检索结果-南通市图书馆

Syntheses and Structural Characterizations of η~5-2,4-Cyclopentadien-1-yl Di-carbonyliron Heteronuclear Bi-Metallic Complexes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2001年第1期17卷 63-68页

作者： GAO jin sheng MA Zhong guo YE Ling BU Wei ming MA Dong sheng YU Chang hua GE Yue FAN Yu guo Department of Chemistry Heilongjiang UniversityHarbin 150080P.R.China Key Laboratory of Supramolecular Structure and Spectroscopy Jilin UniversityChangchun 130023P.R.China

The novel complexes, Cp(CO) 2FeTiCp 2Cl(1) and Cp(CO) 2FeSn(CH 2CMe 2Ph) 3(2), were synthesized and characterized by means of elemental analyses and IR spectra, Cp(CO) 2FeSn· (CH 2CMe 2Ph) 3 was additionally characterized by X ray crystal structure analysis. The results of the elemental analyses are in good agreement with the theoretical values. The IR spectra show the existence of η 5 2,4 cyclopentadien 1 yl, carbonyl and methyl groups in the title complexes. The above experimental results show that the M-M bond exists in Cp(CO) 2FeSn· (CH 2Me 2Ph) 3, while the existence of the M-M bond in Cp(CO) 2FeTiCp 2Cl is highly possible, too. Both the two complexes are rather stable towards air and moisture, easily soluble in tetrahydrofuran and toluene, while their solubilities are greatly different in n hexane.

关键词： Metal metal bond Heteronuclear bimetallic complex Synthesis Characterization Crystal structure

Remaining useful life estimation based on Wiener degradation processes with random failure threshold

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2016年第9期23卷 2230-2241页

作者： TANG sheng-jin YU Chuan-qiang FENG Yong-bao XIE Jian GAO Qin-he SI Xiao-sheng High-Tech Institute of Xi＇an Xi＇an 710025 China

Remaining useful life(RUL) estimation based on condition monitoring data is central to condition based maintenance(CBM). In the current methods about the Wiener process based RUL estimation, the randomness of the failure threshold has not been studied thoroughly. In this work, by using the truncated normal distribution to model random failure threshold(RFT), an analytical and closed-form RUL distribution based on the current observed data was derived considering the posterior distribution of the drift parameter. Then, the Bayesian method was used to update the prior estimation of failure threshold. To solve the uncertainty of the censored in situ data of failure threshold, the expectation maximization(EM) algorithm is used to calculate the posteriori estimation of failure threshold. Numerical examples show that considering the randomness of the failure threshold and updating the prior information of RFT could improve the accuracy of real time RUL estimation.

关键词： condition based maintenance remaining useful life wiener process random failure threshold bayesian EM algorithm

Rheological Evidence of the Lithospheric Destruction of the Eastern Block of the North China Craton

在线全文

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2024年第S01期98卷 36-38页

作者： LI Baochun YE Gaofeng jin sheng WEI Wenbo ZHANG Letian School of Geophysics and Information Technology China University of Geosciences(Beijing)Beijing 100083China School of Resources and Environmental Engineering Inner Mongolia University of TechnologyHohhot 010051China State Key Laboratory of Geological Process and Mineral Resources Beijing 100083China

The Eastern Block of the North China Craton(NCC)(Fig.1)has undergone severe lithospheric destruction,with crustal thinning down to 100 km depth(Chen et al.,2009),contrasting sharply with the stable Kalahari and Rae ***,there remains controversy over the destruction pattern(e.g.,Zhu et al.,2017).During the Early Mesozoic,crustal thickening occurred in the Xuhuai and Qinling orogens,followed by lithospheric delamination leading to crustal thinning(Chen et al.,2023).The middle and upper crustal thinning in the Yanshan and Taihang uplifts was induced by mafic magma underplating(Ji et al.,2009).

关键词： magnetotellurics resistivity viscosity Eastern Block North China Craton

Lowered water table causes species substitution while nitrogen amendment causes species loss in alpine wetland microbial communities

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2021年第6期31卷 912-922页

作者： Yuntao LI jin-sheng HE Hao WANG Jizhong ZHOU Yunfeng YANG Haiyan CHU State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of Sciences71 East Beijing RoadNanjing 210008(China) University of Chinese Academy of Sciences Beijing 100049(China) Department of Ecology College of Urban and Environmental SciencesPeking UniversityBeijing 100871(China) State Key Laboratory of Grassland Agro-Ecosystems College of Pastoral Agriculture Science and TechnologyLanzhou UniversityLanzhou 730000(China) State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084(China) Institute for Environmental Genomics Department of Microbiology and Plant Biology and School of Civil Engineering and Environmental SciencesUniversity of OklahomaNorman OK 73019(USA) Earth Science Division Lawrence Berkeley National LaboratoryBerkeley CA 94270(USA)

