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Acta Geologica Sinica(English Edition) 2007年第3期81卷 442-449页

作者： LI Wenbo HUANG Zhilong qi Liang Laboratory of Orogenic Belts and Crustal Evolution Peking University Beijing 100871 Institute of Geochemistry Chinese Academy of Sciences Guiyang Guizhou 550002

REE abundances in sulfides from the Huize Zn-Pb ore field were determined with the ICPMS after preconcentration. The REE abundances in 26 sulfide samples （including pyrite, galena and sphalerite） are very low, with the ~REE ranging from 1.6×10^-9 to 166.8×10^-9. Their LREE/HREE ratios range from 7.6 to 98, showing LREE enrichment relatively. The JEu values are below 1, indicating that they were deposited from an Eu-depleted and reducing fluid-system. Similar to the ore-hosting carbonate strata, calcite separates from carbonate veinlets filling in the fractures or faults crosscutting the carbonate strata also show clear Eu-depletion. This indicates that the carbonate veinlets and their parent fluid was possibly sourced from the strata and inherited the REE geochemical features of the strata. Therefore, REE-geochemical characteristics of both the sulfides and calcites, which were deposited from an ore-forming hydrothermal system, are similar to those of carbonate strata, and strongly suggest that the ore metals were mainly sourced from carbonate strata.

关键词： Huize Zn-Pb ore field REE geochemistry sulfide fluid ore-forming metal

A bacteria-based index of biotic integrity indicates aquatic ecosystem restoration

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Environmental Science and Ecotechnology 2024年第6期22卷 178-190页

作者： qi Liu Senlu Yin Yujun Yi School of Environment Beijing Normal UniversityBeijing 100875China State Key Laboratory of Water Environment Simulation and Pollution Control Beijing Normal UniversityBeijing 100875China

Intensive ecological interventions have been carried out in highly polluted shallow lakes to improve their environments and restore their ***,certain treatments,such as dredging polluted sediment and stocking fish,can impact the aquatic communities,including benthos and *** impacts can alter the composition and characteristics of aquatic communities,which makes community-based ecological assessments *** we develop a bacteria-based index of biotic integrity(IBI)that can clearly indicate the restoration of aquatic ecosystems with minimal artificial *** applied this method to a restored shallow lake during 3-year intensive ecological *** interventions reduced nutrients and heavy metals by 27.1%and 16.7%in the sediment,while the total organic carbon(TOC)increased by 8.0%due to the proliferation of ***,the abundance of sulfur-related metabolic pathways decreased by 10.5%as the responses to improved *** score of bacteria-based IBI,which is calculated based on the diversity,composition,and function of benthic bacterial communities,increased from 0.62 in 2018 to 0.81 in *** study not only provides an applicable method for aquatic ecological assessment under intensive artificial interventions but also extends the application of IBI to complex application scenarios,such as ecosystems with significantly different aquatic communities and comparisons between different basins.

关键词： Baiyangdian lake 16S rRNA Benthic bacterial community Ecological restoration Aquatic ecological assessment

Perspective towards atomic-resolution imaging of two-dimensional polymers

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SmartMat 2021年第2期2卷 131-138页

作者： Haoyuan qi Baokun Liang Ute Kaiser Central Facility of Electron Microscopy Electron Microscopy Group of Materials ScienceUniversität UlmUlmGermany Center for Advancing Electronics Dresden(cfaed) Faculty of Chemistry and Food ChemistryTechnische Universität DresdenDresdenGermany

Recent years have witnessed the rise of an emerging class of synthetic twodimensional(2D)materials-2D *** combination of organic chemistry and rational design of polymeric crystals has stimulated tremendous research efforts in the controlled synthesis of 2D ***,despite the advancement in synthetic methodologies,the structural characterization of 2D polymers remains a significant *** aberration-corrected high-resolution transmission electron microscopy(AC-HRTEM)is capable of direct imaging of atomic structures with sub-Ångström resolution,electron radiation damage poses a substantial limit on the achievable image resolution due to instant decomposition of the molecular *** this Perspective,we will briefly discuss radiation damage mitigation strategies,which may eventually result in AC-HRTEM imaging of 2D polymers down to the atomic scale.

