制切换网络

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智能反射面室内部署的位置规划方法

电子与信息学报 2024年第4期46卷 1314-1320页

作者：王文鼐耿心怡余锦涵吴炜王斌南京邮电大学通信与信息工程学院南京210003

智能反射面(IRS/RIS)应用于实际无线通信系统时,如何优选布放位置及面板取向,是提升技术实效所面临的主要问题之一。RIS布放的数学规划问题,不仅有优化目标的设计,还要考虑通信环境的建筑物分布和可选部署面的有效散射截面。相比于室外... 详细信息

智能反射面(IRS/RIS)应用于实际无线通信系统时,如何优选布放位置及面板取向,是提升技术实效所面临的主要问题之一。RIS布放的数学规划问题,不仅有优化目标的设计,还要考虑通信环境的建筑物分布和可选部署面的有效散射截面。相比于室外较为开放的空间,RIS的室内部署存在更多限制性条件。针对室内既有墙面的RIS布放,该文设计了多终端接入选址规划模型和等价问题。为约化其非线性计算,通过单终端退化分析,给出目标函数的卡西尼卵形线分布特征,证明RIS布放范围限于各终端及基站在部署面投影的重叠区,提出基于对半搜索法的高效启发式算法。数值仿真了2种复杂室内结构的多终端接入场景,结果表明所提算法不仅有显著加速效益,还可扩展用于多RIS网络规划。

关键词：智能反射面室内部署位置规划算法设计

香根草生物炭负载纳米零价铁去除Cr(Ⅵ)的吸附-还原-共沉淀机理

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环境科学学报 2024年第7期44卷 116-126页

作者：于亚慧吴斌郭舒雅李佳成都理工大学生态环境学院地质灾害防治与地质环境保护国家重点实验室成都610059

热解炭化是重金属富集植物后处理的一种有效途径.本研究以富集重金属后的植物香根草(Chrysopogon zizanioides)为原料,在不同温度下(300、400、500和700℃)裂解制备生物炭(HBC)用于负载纳米零价铁合成复合材料(HBC/nZVI),并探究其物化... 详细信息

热解炭化是重金属富集植物后处理的一种有效途径.本研究以富集重金属后的植物香根草(Chrysopogon zizanioides)为原料,在不同温度下(300、400、500和700℃)裂解制备生物炭(HBC)用于负载纳米零价铁合成复合材料(HBC/nZVI),并探究其物化特征和去除Cr(Ⅵ)的效果与机理.结果表明:在400℃下热解所得生物炭(HBC400)比热解温度在300、500和700℃时生成的生物炭展现出更好的孔隙度和形态结构,HBC400有效地抑制了纳米Fe0粒子的团聚.修复实验表明,HBC400/nZVI对Cr(Ⅵ)的去除率最高,当初始Cr(Ⅵ)浓度为50 mg·L^(-1)、pH=3和投加量为1.0 g·L^(-1)时,HBC400/nZVI对于Cr(Ⅵ)的去除率达到98.9%,吸附过程高度符合准二级动力学方程.FTIR和XPS等结果表明HBC400/nZVI主要通过吸附、还原和共沉淀过程去除Cr(Ⅵ).含氧官能团将Cr(Ⅵ)吸附在HBC400/nZVI表面后,Cr(Ⅵ)被Fe0粒子还原为Cr(Ⅲ),Cr(Ⅲ)和Fe(Ⅲ)会发生共沉淀以CrxFe1-x(OH)3和Fe(OH)3-Cr(OH)3形式附着于HBC400/nZVI表面.同时,整个反应过程中,生物炭中的Cd和Pb等金属离子未析出.本研究表明HBC/nZVI可安全用于处理Cr(Ⅵ)污染水体.

关键词：生物炭纳米零价铁六价铬去除机制

A pan-TE map highlights transposable elements underlying domestication and agronomic traits in Asian rice

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National Science Review 2024年第6期11卷 105-118页

作者： Xiaoxia Li Xiaofan Dai Huiying He Yang Lv Longbo Yang Wenchuang He Congcong Liu Hua Wei Xiangpei Liu Qiaoling yuan Xianmeng Wang Tianyi Wang bintao Zhang Hong Zhang wu Chen yue Leng Xiaoman yu Hongge Qian bin Zhang Mingliang Guo Zhipeng Zhang Chuanlin Shi Qianqian Zhang Yan Cui Qiang Xu Xinglan Cao Dandan Chen Yongfeng Zhou Qian Qian Lianguang Shang Shenzhen Branch Guangdong Laboratory of Lingnan Modern AgricultureGenome Analysis Laboratory of the Ministry of Agriculture and Rural AffairsAgricultural Genomics Institute at ShenzhenChinese Academy of Agricultural Sciences Rice Research Institute Shenyang Agricultural University Yazhouwan National Laboratory State Key Laboratory of Rice Biology China National Rice Research Institute National Key Laboratory of Tropical Crop Breeding Tropical Crops Genetic Resources InstituteChinese Academy of Tropical Agricultural Sciences

Transposable elements(TEs) are ubiquitous genomic components and hard to study due to being highly repetitive. Here we assembled 232 chromosome-level genomes based on long-read sequencing *** the 232 genomes with 15 existing assemblies, we developed a pan-TE map comprising both cultivated and wild Asian rice. We detected 177 084 high-quality TE variations and inferred their derived state using outgroups. We found TEs were one source of phenotypic variation during rice domestication and differentiation. We identified 1246 genes whose expression variation was associated with TEs but not single-nucleotide polymorphisms(SNPs), such as Os Rboh B, and validated Os Rboh B's relative expression activity using a dual-Luciferase(LUC) reporter assays system. Our pan-TE map allowed us to detect multiple novel loci associated with agronomic traits. Collectively, our findings highlight the contributions of TEs to domestication, differentiation and agronomic traits in rice, and there is massive potential for gene cloning and molecular breeding by the high-quality Asian pan-TE map we generated.

