791 research outputs found

    Effect of ZnF2 Coating on Performance of LiNi0.5Mn1.5O4 Cathode Material for Lithium-ion Batteries

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    采用溶胶-凝胶法制备了LiNi0.5Mn1.5O4正极材料,并利用Zn F2对其表面进行包覆改性。XRD、SEM和TEM测试表明,包覆处理不影响材料的晶体结构,2%(质量分数,以LiNi0.5Mn1.5O4质量计,下同)的Zn F2在LiNi0.5Mn1.5O4表面形成了约7 nm厚均匀包覆层。对未包覆的LiNi0.5Mn1.5O4和1%、2%、3%的Zn F2包覆后的LiNi0.5Mn1.5O4的电化学性能进行了考察,发现Zn F2包覆能够减弱电解液与LiNi0.5Mn1.5O4正极材料之间的相互作用,稳定电极表面,提高材料的电化学性能。其中,2%Zn F2包覆样品表现出最佳的循环性能和倍率性能,0.2C电流倍率下循环200圈后,其放电比容量维持在109.0 m A·h/g,保持率为79.7%;5 C电流倍率下循环500圈后,放电比容量维持在94.2 m A·h/g,保持率为85.6%

    福建出口贸易发展与主要出口产品国际竞争力之研究

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    本文对福建省主要出口产品的国际竞争力进行研究,并对促进福建出口贸易发展的相关政策进行探讨。福建省对外经济贸易合作厅委托课题;; 福建省社会科学研究“十五”规划(第二期)项目(项目批准号:2003E172)的部分研究成

    Preliminary Study of Hangzhou Undergraduates Apartment Design

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    大学生人才公寓是国内近年发展起来的新建筑类型,是政府廉租房的一种具体形式。该文主要从总体规划和单体设计两方面,阐述了杭州大学毕业生人才公寓的设计过程,提出大学生人才公寓的规划设计应充分考虑年轻创业者的生活本质,提倡开放、交流、活力的新居住精神。The apartment of undergraduates is the new architectural type which has been developed in recent years, a kind of low rent houses by government. This paper mainly elaborates the design process of Hangzhou Undergraduates Apartment from the two aspects of general planning and architectural design. It brings forward the concept that Undergraduates Apartment design should take into young people's life essence consideration, and advocates the new housing concept of openness, communication and vitality

    大型XML 文档解析技术的应用与研究

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    随着XML 应用的不断深入, XML 文档快速解析技术的研究成为了当前的热点问题. 在研究XM L 相关解析技术 的基础之上, 讨论大型XML 文档的解析和处理问题, 寻求实际问题的最优解决方案. 首先, 对目前较适合大型XML 文 档解析的两种技术( VTDXML 和SAX) 做了简要的介绍, 对其各自的优劣性进行了比较和分析; 其次, 针对作者正在研 发的 核磁共振谱仪控制软件系统 中参数的XM L 设计和处理问题提出了具体的解决方案, 验证了它们在处理大型文 件时的可行性, 并对它们的实际效果进行了对比分析; 最后, 针对以上两种解决方案的不足之处, 提出了大型XML 数据 文件处理的其他解决方案.国家科技支撑计划( 2006BAK03A22) 资