关键词： covalent organic frameworks transmission electron microscopy two-dimensional polymers

Characteristics of authigenic pyrites in shallow core sediments in the Shenhu area of the northern South China Sea: Implications for a possible mud volcano environment

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Science China Earth Sciences 2013年第3期56卷 541-548页

作者： XIE Lei WANG JiaSheng WU NengYou WU DaiDai WANG Zhou ZHU XiaoWei HU jun CHEN HongRen LIN qi State Key Laboratory of Biogeology and Environmental Geology (China University of Geosciences) Faculty of Earth Science China University of Geosciences Guangzhou Institute of Energy Conversion Chinese Academy of Sciences Guangzhou Center for Gas Hydrate Research Chinese Academy of Sciences Guangzhou Institute of Geochemistry Chinese Academy of Sciences

Distinct pyrites have been recovered from a shallow sediment core from Site 4B in the Shenhu area of the northern South China Sea. Based on the lithology, texture and structure of sediments, the stable sulfur isotope of pyrite and the total organic carbon (TOC) concentration of the sediments, a distinctive sediment interface is identified at a depth of about 1 m below the seafloor in the core sediments. The pyrites only accumulate in the lower part of the core as rods and foraminifera-infillings, and mainly within three intervals marked by high pyrite concentrations. The amount of pyrite in the sediments shows no remarkable correlation with TOC in the Site 4B core sediments. The stable sulfur isotopes of the pyrite have extremely negative values ranging from 41.69‰ to 49.16‰. They are considered to be the mutual product of sulfate bacterial reduction and sulfur bacterial disproportionation. Our research proposes that Site 4B might be located in or near a possible mud volcano sedimentary environment; a large amount of methane could migrate from deep to shallow sediments in an active mud volcano and thereby play a key role in the intensity of sulfate bacterial reduction and the amount of pyrite formed at Site 4B. further, the variation in flux of deep methane fluid by intermittent mud volcanic eruptions might result in the deposition of authigenic pyrite intervals.

关键词： pyrite distribution sulfur isotope shallow sediment Shenhu area

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The impact of fear effect on the dynamics of a delayed predator-prey model with stage structure

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International Journal of Biomathematics 2023年第8期16卷 263-296页

作者： qi Cao Guotai Chen Wensheng Yang School of Mathematics and Statistics fujian Normal University Fuzhou 350117 FujianP.R.China FJKLMAA and Center for Applied Mathematics of fujian Province(FJNU)fuzhou350117 FujianP.R.China

In this paper,a stage structure predator-prey model consisting of three nonlinear ordinary differential equations is proposed and *** prey populations are divided into two parts:juvenile prey and adult *** extensive experimental data,it has been found that prey fear of predators can alter the physiological behavior of individual prey,and the fear effect reduces their reproductive rate and increases their *** addition,we also consider the presence of constant ratio refuge in adult prey ***,we consider the existence of intraspecific competition between adult prey species and predator species separately in our model and also introduce the gestation delay of predators to obtain a more realistic and natural eco-dynamic *** study the positivity and boundedness of the solution of the non-delayed system and analyze the existence of various equilibria and the stability of the system at these *** by choosing the intra-specific competition coeficient of adult prey as bifurcation parameter,we demonstrate that Hopf bifurcation may occur near the positive equilibrium *** by taking the gestation delay as bifurcation parameter,the suficient conditions for the existence of Hopf bifurcation of the delayed system at the positive equilibrium point are *** the direction of Hopf bifurcation and the stability of the periodic solution are analyzed by using the center manifold theorem and normal form ***'s more,numerical experiments are performed to test the theoretical results obtained in this paper.

关键词： Stage-structure model fear effect time delay Hopf bifurcation

Growth Rings of Roots in Perennial Forbs in Duolun Grassland, Inner Mongolia, China

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Journal of Integrative Plant Biology 2007年第2期49卷 144-149页

作者： Yong-Bo Liu qi-Bin Zhang Laboratory of Quantitative Vegetation Ecology Institute of Botany the Chinese Academy of Sciences Beijing 100093 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China

Annual growth rings of roots in perennial forbs have been used in studies of climate change and the ecology of grasslands. However, little has been done in this aspect of research in China. In this study, we report the characteristics of growth rings in the main roots of 13 herb species sampled in Duolun of the Inner Mongolia grassland in northern China. The results show that around two thirds of the species possess clearly demarcated annual rings in the root xylem. Some species of the same genera show different patterns in anatomical structure of the root xylem. Standardized annual ring widths of three species, Potentilla anserine L., Cymbaria dahurica L. and Lespedeza daurica （Laxm.） Schindh, show a common linear trend, indicating a continued favorable growth condition in the sampling sites. Our results provide evidence that growth rings in roots of some perennial forbs in the Inner Mongolia grassland can serve as a new and useful indicator of past changes in the grassland environment.

关键词： China growth ring herb-chronology perennial forbs.