关键词： transposable element super pan-genome pan-TE rice

Research status and hotspots in transjugular intrahepatic portosystemic shunts based on CiteSpace bibliometric analysis

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World Journal of Gastrointestinal Surgery 2024年第9期16卷 2996-3007页

作者： Zeng-Long Que Ming-Song wu Shu-Jie Lai yu-Qin He Yin-bin Zhou Shun-Ping Gui Liang-Zhi Wen Department of Gastroenterology Daping HospitalArmy Medical University(Third Military Medical University)Chongqing 400042China Department of Infectious Diseases The 960 Hospital of PLAJinan 250031Shandong ProvinceChina Department of Obstetrics The First Affiliated Hospital of Chongqing Medical UniversityChongqing 400042China

BACKGROUND The transjugular intrahepatic portosystemic shunt(TIPS)is an important technique for treating complications related to portal hypertension in patients with cirrhosis,and the number of publications in the TIPS field continues to *** To facilitate an understanding of the research status and hotspots in the field of TIPS using CiteSpace bibliometric *** CiteSpace is a software that depicts the strength of relationships through graphics and connections with diverse functionalities and can be used to analyze the status and hotspots of areas of *** on TIPS in the Web of Science Core Collection were retrieved,and CiteSpace software was used to visualize and analyze the number of publications,journals,countries,institutions,authors,keywords,and *** A total of 985 relevant documents were included in the *** January 2013 to December 2022,the number of publications increased *** journal,institution,and author with the greatest number of publications in the field of TIPS are the Journal of Vascular and Interventional Radiology,the University of Bonn,and Jonel Trebicka,*** main keywords used in this field are“transjugular intrahepatic portosystemic shunt”,“portal hypertension”,“cirrhosis”,“management”,“stent”,“hepatic encephalopathy”,“refractory ascite”,“survival”,“risk”,and“variceal bleeding”.The greatest obstacle to TIPS placement is currently the occurrence of hepatic *** research hotspots are the mechanism,risk factors,management,and control of hepatic *** This bibliometric analysis reported the research status and hotspots of *** on postoperative hepatic encephalopathy is the research hotspot in this field.

关键词： Liver cirrhosis Transjugular intrahepatic portosystemic shunt CiteSpace Visualization Hotspots

漯河市典型工业源挥发性有机物源成分谱特征及影响

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环境科学 2024年第8期45卷 4484-4492页

作者：杜宇彬吴丽萍牛大伟冷海斌薛爽张楠杨文中国环境科学研究院北京100012 天津城建大学环境与市政工程学院天津300384 漯河市环境监控中心漯河462000

选取漯河市10类典型工业企业开展有组织排放挥发性有机物(VOCs)样品采集,分析各行业VOCs排放特征及其影响.结果表明,包装印刷行业排放VOCs以OVOC(60.9%)为主;工业涂装行业VOCs排放以芳香烃(42.4%)和OVOC(38.9%)为主;制鞋、家具制造和造... 详细信息

选取漯河市10类典型工业企业开展有组织排放挥发性有机物(VOCs)样品采集,分析各行业VOCs排放特征及其影响.结果表明,包装印刷行业排放VOCs以OVOC(60.9%)为主;工业涂装行业VOCs排放以芳香烃(42.4%)和OVOC(38.9%)为主;制鞋、家具制造和造纸行业的VOCs排放特征相似,以OVOC(32.3%~42.6%)和芳香烃(20.7%~33.7%)为主,且卤代烃排放也不容忽视;化工和制药行业排放的VOCs中卤代烃占比最高,分别为59.3%和46.6%;砖瓦制品行业的VOCs排放以烷烃为主(62.7%);热力生产与供应行业的VOCs排放特征以OVOC(48.5%)为主,其次为卤代烃(19.7%);食品制造行业的VOCs排放则以OVOC(48.1%)和烷烃(29.4%)为主.不同行业的VOCs特征物种存在差异,但整体上,丙酮、异丙醇、苯、甲苯、间/对-二甲苯、乙烷、乙醛和二氯甲烷是漯河市多数行业VOCs排放的特征物种.漯河市典型工业有组织排放的VOCs对臭氧生成潜势贡献较大的组分以OVOC和芳香烃为主,对二次有机气溶胶生成潜势较大的组分为芳香烃.食品制造和家具制造行业排放的VOCs生成O_(3)的源活性因子[SR(O_(3))]较高,分别为3.7g·g^(-1)和3.5 g·g^(-1);工业涂装、家具制造和制鞋行业排放的VOCs生成二次有机气溶胶的源活性因子[SR(SOA)]较高,分别为0.021、0.017和0.014 g·g^(-1);基于PM_(2.5)和O_(3)协同管控视角,食品制造、工业涂装和家具制造是漯河市应当优先管控的行业,家具制造行业则是优控行业中的重中之重.

关键词：挥发性有机物(VOCs) 工业排放源成分谱臭氧生成潜势(OFP) 二次有机气溶胶生成潜势(SOAP)