排序方式: 共有1117条查询结果,搜索用时 15 毫秒
991.
基于Z源逆变器,提出了一种新型在线式UPS拓扑.该拓扑无需使用工频变压器,即可实现理想市电的输出,从而减小了电源体积,降低了成本,且还可带感性负载;增加了一个Buck/Boost充放电电路,采用额定电压较低的蓄电池,进一步减小了电源体积,同时降低了充放电电路中开关管的电压应力;在输入端增加Boost型APFC电路,提高了输入功率因数,减小了对电网的谐波污染.仿真实验和结果验证了该拓扑的正确性和有效性. 相似文献
992.
在一定温度条件下,用氨基硅油对苎麻纤维进行表面改性处理.利用红外光谱分析(IR)、接触角测试、X射线衍射分析(XRD)、热重分析(TG)等方法对改性前后苎麻纤维的性能进行分析.结果表明,经氨基硅油改性的苎麻纤维表面成功包覆了有机硅分子,且表面羟基数量减少,吸水性较未改性的苎麻纤维下降,与聚丙烯相容性提高;改性后,苎麻纤维的结晶度提高了15%;在230℃以前,未改性的苎麻纤维质量损耗为5%,而改性后苎麻纤维基本上没有分解,改性后苎麻纤维的耐热性能有了较大的提高。 相似文献
993.
斜拉桥拉索表面形成的覆冰可能会使斜拉索发生不稳定的驰振振动.首先,制作了6种覆冰截面的拉索模型,几何缩尺比为1∶1;然后,进行了静力天平测力风洞试验,得到了6种覆冰截面的平均升力系数和平均阻力系数,并给出了驰振力系数;最后,采用Fluent软件模拟了2种覆冰截面的绕流情况,并给出了平均升力系数.结果表明:上述6种覆冰截面的驰振力系数均远小于零,存在发生驰振的可能性;CFD模拟得到的平均升力系数与试验结果吻合较好. 相似文献
994.
CHEN Juan LI Hong-lian FENG You-mei WANG Jian-zhi .Department of Biochemistry Molecular Biology Tongji Medical College Huazhong University of Science Technology Wuhan China .Department of Pathophysiology Tongji Medical College Huazhong University of Science Technology Wuhan China 《武汉大学学报:自然科学英文版》2005,10(2)
0 IntroductionNeurofibrillary tangle, primarily composed of thehyperphosphorylated microtubule associatedprotein tau[1], is one of the major neuropathologichallmarks in Alzheimar’s disease (AD). In affectedneurons, the major mechanism o… 相似文献
995.
HU Yao-jun~ WEI Lei~ LIU Shu-nan~ YU Jin-hong~ DING Yi~ . Key Laboratory of MOE for Plant Developmental Biology/College of Life Sciences Wuhan University Wuhan Hubei China . College of Life Sciences Hunan University of Science Technology Xiangtan Hunan China . College of Life Sciences Huazhong Normal University Wuhan Hubei China 《武汉大学学报:自然科学英文版》2005,10(3)
0Introduction Malesterilityisacomplicatedphenomenoninhigherplants,whichestablishesthebiologicalbasisofhetero sisutilizationincropsbreeding,especiallyinrice(Oryzasati vaL.).Themolecularandphysiologicalresearchinplantmalesterility,especiallythediscoveryofth… 相似文献
996.
TAO Ning WU Xu-feng QIU Xiao-ping ZHAO Min TAN Yun WU Xin-xing . Institute of Virology Medical School Wuhan University Wuhan Hubei China . Department of Oncology Zhongnan Hospital Wuhan University Wuhan Hubei China 《武汉大学学报:自然科学英文版》2005,10(4):759-766
0Introduction Cervicalcarcinomaisoneofprevalentmalignancy,itisthesecondmostcommoncancerofwomenintheworld wide(thefirstisbreast cancer).Itisestimatedthatthereare450000newcasesinworldeveryyear,ofwhich80%arein developingcountries.Thereare135000newcasesinChin… 相似文献
997.
Ni Bin |bin Zhao Zheng |yu Xie Shu |guo School of Electronic Information Wuhan University Wuhan Hubei China 《武汉大学学报:自然科学英文版》2003,8(3):847-852
0 IntroductionIthasbeenwellknownthattheformationofIonosphericAlfv啨nResonator(IAR)isforthebreakdownofgeometricop tics.ItscentralregionliesneartheheightofF regionelectrondensitypeak .Andatthetypicalheightof 30 0 0kmexiststhemaximumgradientofAlfv啨nvelocity ,whichleadstothereflec tionofshearAlfv啨nwavesandproducestheupperboundaryoftheresonator.Likewise,thelowerboundaryoftheresonatorformsneartheheightof 2 0 0 30 0km .Thus,she… 相似文献
998.
主要研究L1/2正则化问题.首先给出了该问题的最优性条件的分析,得到了一阶和二阶必要条件,同时给出了二阶充分条件.这些最优性条件可以看作是光滑函数最优性条件的推广.在此基础上,提出了一种下降算法,并给出了该算法的全局收敛性分析.该算法可以看作是最速下降法的推广. 相似文献
999.
LIU Zeng-ran~ ZHANG Guang-yi~ LONG Zhang-fu~ LIU Shi-gui~. Life Science College Sichuan University Chengdu Sichuan China . Bioscience Bioengineering College Hebei Economices Business University Shijiazhuang Hebei China 《武汉大学学报:自然科学英文版》2005,10(6):1041-1046
0IntroductionBeoefr y ehaarss baenedn bar epwoperusla orft beenv edreasgceri bfoer b trheowuisnagnadssthe oldest biotechnological process[1]. During thebarley malting and mashed operationin the produc-tion of wort , the lower maltooligosaccharides arehydr… 相似文献
1000.
LIU Xian-li DENG Nan-sheng TAO Shu .College of Environmental Sciences Peking University Beijing China . College of Resources Environmental Sciences Wuhan University Wuhan Hubei China 《武汉大学学报:自然科学英文版》2005,10(2)
0 IntroductionF luorescence has been a tool for the study oforganic matter for a long time. The fluores cence of chromophoric constituents of dissolved or ganic matter at blue green wavelengths has been thesubject of many investigations since its first … 相似文献