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Spacial hindrance induced recovery of over-poisoned active acid sites in pyridine-modified H-mordenite for dimethyl ether carbonylation 被引量:5
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作者 Na Zhao Ye Tian +6 位作者 Lifu Zhang Qingpeng Cheng Shuaishuai Lyu Tong Ding Zhenpeng Hu Xinbin Ma Xingang Li 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2019年第6期895-904,共10页
Zeolite catalysts,such as H-mordenite(H-MOR),are readily deactivated by coke deposition in carbonylation reactions.Pyridine modification of H-MOR can improve its stability but can lead to an undesirable loss in cataly... Zeolite catalysts,such as H-mordenite(H-MOR),are readily deactivated by coke deposition in carbonylation reactions.Pyridine modification of H-MOR can improve its stability but can lead to an undesirable loss in catalytic activity.Herein,we report the intrinsic impact of the pyridine adsorption behavior on H-MOR and the spacial hindrance of the zeolite frameworks on dimethyl ether(DME)carbonylation at a molecular level.We discovered that acid sites at O2 positions,located on common walls of eight-membered ring(8-MR)side pockets and 12-MR channels,were active in DME carbonylation,but were unfortunately poisoned during pyridine modification.Density functional theory calculations revealed that the pyridine-poisoned acid sites at the O2 positions could be easily regenerated due to the spacial hindrance of the zeolite frameworks.Accordingly,they can be facilely regenerated by proper thermal treatment,which induces 60%promotion in the catalytic activity along with a high stability.Our findings demonstrate the determining role of O2 positions in H-MOR for DME carbonylation and provide a new avenue for the rational design of other efficient zeolite-relevant catalytic systems. 展开更多
关键词 H-MORDENITE Pyridine modification Dimethyl ether CARBONYLATION REGENERATION Spacial hindrance
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Spacial Patterns of Fine Root Abundance in Mixed Larch-Ash Plantation 被引量:1
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作者 崔晓阳 《Journal of Forestry Research》 SCIE CAS CSCD 1997年第4期206-210,共5页
Horizontal and veftical distributions of fine root abundance (mass per unit ground surface arca) were investi-gated in a densely planted larch - ash -stripe - mixed tbrest on dark broxvn forest soil in northeast China... Horizontal and veftical distributions of fine root abundance (mass per unit ground surface arca) were investi-gated in a densely planted larch - ash -stripe - mixed tbrest on dark broxvn forest soil in northeast China. There was evidencefor some degree of below-ground niche partitioning (or differentiation) betmpen the two species in hoth the horizontal andvertical directions. The ash fine roots largely penetrated into the larch belt (larch Sub-community) in surttrce soil (0-20 cm),indicating a possible inductive effect of larch ecological field on ash roots, while the penetration of larch tine roots into ashbelt (ash sub-community) was much restricted- which reflected a negative influence of ash ccological tield on Iarch roots. Inthe vertical direction of marginal soil the ash tine roots were mainly distributed in topsoil with a vertical gradient similar tothat as in the internal ash sub-community. but the larch fine roots were relatively compelled to deepcr soil layers by the com-petition (or exclusion) of marginal ash trees. All the dit1brences or complemcntarity wcre considered to the result of inter-specitic competition, which was important to the coexistence of the two tbrest species and the sustainability of mixed planta-tion. 展开更多
关键词 LARIX olgensis FRAXINUS mandshurica Mixture PLANTATION Fine ROOTS Spacial distribution
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Spatiotemporal Change of Agrometeorological Flood Disasters in Heilongjiang Province
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作者 Shi Feng-mei Pei Zhan-jiang +5 位作者 Lu Bin-yu Wang Su Gao Ya-bing Liu Jie Wang Quan-hui Huang Bo 《Journal of Northeast Agricultural University(English Edition)》 CAS 2020年第1期90-96,共7页
