维普中文期刊产品整合服务
307篇 您的检索式:作者名="Xiaoli Xu"
    题名 作者 年代 出处 被引量
1Cosmogenic ^(10)Be dating of Guxiang and Baiyu Glaciations显示文摘Guxiang and Baiyu Glaciations are two previously recognized local glaciations of the Tibetan Plateau. They have been widely used as the reference standard for classifying Late Quaternary glaciations on the Tibetan Plateau and its surrounding mountains. However, the numerical chronologies of both glaciations have been lacking. In this study, cosmogenic 10Be dating was undertaken to define the timing of these two glaciations. The surface boulders deposited by the glaciers of the Guxiang and Baiyu Glaciations have exposure ages of 112.9±16.7―136.5±15.8 ka BP and 11.1±1.9―18.5±2.2 ka BP, respectively. It is likely that the Guxiang and Baiyu Glaciations correspond to marine isotope stages 6 and 2, respectively.ZHOU ShangZhe XU LiuBing PATRICK M. Colgan DAVID M. Mickelson WANG XiaoLi WANG Jie ZHONG Wei 2007Chinese Science Bulletin2007,52,10:28
2Structural changes of gut microbiota in Parkinson's disease and its correlation with clinical features显示文摘The aim of this study was to compare the structure of gut microbiota in Parkinson's disease(PD) patients and healthy controls;and to explore correlations between gut microbiota and PD clinical features. We analyzed fecal bacterial composition of 24 PD patients and 14 healthy volunteers by using 16 S rRNA sequencing. There were significant differences between PD and healthy controls, as well as among different PD stages. The putative cellulose degrading bacteria from the genera Blautia(P=0.018),Faecalibacterium(P=0.048) and Ruminococcus(P=0.019) were significantly decreased in PD compared to healthy controls.The putative pathobionts from the genera Escherichia-Shigella(P=0.038), Streptococcus(P=0.01), Proteus(P=0.022), and Enterococcus(P=0.006) were significantly increased in PD subjects. Correlation analysis indicated that disease severity and PD duration negatively correlated with the putative cellulose degraders, and positively correlated with the putative pathobionts. The results suggest that structural changes of gut microbiota in PD are characterized by the decreases of putative cellulose degraders and the increases of putative pathobionts, which may potentially reduce the production of short chain fatty acids, and produce more endotoxins and neurotoxins; and these changes is potentially associated with the development of PD pathology.Wei Li Xiaoli Wu Xu Hu Tao Wang Shan Liang Yunfeng Duan Feng Jin Bin Qin 2017Science China(Life Sciences)2017,60,11:26
3Effect of Lichong decoction on expression of Bcl-2 and Bcl-2-associated X protein mRNAs in hysteromyoma model rat显示文摘OBJECTIVE:To study on effects of Lichong decoction on expression of apoptosis-controlling genes,Bcl-2 and Bcl-2-associated X protein(Bax) mRNAs in hysteromyoma tissue of the hysteromyoma model rat.METHODS:Fifty Wistar female rats were randomly divided into a normal group,a model group,a Lichong decoction group,a Guizifuling capsule group and a Mifepristone group.The hysteromyoma rat model was established by intraperitoneal injection of exogenous estrin and progestogens.Pathological examination of uterine tissue,uterine coefficient and uterine transverse diameter were made under optic microscope and expressions of Bcl-2 and Bax mRNAs in uterine tissue in the groups were detected with real-time fluorescent quantitative polymerase chain reaction(PCR) technique.RESULTS:After treatment,under microscope it was found that in the Lichong decoction group myometrium thinned,muscle fiber slightly overgrowth or long and thin,regular arrangement,inserting phenomenon of inner circular muscle and external longitudinal muscle was occasionally or not seen in the Lichong decoction group.The uterine coefficient and the uterine transverse diameter significantly decreased(P<0.01),and Bcl-2 mRNA expression significantly decreased(P<0.01) and Bax mRNA expression significantly increased in hysteromyoma tissue(P<0.01) in the Lichong decoction group as compared with the model group.CONCLUSION:Therapeutic effects of Lichong decoction on hysteromyoma is related with decrease of Bcl-2 mRNA expression and increase of Bax mRNA expression.Donghua Li Xin Xu Ruiya Qian Jianguo Geng Yan Zhang Xiaolei Xie Yasong Wang Xiaoli Zou 2013Journal of Traditional Chinese Medicine2013,33,2:24