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基于奇异摄动的柔性机械手预测控制

机械科学与技术 2001年第2期20卷 172-173页

作者：张奇志孙增圻孙富春北京机械工业学院北京100085 清华大学北京100084

讨论了柔性机械手末端位置的控制问题。采用奇异摄动方法将柔性机械臂系统动力学方程分解为慢变(刚性 )和快变 (弹性 )两个子系统。给出了一种预测控制与 I/ O反馈线性化相结合的混合控制方法。该方法采用预测控制消除柔性机械手的弹性... 详细信息

讨论了柔性机械手末端位置的控制问题。采用奇异摄动方法将柔性机械臂系统动力学方程分解为慢变(刚性 )和快变 (弹性 )两个子系统。给出了一种预测控制与 I/ O反馈线性化相结合的混合控制方法。该方法采用预测控制消除柔性机械手的弹性振动 ,可避免逆动力学和 I/ O反馈线性化控制遇到的零动力学不稳定问题。通过一个柔性机械手的仿真表明 ,本文提出的控制方法可实现柔性机械手末端轨迹的准确跟踪 ,同时能消除柔性机械手的弹性振动。

关键词：预测控制柔性机械手奇异摄动机器人

An active base designed in high-counting-rate applications for Hamamatsu R1924A photomultiplier tube

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Nuclear Science and Techniques 2017年第10期28卷 59-63页

作者： Pei-Pei Ren Wei-Ping Lin Roy Wada Xing-Quan Liu Mei-Rong Huang Guo-Yu Tian Fei Luo qi Sun Zhi-qiang Chen Guo-qing Xiao Rui Han fu-Dong Shi Bo-Xing Gou Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Cyclotron Institute Texas A&M UniversityCollege StationTX 77843USA College of Physics and Electronics information InnerMongolia University for NationalitiesTongliao 028000China University of Science and Technology of China Hefei 230026China

Hamamatsu R1924A is one of the most widely used photomultiplier tubes(PMTs) in nuclear *** the active base suitable for R1924A is still not available in market, an active base is designed for Hamamatsu R1924A PMT, and the test results at high counting rates are presented. The active bases with two different sets of resistor chains were tested and compared by a frequency-controlled green straw hat LED light. A stable signal output up to 100 kHz is achieved using frequency-controlled LED pulsed light. The temperature of bases, which reflects the power consumption and is crucial for applications in vacuum, is also monitored with the same LED pulsed light. The temperature of the active base with smaller resistances reaches about twice of that of the active base with larger resistances in the resistor chain. For the applications in vacuum, the active base with resistance between the two sets of resistor chains may be preferable.

关键词：光电倍增管高计数率应用设计松活性基团 LED灯频率控制

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首都圈地区莫霍面起伏及沉积层厚度

地球物理学报 2008年第4期51卷 1135-1145页

作者：罗艳崇加军倪四道陈棋福陈颙中国地震局地震预测研究所北京100036 中国科学技术大学地球与空间科学学院蒙城地球物理国家野外科学观测研究站合肥230026

利用首都圈数字地震台网宽频带和短周期记录提取了接收函数,用H-Kappa叠加方法反演得到了台站下方地壳厚度和泊松比.反演结果显示首都圈地区莫霍面的区域构造方向呈北东或北北东向展布,地壳由东南向西北方向逐渐增厚,平均厚度为34 km.... 详细信息

利用首都圈数字地震台网宽频带和短周期记录提取了接收函数,用H-Kappa叠加方法反演得到了台站下方地壳厚度和泊松比.反演结果显示首都圈地区莫霍面的区域构造方向呈北东或北北东向展布,地壳由东南向西北方向逐渐增厚,平均厚度为34 km.地壳泊松比分布呈现出分块的特征,泊松比高值区对应于岩石比较破碎的多条活动断裂带交汇区.而某些地区堆积有较厚的低速松散沉积层,其下的结晶基底介质速度相对较高,因此,该界面造成径向直达P波能量非常弱,而紧随其后的转换波能量较强,称其为首到波峰.通过正演计算,建立首到波峰和直达P波到时差与沉积层厚度的定量关系,从而可根据首到波峰相对于直达P波的时间延迟来快速判定沉积层的大致厚度.

关键词：接收函数莫霍面沉积层首都圈地区

Scheme for Implementation of an Economic 1→3 Quantum Cloning Machine via Cavity-Assisted Atomic Collisions in Cavity-QED

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Communications in Theoretical Physics 2008年第1期49卷 77-79页

作者： LIU qi ZHANG Wen-Hai YE Liu School of Physics and Material Science Anhui University Hefei 230039 China Department of Physics and Electronic Engineering Hefei Teachers College Hefei 230601 China

A scheme to implement of 1 →3 economic phase-covariant cloning machine for unknown equator state in cavity-QED is proposed. The scheme requires cavity-assisted collision processes between atoms, which cross through nonresonant cavity fields in the vacuum states. The cavity fields are only virtually excited so that the cavity quality factor can be loosened.

关键词： cloning implementation cavi-ty-QED