维普中文期刊产品整合服务
58篇 您的检索式:作者名="Zhiming Yan"
    题名 作者 年代 出处 被引量
1Relief degree of land surface and its influence on population distribution in China显示文摘陆地表面(RDLS ) 的消除度是为在宏规模描述地形的一个重要因素。这研究为 RDLS 定义一个概念并且为全部国家的人口分发学习使用这个概念。FENG Zhiming TANG Yan YANG Yanzhao ZHANG Dan 2008Journal of Geographical Sciences2008,18,2:36
2TRPV1 activation improves exercise endurance and energy metabolism through PGC-1α upregulation in mice显示文摘Zhidan Luo Liqun Ma Zhigang Zhao Hongbo He Dachun Yang Xiaoli Feng Shuangtao Ma Xiaoping Chen Tianqi Zhu Tingbing Cao Daoyan Liu Bernd Nilius Yu Huang Zhencheng Yan Zhiming Zhu 2012Cell Research2012,22,3:18
3Self-powered photoelectrochemical biosensing platform based on Au NPs@ZnO nanorods array显示文摘Photoanodes,它在 photoelectrochemical (PEC ) 被使用切开的水,被显示了在一个 PEC biosensing 平台的构造适用。这被用一个适当测试分子的氧化代替水氧化认识到。这里,我们表明了采用由为谷胱甘肽(GSH ) 的自我动力的 PEC bioanalysis 与 plasmonic 金牌 nanoparticles (Au NPs@ZnO NR ) 装饰在的锌氧化物 nanorods 数组组成的 photoanodes 的可行性缓冲磷酸盐盐(PBS ) 在 0 V 对 Ag/AgCl 的一个应用偏爱潜力。因为 Au/ZnO 接口的介绍,这 heterostructure 展出了提高的 PEC 性质。在可见轻照明下面,从在 Au NP 表面的表面电浆子回声(SPR ) 的热电子被注入邻近的 ZnO 并且随后开车到光阴极。在下面紫外(紫外) 轻照明,在 ZnO 的 photogenerated 电子趋于由于逐步的精力乐队结构和在 ZnO/ 电解质接口弯曲的向上的精力乐队转到做氟的符号的听氧化物。这些结果显示 plasmonic 金属 / 半导体 heterostructure photoanodes 为自我动力的 PEC bioanalysis 应用和另外的光电的烽火的扩大的地有大潜力。Zhuo Kang Xiaoqin Yan Yunfei Wang Yanguang Zhao Zhiming Bai Yichong Liu Kun Zhao Shiyao Cao Yue Zhang 2016Nano Research2016,9,2:8
4The net primary productivity of Mid-Jurassic peatland and its control factors: Evidenced by the Ordos Basin显示文摘Using the large-scale thick 4# coal seam from the Mid-Jurassic in the southern Ordos Basin as an example, this paper studied the net primary productivity(NPP) level of the Mid-Jurassic peatland, and discussed its control factors. Geophysical logging signals were used for a spectrum analysis to obtain the Milankovitch cycle parameters in coal seam. These were then used to calculate the accumulation rate of the residual carbon in 4# coal seam. The carbon loss can be calculated according to the density and residual carbon content of 4# coal seam. Then, the total carbon accumulation rate of the peatland was further derived, and the NPP of peatland was determined. The results show that the NPP of MidJurassic peatland is higher than that of Holocene at the same latitude. Comprehensive analysis indicates that the temperature, carbon dioxide and oxygen levels in atmosphere are the main control factors of the NPP of Mid-Jurassic peatland.Wang Dongdong Yan Zhiming Liu Haiyan Lv Dawei Hou Yijun 2018International Journal of Mining Science and Technology2018,28,2:7
5Research progress in hydrate-based technologies and processes in China:A review显示文摘Natural gas hydrate(NGH) is considered as an alternative energy resource in the future as it is proven to contain about 2 times carbon resources of those contained in the fossil energy on Earth. Gas hydrate technology is a new technology which can be extensively used in methane production from NGH, gas separation and purification, gas transportation, sea–water desalination, pipeline safety and phase change energy storage, etc. Since the 1980s, the gas hydrate technology has become a research hotspot worldwide because of its relatively economic and environmental friendly characteristics. China is a big energy consuming country with coal as a dominant energy.With the development of the society, energy shortage and environmental pollution are becoming great obstacles to the progress of the country. Therefore, in order to ensure the sustainable development of the society, it is of great significance to develop and utilize NGH and vigorously develop the gas hydrate technology. In this paper,the research advances in hydrate-based processes in China are comprehensively reviewed from different aspects,mainly including gas separation and purification, hydrate formation inhibition, sea–water desalination and methane exploitation from NGH by CH4–CO2 replacement. We are trying to show the relevant research in China, and at the same time, summarize the characteristics of the research and put forward the corresponding problems in a technical way.Chungang Xu Xiaosen Li Kefeng Yan Xuke Ruan Zhaoyang Chen Zhiming Xia 2019Chinese Journal of Chemical Engineering2019,27,9:6
