共查询到20条相似文献，搜索用时 15 毫秒
1.
STABILIZED ZNTIO, WAS PREPARED BY DOPING MAGNESIUM OXIDE THROUGH TRADITIONAL SOLID-STATE REACTION. THE EXPERIMENTAL RESULTS INDICATE THAT ZINC TITANATE CRYSTALS DOPED WITH MAGNESIUM OXIDE GROW WELL AND THE DECOMPOSITION INTO ZN2TIO4 AND TIO2 IS RESTRAINED THROUGH TRADITIONAL SOLID STATE REACTION. BY ADJUSTING MOLAR RATIO OF MGO, BETTER PROPERTIES CAN BE OBTAINED. THE DIELECTRIC PROPERTIES OF THE CERAMICS DOPED WITH 30% MGO( MOLAR PERCENTAGE) SINTERED AT 1 060 ℃ ARE AS FOLLOWS:THE VALUE OF QUALITY FACTOR IS GREATER THAN 20 000(6. 5 GHZ), THE TEMPERATURE COEFFICIENT OF RESONANCE FREQUENCY IS ABOUT 2 × 10-6/℃, THE DIELECTRIC CONSTANT RANGES FROM 18 TO 22. BESIDES, IT IS PROVED THAT HEAT TREATMENT CAN OPTIMIZE MICROSTRUCTURE AND THE VALUE OF QUALITY FACTOR, WHICH INCREASES FROM 23 833.93 TO 47 584.00 AFTER 2 H OF HEAT TREATMENT AT 1 040 ℃. 相似文献
2.
Natural and Treated FeS2 in Li/FeS2 Coin Cell 总被引：1，自引：0，他引：1
TREATED FES, SAMPLES WERE PREPARED BY NATURAL FES, SAMPLES WHICH WERE GROUND FIRST, HEATED IN NITROGEN AND THEN WASHED IN ACID. THE LEVELS OF IMPURITY ELEMENTS, PRIMARILY PRESENT AS METALLIC OXIDES AND SULFIDES, ARE HIGHER IN THE NATURAL FES, THAN THOSE IN THE TREATED SAMPLE. SCANNING ELECTRON MICROSCOPY SHOWS THAT THE GRAIN SIZES OF TREATED FES, PARTICLES ARE SMALLER THAN THOSE OF NATURAL FES, PARTICLES. THE ELECTROCHEMICAL PERFORMANCE OF LI/TREATED FES, CELLS IS ATTRIBUTED TO THE SMALLER GRAIN SIZES AND HIGHER PURITY OF TREATED FES, PARTICLES IN COMPARISON TO THE NATURAL FES, SAMPLE. 相似文献
3.
Torsional Oscillation Characteristics of Rotary Shafts Based on Torsion and Bending Coupled Vibration 总被引：1，自引：0，他引：1
THE TORSIONAL OSCILLATION CHARACTERISTICS ON THE BENDING AND TORSION COUPLED VIBRATION OF ROTARY SHAFT SYSTEM WERE INVESTIGATED USING THE ELASTO-DYNAMIC THEORY AND OTHER MATHEMATIC METHODS, SUCH AS DIFFERENCE APPROACH, FOURIER TRANSFORM, AND WAVELET TRANSFORM. IT IS CONCLUDED THAT MASS ECCENTRICITY AND OTHER EXCITING MODALITIES AFFECT THE BENDING AND TORSION COUPLED VIBRATION OF ROTARY SHAFTS. TORSIONAL VIBRATION CAUSED BY BENDING VIBRATION FEATURES LINEARITY ALONG WITH THE CHANGE OF AMPLITUDE OF BENDING VIBRATION. MEANWHILE, ENERGY SPECTRUM CONCENTRATES ON HIGH FREQUENCY ARE-A WITH THE WAVELET ANALYSIS. 相似文献
4.