Agrometeorological disasters severely impact agriculture in Heilongjiang Province.Flood is one of the main agrometeorological disasters in Heilongjiang Province.The temporal change in flood events in Heilongjiang Prov... Agrometeorological disasters severely impact agriculture in Heilongjiang Province.Flood is one of the main agrometeorological disasters in Heilongjiang Province.The temporal change in flood events in Heilongjiang Province from 1986to 2015 was studied using Mann-Kendall and Morlet wavelet methods,respectively.The results of Mann-Kendall analysis showed that the disaster rates of flood gradually stabilized from 1986 to 2015 with a confidence level of 99%.The Morlet wavelet variance analysis revealed that disaster rates of flood changed periodically at time scales of 3a,7a and 18a in Heilongjiang Province during1986-2015.The dominant period of the variation of flood disaster rate was about 18a over the past 30 years.The flood disaster rates were indicated in a positive phase during the period of 2016-2020 by the fitting curve of Morlet wavelet analysis.The annual average flood disaster indexes of single station,during 1986-2015 years were calculated,according to the precipitation data at 31 stations in Heilongjiang Province and the GIS software was used to analyze the spatial change in flood disasters in Heilongjiang Province from1986-2015.The results demonstrated that the southwest area of Heilongjiang Province was highly hazardous region of flood.The flood indices in the northern part of Songnen Plain and southwest of Heilongjiang Province presented the increment trends. 展开更多
关键词 FLOOD DISASTER rate temporal and spacial change characteristic MANN-KENDALL METHOD Morlet WAVELET METHOD
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Spacial organization on the rural settlements in plain areas—taking Pinghu city in Zhejiang of China as an example
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作者 XUE Dong-qian1, YAO Shi-mou2, ZHANG Hong1 (1. Dept. of Tourism and Environment, Shaanxi Normal University, Xi’an 710062, China 2. Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China) 《Journal of Geographical Sciences》 SCIE CSCD 2000年第3期59-64,共2页
This paper analyses the spacial distribution, quantity-scale, function-structure and facilities from the angle of spacial organizational optimizing theory and sustainable development thought. The authors point out the... This paper analyses the spacial distribution, quantity-scale, function-structure and facilities from the angle of spacial organizational optimizing theory and sustainable development thought. The authors point out the distributional principles of rural settlements in plain areas, and put forward planning and distribution of various levels of rural settlements (central villages, basic villages and natural villages). 展开更多
关键词 plain area central villages basic villages natural villages spacial organization
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RESEARCH ON MICROWAVE HUMIDITY TESTING OF CERAMIC PRODUCTS
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作者 刘泉 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2000年第2期45-48,共4页
This paper analyses the principle of microwave humidity testing. According to the problems in the production procedure of ceramic products, a microwave humidity testing system is designed and analyzed for its advantag... This paper analyses the principle of microwave humidity testing. According to the problems in the production procedure of ceramic products, a microwave humidity testing system is designed and analyzed for its advantages. Furthermore, the system has been applied to the production line that produces ceramic products and the testing results are also satisfying. 展开更多
关键词 ceramic products microwave humidity testing spacial wave testing method
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Geospacial information utilized under the access control strategy
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作者 田捷 《Journal of Chongqing University》 CAS 2007年第4期256-264,共9页
This paper introduces a solution to the secure requirement for digital rights management (DRM) by the way of geospacial access control named geospacial access control (GeoAC) in geospacial field. The issues of aut... This paper introduces a solution to the secure requirement for digital rights management (DRM) by the way of geospacial access control named geospacial access control (GeoAC) in geospacial field. The issues of authorization for geospacial DRM are concentrated on. To geospacial DRM, one aspect is the declaration and enforcement of access rights, based on geographic aspects. To the approbation of digital geographic content, it is important to adopt online access to geodata through a special data infrastructure (SDI). This results in the interoperability requirements on three different levels: data model level, service level and access control level. The interaction between the data model and service level can be obtained by criterions of the open geospacial consortium (OGC), and the interaction of the access control level may be reached by declaring and enforcing access restrictions in GeoAC. Then an archetype enforcement based on GeoAC is elucidated. As one aspect of performing usage rights, the execution of access restrictions as an extension to a regular SDI is illuminated. 展开更多