6Identification of odorous compounds in reclaimed water using FPA combined with sensory GC-MS显示文摘Odorous compounds in the influent of a reclaimed water treatment plant (RWTP),consisting of coagulation,sedimentation,continuous micro-filtration (CMF),and chlorination in succession,in a north China city,were identified by combining flavor profile analysis (FPA) with sensory gas chromatograph-mass spectrometry (GC-MS).The sewery/swampy/septic odor with an odor intensity of 6.4 was found to be the major odor group in the RWTP influent,and the existence of well-known odorant including dimethyl disulfide,dimethyl trisulfide,indole and skatole were confirmed using GC-MS.The result of a spiking test showed that the intensity (3.6) of the sewery/swampy/septic odor caused by these four chemicals contributed to over 50% of the odor intensity of the influent.The FPA intensity for sewery/swampy/septic odor in the RWTP effluent was 3.8,showing that the treatment process was not efficient for the removal of odorants,particularly indole and skatole.Zhiming Yan Yu Zhang Jianwei Yu Hongying Yuan Min Yang 2011Journal of Environmental Sciences2011,23,10:6
7Toward automatic estimation of urban green volume using airborne LiDAR data and high resolution Remote Sensing images显示文摘城市的绿体积是为分析城市的植被结构,生态的评估,和绿经济的评价的重要指示物。这份报纸为城市的绿体积联合的自动化评价建议一个基于目标的方法三维(3D ) 从在空中的轻察觉的信息并且变化(激光雷达) 从高分辨率的数据和植被信息遥远地通过 Lujiazui 区域的案例研究察觉到图象,上海,中国。在空中的在红外线附近的相片被用于识别城市的植被分发的高分辨率。在空中的激光雷达数据提议提取单个树并且测量树的属性的可能性,例如树高度和王冠直径。在这研究,单个树和草地作为城市的植被的独立对象被识别,并且城市的绿卷作为二宽广部分的和被计算:单个树体积和草地体积。方法由后面的步骤组成:产生并且过滤规范的数字表面模型( nDSM ),定位本地最大值点,分割植被,提取基于规范的差别植被索引( NDVI )的城市的植被的 nDSM 单个树王冠和草地反对,并且计算每个植被目标的城市的绿体积。结果在 Lujiazui 区域显示出数量和城市的绿体积的分发特征,并且为城市的绿计划和管理提供珍贵参数。激光雷达数据和图象数据的综合申请介绍一个有效方法估计城市的绿体积,这也从这份报纸被结束[出版摘要]Yan HUANG Bailang YU Jianhua ZHOU Chunlin HU Wenqi TAN Zhiming HU Jianping WU 2013Frontiers of Earth Science2013,7,1:6
8Emergency logistics scheduling with multiple supply-demand points based on grey interval显示文摘This study aimed to address the problem of post-disaster emergency material dispatching from multiple supply points to multiple demand points.In large-scale natural disasters,it is very important for multiple emergency material supply points to serve as sources of materials for multiple disaster sites and to determine emergency material scheduling solutions accurately.Furthermore,the quantity of emergency materials required at each disaster site is uncertain.To address this issue,in this study,we developed an emergency material scheduling model with multiple logistics supply points for multiple demand points based on the grey interval numbers.To optimize the proposed multi-supply-point and multi-demand-point emergency material scheduling mode,a multi-objective optimization algorithm based on a genetic algorithm was used.Experimental results demonstrate that the multi-objective optimization method can solve the emergency logistics scheduling problem better than the particle swarm optimization multi-objective solution algorithm.Additionally,the multi-supply point and multi-demand point emergency material dispatch model and optimization algorithm provides robust support for emergency management system decision-makers when they need to respond quickly to disaster relief activities.Zhiming Ding Xinrun Xu Shan Jiang Jin Yan Yanbo Han 2022Journal of Safety Science and Resilience2022,3,2:5
9Effect of the degree of milling on the physicochemical properties,pasting properties and in vitro digestibility of Simiao rice显示文摘Simiao rice is a variety of long-grain Indica rice popular in South China.However,researches on the milling technology of Simiao rice are limited.The effect of different degrees of milling(DOMs)of Simiao rice(0-12%)were evaluated in terms of the physicochemical properties and in vitro starch digestibility of the rice.The results showed that,as the DOM increased from 0 to 12%,the head rice yield(HRY)and the content of protein,lipid,dietary fiber,vitamin B1,vitamin E and niacin nonlinearly decreased,while the content of total starch and amylose and paste viscosity parameters nonlinearly increased.The differences in chemical