    Study on antioxidant activity of polyphenols from Canarium album fruits

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    开发利用天然抗氧化剂是当前食品科技发展的趋势,橄榄果实中富含各种多酚类物质,是理想的天然抗氧化剂。本文对橄榄中的多酚含量进行了测定,用二苯基苦基苯肼自由基(DPPH.)和铁离子还原/抗氧化能力测定(FRAP)法,研究了橄榄多酚提取物的自由基清除能力及抗氧化活性。结果表明:橄榄中多酚含量高达572.30±39.71mg/g干重;橄榄多酚提取物具有较高的自由基清除能力(IC50为40.14μg/mL)及较强的抗氧化能力(4.271mmol/LAAE/g)。Exploitalion and applieation natural is trend for development food technology,there are abundant of polyphenols which are the perfect natural antioxidant.Polyphenols content of Canarium album(Lour) Rauesch fruits were determined.In addition,the effects of polyphenols from C.album fruits on free radical-scavenging and antioxidant activity were determined by using 1,1-diphenyl-2-picryhydrazyl(DPPH·) radical scavenging activity and ferric reducing/antioxidant power(FRAP) model systems.The results showed as follows:polyphenols content were 572.30 ± 39.71mg/g DW;polyphenols extracted from C.album fruits showed a very good DPPH· radical scavenging activity(IC_ 50 of 40.14μg/mL) and ferric reducing/antioxidant power(4.271mmol/L AAE/g).The DPPH· radical scavenging activities were well proved with the ferric reducing/antioxidant capacity of the studied polyphenols.国家自然科学基金资助项目(40376026,30671646

    Microbial Study of Mangrove Soil at Dongzhai Harbor in Hainan.

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    Three groups of microbial amount of mangrove soil at Dongzhai harbor in Hainan were studied.The results show as follows:①Mean amount of soil bacteria in Kandelia candel forest and Bruguiera sexangula forest is 4 87×10 7 and 7 55×10 7〔ind·(g.dry soil) -1 〕 respectively,which is higher than that of controlled mudflat without mangrove forest〔1 22×10 7ind·(g.dry soil) -1 〕;②The amount of bacteria at layer of 10-20cm is the most in three layers of 0-10、10-20 and 20-30cm;③Mean amount of soil bacteria in Bruguiera sexangula forest is higher than that in Kandelia candel forest;④The amount of bacteria is related to the amount and distribution of plant residue and litter;⑤Filamentous fungi and actinomyces are not found out by normal isolation methods,which is perhaps related to least amount and special habitat of local mangrove soil.国家教委高校湿地研究中心专项经费资助项

    Preliminary studies on the scale insect pest of Pseudaulacaspis cockerelli in mangrove

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    首次发现陆生考氏白盾蚧严重为害潮间带红树植物秋茄。通过野外定位调查和室内饲养观察,研究其危害特征、种群分布、生殖力和自然死亡率。结果表明,考氏白盾蚧主要分布在秋茄叶片主脉两侧,叶背虫口数显著多于叶面(P<0.01),单叶虫口数多为1-50头,平均25.65头,最高418头;秋茄植株不同垂直空间层次的虫口密度无显著差异,但聚集度随垂直空间下降而增大;种群平均产卵量每雌52.22粒,自然死亡率69.35%,寄生蜂寄生是最主要的死亡因子,寄生率达34.23%;与几种陆生寄主植物相比,红树林考氏白盾蚧的种群密度、生殖力、叶最高虫口数均较高,该虫对潮间带生境及寄主秋茄具有适应性。The scale insect,Pseudaulacaspis cockerelli is an important pest for many kinds of plants for a long time in the land.In 2006,it was found firstly attacking the mangrove plant of Kandelia obovata in the tideland in Xiamen City,and had led to badly damages.Based on the field surveys and lab feeding,this paper dealed with its damage characteristic,population distribution,fecundity and natural mortality etc.The results showed that the scale insect mainly distributed on both sides of the midvien of K.obovata leaves,but the individual on the abaxial surface was significantly more than those on the adaxial surface(P<0.01).The individual number of one leaf mostly fluctuated from 1 to 50,and the average and tiptop numbers were 25.65 and 418,respectively.The pest population density had no remarkable discrepancies among different vertical spatial layer of K.obovata,however,its aggregating degree increased with falling of the layer.The population had an avarage fecundity of 52.22 each female and a high natural mortality of 69.53%.The main natural death factor were two species of parasites(Hymenoptera: Chalcididae),and their total parasitical ratio reached 34.23%.In the mass,the pest population density,fecundity and tiptop individual number of a leaf in the mongrove were all more than those in serval other host plants on land,which implied that this scale insect had a high adaptability to the habitat of tideland and the plant of K.obovata

