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Residues of organochlorine pesticides in surface soils from college school yards in Beijing, China

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Journal of Environmental Sciences 2008年第9期20卷 1090-1096页

作者： WANG Xiaofei WANG Dianzhong QIN Xiaofei XU xiaobai State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China State Key Laboratory of Remote Sensing Science Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China

Organochlorine pesticides (OCPs) have been a major environmental issue, attracting much scientific concern because of their nature of toxicity, persistence, and endocrine disrupting effects. Soil samples were collected from ten college school yards in Beijing in 2006 and analyzed to determine fifteen OCPs. Dichlorodiphenyltrichloroethanes (DDTs) were found to be the main pollutants, accounting for 93.70% of total OCPs, followed by hexachlorohexanes (HCHs) (2.25%) and hexachlorobenzene (HCB) (1.82%). Content...

关键词： organochlorine pesticides (OCPs) pollution soil college school yards

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复杂构造变形区断控裂缝发育分布模式

地学前缘 2024年第5期31卷 130-138页

作者：鞠玮杨慧侯贵廷宁卫科李永康梁孝柏中国矿业大学煤层气资源与成藏过程教育部重点实验室江苏徐州221008 中国矿业大学资源与地球科学学院江苏徐州221116 北京大学地球与空间科学学院北京100871

天然裂缝是油气重要的储集空间和渗流通道。在复杂构造变形区,裂缝明显受断层影响控制,但其规律和模式尚不清晰。为此,本次研究以库车坳陷为例,通过现场地质观测、成像测井裂缝解译和理论分析,计算断控裂缝系数,揭示走滑断层、逆冲断层... 详细信息

天然裂缝是油气重要的储集空间和渗流通道。在复杂构造变形区,裂缝明显受断层影响控制,但其规律和模式尚不清晰。为此,本次研究以库车坳陷为例,通过现场地质观测、成像测井裂缝解译和理论分析,计算断控裂缝系数,揭示走滑断层、逆冲断层控制复杂构造变形区天然裂缝的规律,提出断控裂缝发育分布模式。结果表明:(1)逆冲断层对天然裂缝产状和发育程度均具有明显的控制作用,裂缝密度与距断层距离呈现负指数关系,距断层由近及远可以划分为断层强控制裂缝带、断层弱控制裂缝带和区域裂缝带。(2)走滑断层包括调节走滑断层和逆冲走滑断层。调节走滑断层与地层走向近垂直或大角度斜交,发育断层控制裂缝带,其受断层规模影响显著;逆冲走滑断层与地层走向近平行或者小角度斜交,天然裂缝主要局限于断层带内,沿断层走向断裂带宽度发生变化。(3)定义断控裂缝系数(K),即断层强控制裂缝带宽度与断层断距(滑距)的比值,通过分析,库车坳陷逆冲断层K值为1.50~1.80,走滑断层K值为0.125~0.150。研究成果对复杂构造变形区油气勘探开发具有理论和实践指导意义。

关键词：裂缝发育分布模式断控裂缝系数走滑断层复杂构造变形区库车坳陷

Progress in study on endocrine disrupting pesticides (EDPs) in aquatic environment

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Chinese Science Bulletin 2005年第20期50卷 2257-2266页

作者： XUE Nandong WANG Hongbo XU xiaobai State Key Laboratory of Environmental Chemistry and Ecotoxicology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Department of Environmental Sciences and Engineering Hunan Agricultural University Changsha 410128 China

Background on the generation of the problems of endocrine disrupting pesticides (EDPs) in aquatic environment, characteristics of EDPs, adverse effects and their effect mechanism of EDPs on human and wildlife, the transportation and degradation pathways of EDPs in water and analysis methods of EDPs in water were reviewed. The importance of EDPs in water should be attached to adverse effects on wildlife and human health. It was advised to estab- lish research programs on EDPs in aquatic environment es- pecially in water supply source.