4A quantitative study on morphological responses of osteoblastic cells to fluid shear stress显示文摘液体砍应力(FSS ) 广泛地关于它对造骨细胞的影响被探索。在 vitro,研究证明了细胞骨架在对 FSS 的细胞的回答是很重要的。然而,词法变化,将象另外的细胞的回答一样反映细胞骨架变化,是份量上很少在过去的年里学习了。因此,在造骨细胞的导致 FSS 的词法变化在这研究被确定。实时快速的词法回答被为 1 h 与 1.2, 1.6,和 1.9 Pa 的大小暴露造骨细胞到 FSS 观察。后来,造骨细胞肌动朊细胞骨架用玫瑰精 phalloidin 被标记并且遵守了使用荧光显微镜学。结果证明 1.6 和 1.9 Pa FFS 沿着液体流动的方向导致了重要细胞的延伸和重取向。与 FSS 大小的改进一起,而且,细胞骨架显著地聚集了更多。而且,细胞外的弄空 Ca2+ 的液体流动也被用来与 1.6 和 1.9 Pa 的大小为 1 h 刺激造骨细胞。没有词法变化在移开细胞外的钙以后被观察。我们的学习建议从 1.2 ~ 1.9 Pa 的 FSS 的水平能够影响细胞的形态学,和细胞外的钙可能在造骨细胞对 FSS 刺激的反应起一个作用。Xiaoli Liu Xu Zhang Imshik Lee 2010Acta Biochimica et Biophysica Sinica2010,42,3:14
5Hierarchical Control of Ride Height System for Electronically Controlled Air Suspension Based on Variable Structure and Fuzzy Control Theory显示文摘The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension(ECAS) has excellent performance in flexible height adjustment during different driving conditions. However, the nonlinearity of the ride height adjusting system and the uneven distribution of payload affect the control accuracy of ride height and the body attitude. Firstly, the three-point measurement system of three height sensors is used to establish the mathematical model of the ride height adjusting system. The decentralized control of ride height and the centralized control of body attitude are presented to design the ride height control system for ECAS. The exact feedback linearization method is adopted for the nonlinear mathematical model of the ride height system. Secondly, according to the hierarchical control theory, the variable structure control(VSC) technique is used to design a controller that is able to adjust the ride height for the quarter-vehicle anywhere, and each quarter-vehicle height control system is independent. Meanwhile, the three-point height signals obtained by three height sensors are tracked to calculate the body pitch and roll attitude over time, and then by calculating the deviation of pitch and roll and its rates, the height control correction is reassigned based on the fuzzy algorithm. Finally, to verify the effectiveness and performance of the proposed combined control strategy, a validating test of ride height control system with and without road disturbance is carried out. Testing results show that the height adjusting time of both lifting and lowering is over 5 s, and the pitch angle and the roll angle of body attitude are less than 0.15?. This research proposes a hierarchical control method that can guarantee the attitude stability, as well as satisfy the ride height tracking system.XU Xing ZHOU Kongkang ZOU Nannan JIANG Hong CUI Xiaoli 2015Chinese Journal of Mechanical Engineering2015,28,5:13