关键词 spacial technologies geospacial services access control rights expression languages
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Primary study on the "θ" letter type overlying multi-strata spatial structure of mining face surrounded by mined areas
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作者 汪华君 姜福兴 《Journal of Coal Science & Engineering(China)》 2007年第3期256-260,共5页
The overlying strata spatial structure academic viewpoint thinks the primary factor which controls the stope presses is the overlying strata spatial structure movement; the spatial structure above the later period coa... The overlying strata spatial structure academic viewpoint thinks the primary factor which controls the stope presses is the overlying strata spatial structure movement; the spatial structure above the later period coal pillar surrounded by mined areas is the most complex overlying strata spatial structure and study on its evolution law has the important realistic project significance for strata movement control and production safety. The existing research results indicate that the special structure of the first working face of the mine begins to develop lengthways from stratum movement above mined areas and extends level in the exploitation direction. From existing overlying strata spatial structure fundamental research achievement, the spatial structure above the later period coal column surrounded by mined areas have following characteristic: The spatial structure formation is from the top to the lower and from large to small. According to the findings, a formula with the use of rock layer migration angle delta was put forward to estimate isolated island coal column width on which different stratum structure is gonging to form. 展开更多
关键词 mining face overlying strata spacial structure supporting press isolated coal pillar
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Spacial Discipline in Carson McCullers’s The Ballad of the Sad Café
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作者 LU Ying-ru 《Journal of Literature and Art Studies》 2019年第2期204-208,共5页
Mainly applying Michel Foucault’s idea about spacial discipline plus gender studies,in particular,of the correlation between gender and space as well as the power hierarchy in the distribution of space,this paper ana... Mainly applying Michel Foucault’s idea about spacial discipline plus gender studies,in particular,of the correlation between gender and space as well as the power hierarchy in the distribution of space,this paper analyzes the female protagonist Miss Amelia in Carson McCullers’s The Ballad of the Sad Café.This paper argues that Amelia utilizes space as a means of self-empowerment,challenging the conventional gender dichotomy sanctioned by patriarchal norms.However,her spacial transgression is seen as a deconstruction of gender conventionality and causes masculine crisis as embodied by the male characters Marvin Macy and Cousin Lymon.As spacial discipline is collaboratively exerted by Macy and Lymon on Amelia to“correct”her transgression,Amelia finally concedes defeat and submits to patriarchal gender norms. 展开更多
关键词 CARSON MCCULLERS The BALLAD of the SAD CAFE spacial DISCIPLINE
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Seismicity Factor A-Value and Its Application to Mid-Term Earthquake Prediction in North China
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作者 Wang Wei, Song Xianyue, and Liu Zheng, and Wang ZhengzhengSeismological Bureau of Shanghai Municipality, Shanghai 200062, China Seismological Bureau of Jiangsu Province, Nanjing 210014, China 《Earthquake Research in China》 1999年第4期37-47,共11页
The seismicity factor A-value is defined by synthesizing the seismicity precursors in time, space and magnitude in this paper. The seismicity data of moderate or small earthquakes during 1972 ~ 1996 in North China are... The seismicity factor A-value is defined by synthesizing the seismicity precursors in time, space and magnitude in this paper. The seismicity data of moderate or small earthquakes during 1972 ~ 1996 in North China are used to perform spacial scanning of seismicity factor A-value. The result shows that there are obviously anomaly zones of A-value with better prediction effect in the mid-term of 2~3 years before most moderately strong earthquakes. Some problems regarding the mid-term prediction using A-value have been discussed. 展开更多
关键词 SEISMICITY FACTOR A-value SEISMIC spacial concentrative DEGREE C-VALUE SEISMIC dangerous DEGREE D-VALUE SEISMIC magnitude FACTOR Mf-value.