关键词：水生环境内分泌紊乱杀虫剂 EDPs 人类健康化学物质

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中药材白及分子鉴定研究进展

分子植物育种 2024年第2期22卷 446-452页

作者：金亮郭方其付曼曼吴超李小白浙江省园林植物与花卉研究所杭州311251 浙江省农业科学院园艺研究所杭州310021

白及(Bletilla striata)的干燥块茎是一味传统的中药,具有较高的药用价值。由于其价格逐步走高,市场上充斥着各种白及混伪品。相对于传统的形态、理化、显微鉴定,分子鉴定较为快速、准确、客观。分子鉴定方法根据生物间的分子特征差异... 详细信息

白及(Bletilla striata)的干燥块茎是一味传统的中药,具有较高的药用价值。由于其价格逐步走高,市场上充斥着各种白及混伪品。相对于传统的形态、理化、显微鉴定,分子鉴定较为快速、准确、客观。分子鉴定方法根据生物间的分子特征差异进行鉴定,不受自然环境、生长发育阶段等外部因素影响。本研究综述了分子标记、DNA条形码策略在白及鉴定上的应用:分子标记可鉴定白及及其近源物种,主要涉及ISSR、SCAR、SSR、SNP等标记;采用ITS2序列结合二级结构分析、ITS+ycf1序列可以鉴定白及属内及其他混伪品。本综述旨在为白及分子鉴定方法的深入研究提供有价值的参考和借鉴。

关键词：白及(Bletilla striata) 混伪品分子鉴定分子标记 DNA条形码

Sorption phenomena of PCBs in environment

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Chinese Science Bulletin 2001年第2期46卷 89-97页

作者： Qingyu Meng Shaogang Chu xiaobai Xu Chinese Acad Sci Ecoenvironm Sci Res Ctr Beijing 100085 Peoples R China

The relationship between the properties of PCBs and the behavior of soil and sediment is reviewed. The sorp-tion phenomena of PCBs in the environment are described with different models. The research progress on the s... 详细信息

关键词： PCBs sorption environmental transport.

Aspects of formation and degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans

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Chinese Science Bulletin 1999年第14期44卷 1249-1257页

作者： Minghui Zheng Pengyan Liu Zhicheng Bao xiaobai Xu Chinese Acad Sci Ecoenvironm Sci Res Ctr Beijing 100085 Peoples R China Hebei Univ Dept Chem Baoding 071002 Peoples R China

The research progress on the mechanisms of formation and degradation of polychlorinated dibenzo-p-dioxins ( PCDDs ) and dibenzofurans ( PCDFs ) is reviewed. The primary sources of PCDD/Fs are chemical, thermal, photochemical and enzymatic reactions. Most of the thermal sources result in emissions into air. The studies on the photodegradation and biodegradation offer promise for destruction of PCDD/Fs in environment.

关键词： polychlorinated dibenzo-p-dioxins polychlorinated dibenzofurans mechanism formation degradation.

Chemical synthesis and coercivity enhancement of Nd2Fe14B nanostructures mediated by non-magnetic layer

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Nano Research 2020年第4期13卷 1141-1148页

作者： Kai Zhu Junjie Xu xiaobai Wang Wei Li Kesong Tian Yanglong Hou Beijing Key Laboratory for Magnetoelectric Materials and Devices(BKLMMD) Beijing Innovation Centre for Engineering Science and Advanced TechnologyDepartment of Materials Science and EngineeringCollege of EngineeringPeking UniversityBeijing 100871China Academy for Advanced Interdisciplinary Studies Peking UniversityBeijing 100871China

High-performance Nd2Fei4B magnets have been widely required in various fields recently due to the lightweight and miniaturization of *** this work,we synthesize Nd2Fei4B nanostructures with tunable magnetic properties through surfactant-assisted high energy ball milling(SAHEBM)process,achieving prominently enhanced coercivity by forming non-magnetic layers as grain boundary *** the reduction annealing process was carried out as pellet with Ca,the coercivity increased from 0.8 kOe to over 3 kOe as Nd2Fei4B powder,which is proved to be the contribution of the chemical diffusion of Nd elements and the formation of Nd-rich layer as magnetic insulating *** addition,two-dimensional graphene oxide(GO)was employed to build extra grain boundary,by which the coercivity of the core@dual-shell structure can achieve up to 8 kOe,tenfold of the original *** intrinsic mechanism indicated that the Nd-diffusion induced Nd-rich phase along with the reduced GO in the system could form non-magnetic layer as grain boundary and magnetically isolate the adjacent grains,significantly enhancing the exchange coupling *** work markedly opens up an effective approach for the chemical preparation of high-performance Nd2Fe14B nanostructured magnets,especially after post treatment,and gives an insight on the interactions at nanoscale.