6Lichong decoction reduces Matrix Metalloproteinases-2 expression but increases Tissue Inhibitors of Matrix Metalloproteinases-2 ex-pression in a rat model of uterine leiomyoma显示文摘OBJECTIVE:To study the effect of Lichong decoction(LD) on expression of matrix metalloproteinase-2(MMP-2) and metalloproteinase-2(TIMP-2) in a rat model of uterine leiomyoma(UL).METHODS:UL was induced in rats using exogenous estrogen and progesterone.LD was administered(p.o.) for 4 weeks,and mifepristone(RU-486)used as a control.To observe the effect of LD on the uterine coefficient and uterine transverse diameter,a radioimmunoassay method was used to detect serum levels of sex hormones.Light microscopic analyses of pathologic changes in the tissues of UL rats were evaluated.Expression of the proteins of matrix metalloproteinases(MMPs) and tissue inhibitors of metalloproteinases(TIMPs) in uterine tissues was assessed by immunohistochemical staining and western blotting.RESULTS:A UL model in rats was established successfully.LD reduced uterine weight,uterine coefficient,and uterine transverse diameter compared with untreated controls.LD reduced levels of estradiol,progesterone,follicle-stimulating hormone,and luteinizing hormone in our UL models.LD improved the pathologic condition of uterine muscle.Expression of MMP-2 protein decreased to varying extents in LD-treated groups,but TIMP-2 levels were enhanced.LD appears to reduce MMP-2 expression and increase TIMP-2 expression in UL tissue.CONCLUSION:These data suggest that the mechanism of action of LD on ULs may involve reduction of MMP-2 expression and increase in TIMP-2 expression in rats.Wang Yasong Li Donghua Xu Xin Qian Ruiya Zhang Yalan Huang Yuhua Geng Jianguo Zou Xiaoli Han Hon-gjuan Zhang Wufang 2016Journal of Traditional Chinese Medicine2016,36,4:12
7A DNA computer model for solving vertex coloring prob-lem显示文摘A special DNA computer was designed to solve the vertex coloring problem. The main body of this kind of DNA computer was polyacrylamide gel electrophoresis which could be classified into three parts: melting region, unsatisfied solution region and solution region. This polyacrylamide gel was con- nected with a controllable temperature device, and the relevant temperature was Tm1, Tm2 and Tm3, res- pectively. Furthermore, with emphasis on the encod- ing way, we succeeded in performing the experiment of a graph with 5 vertices. In this paper we introduce the basic structure, the principle and the method of forming the library DNA sequences.XU Jin QIANG Xiaoli FANG Gang ZHOU Kang 2006Chinese Science Bulletin2006,51,20:12
8Urban expansion in China and its effect on cultivated land before and after initiating'Reform and Open Policy'显示文摘Urbanization in China has expanded at an unprecedented speed since the declaration of 'Reform and Open Policy'and presented many challenges. Unbalanced regional development, appearance of super megacities and concomitant problems,and conflicts between urbanization and cultivated land protection are three critical problems that Chinese urbanization has to face. To develop new plans for foreseeable future urbanization in China, it is critical to understand the evolving history of cities across China. This study maps urban expansion of 60 typical Chinese cities based on large amount of remote sensing data and the labor-intensive image interpretation method, in order to understand the history of urban expansion from the 1970 s to 2013.Results showed that area of cities expanded 5.23 times compared to their area in the 1970 s. Urban expansion in China accelerated three times(1988–1996, 1999–2006, and 2009–2011) and decelerated three times(1997–1998, 2007–2008, and 2012–2013) over the 40 years. The urban area of South China expanded most significantly 9.42 times, while the urban area in Northeast China expanded only 2.37 times. The disparity among different administrative ranks of cities was even greater than(3.81 times) the differences among different regions. Super megacities have been continuously expanding at a fast rate(8.60-fold), and have not shown obvious signs of slowing down. The proportion of cultivated land among the land sources for urban expansion decreased to a small extent in the 1990 s, but cultivated land continues to be the major land source for urban expansion. Effective future urbanization needs controlling the expansion scale of large cities and reasonably developing medium and small cities, as well as balancing regional development.ZHANG ZengXiang WEN QingKe LIU Fang ZHAO XiaoLi LIU Bin XU JinYong YI Ling HU ShunGuang WANG Xiao ZUO LiJun LI Na LI MinMin SHI LiFeng ZENG Tian JU HongRun 2016Science China Earth Sciences2016,59,10:12