constituents between the brown and milled Simiao rice with different DOMs lead to the variation in their pasting properties and in vitro digestibility.Because of lower content of slowly digestible starch(SDS)and resistant starch(RS),milled Simiao rice exhibited greater digestibility and a higher estimated glycaemic index(EGI).The EGI of Simiao rice ranged from 77.98 to 85.55,and remained almost constant(approximately 84)when the DOM was above 4%.Correlation analysis indicated that the EGI had strong negative correlations with lipid,protein,dietary fiber and RS,but a positive correlation with amylose.These results provide theoretical guidance for the production of Simiao rice with desired physicochemical properties and digestibility by adjusting the DOM.Zhiming Wang Mingwei Zhang Guang Liu Yuanyuan Deng Yan Zhang Xiaojun Tang Ping Li Zhencheng Wei 2021Grain & Oil Science and Technology2021,4,2:5
10MATRIEX imaging:multiarea two-photon real-time in vivo explorer显示文摘Two-photon laser scanning microscopy has been extensively applied to study in vivo neuronal activity at cellular and subcellular resolutions in mammalian brains.However,the extent of such studies is typically confined to a single functional region of the brain.Here,we demonstrate a novel technique,termed the multiarea two-photon real-time in vivo explorer(MATRIEX),that allows the user to target multiple functional brain regions distributed within a zone of up to 12mm in diameter,each with a field of view(FOV)of ~200μm in diameter,thus performing two-photon Ca2+imaging with single-cell resolution in all of the regions simultaneously.For example,we demonstrate real-time functional imaging of single-neuron activities in the primary visual cortex,primary motor cortex and hippocampal CA1 region of mice in both anesthetized and awake states.A unique advantage of the MATRIEX technique is the configuration of multiple microscopic FOVs that are distributed in three-dimensional space over macroscopic distances(>1 mm)both laterally and axially but that are imaged by a single conventional laser scanning device.In particular,the MATRIEX technique can be effectively implemented as an add-on optical module for an existing conventional single-beam-scanning two-photon microscope without requiring any modification to the microscope itself.Thus,the MATRIEX technique can be readily applied to substantially facilitate the exploration of multiarea neuronal activity in vivo for studies of brain-wide neural circuit function with single-cell resolution.Mengke Yang Zhenqiao Zhou Jianxiong Zhang Shanshan Jia Tong Li Jiangheng Guan Xiang Liao Bing Leng Jing Lyu Kuan Zhang Min Li Yan Gong Zhiming Zhu Junan Yan Yi Zhou Jian K Liu Zsuzsanna Varga Arthur Konnerth Yuguo Tang Jinsong Gao Xiaowei Chen Hongbo Jia 2019Light(Science & Applications)2019,8,1:4
11An NIR photothermal-responsive hybrid hydrogel for enhanced wound healing显示文摘Moderately regulating vascularization and immune microenvironment of wound site is necessary to achieve scarless wound healing of the skin.Herein,we have prepared an angiogenesis-promoting and scar-preventing band-aid with a core-shell structure,that consists of MXene-loaded nanofibers(MNFs)as the core and dopamine-hyaluronic acid hydrogel(H)as the shell(MNFs@V-H@DA)to encapsulate a growth factor(vascular endothelial growth factor,VEGF,abbreviated as V)and H2S donor(diallyl trisulfide,DATS,abbreviated as DA).The continuous release of DA from this system produced H2S,which would successfully induce macrophages to polarize into M2-lile phenotype,regulating the immune microenvironment and inhibiting an excessive inflammatory response at the wound sites.It is conducive to the proliferation of skin cells,facilitating the wound healing.In addition,an appropriate amount of VEGF can be released from the MXene nanofibrous skeleton by adjusting the time of near-infrared(NIR)light exposure,preventing excessive neovascularization and extracellular matrix deposition at the wound sites.Collectively,this NIR photothermal-responsive band-aid achieved scarless wound healing through gradient-controlled vascularization and a related immune sequential reaction of damaged skin tissue.Lin Jin Xiaoqing Guo Di Gao Yan Liu Jiahua Ni Zhiming Zhang Yiqiao Huang Guibin Xu Zhe Yang Xingcai Zhang Xianhan Jiang 2022Bioactive Materials2022,7,10:4