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A Model of Spatial Spread of an Infection with Applications to HIV/AIDS in Mali
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作者 Ouateni Diallo Yaya Kone Jerome Pousin 《Applied Mathematics》 2012年第12期1877-1881,共5页
In this paper we introduce a classical SI model to capture the spread of an infectious disease within a population. More precisely, the spatial diffusion of HIV/AIDS in a population is modeled. For that, we assume tha... In this paper we introduce a classical SI model to capture the spread of an infectious disease within a population. More precisely, the spatial diffusion of HIV/AIDS in a population is modeled. For that, we assume that the spread is due to the anarchical comportment of infected individuals along a road, especially, “lorry drivers”. The question which consists of the control of the infection is also addressed. Infected individuals moving from a town to another one, the diffusion is then anisotropic with a main direction of propagation, namely the road direction. Using a semi-group argument and a maximum principle, the uniqueness of a solution to the problem is established. This solution is also estimated. We end this paper by considering some numerical experiments in the case of HIV/AIDS spread in Mali along a road connecting two towns. 展开更多
关键词 Spacial Spread of Infections Controlability Maximum Principle
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Partition and planning:A human-like motion decision for UAV in trap environment
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作者 CHEN JinTao ZHOU Qi +1 位作者 REN HongRu LI HongYi 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2024年第4期1226-1237,共12页
This paper presents a human-like motion decision-making method for unmanned aerial vehicles(UAVs)navigating in trap environments.We proposed a space partitioning method based on sampling and consistency control to con... This paper presents a human-like motion decision-making method for unmanned aerial vehicles(UAVs)navigating in trap environments.We proposed a space partitioning method based on sampling and consistency control to conduct a preliminary analysis of the indoor environment based on architectural blueprints.This method reduces the dimensionality of the path planning problem,thereby enhancing the efficiency.Then,we designed a target-switching logic for the dynamic window approach.This improvement endows the UAV with the capability of both real-time obstacle avoidance and global navigation,enhancing the efficiency of the UAV in flying to task spots indoors.Additionally,by applying human-like methods of batch distance perception and obstacle perception to this scheme,we have further enhanced the robustness and efficiency of path decisions.Finally,considering the scenario of high-rise fire rescue,we conducted simulation verification.It demonstrates that our scheme enhances the efficiency and robustness of path planning. 展开更多
关键词 path planning indoor environment spacial partition high-rise fire rescue
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The Ultimate Female Auteur: Visuality, Subjectivity, and History in the Works of Peng Xiaolian
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作者 S. Louisa Wei 《Frontiers of Literary Studies in China-Selected Publications from Chinese Universities》 2017年第1期157-179,共23页
Peng Xiaolian is a rare and prolific Chinese author who writes both fiction and non-fiction works and directs both dramatic and documentary films. Peng has not only written, cowritten, or rewritten all the screenplays... Peng Xiaolian is a rare and prolific Chinese author who writes both fiction and non-fiction works and directs both dramatic and documentary films. Peng has not only written, cowritten, or rewritten all the screenplays of her eight dramatic features and two documentaries but is also the author of one novel, twelve novellas, over a dozen short stories, four book-length memoirs, three collections of film reviews, and numerous essays. The existing scholarly studies, however, nearly all focus on Peng's dramatic films, with much less, if any, attention directed at her writing and documentaries. To really understand Peng as a film auteur, however, it is necessary to look at her films and writings together. Given the quantity and complexity of her works and the space limitations of this article, I examine Peng's subversion of the conventional treatment of character, location, and time in three thematic sections reflecting the key narrative motifs in her work. I first summarize existing studies of Peng's films, highlighting the rarely examined interaction between visuality and spatiality in her films. Then, after defining her sense of time in narrative, I demonstrate how family history and self-reflexivity are the major difference between her films and her nonfiction works. Last but not least, I discuss how, through her use of multilayered narratives constructed by the female voice and subjectivity, her complete repertoire constitutes a unique history of modern Chinese women. This article aims to demonstrate how, through her use of multilayered narratives constructed by the female voice and subjectivity, her complete repertoire constitutes a unique history of modern Chinese women. 展开更多
关键词 female auteur visuality and spaciality female subjectivity women's history women's writing women's film
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THE USE OF THREE-DIMENSIONAL EOF TECHNIQUE TO ANALYZE CLIMATIC CHARACTERISTICS OF PRECIPITATION IN CHINA 被引量:1
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作者 苏炳凯 徐桂玉 符淙斌 《Acta meteorologica Sinica》 SCIE 1991年第5期617-627,共11页
In this paper,a three-dimensional EOF technique is used to analyze the precipitation and its anomaly over whole China and sanely selected regions,i.e.the Changjiang Valley,the Huanghe Valley and the South part of Chin... In this paper,a three-dimensional EOF technique is used to analyze the precipitation and its anomaly over whole China and sanely selected regions,i.e.the Changjiang Valley,the Huanghe Valley and the South part of China in last decades.The structural characteristics of spacial distribution,seasonal and interannual variation are revealed.As a better technique than 2-D EOF,the 3-D EOF alse provides a way to expose interac- tions between temporal and spacial variations. 展开更多
关键词 3D EOF precipitation distribution and anomalies spacial loading seasonal loading interannual loading
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Self-assembled InAs/GaAs quantum dots and quantum dot laser
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作者 王占国 刘峰奇 +1 位作者 梁基本 徐波 《Science China Mathematics》 SCIE 2000年第8期861-870,共10页
Systematic study of molecular beam epitaxy-grown self-assembled In(Ga)As/GaAs, In-AIAs/AIGaAs/GaAs, and InAs/lnAIAs/lnP quantum dots (QDs) is demonstrated. By adjusting growth conditions, surprising alignment, prefere... Systematic study of molecular beam epitaxy-grown self-assembled In(Ga)As/GaAs, In-AIAs/AIGaAs/GaAs, and InAs/lnAIAs/lnP quantum dots (QDs) is demonstrated. By adjusting growth conditions, surprising alignment, preferential elongation, and pronounced sequential coalescence of dots under the specific condition are realized. Room-temperature (RT) continuous-wave (CW) lasing at the wavelength of 960 nm with output power of 1 W is achieved from vertical coupled InAs/GaAs QDs ensemble. The FIT threshold current density is 218 A/cm2. An RT CW output power of 0.53 W ensures at least 3 000 h lasing (only drops 0.83 db). This is one of the best results ever reported. 展开更多
关键词 QUANTUM DOT spacial ORDERING QUANTUM DOT laser.
