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洪泛湿地潜流带水动力过程研究综述

湿地科学 2024年第2期22卷 282-290页

作者：崔庚佟守正吕宪国刘言王磊璩向宁中国科学院东北地理与农业生态研究所吉林长春130102 西北退化生态系统恢复与重建教育部重点实验室宁夏银川750021 长春师范大学地理科学学院吉林长春130032

洪泛湿地是洪水周期作用下形成的水陆交错关键带。水体的补给、径流、排泄等水动力过程驱动着湿地元素循环和生物演化,从而实现洪泛湿地的生态功能。洪水的周期性淹没造成湿地潜流带结构和渗透性的时空异质性,导致量化洪泛湿地水动力过... 详细信息

洪泛湿地是洪水周期作用下形成的水陆交错关键带。水体的补给、径流、排泄等水动力过程驱动着湿地元素循环和生物演化,从而实现洪泛湿地的生态功能。洪水的周期性淹没造成湿地潜流带结构和渗透性的时空异质性,导致量化洪泛湿地水动力过程的不确定性。综述了洪泛湿地潜流带水动力过程的研究进展,从洪泛湿地沉积物-水界面动态变化的角度提出了未来洪泛湿地水动力过程的研究方向,旨在揭示洪泛湿地潜流带水动力过程对洪水脉冲的响应机制,丰富和完善湿地系统多环境要素耦合研究的理论和方法,为洪涝灾害导致的退化湿地生态功能恢复、洪水资源化利用及湿地的可持续发展提供科学依据。

关键词：洪泛湿地洪水脉冲潜流带水动力过程

TFAP2A对肾小球硬化相关基因ADCK4转录调控机制的研究

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天津医药 2024年第5期52卷 449-453页

作者：张小田任献国南京医科大学附属逸夫医院儿科 211112

目的探索细胞中TFAP2A对局灶节段性肾小球硬化(FSGS)相关基因含aarF结构域的激酶4(ADCK4)的转录调控机制及TFAP2A与ADCK4是否存在特定的结合区域。方法生物信息学分析肾小球硬化基因火山图,ADCK4及TFAP2A表达水平的关系。JASPAR数据库预... 详细信息

目的探索细胞中TFAP2A对局灶节段性肾小球硬化(FSGS)相关基因含aarF结构域的激酶4(ADCK4)的转录调控机制及TFAP2A与ADCK4是否存在特定的结合区域。方法生物信息学分析肾小球硬化基因火山图,ADCK4及TFAP2A表达水平的关系。JASPAR数据库预测ADCK4基因转录起始位点-464 bp/+206 bp区域包含TFAP2A转录因子结合位点;TFAP2A siRNA浓度分别为5、10、15µmol/L,TFAP2A过表达质粒质量浓度分别为50、100、300µg/L,通过双萤光素酶报告基因实验验证TFAP2A对ADCK4基因启动子水平的调控作用。TFAP2A siRNA及TFAP2A过表达质粒转染细胞,实时荧光定量PCR检测TFAP2A、ADCK4 mRNA表达,蛋白免疫印迹实验检测TFAP2A、ADCK4蛋白表达。染色质免疫沉淀试验验证TFAP2A与ADCK4启动子的特定区域结合。结果生物信息学分析显示FSGS肾组织中RNA-Seq RNA表达上调的基因273个,表达下调的基因219个;ADCK4与TFAP2A表达水平呈正相关(P<0.01)。双萤光素酶报告基因实验证明TFAP2A siRNA浓度为10、15µmol/L的ADCK4启动子相对萤光素酶活性增强,TFAP2A过表达质粒质量浓度为100、300µg/L的ADCK4启动子萤光素酶活性降低(P<0.05)。与对照组相比,实验组ADCK4 mRNA和蛋白表达水平升高;过表达实验中,与对照组比较,实验组ADCK4 mRNA和蛋白表达水平降低(P<0.05)。染色质免疫沉淀试验发现TFAP2A能与ADCK4启动子的特定区域结合。结论转录因子TFAP2A负向调控ADCK4基因表达,增加了调控足细胞重要基因的转录因子成员。

关键词：肾小球硬化症,局灶节段性转录因子AP-2 启动区,遗传转录调控含aarF结构域的激酶4

Assessing the collapse risk of Stipa bungeana grassland in China based on its distribution changes

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Journal of Arid Land 2020年第2期12卷 303-317页

作者： QIAO xianguo GUO Ke LI Guoqing zhao Liqing LI Frank Yonghong GAO Chenguang State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau Northwest A&F UniversityYangling 712100China Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water ResourcesYangling 712100China Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau&Inner Mongolia Key Laboratory of Grassland Ecology School of Ecology and EnvironmentInner Mongolia UniversityHohhot 010021China