BY USING THE OUTPUT INDUCTORS AND BODY CAPACITANCES WITHOUT ADDING ANY COMPONENT COMPARED WITH HARD SWITCHING SYNCHRONOUS RECTIFIER,THE TOPOLOGY OF A SOFT SWITCHED SYNCHRONOUS RECTIFIER WITH PHASE-SHIFTED FULL BRIDGE ZERO VOLTAGE SWITCHING DC/DC CONVERTER IS PROPOSED. THE CONVERTER EFFICIENCY IS MAXIMIZED DUE TO SOFT SWITCHING OF THE FULL BRIDGE MOSFETS AND THE SYNCHRONOUS MOS-FETS, AND ALSO THE LOW CONDUCTION LOSS OF SYNCHRONOUS MOSFET. THE OPERATION PRINCIPLES OF THE CIRCUIT ARE ANALYZED IN DETAIL AND THE SMALL-SIGNAL MODEL IS DERIVED, ALSO THE CONVERTER DYNAMIC CHARACTERISTICS ARE ANALYZED. FREQUENCY RESPONSES OF TRANSFER FUNCTIONS UNDER DIFFERENT VALUES OF TRANSFORMER PRIMARY LEAKAGE INDUCTANCE ARE DISCUSSED. THE EXPERIMENTAL RESULTS WERE OBTAINED FROM A 400 V INPUT AND 100 A/12 V OUTPUT DC/DC CONVERTER OPERATING AT 100 KHZ. THE RESULTS SHOW THAT THE CONVERTER EFFICIENCY IS 2% HIGHER IN RATED POWER THAN TRADITIONAL DIODE RECTIFIER. 相似文献
5.
THE CONTROL VALUE OF THE DEFLECTION OF THE EMBEDDED CYLINDRICAL STRUCTURE, WHICH IS THE MAXIMUM DEFLECTION ALLOWED FOR STABILITY OF THE CYLINDER, IS A VITAL QUANTITY OF STABILITY CALCULATION. THE DEFLECTION AND THE SOIL PRESSURE ON THE EMBEDDED CYLINDER WERE INVESTIGATED BY MODEL EXPERIMENT. WHEN THE INCLINED ANGLE OF CYLINDER IS LESS THAN OR EQUAL TO 0. 25°, THE EFFECTIVE ANTI-OVERTURNING RATIO INCREASES GRADUALLY AND REACHES THE MAXIMUM. WHEN THE INCLINED ANGLE OF CYLINDER IS MORE THAN 0.25°, THE EFFECTIVE ANTI-OVERTURNING RATIO DECREASES GRADUALLY. THE CONTROL VALUE OF INSTABILITY OF THE CYLINDRICAL STRUCTURE APPROXIMATES 0. 2°, AND THE BEARING STRESS AT THE BACK EDGE OF THE CYLINDER IS EQUAL TO ZERO. 相似文献
6.
AMERICAN EATING IS FUNNY. THEY EAT ALMOST EVERYTHING WITH A FORK, AND IT APPEARS THAT HOLDING A KNIFE IN ONE’S RIGHT HAND LONGER THAN A FEW SECONDS IS CONSIDERED TO BE AGAINST GOOD TABLE MANNERS. THE SYSTEM IS THAT IF IT IS ABSOLUTELY NECESSARY TO USE A KNIFE, PEOPLE TAKE THE FORK IN THEIR LEFT HAND, AND CUT OFF A PIECE OF MEAT OR WHATEVER IT IS IN THE NORMAL MANNER. THEN THEY… 相似文献
7.
Exploring the Relationship Between Policy and Media: A Case Study of Road Pricing in the Netherlands
THE ROLE AND INFLUENCE OF MASS MEDIA IN PEOPLE’S LIVES HAVE ALWAYS BEEN A TOPIC OF CONCERN TO EVERYONE.IN THE FIELD OF MEDIA RESEARCH,THE RELATIONSHIP BETWEEN THE MEDIA AND POLITICS HAS ALWAYS BEEN THE SUBJECT OF DISCUSSION AND RESEARCH BY SCHOLARS.THIS STUDY MAINLY USES THE NETHERLANDS ROAD PRICING POLICY AS A CASE TO EXPLORE THE RELATIONSHIP BETWEEN MEDIA AND POLITICS IN POLITICAL ACTIVITIES BY RESEARCHING THE CHANGES AND INFLUENCES OF THE MEDIA IN THIS POLITICAL ACTIVITY.THIS PAPER MAINLY SELECTS THE CHANGES AND INFLUENCES OF THE DUTCH MEDIA IN TWO MAJOR ROAD PRICING POLICY ACTIVITIES DURING THE 12 YEARS FROM 1998 TO 2010 THROUGH LITERATURE RESEARCH AND OTHER METHODS.IN THIS WAY,IT CAN EXPLORE THE RELATIONSHIP BETWEEN MEDIA AND POLITICS. 相似文献
8.