Alpine wetlands are hotspots of carbon(C)storage and methane emission,and they could be key contributors to global *** recent years,rapid warming has lowered the water table in alpine wetlands on the Tibetan Plateau,concurrent with intensified nitrogen(N)deposition via anthropogenic *** carried out a field experiment to investigate the ecological impacts of these two factors on soil bacterial and functional communities,which are essential drivers of greenhouse gas *** amendment alone decreased the phylogenetic alpha-diversity of bacterial communities which could be offset by lowered water *** contrast,microbial functional alpha-diversity,revealed by a high-throughput microarray,remained *** bacterial and functional beta-diversity responded to lowered water table,but only bacterial community responded to N *** alpha-Proteobacteria,beta-Proteobacteria,and Bacteroidetes were the major responsive bacterial lineages,and C degradation,methanogenesis,alkaline shock,and phosphorus oxidation were the major responsive functional *** analysis revealed that N amendment changed bacterial community structure mainly via species loss processes but did not affect bacterial functional communities,with soil pH and ammonium as the key factors influencing changes in bacterial community ***,lowered water table altered bacterial and functional communities through species substitution processes linked to soil pH and soil *** to our results,the response mechanisms of microbial communities to lowered water table and N amendment are fundamentally different in alpine wetlands.

关键词： alpha-diversity bacterial community beta-diversity microbial functional community N amendment water table lowering

EFFECTS OF WATER TABLE AND NITROGEN ADDITION ON CO_2 EMISSION FROM WETLAND SOIL

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2005年第3期15卷 262-268页

作者： YANG Ji-song LIU jing-shuang YU Jun-bao WANG jin-da QIN sheng-jin LI Xin-hua Northeast institute of Geography and Agricuhural Ecology Chinese A ctutemy of Sciences Changchun 130012 P. R.China Graduate School of Chinese Academy of Sciences Beijing 100019 P. R. China

Soil respiration is a main dynamic process of carbon cycle in wetland. It is important to contribute to global climate changes. Water table and nutritious availability are significant impact factors to influence responses of CO2 emission from wetland soil to climate changes. Twenty-four wetland soil monoliths at 4 water-table positions and in 3 nitrogen status have been incubated to measure rates of CO2 emission from wetland soils in this study. Three static water-table controls and a fluctuant water-table control, with 3 nitrogen additions in every water-table control, were carried out. In no nitrogen addition treatment, high CO2 emissions were found at a static low water table (Ⅰ) and a fluctuant water table (Ⅳ), averaging 306.7mg/(m2·h) and 307.89mg/(m2·h), respectively, which were 51%-57% higher than that at static high water table (Ⅱ and Ⅲ). After nitrogen addition, however, highest CO2 emission was found at Ⅱ and lowest emission at Ⅲ. The results suggested that nutritious availability of wetland soil might be important to influence the effect of water table on the CO2 emission from the wetland soil. Nitrogen addition led to enhancing CO2 emissions from wetland soil, while the highest emission was found in 1N treatments other than in 2N treatments. In 3 nutritious treatments, low CO2 emissions at high water tables and high CO2 emissions at low water tables were also observed when water table fluctuated. Our results suggested that both water table changes and nutritious imports would effect the CO2 emission from wetland.

关键词： CO2 emission water table nitrogen addition wetland soil

Carbon nanotube enhanced water-based drilling fluid for high temperature and high salinity deep resource development

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第2期19卷 916-926页

作者： jing-Ping Liu Xian-Fa Zhang Wen-Chao Zhang Kai-He Lv Yin-Rui Bai jin-Tang Wang Xian-Bin Huang Jia-Feng jin jin-sheng Sun College of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China CNPC Engineering Technology R&D Company Limited Beijing 102206China

Drilling fluids face failure during drilling deep reservoir with high temperature and high *** experimental results show that high temperature and salinity reduce the negative charge on the surface of bentonite in the drilling fluid and cause the coalescence of bentonite *** a result,the particles coalesce,the grid structure is destroyed,and the rheological properties,rock-carrying capacity and filtration properties are *** resolve the foregoing,in this study,0.05-wt%carbon nanotubes are introduced into a 4%bentonite drilling fluid under conditions where the temperature and concentration of added Na Cl reach 180°C and 10 wt%,*** carbon nanotubes adsorb on the bentonite surface and increase the space among bentonite *** steric hindrance prevents the coalescence of bentonite in high temperature and high salt *** bentonite maintains the small size distribution of bentonite and supports the bentonite grid structure in the drilling *** a result,the rock-carrying capacity of the drilling fluid increases by 85.1%.Moreover,the mud cake formed by the accumulation of small-sized bentonite particles is dense;consequently,the filtration of bentonite drilling fluid reduced by 30.2%.

