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881.
《华侨大学学报 《华侨大学学报(自然科学版)》2007,28(3)
《华侨大学学报(自然科学版)》是华侨大学主办的,面向国内外公开发行的自然科学综合性学术刊物·本刊坚持四项基本原则,贯彻“百花齐放,百家争鸣”和理论与实践相结合的方针,广泛联系海外华侨和港、澳、台、特区的科技信息,及时反映国内尤其是华侨大学等高等学府在基础研究、应用研究和开发研究等方面的科技成果,为发展华侨高等教育和繁荣社会主义科技事业服务·本刊主要刊登机械工程及自动化、测控技术与仪器、电气工程、电子工程、计算机技术、应用化学、材料与环境工程、化工与生化工程、土木工程、建筑学、数学和管理工程等基础研究和应… 相似文献
882.
Based on Quick Bird satellite image data, the present study examined small-scale herbaceous community patches in the marsh of the Sanjiang Plain and measured patch characteristics such as the area, perimeter and shape by GPS. The coenological characteristics of the patches were investigated using quadrat method, and the vascular plant species were recorded using transect method. A total of 219 plant species were recorded, which represents 12.2% of the vascular flora in Heilongjiang Province. Our results showed that species number S correlated with patch area and perimeter; richness index (R) correlated with patch perimeter; Simpson index (D) correlated with patch area and perimeter/area; Shannon-Wiener index (H′) correlated with patch area, perimeter and perimeter/area; Evenness index (Jsw) correlated with perimeter/area. Both S and R have significant difference between different size of patches. Plant diversity in the small-scale herbaceous communities tended to increase with the patch area and perimeter. We concluded that edge effects and the habitat heterogeneity of the patches are important in determining the number of species. The relative smoothness of the patch edges also affects the plant diversity of the patches. The richness of plant species in the marsh in the Sanjiang Plain is highly sensitive to the small-scale patches, which continues to play an important role in preserving plant diversity in the local area. 相似文献
883.
High resolutionhistoricalclimaticdataarevitalforunderstandingthemechanismsofclimaticvariabil ity ,improvingclimatemodel,anddistinguishingan thropogeniceffectsfromthenaturalforcingoncli matechange[1,2 ] .China ,withcontinuousandabun danthistoricaldocuments ,isoneofthemostpotentialregionstoprovidehigh resolutionclimaticseries[3,4 ] .Sincethe 1970s ,manyhistoricalclimaticserieshavebeenestablishedbyproxydata ,forexample ,thegradeofdryness/wetnessfor 12 0stationsoverthepastfivecenturies[5] ,andfor … 相似文献
884.
Theanalysesofpaleoecologicalprocessesondifferenttemporalandspatialscales,thetimeexpansionofthetraditionalecology,areimportantforpredictingthefutureglobalchanges[1].However,itisdifficulttoperformsuchanalysesonalargetemporal,forexamplethousandyear,scale.Currentpaleoecologicalstudiesstronglyrelyonfossilrelicssuchasfootprint,moulage,reliquiae,boneandothermaterials,butthesematerialsarerarelyavailableanddifficulttopreserve.Recently,stableisotopeanalysishasbeenusedasaneffectivetechniqueforstudyingthe… 相似文献
885.
在反铁磁性近藤化合物CePdAl3的Pd位置,用Ag进行替代,制备了Ce(Pd1-xAgx)2Al3化合物,并用X线衍射方法对样品进行表征,计算得到了样品的晶格常数和晶胞体积。 相似文献
886.
基于多代理的复杂快速调运系统研究 总被引:1,自引:0,他引:1
针对以缩短时间为首要目标,以节约成本为优化原则,且面临组织因素复杂等背景的快速物资调运问题,结合人工智能合作分布式规划的思想和运筹学解析模型特点,提出了基于多代理的分布式分层求解体系框架,给出体现面向对象特点的系统描述以及系统分层、体系构建和仿真的说明,为现实问题的解决提供了新的思路。 相似文献
887.