12Preparation and analysis of active rat model of rheumatoid arthritis with features of TCM toxic heat-stasis painful obstruction显示文摘Objective:To establish a collagen type II-induced rat model of rheumatoid arthritis(RA)presenting characteristics of the human form of the traditional Chinese syndrome pattern of toxic heat-stasis painful obstruction(bi zheng;arthromyodynia)as well as pathologic features of active RA.The Chinese herbal medicine Tengmei decoction was used to validate the animal model.Methods:Ninety specific pathogen free Sprague-Dawley rats were randomly divided into a normal group of 6 rats and a model group of 84 rats.To establish the rat model of collageninduced arthritis(CIA),bovine type II collagen in complete Freund’s adjuvant was injected into the model group rats as a priming dose(Day 0)and boosting dose(Day 9).Changes in arthritic index(AI)scores,including limb swelling,were monitored.Thereafter,24 successfullyestablished CIA rats were randomly assigned to 4 groups with 6 animals each:model,positive control drug,high-dose traditional Chinese herbal medicine,and traditional Chinese herbal medicine.A blank control group of 6 rats was included.After 12 weeks of intervention with Tengmei decoction,articular synovial tissue and serum specimens were collected to detect interleukin-2(IL-2)and IL-17 transcription and protein expression levels.Yanan Wang Yan Lu Jie Wang Zhiming Shen Hui Liu Weiguo Ma Jisheng Zhang Xuehong Ma Kang Wang Fengxian Meng 2015Journal of Traditional Chinese Medical Sciences2015,2,3:3
13Prediction of pilot workload in helicopter landing after one engine failure显示文摘This paper presents a method to predict the pilot workload in helicopter landing after one engine failure.The landing procedure is simulated numerically via applying nonlinear optimal control method in the form of performance index,path constraints and boundary conditions based on an augmented six-degree-of-freedom rigid-body flight dynamics model,solved by collocation and numerical optimization method.UH-60 A helicopter is taken as the sample for the demonstration of landing after one engine failure.The numerical simulation was conducted to find the trajectory of helicopter and the controls from pilot for landing after one engine failure with different performance index considering the factor of pilot workload.The reasonable performance index and corresponding landing trajectory and controls are obtained by making a comparison with those from the flight test data.Furthermore,the pilot workload is evaluated based on wavelet transform analysis of the pilot control activities.The workloads of pilot control activities for collective control,longitudinal and lateral cyclic controls and pedal control during the helicopter landing after one engine failure are examined and compared with those of flight test.The results show that when the performance index considers the factor of pilot workload properly,the characteristics of amplitudes and constituent frequencies of pilot control inputs in the optimal solution are consistent with those of the pilot control inputs in the flight test.Therefore,the proposed method provides a tool of predicting the pilot workload in helicopter landing after one engine failure.Zhiming YU Xufei YAN Renliang CHEN 2020Chinese Journal of Aeronautics2020,33,12:3
14Blast furnace ironmaking process with super high TiO_(2) in the slag:Density and surface tension of the slag显示文摘Aiming at the process of smelting ultra-high(>80%)or even full vanadium titanomagnetite in blast furnace,we are conducting a series of works on physics character of high TiO_(2) bearing blast furnace slag(BFS)for slag optimization.This work discussed the density and surface tension of high TiO_(2) bearing BFS using the Archimedean principle and the maximum bubble pressure method,respectively.The influence of TiO_(2) content and the MgO/CaO mass ratio on the density and surface tension of CaO-SiO_(2)-TiO_(2)-MgO-Al_(2)O_(3)slags were investigated Results indicated that the density of slags decreased with the