检索结果-南通市图书馆

Seasonal variation and sources of atmospheric polycyclic aromatic hydrocarbons in a background site on the Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2023年第3期125卷 524-532页

作者： Xuemei Wu Weijun sun Baojuan Huai LeiWang Chuntan Han Yetang Wang Wenying mi College of Geography and Environment Shandong Normal UniversityJinan 250014China Qilian Alpine Ecology and Hydrology Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China miNJIE Institute of Environmental Science and Health Research Geesthacht 21502Germany

The study of atmospheric polycyclic aromatic hydrocarbons(PAHs) in northeastern Tibetan Plateau with fragile ecological environment and complex atmospheric circulation system is blank. To understand the characteristics and sources of persistent organic pollutants in the atmosphere of the northeastern Tibetan Plateau, we monitored levels in the central Qilian Mountain. From 2016 to 2017, we collected 45-pair(particle + gas) samples using active air samplers to investigate the sources, transport paths, and their influencing *** of PAHs were analysed with a source diagnostic model, and atmospheric transport paths were calculated. The concentration range for Σ15PAHs was 439–4666 pg/m^(3), and the average was 2015 pg/m^(3). The PAHs in central Qilian Mountain are mainly low molecular weight(LMW) PAHs. Winter concentrations of PAHs were higher than those in summer. The transport of PAHs is mainly affected by westerlies, and there are seasonal differences. Source analysis showed that PAHs mainly came from coal and biomass combustion and vehicle emissions, with seasonal differences. This study clarifies the concentration and seasonal variation of PAHs in the northern Tibetan Plateau, which is conducive to understanding the atmospheric transport process and fate of pollutants. The background site of Qilian Mountains located in the Silk Road economic belt has the value and significance of longterm observation of pollutants.

关键词： Long-range atmospheric transport Seasonal variation concentration Meteorological factors Qilian Mountain

在线全文

学校读者我要写书评

暂无评论

青藏高原高寒草地土壤酶活性海拔地带性特征

生态学报 2024年第1期44卷 405-415页

作者：霍皇煜米琦周天财李洋张建香陈俊合汪亚峰孙建青藏高原地球系统与资源环境全国重点实验室中国科学院青藏高原研究所北京100101 中国科学院大学资源与环境学院北京100049 兰州大学生态学院兰州730000 兰州大学资源环境学院兰州730000

土壤酶是土壤生态系统中具有催化功能的一类蛋白质,由植物根系分泌物、微生物和动植物残体释放到土壤中,参与了土壤中所有的生物化学过程,其活性的大小可以灵敏地反应土壤中生化反应的方向和强度。青藏高原因海拔高和气候寒冷,被认为是... 详细信息

土壤酶是土壤生态系统中具有催化功能的一类蛋白质,由植物根系分泌物、微生物和动植物残体释放到土壤中,参与了土壤中所有的生物化学过程,其活性的大小可以灵敏地反应土壤中生化反应的方向和强度。青藏高原因海拔高和气候寒冷,被认为是气候变化的敏感区和脆弱区。全球气候变化使土壤酶活性受到强烈的影响,这些影响可能使土壤的质量发生改变,进而对青藏高原高寒草地植被生产力产生一定影响。土壤酶在生态系统物质循环和能量流动中起着关键作用,其格局、功能和转换过程已被广泛的研究,但高寒草地生态系统土壤酶活性的海拔地带性特征还需深入探讨。因此,以青藏高原高寒草地为研究对象,将土壤酶活性海拔梯度研究从站点尺度拓展到样带尺度,分析了与土壤碳循环密切相关的土壤β-1,4-葡萄糖苷酶(βG)、与土壤氮循环密切相关的土壤N-乙酰-β氨基葡萄糖苷酶(NAG)、土壤亮氨酸肌肽酶(LAP)以及与土壤磷循环密切相关的土壤碱性磷酸酶(ALP)的海拔地带性,进一步明晰其主要驱动因子。结果表明:(1)ALP和βG活性在海拔梯度上,展现出显著分异,在约为3546 m和3364 m出现拐点,且低海拔显著高于高海拔(P<0.01)。而NAG和LAP的活性与海拔无显著关系。(2)高低海拔模式下,ALP活性均与年平均降水量显著相关(P<0.01),而不受年平均温度的影响。高海拔模式下,βG活性受降水的影响;低海拔模式下,气候影响不明显。综合而言,海拔变化引起的温度和降水变化会直接或间接地影响土壤酶活性,其中降水是影响青藏高原高寒草地土壤酶活性的关键因子之一,这种适应性的改变使土壤酶能够在不同的环境条件下适应并发挥其功能,从而影响着土壤生态系统的物质循环和能量转化过程。研究结果可以评估不同海拔地带土壤的养分转化、有机质分解和循环等生态系统功能,为生态系统管理和保护提供科学依据,对理解高寒草地生物地球化学循环过程和机制具有重要意义。