    Study on the characteristics of Syzygium cumini L. pigment

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    以海南蒲桃成熟果实为原料提取天然色素,并对其理化性质进行了分析研究。同时比较了D-072、D-401、D-301-G、D-101、D-110、DF01六种树脂对该色素的静态吸附情况及不同极性解吸剂对吸附色素的树脂洗脱的效果,从中选择吸附和解吸附效果最好的树脂以及适合的解吸剂。研究表明:该色素在酸性条件下对热、金属离子和常用食品添加剂均具有较好的稳定性,对光稳定性稍差;D-072大孔吸附树脂对海南蒲桃色素吸附效果最好,色素吸附率达90.7%;解吸剂用含0.2%三氟乙酸的50%酸化乙醇,色素可被充分洗脱下来。此研究结果为以海南蒲桃成熟果实为原料来生产食用色素提供了理论依据。The stability of pigment which was extracted from the fruit of Syzygium cumini was studied. In addition, absorbing and separating Syzygium cumini pingment with macroreticular resin was also studied. Static absorption capacity of six resins(D-072, D-401, D-301-G, D-101, D-110, DF01) for the pigment was compared. From these resins, the one with the best absorpting and desorpting effect was elected. The results showed that this kind of pigment has a better stability toward heat, metal ion and common food additives under acidic condition, and it is more tolerable of heat than light. The adsorption ability of D-072 resin was the best and the adsorptive rate of pigment reached 90.7%. When 50% ethanol contained 0.2% TFA was used as desorptive solvent, the pigment could be sufficiently desorpted and the effect of desorption would be better. It has a great prospect in the exploration and application in food industry to produce the food pigment from the fruit of Syzygium cumini.国家自然科学基金项目(30671646

    Construction of Normalized cDNA Library from Hepatopancreas of Abalone Haliotis diversicolor supertexta Exposure to Tributyltin

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    用rdP试剂提取三丁基锡暴露诱导的杂色鲍肝胰腺总rnA,经OlIgOTEX纯化得到MrnA;应用SMArT技术合成双链CdnA,双链特异核酸酶(dSn)进行双链CdnA的均一化,构建了杂色鲍三丁基锡暴露诱导下的均一化CdnA文库。原始文库的库容为4.3x106Cfu/Ml,重组率为97.9%。从文库中随机挑选了3288个克隆进行测序,得到3048个高质量EST序列,其中有370条COnTIgS,2103条SInglETS,unIgEnES共2473条,冗余率为18.86%。以上结果说明该文库质量较好,为进一步筛选相关功能基因打下基础;较低的冗余率说明该文库值得继续使用大规模ESTS测序的方法寻找相关功能基因,并为进一步使用基因芯片技术研究相关功能基因的表达谱提供便利。A normalized cDNA library from hepatopancreas of abalone Haliotis diversicolor supertexta exposure to Tributyltin was constructed.Total RNA were prepared using RDP reagent.Oligotex(QIAGEN)was used to separate the mRNA from total RNA.The first strand cDNA was synthesized by transcription of mRNA with the SMART technique.The LD-PCR was performed using a modified SMART primer as the primer set,and the first-strand cDNA as the template to synthesize double strand cDNA.Double strand cDNA was normalized using Duplex-Specific Nuclease(DSN).The containing capacity of the unamplified cDNA library was 4.3×106 CFU/ml with a recombinant rate of 97.9%.A total of 3 288 clones were random selected to be sequenced,and 3 048 high quality ESTs were generated.After processing,a total of 2 473 unigenes comprising 370 contigs and 2 103 singlets were obtained.The redundancy was 18.86%.These results indicate that the normalized cDNA library is suitable to be used for further cloning and analysis of genes related to tributyltin exposure.厦门市科技计划项目(3502Z20055024);国家自然科学基金(20877034);集美大学创新团队基金(2008A001
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