TiO_(2) content increasing from 20wt%to 30wt%,but it increased slightly with the MgO/CaO mass ratio increasing from 0.32 to 0.73.In view of silicate network structure,the density and the degree of polymerization(DOP)of network structure have a consistent trend.The addition of TiO_(2) reduced(Q^(3))^(2)/(Q^(2)) ratio(Q^(2) and Q^(3) represent structural unit with bridge oxygen number of 2 and 3,respectively)and then decreased DOP,which led to the decrease of slag density.The surface tension of CaO-SiO_(2)-TiO_(2)-MgO-Al_(2)O_(3) slags decreased dramatically with the TiO_(2) content increasing from 20wt%to 30wt%.Conversely,it increased with the MgO/CaO mass ratio increasing from 0.32 to 0.73.Furthermore,the iso-surface tension lines were obtained under 1723 K using the Tanaka developed model in view of Butler formula.It may be useful for slag optimization of ultra-high proportion(>80%)or even full vanadium titanomagnetite under BF smelting.Zhengde Pang Yuyang Jiang Jiawei Ling Xuewei Lü Zhiming Yan 2022International Journal of Minerals,Metallurgy and Materials2022,29,6:3
15Activation of Piezo1 contributes to matrix stiffness-induced angiogenesis in hepatocellular carcinoma显示文摘Background:Despite integrin being highlighted as a stiffness-sensor molecule in matrix stiffness-driven angiogenesis,other stiffness-sensor molecules and their mechanosensory pathways related to angiogenesis in hepatocellular carcinoma(HCC)remain obscure.Here,we explored the interplay between Piezo1 and integrinβ1 in the mechanosensory pathway and their effects on HCC angiogenesis to better understand matrix stiffness-induced angiogenesis.Methods:The role of Piezo1 in matrix stiffness-induced angiogenesis was investigated using orthotopic liver cancer SD rat models with high liver stiffness background,and its clinical significance was evaluated in human HCC tissues.Matrix stiffness-mediated Piezo1 upregulation and activation were assayed using an in vitro fibronectin(FN)-coated cell culture system with different stiffness,Western blotting and Ca^(2+)probe.The effects of shPiezo1-conditioned medium(CM)on angiogenesis were examined by tube formation assay,wound healing assay and angiogenesis array.The underlying mechanism by which Piezo1 participated in matrix stiffness-induced angiogenesis was analyzed by microRNA quantitative real-time polymerase chain reaction(qRT-PCR),matrix stiffness measurement,dual-luciferase reporter assay,ubiquitination assay and co-immunoprecipitation.Results:Increased matrix stiffness significantly upregulated Piezo1 expression at both cellular and tissue levels,and high expression of Piezo1 indicated an unfavorable prognosis.High matrix stiffness also noticeably enhanced the activation level of Piezo1,similar to its expression level.Piezo1 knockdown significantly suppressed tumor growth,angiogenesis,and lung metastasis of HCC rat models with high liver stiffness background.shPiezo1-CM from HCC cells attenuated tube formation and migration abilities of vascular endothelial cells remarkably,and analysis of differentially expressed pro-angiogenic factors revealed that Piezo1 promoted the expression and secretion of vascular endothelial growth factor(VEGF),CXC chemokine ligand 16(CXCL16)and insulin-like growth factor binding protein 2(IGFBP2).Matrix stiffness-caused Piezo1 upregulation/activation restrained hypoxia inducible factor-1α(HIF-1α)ubiquitination,subsequently enhanced the expression of downstream pro-angiogenic factors to accelerate HCC angiogenesis.Besides,collagen 1(COL1)-reinforced tissue stiffening resulted in more expression of Piezo1 via miR-625-5p.Conclusions:This study unravels a new mechanism by which the inte-grinβ1/Piezo1 activation/Ca2+influx/HIF-1αubiquitination/VEGF,CXCL16 and IGFBP2 pathway participates in matrix stiffness-driven HCC angiogenesis.Simultaneously,a positive feedback regulation loop as stiff matrix/integrinβ1/miR-625-5p/Piezo1 and COL1/stiffer matrix mediates matrix stiffness-caused Piezo1 upregulation.Miao Li Xi Zhang Mimi Wang Yaohui Wang Jiali Qian Xiaoxia Xing Zhiming Wang Yang You Kun Guo Jie Chen Dongmei Gao Yan Zhao Lan Zhang Rongxin Chen Jiefeng Cui Zhenggang Ren 2022Cancer Communications2022,42,11:3