9The enhanced X-ray Timing and Polarimetry mission—eXTP显示文摘In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The mission aims at determining the equation of state of matter at supra-nuclear density, measuring effects of QED, and understanding the dynamics of matter in strong-field gravity. In addition to investigating fundamental physics, eXTP will be a very powerful observatory for astrophysics that will provide observations of unprecedented quality on a variety of galactic and extragalactic objects. In particular, its wide field monitoring capabilities will be highly instrumental to detect the electro-magnetic counterparts of gravitational wave sources.The paper provides a detailed description of:(1) the technological and technical aspects, and the expected performance of the instruments of the scientific payload;(2) the elements and functions of the mission, from the spacecraft to the ground segment.ShuangNan Zhang Andrea Santangelo Marco Feroci YuPeng Xu FangJun Lu Yong Chen Hua Feng Shu Zhang Sφren Brandt Margarita Hernanz Luca Baldini Enrico Bozzo Riccardo Campana Alessandra De Rosa YongWei Dong Yuri Evangelista Vladimir Karas Norbert Meidinger Aline Meuris Kirpal Nandra Teng Pan Giovanni Pareschi Piotr Orleanski QiuShi Huang Stephane Schanne Giorgia Sironi Daniele Spiga Jiri Svoboda Gianpiero Tagliaferri Christoph Tenzer Andrea Vacchi Silvia Zane Dave Walton ZhanShan Wang Berend Winter Xin Wu Jean J.M.in't Zand Mahdi Ahangarianabhari Giovanni Ambrosi Filippo Ambrosino Marco Barbera Stefano Basso Jörg Bayer Ronaldo Bellazzini Pierluigi Bellutti Bruna Bertucci Giuseppe Bertuccio Giacomo Borghi XueLei Cao Franck Cadoux Francesco Ceraudo TianXiang Chen Yu Peng Chen Jerome Chevenez Marta Civitani Wei Cui WeiWei Cui Thomas Dauser Ettore Del Monte Sergio Di Cosimo Sebastian Diebold Victor Doroshenko Michal Dovciak YuanYuan Du Lorenzo Ducci QingMei Fan Yannick Favre Fabio Fuschino JoséLuis Ga'lvez Min Gao MingYu Ge Olivier Gevin Marco Grassi QuanYing Gu YuDong Gu DaWei Han Bin Hong Wei Hu Long Ji ShuMei Jia WeiChun Jiang Thomas Kennedy Ingo Kreykenbohm Irfan Kuvvetli Claudio Labanti Luca Latronico Gang Li MaoShun Li Xian Li Wei Li ZhengWei Li Olivier Limousin HongWei Liu XiaoJing Liu Bo Lu Tao Luo Daniele Macera Piero Malcovati Adrian Martindale Malgorzata Michalska Bin Meng Massimo Minuti Alfredo Morbidini Fabio Muleri Stephane Paltani Emanuele Perinati Antonino Picciotto Claudio Piemonte JinLu Qu Alexandre Rachevski Irina Rashevskaya Jerome Rodriguez Thomas Schanz ZhengXiang Shen LiZhi Sheng JiangBo Song LiMing Song Carmelo Sgro Liang Sun Ying Tan Phil Uttley Bo Wang DianLong Wang GuoFeng Wang Juan Wang LangPing Wang YuSa Wang Anna L.Watts XiangYang Wen Jörn Wilms ShaoLin Xiong JiaWei Yang Sheng Yang YanJi Yang Nian Yu WenDa Zhang Gianluigi Zampa Nicola Zampa Andrzej A.Zdziarski AiMei Zhang ChengMo Zhang Fan Zhang Long Zhang Tong Zhang Yi Zhang XiaoLi Zhang ZiLiang Zhang BaoSheng Zhao ShiJie Zheng Yu Peng Zhou Nicola Zorzi J.Frans Zwart 2019Science China(Physics,Mechanics & Astronomy)2019,62,2:11
10Ag nanoparticles sensitize IR-induced killing of cancer cells显示文摘Ruizhi Xu Jun Ma Xinchen Sun ZhongpingChen Xiaoli Jiang Zhirui auo Lan Huang YangLi Meng Wang Changling Wang Jiwei Liu XuFan Jiayu Gu Xi Chen Yu Zhang Ning Gu 2009Cell Research2009,19,8:11