The criteria used by International Union for Conservation of Nature(IUCN) for its Red List of Ecosystems(RLE) are the global standards for ecosystem-level risk assessment, and they have been increasingly used for biodiversity conservation. The changed distribution area of an ecosystem is one of the key criteria in such assessments. The Stipa bungeana grassland is one of the most widely distributed grasslands in the warm-temperate semi-arid regions of China. However, the total distribution area of this grassland was noted to have shrunk and become fragmented because of its conversion to cropland and grazing-induced degradation. Following the IUCN-RLE standards, here we analyzed changes in the geographical distribution of this degraded grassland, to evaluate its degradation and risk of collapse. Past(1950-1980) distribution areas were extracted from the Vegetation Map of China(1:1,000,000). Present realizable distribution areas were equated to these past areas minus any habitat area losses. We then predicted the grassland’s present and future(under the Representative Concentration Pathway 8.5 scenario) potential distribution areas using maximum entropy algorithm(MaxEnt), based on field survey data and nine environmental layers. Our results showed that the S. bungeana grassland was mainly distributed in the Loess Plateau, Hexi Corridor, and low altitudes of the Qilian Mountains and Longshou Mountain. This ecosystem occurred mainly on loess soils, kastanozems, steppe aeolian soils and sierozems. Thermal and edaphic factors were the most important factors limiting the distribution of S. bungeana grassland across China. Since 56.1% of its past distribution area(4.9×10~4 km^2) disappeared in the last 50 a, the present realizable distribution area only amounts to 2.2×10~4 km^2. But only 15.7% of its present potential distribution area(14.0×10~4 km^2) is actually occupied by the S. bungeana grassland. The future potential distribution of S. bungeana grassland was predicted t

关键词： climate change limiting factors maximum entropy algorithm potential distribution realizable distribution Red List of Ecosystems Loess Plateau

某轨道运输工具车制动系统性能分析与优化设计

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机械 2024年第7期51卷 45-51页

作者：王乐裴佳志雷显国赵建超安康职业技术学院工程学院陕西安康725000

为了提高某轨道运输工具车制动性能的安全性与可靠性,一方面通过建立单目标数学优化模型与鼓式制动器计算模型开展最大制动力、满载最大停留坡度、制动距离、极限载重量以及轴承寿命等性能参数校验;另一方面,基于ANSYS/Workbench软件开... 详细信息

为了提高某轨道运输工具车制动性能的安全性与可靠性,一方面通过建立单目标数学优化模型与鼓式制动器计算模型开展最大制动力、满载最大停留坡度、制动距离、极限载重量以及轴承寿命等性能参数校验;另一方面,基于ANSYS/Workbench软件开展目标工具车核心部件结构强度的仿真分析(车架静态应力分析、轮轴应力分析及车轮应力分析)。其中,参数校验结果表明目标工具车制动性能满足使用需求,仿真分析结果表明车架极限破坏节点位于内外侧立板拓扑圆弧处、内侧立板与车架顶板连接区域。因此可知,该目标工具车制动性能满足使用要求,结构设计富余量偏高,可指导后续结构改进与轻量化拓扑优化设计。

关键词：轨道运输工具车 ANSYS/Workbench 制动系统结构强度

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斯图特雪球地球存在持续的海洋碳循环

沉积学报 2024年第1期42卷 29-38页

作者：满玲祝圣贤邓宾李玉坤郎咸国成都理工大学沉积地质研究院成都610059 广西地质调查院南宁530023

[目的]斯图特雪球地球事件是地质历史时期最极端的冰室气候。在冰期过程中,冰盖分布范围达到低纬度甚至古赤道区域,海洋被完全冰冻。目前,斯图特雪球地球过程中的古海洋化学研究相对薄弱,且生物地球化学循环机制尚不明确。[方法]对桂北... 详细信息

[目的]斯图特雪球地球事件是地质历史时期最极端的冰室气候。在冰期过程中,冰盖分布范围达到低纬度甚至古赤道区域,海洋被完全冰冻。目前,斯图特雪球地球过程中的古海洋化学研究相对薄弱,且生物地球化学循环机制尚不明确。[方法]对桂北地区成冰系富禄组开展了详细的野外调查和碳氧同位素及元素地球化学研究。[结果]桂北地区成冰系富禄组形成于斯图特雪球地球过程中,岩性主要为一套碎屑岩,并发育多套碳酸盐岩夹层。地球化学分析显示这些碳酸盐岩具有相对稳定的碳同位素值(平均值为-3.5‰),并与伴生的有机碳同位素呈现不耦合关系。[结论]富禄组碳酸盐岩的碳同位素值明显高于地幔碳同位素值(-6‰),指示斯图特雪球地球过程中的海洋初级生产力并未完全停止,只是表现为较低的水平。海洋热液系统提供的磷可能是维持冰期海洋初级生产力的主要原因。

关键词：碳同位素碳酸盐岩富禄组新元古代

Geometric Condition of 3UPS-S Parallel Mechanism in Singular Configuration

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Chinese Journal of Mechanical Engineering 2014年第1期27卷 130-137页

作者： HAN xianguo LIU Yanlong College of Mechanical Engineering and Automation Beihang University