16Anisotropic coal permeability and its stress sensitivity显示文摘This paper focuses on anisotropy of coal permeability and its stress sensitivity.Coal blocks were taken from Xinjing Coal Mine in Yangquan Coal District.Coal cores were then drilled along the strike,dip,and vertical directions.Coal permeabilities were measured with respect to stress by using a self-developed coal permeability measurement system.The used samples exhibited significant permeability anisotropy.The permeability along the strike direction was greatest among the three directions,the permeability along the vertical direction was the smallest,and the permeability along the dip direction was between the other two directions.The sensitivity of coal permeability to stress was transversely isotropic.The stress sensitivity coefficient was greater along the horizontal directions than along the vertical directions.Coal permeability exhibited anisotropic stress sensitivity due to anisotropy in Young’s modulus and porosity.The results obtained in this study are useful for optimizing the arrangement of pre-drainage boreholes.Zhiming Yan Kai Wang Jie Zang Chuan Wang Ang Liu 2019International Journal of Mining Science and Technology2019,29,3:2
17Methane hydrate formation and dissociation behaviors in montmorillonite显示文摘The methane hydrate formation and the methane hydrate dissociation behaviors in montmorillonite are experimentally studied. Through the analyses of the microstructure characteristic, the study obtains the porous characteristic of montmorillonite. It is indicated that methane hydrate in montmorillonite forms the structure I (si) crystal. Meanwhile, molecular dynamics simulation is carried out to study the processes of the methane hydrate formation and the methane hydrate dissociation in montmorillonite. The microstructure and microscopic properties are analyzed. The methane hydrate formation and methane hydrate dissociation mechanisms in the montmorillonite nanopore and on the montmorillonite surface are expounded. Combining the experimental and simulating analyses, the results indicate the methane hydrate formation and methane hydrate dissociation processes have little influence upon the crystal structure of porous media from either micro- or macro-analysis. It is beneficial to the fundamental researches on the exploitation and security control technologies of natural gas hydrate in deep-sea sediments.Kefeng Yan Xiaosen Li Zhaoyang Chen Yu Zhang Chungang Xu Zhiming Xia 2019Chinese Journal of Chemical Engineering2019,27,5:2
18Advances in Technologies of Piezoelectric Pumping with Valves显示文摘Piezoelectric pump faces unprecedented challenges when higher expectation and requirements need to be met in their applications mainly to medical treatment,hygiene and public health,and preventive healthcare.Specifically,the piezoelectric pump with valve has the disadvantages of complex structure,high duty cycle of valves,and valve movement lagged behind piezoelectric ceramics oscillation.In an attempt to inhibit its shortcomings,some researchers presented novel concepts for structural design of piezoelectric pump with valve,which could become a new research focus.Among them,the investigation into various soft valves,represented by soft structure valves made of rigid materials and soft material valves made of flexible materials,has been fruitful in recent years.The integrated design of both material and structure can tackle the problems encountered in the study of piezoelectric pump with valve,thus simplifying the pump structure,reducing the duty-cycle of valves,and improving the lagging of valve motion.In addition,new inventions of pump structure have sprung up,such as the pumps containing a single-chamber with double-drive,single-chamber with single-drive in series and single-chamber with single-drive in parallel,as well as the mixed-chamber in series and parallel.After surveying the recent progresses made by dominant academia in the development of piezoelectric pump encompassing valve,with a particular emphasis on structure design of both valve and pump body,we also summarize and identify the future research directions.Zhang Jianhui Wang Ying Fu Jun Yan Kang Li Zhiming Zhao Chunsheng 2016Transactions of Nanjing University of Aeronautics and Astronautics2016,33,3:2
