排序方式: 共有92条查询结果,搜索用时 15 毫秒
61.
62.
为了提高智能电网中家域网的传输控制协议(TCP)性能,提出一种自适应速率控制方法。家域网采用电力线通信(PLC)和无线局域网(WLAN)技术,具有异构特点。该控制方法利用WLAN的通信机制提高PLC的链路利用率,采用启发式动态规划,通过神经网络训练估计瓶颈链路的容量,根据应用的长期服务质量调整TCP数据包的发送速率。仿真结果表明,该方法可以有效滤除PLC信道中冲击噪声的负面影响,其性能优于现有TCP的拥塞控制。 相似文献
63.
ZENG ChangJun~ YE Qing~ & FANG ShengGuo~* College of Animal Science Technology Sichuan Agricultural University Ya’an China The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education State Conservation Center for Gene Resources of Endangered Wildlife College of Life Sciences Zhejiang University Hangzhou 《科学通报(英文版)》2011,56(24):2576-2579
The Chinese alligator, Alligator sinensis, is a critically endangered species. A conservation project of gene resources for an endangered species first involves the preservation of organs, tissues, gametes, genomic DNA libraries and cell lines. The present study is the first to establish and cryopreserve cell lines of liver, heart and muscle tissues from the Chinese alligator. The study revealed that there was a large discrepancy in cell migration time in primary cultures among liver (11-12 d), heart (13-14 d) and muscle (17-18 d) tissue pieces. The differences in time in primary cell culture suggested that it was relatively easy to build visceral-derived cell lines for reptiles. Biological analysis showed that the population doubling time for thawed cells was approxi- mately 36 h. Karyotyping revealed that the frequency of Chinese alligator cells showing chromosome number as 2n=32 was 88.6%-93.4%. Chinese alligator cell lines established here provide a vital resource for research and are likely to be useful for protection of this rare and critically endangered species. Furthermore, the establishment of these methods may supply technical and theoretical support for preserving genetic resources at the cellular level for other reptile species. 相似文献
64.
Nowadays,thedevelopmentandapplicationofsuperconductionisbecomingmoreandmoreimpor tantinmanyareas .Duringtheworkingprocessofsu perconductor,somefactors ,forinstance ,deforma tion ,friction ,andmagneticvortex ,canresultinin stantaneousandrandomheatimpulsion ,andmakeitover heatedtothecriticaltemperatureanddeviatefromthenormaloperationcondition .Undersomeex tremeconditions ,thesuperconductorcannotgobacktothenormalstateevenifremovingthetransientheat load ,thusverysevereandunexpectableconse quencema… 相似文献
65.
LI Pengyun WANG Liwei WU Beili SHU Cuiling NIE Aihua SHEN Beifen LI Song * RAO Zihe * 《自然科学进展(英文版)》2003,13(10)
Thetherapyofnerveinjuryandneurode generativediseasessuchasAlzheimer’sdiseaseandParkinson’sdiseaseisadifficultprojectforscientiststosurmount.Manydrugsandtherapeuticapproacheshavebeenusedtotreatthesediseases ,buttheresultisunsatisfactory[1] .Inrecent years ,neurotrophinsincludingnervegrowthfactor (NGF) ,neurotrophin3(NT3) ,neurotrophin 4 / 5 (NT4 / 5 )andbrain de rivedneurotrophicfactor (BDNF)werestudiedex tensivelyandfoundtoaffectthesurvival,growth ,and/ordifferentiationofneuronsandsever… 相似文献
66.
Thenotionofpackingmeasure ,introducedinRefs.[1— 3],hasbeenusedincomparisonwithHausdorffmeasuretostudytheregularityandrectifi abilityofsetsintheplane[4 ] .TheHausdorffmeasureisdefinedusingeconomicalcoversofaset,whilethepackingmeasureisdefinedviapackingwithdisjointballscenteredinthegivenset (formoredetailsseeRefs .[5— 7]) .Asasymmetryofthepackingmea sure ,theHausdorffcenteredmeasure ,definedbythecoverswithballscenteredinthegivenset,wasintro ducedinRef .[4 ].RaymondandTricot[8] verifiedthatt… 相似文献
67.
68.
Polyoxometalates (POMs) form a large class ofmetal oxide cluster type compounds. Their wealthytopology, physical and chemical properties have at tracted increasing interests. In this paper, based onour group’s research, we review the latest progress inthe synthetic chemistry and catalysis of POMs and in troduce some POMs with novel structure and theirderivatives that emerged in 2002—2004. Most of thecited references come from those published in 2003.Due to POMs’superio… 相似文献
69.
Masahiro Shoji *Department of Mechanical Engineering School of Engineering the University of Tokyo Hongo Bunkyo ku Tokyo Japan 《清华大学学报》2002,7(2)
IntroductionThe behavior of bubbles,especially theirformation,interaction and coalescence,are of keyimportance in such fields as gas- liquid contact,gas- liquid separation,bubble absorption,bubblecolumns,fermentation,cavitations,etc. Theinduced fluid moti… 相似文献
70.
CHEN Xiaohong * LIU Mai * YASUHIKO Takahara ** *College of Business Management Central South University of Technology Changsha Hunan P.R. China ** Department of Management Systems Engineering China Institute of Technology Ch 《系统科学与系统工程学报(英文版)》1998,(1)
ComparativeAnalysisandFuzzySelectionofInformationSystemDevelopmentApproach⒇CHENXiaohong*LIUMai*YASUHIKOTakahara***ColegeofBus... 相似文献