关键词： High temperature Water-based drilling fluid High salinity Carbon nanotube Deep resources

STOCHASTIC ANALYSIS OF GROUNDWATER FLOW SUBJECT TO RANDOM BOUNDARY CONDITIONS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第5期20卷 553-560页

作者： SHI Liang-sheng YANG jin-zhong CAI Shu-ying LIN Lin State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Wuhan 430072 China

A stochastic model was developed to simulate the flow in heterogeneous media subject to random boundary conditions. Approximate partial differential equations were derived based on the Karhunen-Loeve （KL） expansion and perturbation expansion. The effect of random boundary conditions on the two-dimensional flow was examined. It is shown that the proposed stochastic model is efficient to include the random boundary conditions. The random boundaries lead to the increase of head variance and velocity variance. The influence of the random boundary conditions on head uncertainty is exerted over the whole simulated region, while the randomness of the boundary conditions leads to the increase of the velocity variance in the vicinity of boundaries.

关键词： groundwater flow Karhunen-Loeve (KL) expansion hydraulic head random boundary variance

Selective depression mechanism of ferric chromium lignin sulfonate for chalcopyrite–galena flotation separation

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2018年第5期25卷 489-497页

作者： jin-sheng Yu Run-qing Liu Li Wang Wei Sun Hong Peng Yue-hua Hu School of Minerals Processing and Bioengineering Central South University School of Chemical Engineering The University of Queensland

Selective recovery of chalcopyrite–galena ore by flotation remains a challenging *** development of highly efficient,low-cost,and environmentally friendly depressants for this flotation is necessary because most of available reagents(e.g.,K_2Cr_2O_4)are expensive and adversely affect the *** this study,ferric chromium lignin sulfonate(FCLS),which is a waste-product from the paper and pulp industry,was introduced as a selective depressant for galena with butyl xanthate(BX)as a *** show that the residue recovery of Pb in Cu concentrate was substantially reduced to 4.73%using FCLS compared with 10.71%using the common depressant K_2Cr_2O_*** underlying mechanisms were revealed using zeta-potential measurements and X-ray photoelectron spectroscopy(XPS).Zeta-potential measurements revealed that FCLS was more efficiently absorbed onto galena than onto *** measurements further suggested that FCLS enhanced the surface oxidation of galena but prevented that of ***,FCLS could be a potential candidate as a depressant for chalcopyrite–galena flotation because of its low cost and its lack of detrimental effects on the environment.

关键词： chalcopyrite galena depressant flotation separation

Double network self-healing hydrogel based on hydrophobic association and ionic bond for formation plugging

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2022年第5期19卷 2150-2164页

作者： Ying-Rui Bai Qi-Tao Zhang jin-sheng Sun Guan-Cheng Jiang Kai-He Lv School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina CNPC Engineering Technology R&D Company Limited Beijing102206China College of Petroleum Engineering China University of Petroleum(Beijing)Beijing102249China

Self-healing hydrogels have attracted tremendous attention in the field of oil and gas drilling and production engineering because of their excellent self-healing performance after physical *** this study,a series of double network self-healing(DN_(SA))hydrogels based on hydrophobic association and ionic bond were prepared for plugging pores and fractures in formations in oil and gas drilling and production *** mechanical,rheological,and self-healing properties of the DN_(SA)hydrogels were *** revealed that the DN_(SA)hydrogels exhibited excellent mechanical properties with a tensile stress of 0.67 MPa and toughness of 7069 kJ/cm^(3) owing to the synergistic effect of the double *** addition,the DN_(SA)hydrogels exhibited excellent compression resistance,notch insensitivity,and self-healing *** DN_(SA)-2 hydrogel was granulated and made into gel particles with different particle sizes and used as a plugging *** self-healing mechanism of DN_(SA)-2 hydrogel particles in fractures was explored,and it’s plugging effect on fractures of different widths and porous media of different permeabilities were *** results revealed that the plugging capacity of the DN_(SA)-2 hydrogel particles for a fracture with width of 5 mm and a porous medium with a permeability of 30μm^(2) was 3.45 and 4.21 MPa,respectively,which is significantly higher than those of commonly used plugging agents in the *** DN_(SA)hydrogels with excellent mechanical and self-healing properties prepared in this study will provide a new approach for applying hydrogels in oil and gas drilling and production engineering.

关键词： Self-healing hydrogel Hydrophobic association Ionic bond Mechanical property Rheological property Formation plugging