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Performance testing of a long-strip two-end readout multi-gap resistive plate chamber
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作者 王小斌 王义 +2 位作者 罗明 李元景 程建平 《Chinese Physics C》 SCIE CAS CSCD 2009年第2期114-118,共5页
Multi-gap Resistive Plate Chamber (MRPC) is a new generation of gas detector with good timing and spacial resolution, whose technique is widely applied in some recent high energy (nuclear) physics experiments. In ... Multi-gap Resistive Plate Chamber (MRPC) is a new generation of gas detector with good timing and spacial resolution, whose technique is widely applied in some recent high energy (nuclear) physics experiments. In this letter, we report a long-strip two-end readout MRPC and its test beam performance. The measurements show that the long-strip performs a transmission line characteristic and the impedance is independent of the length of strip. The MRPC module we developed is presented to gain a timing resolution of -80 ps and a spacial resolution of -6.4 mm. The possible application of the MRPC is also discussed. 展开更多
关键词 MRPC timing resolution spacial resolution
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Lipopeptides in promoting signals at surface/interface of micelles:Their roles in repairing cellular and nuclear damages
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作者 Sami Saadi Nazamid Saari +4 位作者 Hasanah Mohd Ghazali Abdulkarim Sabo Mohammed Azizah Abdul-Hamid Nor Elhouda Nacer Farooq Anwar 《Food Bioscience》 SCIE 2022年第2期73-90,共18页
Lipopeptides are recognized as a structurally diverse group of functional biopeptides.They possess multiple biological,biotechnological and therapeutic applications and are able to affect cell membrane integrity and p... Lipopeptides are recognized as a structurally diverse group of functional biopeptides.They possess multiple biological,biotechnological and therapeutic applications and are able to affect cell membrane integrity and permeability.It is widely accepted that suppressing the interaction of redooxidation is mainly aimed by inserting functional biopeptides on form alpha-helical peptides or on form antibody.Such types of structured biomaterials have great potential in promoting signal transductions to the most organelles having geometrical and spacial structures similar to endogenous liposome forms such as lysosomes,ribosomes,mitochondria and platelets..Thus,inserting radioactive trace-elements along with biopeptides is necessary in tracing the trajectory of those radioactive micelles that are destined in targeting further complicated disease and growth factor propagation.These techniques are important in determining structure-symmetry and asymmetry leading to meso-spherical crystal-packing modes or to copolymer vesiculization.The main objective of this review is to highlight and elucidate the potential role of lipopeptides in promoting signals at surface/interface of micelles along with their functionalities in repairing cellular and nuclear damages.Moreover,state-of-the-art scientific knowledge is reviewed regarding bioconjugation and structuring charged-mono-layer and/or bi-layer phospholipidic membranes in adherent to signal-biopeptides using some advanced techniques such as ultra-sound probe based polydispersity of radioactive trace-elements assisted microdialysis as micro-separating techniques in between those miscible and immiscible compounds. 展开更多
关键词 LIPOPEPTIDES Biopeptides BIOMATERIALS Spacial structure Transduction signal
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