祝灵琴 《宿州教育学院学报》2005,8(5):104-106,127
TRANSLATION OF BRAND NAMES IS A KIND OF INTERCULTURAL COMMUNICATION,WHICH INVOLVES REGIONAL CULTURES,CONSUMER PSYCHOLOGY ,AESTHETIC INTEREST AND SOME OTHER FACTORS.IT IS IMPORTANT TO ACHIEVE THE PRAGMATIC EQUIVALENCE IN THE BRAND NAME TRANSLATION. THIS PAPER FIRST BRIEFLY GOES OVER EQUIVALENT -EFFECT PRINCIPLES AND THE FEATURES OF BRAND AND BRAND NAMES.THEN IT ANALYSES THE CHARACTERISTICS OF ENGLISH AND CHINESE BRAND NAMES AND DISCUSSES FIVE APPROACHES TO THE TRANSLATION OF BRAND NAMES--LITERAL TRANSLATION; TRANSLITERATION; MIXED TRANSLATION; FLEXIBLE TRANSLATION AND ZERO TRANSLATION. 相似文献
9.
《海外英语》2014,(12):31-31
PEOPLE ASK ME IF I＇D PREFER TO GO TO HELL OR HEAVEN.I SAY HELL BECAUSE IT＇S NICE AND WARM DOWN THERE.WE MAY BE ALONE.WE MAY NOT BE ALONE.EITHER,THE THOUGHT IS STAGGERING.PAINTING IS THE ART OF PROTECTING FLAT SURFACES FROM THE WEATHER AND EXPROSING THEM TO THE CRITICS.PLEASE PUT YOUR BRAIN IN GEAR BEFORE ENGAGING YOUR MOUTH.TO ERR IS HUMAN,BUT TO REALLY FOUL THINGS UP REQUIRES A COMPUTER.I＇MA NOBODY.NOBODY＇S PERFECT.THERERORE,I＇M PERFECT! 相似文献
10.
何富臣 《初中生世界(初三物理版)》2006,(Z1)
THERE IS A SMALL ISLAND NEAR LVSHUN(旅顺)AND DALIAN(大连)IN LIAONING PROVINCE.ITHAS ABOUT ONE HUNDRED THOUSAND VIPERS(毒蛇).ON THE ISLAND YOU CAN FIND VIPERSEVERYWHERE.BE CAREFUL,THEY ARE VERYDANGEROUS!YOU CAN SEE MANY TREES ON THE ISLAND,AND ALL OF THEM 相似文献
11.
采用基于密度泛函（DFT）理论的第一性原理平面波超软赝势计算方法,对Zn2SiO4∶Mn2＋的电子结构（能结构、态密度）和光学性质进行了理论计算。计算结果表明,Zn2SiO4∶Mn2＋是一种间接带隙半导体,禁带宽度为2.934 eV;其能态密度主要由Zn-3d,O-2p和Si-3p决定;静态介电函数ε1（0）=2.82;折射率n0=1.75;吸收系数最大峰值为7.37×104cm-1;利用计算的能带结构和态密度分析了Zn2SiO4∶Mn2＋材料的介电函数、反射谱、复折射率以及消光系数等光学性质,为Zn2SiO4∶Mn2＋发光材料的设计与应用提供了理论依据。 相似文献
12.
This paper reports the detailed preparation and phosphorescence properties of Eu2+-activated Ca2 ZnSi2O7 phosphors by a modified solid-state reaction. Phase-pure crystalline Ca2ZnSi2O7 is obtained at 600℃, a much lower temperature than by conventional solid-state reaction and the preparation process of Ca2ZnSi2O7 is simple. The obtained phosphors showed three emission peaks at 480,580 and 620 nm,respectively. Auxiliary activator R3+(R=Dy, Nd, Tm) would enhance their luminescent properties. 相似文献
13.
Structure and Dielectric Properties of Sb2O5-Doped ZrO2-SnO2-TiO2 Microwave Ceramics 总被引：1，自引：0，他引：1
The microwave frequency band is generally con-sidered in the range of 0.3—3 000 GHz. Its impor-tance is recognizable in the current growth of micro-wave communications systems which make use of thesuperior information density. Many kinds of dielectricmaterials have been developed for microwave applica-tions[1,2]. Among them, solid solution ZrO2-SnO2-TiO2(ZST) has a higher dielectric constant, a highquality factor (Q) value and a lowtemperature coeffi-cient of resonant frequency (TCF). B… 相似文献
14.