关键词： Nd2Fei4B nanostructures chemical reduction diffusion process grain boundary graphene oxide coercivity enchantment

面向Vision Transformer模型的剪枝技术研究

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软件 2024年第3期45卷 83-86,97页

作者：查秉坤李朋阳陈小柏南京邮电大学计算机学院软件学院网络空间安全学院江苏南京210023

本文针对Vision Transformer(ViT)模型开展剪枝技术研究,探索了多头自注意力机制中的QKV(Query、Key、Value)权重和全连接层(Fully Connected,FC)权重的剪枝问题。针对ViT模型本文提出了3组剪枝方案:只对QKV剪枝、只对FC剪枝以及对QKV... 详细信息

本文针对Vision Transformer(ViT)模型开展剪枝技术研究,探索了多头自注意力机制中的QKV(Query、Key、Value)权重和全连接层(Fully Connected,FC)权重的剪枝问题。针对ViT模型本文提出了3组剪枝方案:只对QKV剪枝、只对FC剪枝以及对QKV和FC同时进行剪枝,以探究不同剪枝策略对ViT模型准确率和模型参数压缩率的影响。本文开展的研究工作为深度学习模型的压缩和优化提供了重要参考,对于实际应用中的模型精简和性能优化具有指导意义。

关键词： Vision Transformer模型剪枝准确率

Controllable preparation of graphene glass fiber fabric towards mass production and its application in self-adaptive thermal management

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Science Bulletin 2024年第17期69卷 2712-2722页

作者： Ruojuan Liu Fan Yang Shuting Cheng Xianghe Yue Fushun Liang Wenjuan Li Jingnan Wang Qinchi Zhang Liangyu Zou Hao Yuan Yuyao Yang Kangyi Zheng Longfei Liu Mengxiong Liu Wei Gu Ce Tu Xinyu Mao xiaobai Wang Yue Qi Zhongfan Liu Centre for Nanochemistry Beijing Science and Engineering Centre for NanocarbonsBeijing National Laboratory for Molecular SciencesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Beijing Graphene Institute(BGI) Beijing 100095China State Key Laboratory of Heavy Oil Processing College of ScienceChina University of PetroleumBeijing 102249China School of Materials Science and Chemical Engineering Harbin Engineering UniversityHarbin 150001China Soochow Institute for Energy and Materials Innovations(SIEMIS) College of EnergySoochow UniversitySuzhou 215006China Academy for Advanced Interdisciplinary Research North University of ChinaTaiyuan 030051China Department of Chemistry College of Chemistry and Materials EngineeringBeijing Technology and Business UniversityBeijing 100048China

Direct synthesis of graphene on nonmetallic substrates via chemical vapor deposition (CVD) has become a frontier research realm targeting transfer-free applications of CVD ***,the stable mass production of graphene with a favorable growth rate and quality remains a grand ***,graphene glass fiber fabric (GGFF) was successfully developed through the controllable growth of graphene on non-catalytic glass fiber fabric,employing a synergistic binary-precursor CVD strategy to alleviate the dilemma between growth rate and *** binary precursors consisted of acetylene and acetone,where acetylene with high decomposition efficiency fed rapid graphene growth while oxygencontaining acetone was adopted for improving the layer uniformity and ***,the bifurcating introducing-confluent premixing (BI-CP) system was self-built for the controllable introduction of gas and liquid precursors,enabling the stable production of *** features solar absorption and infrared emission properties,based on which the self-adaptive dual-mode thermal management film was *** film can automatically switch between heating and cooling modes by spontaneously perceiving the temperature,achieving excellent thermal management performances with heating and cooling power of~501.2 and~108.6 W m-2,*** findings unlock a new strategy for the large-scale batch production of graphene materials and inspire advanced possibilities for further applications.

关键词： Graphene Graphene glass fiber fabric Synergistic binary-precursor strategy Mass production Thermal management