The existing researches on singularity of parallel mechanism are mostly limited to the property and regularity of singularity locus and there is no further research into the geometric relationship between uncontrolled kinematic screw and parallel mechanism in singularity. A 3UPS-S parallel mechanism is presented which fulfils 3-DOF in rotation. The regularity of nutation angle singularity is analyzed based on the Jacobian matrix, and the singularity surface of 3UPS-S parallel mechanisms is obtained. By applying the concept of reciprocal product in screw theory, the singular kinematic screw is derived when 3UPS-S parallel mechanism is in singularity. The geometric relationship between singular kinematic screw and singular configuration of 3UPS-S parallel mechanism is investigated by using programs in MATLAB. It is revealed that there are two kinds of situation. Firstly, the three limbs of 3UPS-S parallel mechanism intersect the singular kinematic screw in space simultaneously; Secondly, two limbs cross the singular kinematic screw while the third limb parallels with that screw. It is concluded that the nutation angle singularity of 3UPS-S parallel mechanism belongs to the singular linear complexes. This paper sheds light into and clarifies the geometric relationship between singular kinematic screw and singular configuration of 3UPS-S parallel mechanism.

关键词： parallel mechanism condition number of Jacobian matrix screw theory singular linear complexes

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某新型核电汽轮机再热阀卡涩问题的研究

热力透平 2016年第4期45卷 319-322页

作者：孙振平周李军李庆华赵显国侯敬宏中广核工程有限公司深圳518124

核电汽轮机再热阀在机组运行过程中起着重要的作用。某新型再热阀在定期试验时发生卡涩问题,阀门无法关闭。分析了再热阀卡涩的原因,制定并实施了解决方案。实践表明,在运行工况下,核电汽轮机再热阀的机械密封无法完全隔离蒸汽,蒸汽泄... 详细信息

核电汽轮机再热阀在机组运行过程中起着重要的作用。某新型再热阀在定期试验时发生卡涩问题,阀门无法关闭。分析了再热阀卡涩的原因,制定并实施了解决方案。实践表明,在运行工况下,核电汽轮机再热阀的机械密封无法完全隔离蒸汽,蒸汽泄漏是不可避免的;采用机械密封的再热阀,需要保守考虑轴承和润滑脂选型,解决蒸汽泄漏、阀轴窜动等问题。

关键词：核电汽轮机再热阀卡涩轴承机械密封

Catalytic Hydrothermal Liquefaction of Algae for Production of Bio-oil with Solid Superacid Catalyst SO_(4)^(2−)/ZrO_(2)

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Journal of Ocean University of China 2022年第5期21卷 1214-1226页

作者： LIU Mengfan YU Xin YU Xiaofan zhao Yongnian FENG Lijuan LI xianguo YAO Shuo Key Laboratory of Marine Chemistry Theory and Technology Ministry of EducationCollege of Chemistry and Chemical EngineeringOcean University of ChinaQingdao 266100China

Solid superacid SO_(4)^(2−)/ZrO_(2)as heterogeneous catalyst was prepared to upgrade the bio-oil in the progress of hydrother-mal liquefaction(HTL)for the represented algae of Chlorella vulgaris and Enteromorpha *** solid superacid catalyst could obviously adjust the composition of the bio-oil and improve the higher heating values(HHVs).The catalytic performance could be regulated by adjusting the acid amount and acid strength of SO_(4)^(2−)/ZrO_(2).Furthermore,it was explored the catalytic effects of SO_(4)^(2−)/ZrO_(2)by the HTL for algae major model components,including polysaccharides,proteins,lipids,binary mixture and ternary *** results showed that the introducing of SO_(4)^(2−)/ZrO_(2)catalyst could increase the yields of bio-oil from proteins and lipids,and avoid the Maillard reaction between polysaccharides and ***,a possible reaction pathway and mechanisms has proposed for the formation of bio-oils from HTL of algae catalyzed by SO_(4)^(2−)/ZrO_(2)based on the systematic research of the producing bio-oil from major model components.

关键词： bio-oil heterogeneous catalyst solid superacid catalyst hydrothermal liquefaction algae major model components

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新型舰炮对临近空间飞艇射击技术研究

火力与指挥控制 2024年第8期49卷 199-205页

作者：邹先国刘健龚长红夏令祥陆军工程大学军械士官学校武汉430033 海军工程大学兵器工程学院武汉430075

新型舰炮发射初速高、能量大、成本低的特点使其具备打击远程空中目标能力,对临近空间飞艇的打击较远程防空导弹有明显优势。基于火炮弹道解算方法,研究了新型舰炮打击临近空间飞艇的临界初速与射角,分析射击误差对精度的影响,用射角逼... 详细信息

新型舰炮发射初速高、能量大、成本低的特点使其具备打击远程空中目标能力,对临近空间飞艇的打击较远程防空导弹有明显优势。基于火炮弹道解算方法,研究了新型舰炮打击临近空间飞艇的临界初速与射角,分析射击误差对精度的影响,用射角逼近法求取舰炮射击诸元,并计算命中概率,分析初速、距离对命中概率的影响。得到结论:适当提高弹丸初速或缩短与目标距离能显著提高命中概率。

关键词：弹道误差诸元解算命中概率