11Association Between Homocysteine Level and Methylenetetrahydrofolate Reductase Gene Polymorphisms in Type 2 Diabetes Accompanied by Dyslipidemia显示文摘Objective To investigate the association between total homocysteine(tHcy)level in plasma and methylenetetrahydrofblate reductase(MTHFR)C677T and A1298C genetic polymorphisms in a Chinese Han nationality population with type 2 diabetes mellitus(T2DM)accompanied by dyslipidemia.Methods This case-control study enrolled T2DM patients with dyslipidemia and without dyslipidemia respectively.Sanger dideoxy-mediated chain-termination method was used to detect the gene polymorphisms of MTHFR C677T and A1298C.Plasma tHcy and lipid levels were measured as well.The genotype frequency and allele frequency between the dyslipidemia and non-dyslipidemia groups were compared by using Chi-square test.Plasma tHcy level ofT2DM patients who carried the different genotypes was compared by Student's t test.Results Finally,82 T2DM patients with dyslipidemia and 94 ones without dyslipidemia were included in this study.There was a significant correlation between tHcy level and MTHFR C677T gene polymorphism inT2DM patients(t=2.27,P=0.02).Moreover,the plasma tHcy level in the dyslipidemia patients who carried MTHFR 677TT genotype was significantly higher than that in those with CT+CC genotype(13.62+6.97 vs.10.95+3.62pmol/L,t=2.2O,P=0.03);while for patients without dyslipidemia,comparison of the tHcy level between those who carried the above two alleles showed no significantly difference(13.34±6.03 vs.12.04±5.09μmol/L,t=1.08,P=0.29).Conclusion MTHFR 677TT genotype might associate with higher tHcy level in T2DM patients with dyslipidemia.Ying Yin Rui Li Xiaoli Li Kunrong Wu Ling Li Yuedong Xu Lin Liao Rui Yang Yan Li 2020Chinese Medical Sciences Journal2020,35,1:10
12Isolation and characterization of Sporobolomyces sp. LF1 capable of degrading chlorimuron-ethyl显示文摘A yeast strain which was capable of degrading sulfonylurea herbicide chlorimuron-ethyl named as LF1 was isolated from a chlorimuron-ethyl contaminated soil near the warehouse of the factory producing chlorimuron-ethyl in Shenyang City,Northeast China. The strain was identified as Sporobolomyces sp.,based on its morphological and physiological characteristics and the phylogenetic analysis of 18S rRNA gene sequence.So far,this is the only yeast strain of Sporobolomyces sp.which is able to degrade chlorimuron-ethyl.Incubation tests showed that when the initial concentration of chlorimuron-ethyl in culture was 5 mg/L,LF1 could degrade more than 77%of the herbicide after incubation for 4 d at 30°C.The possible mechanism of chlorimuron-ethyl degradation by LF1 could be the acidic hydrolysis caused by the acids from the metabolism of the yeast strain.Further study should be conducted to examine the pathways of chlorimuron-ethyl degradation by LF1 and to approach the feasibility of using LF1 to degrade the chlorimuron-ethyl in soil system.ZHANG Xiaoli ZHANG Huiwen LI Xu SU Zhencheng WANG Jingjing ZHANG Chenggang 2009Journal of Environmental Sciences2009,21,9:10
13Spatial and temporal variations of coastlines in northern China (2000-2012)显示文摘This study examined the spatial distribution of the continent coastline in northern China using remote sensing and GIS techniques,and calculated the fractal dimension of the coastline by box-counting method,with a time span from 2000 to 2012.Moreover,we analyzed the characteristics of spatial-temporal changes in the coastline's length and fractal dimension,the relationship between the length change and fractal dimension change,and the driving forces of coastline changes in northern China.During the research period,the coastline of the study area increased by 637.95 km,at a rate of 53.16 km per year.On the regional level,the most significant change in coastline length was observed in Tianjin and Hebei.Temporally,the northern China coastline grew faster after 2008.The most dramatic growth was