关键词：青藏高原高寒草地土壤酶活性垂直地带性降水

基于不同评价单元的三峡库区滑坡易发性对比——以重庆市云阳县为例

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

吉林大学学报（地球科学版） 2024年第5期54卷 1629-1644页

作者：安雪莲密长林孙德亮文海家李晓琴辜庆渝丁悦凯地理信息系统应用研究重庆市高校重点实验室(重庆师范大学) 重庆401331 山东省临沂市自然资源开发服务中心山东临沂276000 山地城镇建设与新技术教育部重点实验室(重庆大学) 重庆400045

为探究不同评价单元对区域滑坡易发性评估的影响,基于网格单元与斜坡单元对三峡库区典型县域重庆市云阳县开展了滑坡易发性研究。首先选取高程、坡度、曲率等22个评价因子,根据研究区988个历史滑坡数据,通过30 m×30 m的栅格数据提取斜... 详细信息

为探究不同评价单元对区域滑坡易发性评估的影响,基于网格单元与斜坡单元对三峡库区典型县域重庆市云阳县开展了滑坡易发性研究。首先选取高程、坡度、曲率等22个评价因子,根据研究区988个历史滑坡数据,通过30 m×30 m的栅格数据提取斜坡单元,并基于网格单元及斜坡单元分别建立22个滑坡影响因子地理空间数据库;然后利用随机森林与贝叶斯优化算法来构建滑坡易发性模型,对研究区滑坡进行易发性评估;最后结合ROC(受试者工作特征)曲线与混淆矩阵结果检验评价单元的易发性模型预测精度。结果表明:易发性评估的结果可划分为低、较低、中、较高、高5个等级;基于网格单元的滑坡易发性模型中,高程、与道路距离、坡度这3个因子对滑坡发生的贡献率大,基于斜坡单元的模型中,I_(NDV)(归一化植被指数)、剖面曲率、平面曲率这3个因子对滑坡发生的贡献率大,并且2个模型的滑坡密度均随着滑坡易发性等级的升高而变大;与网格单元相比,斜坡单元能更好地解释地形间的联系,以斜坡单元(AUC=0.744)为最小评价单元的滑坡易发性模型比网格单元(AUC=0.714)精度更高。

关键词：滑坡滑坡评价单元斜坡单元网格单元滑坡易发性随机森林三峡库区重庆市云阳县

Progressive Collapse Resistance of a New Staggered Story Isolated System

在线全文

学校读者我要写书评

暂无评论

Ultra-high specifi c surface area activated carbon from Taihu cyanobacteria via KOH activation for enhanced methylene blue adsorption

Open Journal of Applied Sciences（应用科学） 2024年第3期 643页

作者： Yutong Yang Yuancheng mi Hong Li Zhongfa Guo Dewen Liu Weiwei sun min Lei

来源：博看期刊评论

在线全文

博看期刊

学校读者我要写书评

暂无评论

Separation of chitin from shrimp shells enabled by transition metal salt aqueous solution and ionic liquid

中国化学工程学报（英文版） 2024年第3期 106页

作者： Yifang mi Wenqiang Wang Sen Zhang Yalong Guo Yufeng Zhao Guojin sun Zhihai Cao

来源：博看期刊评论

在线全文

博看期刊

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2023年第1期53卷 133-141页

作者： mi Feng Bin He Xinyan Chen Junli Xu Xingmei Lu Cai Jia Jian sun Key Laboratory of Molecular Medicine and Biotherapy Ministry of Industry and Information TechnologySchool of Life SciencesBeijing Institute of TechnologyBeijing 100081China Key Laboratory of Medical Molecule Science and Pharmaceutics Engineering Ministry of Industry and Information TechnologyAdvanced Research Institute of Multidisciplinary ScienceBeijing Institute of TechnologyBeijing 100081China CAS Key Laboratory of Green Process and Engineering State Key Laboratory of Multiphase Complex SystemsState Key Laboratory of Biochemical EngineeringBeijing Key Laboratory of Ionic Liquids Clean ProcessInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical and Engineering University of Chinese Academy of SciencesBeijing 100049China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing 100190China

Chitin is a widely used important industrial polymer mainly from shrimp shells, but its commercial preparation is under the great challenge of serious pollution due to the requirement of HCl and Na ***, we demonstrated that high purity chitin can be obtained from waste shrimp shells(WSSs) by cascade separation with transition metal salt aqueous solution and ionic liquid(IL). Firstly, calcium carbonate of WSSs was effectively removed in the metal salt aqueous solution driven by the ion exchange interaction. Subsequently, 1-butyl-3-methylimidazolium chloride([Bmim]Cl) had bifunctional abilities to remove residual protein and introduced metal salts simultaneously by hydrogen bonding and coordination interactions. The key experimental factors affecting the separation process were systematically studied, including the type of metal salts, temperature, and [Bmim]Cl loading. After sequential treatment with a 20%(mass) Ni SO4aqueous solution at 130 ℃ and [Bmim]Cl at 150 ℃, the purity of a-chitin can be up to 96.5%(mass) that meets commercial requirements. The use of metal salts with higher coordination ability makes the preparation of chitin no longer depend on the commonly acid-base reaction, which is conducive to the preservation of chitin structure.