采用溶胶-凝胶法合成了Zn2+取代的锂离子电池正极材料Li1+xZnxMn2-xO4。结构研究结果表明,用这种方法可以在比固相反应低得多的温度下得到单相的尖晶石且制得的材料粒度均匀,粒径大多在150nm左右。半电池循环测试结果表明,起始组成为x=0.06的样品性能最佳,其与锂片组成的半电池在3.0V—4.6V间,以0.10mA/cm2的电流密度进行充放电的首次充、放电容量分别为131.4mAh/g和129.2mAh/g,经35次循环后容量仍保持在100mAh/g。 相似文献
15.
使用水热法合成了NaGd(WO4)2:Yb3+,Er3+,Tm3+荧光粉,借助PMMA胶体模板自组装法制备了三维反蛋白石光子晶体,并表征了样品的表面形貌和结构特征。样品具有四方晶系NaGd(WO4)2的晶格结构,电子显微镜观察到规则排布的微球蛋白石模板和退火之后形成的正六边形空腔结构。光谱测试发现,在反蛋白石光子晶体微孔直径185 nm左右时,得到了相对最强的发光增强效果;实验样品中光子带隙的存在显著增强了蓝光发光而抑制了红光发光,导致光子晶体样品整体发光从荧光粉的暖白光转变为偏绿色。对比荧光粉样品,反蛋白石光子晶体样品中Er3+离子4S3/2→4 I15/2的发光寿命显著增加,但光子带隙的变化对寿命影响不大。与参考样品相比,反蛋白石光子晶体样品对温度淬灭现象具有显著的抑制作用。 相似文献
16.
采用化学气相沉积的实验方法,以纯Zn粉为锌源,O_2为反应气,N_2为载气,在双管管式炉内制备了多脚结构的纳米ZnO,研究了载气流量对产物形貌和光致发光性能的影响;通过计算流体动力学软件FLUENT对实验条件下管式炉内O_2和Zn蒸汽的浓度分布进行了模拟。实验和模拟结果表明:随着N2流量的增大,O_2浓度减小,产物由钉状多脚结构向针状多脚结构转变;沉积位置处Zn蒸汽的浓度远大于O_2浓度,绿光发射峰主要是由ZnO纳米晶体氧空位引起的,沉积反应主要由O_2控制。 相似文献
17.
文中利用啤酒酵母去除模拟废水中Zn2+、Mn2、Cu2+,通过对预处理试剂、吸附温度、吸附液pH值与浸泡时间等因素进行正交分析,确定了影响吸附的主要因素是酸度和预处理试剂.研究pH值、离子初始浓度、吸附时间、离子强度等条件对吸附率的影响,结果表明,用NaOH浸泡后2h,在pH=5~6时吸附效果最好.用吸附等温线Langmuir(exe)、Freundlich和Temkin方程拟合,相关性都比较好.用不同的吸附动力学方程描述啤酒酵母吸附金属离子的最优模型为Elovich方程. 相似文献
18.
以有机物前驱体法制备铝酸盐尖晶石MAl2O4（M为Cu,Zn）,采用X-射线衍射、透射电镜等方法对试样进行表征．结果表明：700℃焙烧得ZnAl2O4,800℃焙烧得到CuAlz04和微量Cu0．在以甲基橙为降解物和100W汞灯辐照2h的光催化实验中,700℃焙烧ZnAl2O4粉体对甲基橙的脱色率为89．4％;而800℃的CuAl2O4对甲基橙的脱色率可以达到96．7％． 相似文献
19.
采用溶胶-凝胶法制备了不同掺杂浓度的Mn-Al共掺杂Zn O粉末。用XRD分析了粉末的晶格结构。表明所有样品都具有纤锌矿结构。当Mn(1wt%)掺入纯Zn O时晶格常数明显变大,这表明Mn已经进入了Zn O晶格,且Mn离子处于正二价态。随着粉末中Al浓度的增加,发现晶胞参数a,c开始略有减小,而后随Al离子浓度增大而变大。确定了在Mn(1wt%)掺杂的前提下,Al对Zn O掺杂的最佳浓度为2wt%。 相似文献
20.
介绍一个新的适于材料化学专业开设的综合化学实验,拟采用溶胶一凝胶法制备SrAl2O4：Eu^2＋,Dy^3＋绿色长余辉荧光粉．整个实验包括了溶胶-凝胶法全部基本操作以及材料的结构测试（X-射线粉末衍射）、形貌测试（扫描电子显微镜）、光谱测试（激发和发射光谱）等．该实验不仅可以使学生对溶胶-凝胶软化学方法制备材料的过程及原理有所了解,而且能够学习材料基本表征方法,是一个涵盖内容全面,适于学生操作的典型实验． 相似文献