found between 2010 and 2011,with an increasing rate of 2.49% per year.The fractal dimension of the coastline in northern China was increasing during the research period,and the most dramatic increase occurred in Bohai Rim.There is a strong-positive linear relationship between the historical coastline length and fractal dimension(the correlation coefficient was 0.9962).Through statistical analysis of a large number of local coastline changes,it can be found that the increase(or decrease) of local coastline length will,in most cases,lead to the increase(or decrease) of the whole coastline fractal dimension.Civil-coastal engineering construction was the most important factor driving the coastline change in northern China.Port construction,fisheries facilities and salt factories were the top three construction activities.Compared to human activities,the influence of natural processes such as estuarine deposit and erosion were relatively small.XU Jinyong ZHANG Zengxiang ZHAO Xiaoli WEN Qingke ZUO Lijun WANG Xiao YI Ling 2014Journal of Geographical Sciences2014,24,1:10
14A Transgenic Study on Affecting Potato Tuber Yield by Expressing the Rice Sucrose Transporter Genes OsSUT5Z and OsSUT2M显示文摘在许多植物,蔗糖 transporters 为从来源和进口的两个蔗糖出口是必要的进水池,显示功能在吸收划分。为了调查蔗糖 transporters 是否能改进淀粉的收益,种,土豆植物(茄属 tuberosum L。cv。Aijun Sun Yan Dai Xinsheng Zhang Chunmin Li Kun Meng Honglin Xu Xiaoli Wei Guifang Xiao Pieter B.F, Ouwerkerk Mei Wang Zhen Zhu 2011Journal of Integrative Plant Biology2011,53,7:9
15Poly-Acrylic Acid Derivatives as Diesel Flow Improver for Paraffin-Based Daqing Diesel显示文摘自从从基于石蜡的 Daqing 的柴油机产品,原油显示出低敏感到源于石蜡的高内容的某些商业柴油机倾点下降剂( PPD ),有 COOR 的某些poly丙烯酸的酸衍生物( PADE ), COOH , CONHR ,并且咕咕叫由柴油机的力学上的分子设计的(?) NH3 (+) R 组;PPD 被综合并且在这篇论文为 Daqing 0 (#) 柴油机评估了同样冷的流动十六烷值增进剂。纯 PADE 比商业 PPD 优异并且显示了蜡晶体分散的一个实质的能力。在 PADE 和 T1804 和第二等的胺之中有 synergistic。协同清楚地改进了 Daqing 柴油机产品的低温表演并且能减少由 6 ¨ C 插 0 (#) 柴油机的点的冷过滤器 7 ?? 。给词调音:柴油机;冷流动十六烷值增进剂;丙烯酸的酸;Cuiyu Jiang Ming Xu Xiaoli Xi Panlun Qi Hongyan Shang 2006Journal of Natural Gas Chemistry2006,15,3:9
16A DNA Computing Model for the Graph Vertex Coloring Problem Based on a Probe Graph显示文摘Jin xu Xiaoli Qiang Kai Zhang Cheng Zhang Jing Yang 2018Engineering2018,4,1:8
17A novel computing model of the maximum clique problem based on circular DNA显示文摘A novel DNA-based model is developed to calculate NP-complete problems, which is made of circular DNA molecules, streptavidin-coated magnetic beads and DNA circligase. To test the feasibility of the model, we apply it to compute a five-node maximum clique problem (MCP). During the computation, DNA molecule structures were transformed between linear DNA and circular DNA by streptavidin-coated magnetic beads and circligase, in order to search for the truth solutions. This greatly reduces the quantity of time and space consumed in calculation, and its time and space complexity both are O(n + m). Compared with the brute force method, using this algorithm searching process at most needs in n + 1 test tubes for an MCP with n vertices, while brute force method requires 2n test tubes. Furthermore, the constructed unenumerable initial solution space greatly improved the processing ability of the DNA computer. This novel model indicates that it may be a powerful DNA-based computer for solving some NP-complete problems.YANG Jing ZHANG Cheng XU Jin LIU XiangRong QIANG XiaoLi 2010Science China(Information Sciences)2010,53,7:7