关键词： Chitin Ionic liquids Transition metal salts Separation Sustainability

Radio Communication Scenarios in 5G-Railways

在线全文

学校读者我要写书评

暂无评论

中国通信:英文版 2023年第9期20卷 235-246页

作者： Ruisi He Bo Ai Zhangdui Zhong mi Yang Chen Huang Ruifeng Chen Jianwen Ding Hang mi Zhangfeng Ma Guiqi sun Changzhu Liu State Key Lab of Rail Traffic Control and Safety Beijing Jiaotong UniversityBeijing 100044China Pervasive Communication Research Center Purple Mountain LaboratoriesNanjing 211111China Institute of Computing Technology China Academy of Railway SciencesBeijing 100081China College of Information Engineering Shaoyang UniversityShaoyang 422000China National Research Center of Railway Safety Assessment Beijing Jiaotong UniversityBeijing 100044China Key Laboratory of Railway Industry of Broadband Mobile Information Communications Beijing Jiaotong UniversityBeijing 100044China Beijing Engineering Research Center of High-speed Railway Broadband Mobile Communications Beijing Jiaotong UniversityBeijing 100044China

With the rapid development of railways,especially high-speed railways,there is an increasingly urgent demand for new wireless communication system for *** the mature 5G technology as an opportunity,5G-railways(5G-R)have been widely regarded as a solution to meet the diversified demands of railway wireless *** the design,deployment and improvement of 5GR networks,radio communication scenario classification plays an important role,affecting channel modeling and system performance *** this paper,a standardized radio communication scenario classification,including 18 scenarios,is proposed for *** paper analyzes the differences of 5G-R scenarios compared with the traditional cellular networks and GSM-railways,according to 5G-R requirements and the unique physical environment and propagation *** proposed standardized scenario classification helps deepen the research of 5G-R and promote the development and application of the existing advanced technologies in railways.

关键词： 5G-R scenario classification smart rail-ways

在线全文

学校读者我要写书评

暂无评论

基于“五感”的疗愈景观场所设计研究

设计 2024年第13期37卷 76-79页

作者：孙文轩凌秋月米昊佳海南师范大学美术学院哈尔滨师范大学美术学院

为缓解工具理性给人带来的精神压力,缓和生活中的紧张情绪,促进现代人的心理和谐与身体健康恢复,文章将“五感”与“疗愈景观”相结合,利用心理学、美学、生物学等研究,提出了基于“五感”的疗愈景观场所设计原则,提供了以“五感”为视... 详细信息

为缓解工具理性给人带来的精神压力,缓和生活中的紧张情绪,促进现代人的心理和谐与身体健康恢复,文章将“五感”与“疗愈景观”相结合,利用心理学、美学、生物学等研究,提出了基于“五感”的疗愈景观场所设计原则,提供了以“五感”为视角的疗愈景观场所塑造策略。为疗愈景观场所的塑造总结了新的视角与方法。

关键词：五感景观疗愈性场所设计

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

激光光束整形技术研究进展

激光与光电子学进展 2024年第5期61卷 47-58页

作者：亓岩朱英杰张晶王延伟周密孙晨曦颜博霞韩巍王宇中国科学院大学集成电路学院北京100049 中国科学院微电子研究所光电技术研发中心北京100094 北京积水潭医院北京100035

激光器谐振腔输出的光束呈高斯分布,需要通过光束整形来提高均匀性,以满足应用的需求。从光学系统的特性出发,总结归纳了当前主要的三种激光光束整形技术,包括光阑法、场映射器法和多孔径光束聚焦法,分别介绍了三种激光光束整形技术的... 详细信息

激光器谐振腔输出的光束呈高斯分布,需要通过光束整形来提高均匀性,以满足应用的需求。从光学系统的特性出发,总结归纳了当前主要的三种激光光束整形技术,包括光阑法、场映射器法和多孔径光束聚焦法,分别介绍了三种激光光束整形技术的基本原理、应用范围和主要实现方法,阐述了不同激光光束整形方法的典型应用和研究进展,最后,综合讨论了激光光束整形技术目前所面临的问题及未来的发展方向。本综述对激光光束整形技术的研究具有一定的参考意义。

关键词：光束整形光阑场映射器多孔径光束聚焦