Preliminary analysis of grain-size populations with environmentally sensitive terrigenous components in marginal sea setting 总被引:6,自引:0,他引:6
SUN Youbin GAO Shu & LI Jun . Institute of Oceanology Chinese Academy of Sciences Qingdao China . Ministry of Education Key Laboratory of Coast Island Develop-ment Nanjing University Nanjing China Correspondence should be addressed to Sun Youbin 《科学通报(英文版)》2003,48(2)
Grain-size data have been widely used to determine sediment transport patterns and to reconstruct the sedi-mentary environment. Because the natural occurring sediments deposited in the geologic periods and modern times are mostly mixtures of materials transported from multi-sources or/and by different sedimentary processes, the grain size of bulk samples is an incomplete, approxi-mate index for sedimentary environment changes[1,2]. Thus, further studies on the quantitative reconstruction of th… 相似文献
888.
WANG Shuguang LI Yanhui Gong Xiaoyan ZHAO Huazhang LUAN Zhaokun XU Cailu & WU Dehai . State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sci-ences Beijing China . Department of Mechanical Engineering State Key Laboratory ofAutomotive Safety Energy Tsinghua University Beijing China Correspondence should be addressed to Wang Shuguang 《科学通报(英文版)》2003,(5)
The properties and applications of CNT, one new carbon material, have been studied extensively since their discovery by Iijima of NEC Co. of Japan[1] and batch production[2]. They have exceptional mechanical proper-ties and unique electrical property, large aspect ratio and highly chemical stability. Thus far, they have widely po-tential applications in many fields. They can be used as reinforcing materials in composites[3—5], field emissions[6,7], hydrogen storage[8], nanoelectronic comp… 相似文献
889.
CHEN Nuofu ZHANG Fuqiang YANG Junling LIU Zhikai YANG Shaoyan CHAI Chunlin WANG Zhanguo HU Wenrui & LIN Lanying . Key Laboratory of Semiconductor Materials Science Institute of Semiconductors Chinese Academy of Sciences Beijing China . National Microgravity Laboratory Chinese Academy of Sciences Institute of Mechanics Beijing China Correspondence should be addressed to Chen Nuofu 《科学通报(英文版)》2003,48(6):516-518
Magnetic semiconductors can combine the semi- conducting properties with magnetic properties, and be used in these applications, such as magnetic field sensors, magnetic memory elements and, in long range, quantum computation and communication.Ⅱ-Ⅵ based diluted magnetic semiconductors (DMSs) have been extensively studied[1—3], because some magnetic ions are easily incor-porated into Ⅱ-Ⅵ compounds by substituting group Ⅱ atoms. It was conventionally considered that the equilib-rium solubi… 相似文献
890.
Therapeutic angiogenesis induced by human hepatocyte growth factor gene in hindlimb ischemia of dogs 总被引:2,自引:0,他引:2
HAXiaoqin RENJianping BIJianjin ZHANGJinhui WUZuze 《科学通报(英文版)》2003,48(7):676-680
A preclinical study of treating peripheral srtery occlusive disease(PAD) was performed by using a hepatocyte growth factor(HGF) gene-expressing vector,plasmid pUDKH,in a dog model with complete ischemia of one hindlimb.After ligation of femoral artery of one hindlimb,pUDKH was transferred directly into the ischemic limb muscles.The angiogenic activity of the plasmid pUDKH was evaluated.On D 30 after injecting once of pUDKH at differ-ent doses into local muscles immediately after operation,the degree of augmentation of collateral vessel formation was significantly greater than that treated by blank vector.In addition,the blood flow rate of femoral artery in dogs treated with pUDKH was recovered on D90,while the folw rate was only 1/5 tp 1/3 in control dogs.The pulse amplitude of pUDKH-treated dogs was recovered on D90,but it was hardly detectable in most of the control dogs.The side effects of intramuscular transfection of pUDKH were also investi-gated,and no significant positive change was found.It is suggested that angiogenesis induced by HGF gene has the potential for clincal use in the treatment of peripheral arte-rial diseases. 相似文献