18SARS-CoV-2 envelope protein causes acute respiratory distress syndrome (ARDS)-like pathological damages and constitutes an antiviral target显示文摘Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death.However,the origin of excessive damages caused by SARS-CoV-2 remains largely unknown.Here we show that the SARS-CoV-2 envelope(2-E)protein alone is able to cause acute respiratory distress syndrome(ARDS)-like damages in vitro and in vivo.Bingqing Xia Xurui Shen Yang He Xiaoyan Pan Feng-Liang Liu Yi Wang Feipu Yang Sui Fang Yan Wu Zilei Duan Xiaoli Zuo Zhuqing Xie Xiangrui Jiang Ling Xu Hao Chi Shuangqu Li Qian Meng Hu Zhou Yubo Zhou Xi Cheng Xiaoming Xin Lin Jin Hai-Lin Zhang Dan-Dan Yu Ming-Hua Li Xiao-Li Feng Jiekai Chen Hualiang Jiang Gengfu Xiao Yong-Tang Zheng Lei-Ke Zhang Jingshan Shen Jia Li Zhaobing Gao 2021Cell Research2021,31,8:7
19Spatial Differences of Coastal Urban Expansion in China from 1970s to 2013显示文摘As the ′economic engines′ of China,coastal cities have developed and expanded considerably since the 1970 s.In this study,information on the urban expansion process of Chinese coastal cities from the 1970 s to 2013 was retrieved.Through the analysis of stage characteristics,spatial expansion modes,influences on land use,centroid shifts,and spatial morphological evolutions,the spatial differences of coastal urban expansion were revealed.Results indicate that 1) the expansion stages of southern coastal cities are more complex than those of northern coastal cities,and the expansion ranges and speeds of the former are far higher than those of the latter;2) the spatial expansion of southern coastal cities mostly adopt a single mode,whereas northern coastal cities mostly adopt a mixed mode;3) significant spatial differences in the occupations of different land sources exist between the south and the north along the coastline;4) the centroid of coastal cities tends to migrate toward the coastline,and the centroid shift distances of southern coastal cities are clearly higher than those of northern coastal cities;and 5) the spatial morphology of southern coastal cities tends to be compact,whereas that of northern coastal cities tends to be loose.Policies have a powerful significance in terms of guiding urban expansion and its spatial differences in coastal cities.Urban expansion in coastal cities will encounter new opportunities and challenges under the guidance of new types of urbanization strategies.SHI Lifeng LIU Fang ZHANG Zengxiang ZHAO Xiaoli LIU Bin XU Jinyong WEN Qingke YI Ling HU Shunguang 2015Chinese Geographical Science2015,25,4:7
20Synergetic Effect of Y Zeolite and ZSM-5 Zeolite Ratios on Cracking, Oligomerization and Hydrogen Transfer Reactions显示文摘The objective of this study is to explore the optimum composition of Y and ZSM-5 zeolites to develop novel catalysts for obtaining lower gasoline olefins content and higher propylene yield. Five composite zeolite catalysts with varying Y zeolite/ZSM-5 zeolite ratios have been prepared in this work to investigate the synergy between the Y zeolite and ZSM-5 zeolite on the selectivity to protolytic cracking, β-scission, oligomerization, and hydrogen transfer reactions using a FCC naphtha feedstock at 480 ℃ in a confined fluidized bed reactor. Experimental results showed that the composite catalyst with a Y zeolite/ZSM-5 zeolite ratio of 1:4 had the highest protolytic cracking and β-scission ability, which was even higher than that of pure ZSM-5 catalyst. On the other hand, the catalyst with a Y zeolite/ZSM-5 zeolite ratio of 3:2 exhibited the strongest hydrogen transfer functionality while the pure Y zeolite based catalyst had the highest oligomerization ability. For all the catalysts tested, increasing conversion enhanced the selectivity to protolytic cracking and hydrogen transfer reactions but reduced the selectivity to β-scission reaction. However, no clear trend was identified for the selectivity to oligomerization when an increased conversion was experienced.Gong Jianhong Xu Youhao Long Jun Wei Xiaoli 2014China Petroleum Processing & Petrochemical Technology2014,16,3:7
返回顶部 每页显示:
共16页 首页 上一页 第1页 下一页 末页 /16 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