19Effect of high magnetic fields on the solidification microstructure of an Al-Mn alloy显示文摘The effect of high magnetic fields on the morphology of Al-Mn phases was investigated. It is found that the tropism and the alignment of Al6Mn precipitated phases become regular under high magnetic fields. The stronger the high magnetic fields, the more regular the alignment of Al6Mn precipitated phases. Al6Mn precipitated phases can generate oriented alignment and aggregation under high magnetic fields through the observation of the quenched microstructure of the Al-Mn alloy at different temperatures. Meanwhile, the number of Al6Mn phases increases continuously along with the increasing function time of high magnetic fields. X-ray diffraction also indicates that Al6Mn phases generate obvious tropism under high magnetic fields. The process of aggregation and growth of Al6Mn precipitated phases under the function of high magnetic fields after orientation were analyzed and discussed.LUO Dawei GUO Jin YAN Zhiming LI Tingju 2009Rare Metals2009,28,3:2
20Net primary productivity and its control of the Middle Jurassic peatlands: An example from the southern Junggar coalfield显示文摘The Jurassic is an important period of global coal formation, including the development of several large coalfields in central Asia and northern China. Individual seams within these peatlands represent sustained periods of terrestrial carbon accumulation and a key environmental indicator attributed to this record is the rate of carbon accumulation. Determining the rate of carbon accumulation requires a measure of time contained within the coal and this study aimed at determining the rate via the identification of Milankovitch orbital cycles using spectral analysis. Spectral analyses of geophysical data from two thick coal seams, No. 43(35.9 m) and No. 3(13.2 m), of the Middle Jurassic of the southern Junggar coalfield were conducted to identify significant signals of variations in ash content. The results showed that the variations in ash content of the coal showed spatial cycles at 0.2, 0.7 and 1.1 m^(-1), which were interpreted to represent 123 ka(eccentricity), 37.1 ka(obliquity), and 21.2 ka(precession) orbital periodicities, respectively. Using this timeframe, the depositional time of the No. 43 and No. 3 coal seams were calculated to be 876–970 and 322–357 ka, respectively. In combination with an understanding of carbon loss during coalification, the carbon accumulation rates of these Middle Jurassic peatlands were calculated to be 58.6–64.9 and60.3–66.8 g C m^(-2) a^(-1) for the No. 43 and No. 3 coal seams, respectively. Given that the net primary productivity(NPP) was 4.3 times the value of the carbon accumulation in a mid-latitude region of 40°–45°N, an NPP of 251.8–279.1 and259.1–287.1 g C m^(-2) a^(-1) was calculated for the No. 43 and No. 3 coal seams, respectively. In the context of the same paleolatitude(40°–45°N) and peat type, the NPP values of the Middle Jurassic strata in the study area were higher than those of the peatlands of the Holocene and Permian, and were similar to the NPP values of Early Cretaceous peatlands. Considering the NPP of a peatland is predominantly controlled by atmospheric CO_2 and O_2 levels and temperature, the lower content of CO_2 and an excessive O_2 level in the temporal atmosphere would lead to a decrease in peatland NPP. Therefore, it is inferred that the CO_2 level during the Middle Jurassic was higher than that of the icehouse Permian and Holocene periods, and it was similar to the CO_2 level of the greenhouse Cretaceous period. The results are consistent with the global CO_2 variation curve of Berner. In conclusion, Milankovitch orbital cycles calculated from geophysical logs can be used to infer the NPP of temporal peatlands during different geological periods, based on which the deep-time paleoclimates can be analyzed.Yanan LI Longyi SHAO Zhiming YAN Haihai HOU Yue TANG David J.LARGE 2018Science China Earth Sciences2018,61,11:2
返回顶部 每页显示:
共3页 首页 上一页 第1页 下一页 末页 /3 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费