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1.
用Na+做电荷补偿剂,Sm3+做敏化剂,采用高温固相法制备了Ca0.5MoO4:Eu3+0.25-x,Sm3+x,Na+0.25(x=0,0.001,0.003,0.005,0.008,0.01,0.02,0.03,0.05,0.07,0.09)系列红色荧光粉,实验结果表明:Sm3+的加入没有改变CaMoO4:Eu3+,Na+的晶体结构,也没有改变粉体发射光谱的形状和发射峰的位置,而是加宽了荧光粉CaMoO4:Eu3+,Na+激发光谱在400 nm左右的吸收峰,有利于样品的激发峰和近紫外LED芯片相匹配,并且提高了荧光粉在615 nm处发射光谱的发光强度.本文主要对Sm3+提高荧光粉的发光强度的原理进行探讨,研究结果证明在CaMoO4基质中存在Sm3+-Eu3+之间能量传递,此外得出Sm3+的最佳掺杂浓度是0.5 at.%.  相似文献   

2.
High-efficiency white organic light-emitting devices with single emitting layer are demonstrated. N,N‘-diphenyI-N,N‘-bis(1,1‘-biphenyl)-4,4‘-diamine (NPB) is used as hole transport layer, while 4,7-diphenyl-l,10-phenan-throline (BPhen) as electron transport layer and 9,10-di-(2-naphthyl)-2-terbutyl-anthracene (TADN) doped with the fluorescent dye 4-(dicyanomethylene)-2-t-buty1-6-(1,1,7,7-tetramethyljulolidyl-9-enyl) (DCJTB) as single emissive layer. The effects of performance by the concentration of DCJTB and the thickness of emissive layer are studied. The device with a structure of indium tin oxide/NPB (50 nm)/TADN: 0.2% DCJTB (15 nm)/BPhen (40 nm)/Mg: Ag shows a maximum brightness of 11400 cd/m^2, a peak current efficiency of 5.6 cd/A and power efficiency of 4.1 Ira/W, while the low turn-on voltage of 3.1 V and the stability of the Commission International De L‘Eclairage coordinate. The spectra through color filter of the device are also studied.  相似文献   

3.
建立了单层 (有机发光二极管 )中载流子注入、输运和复合的理论模型 ,通过求解非线性Painleve方程得到了电场强度随坐标变化的解析函数关系式 ,计算并讨论了载流子迁移率对电场强度、载流子密度等的影响。结果表明 :空间电荷分布不均匀造成了电场强度的不均匀分布。当在器件中占主导地位的载流子具有较低的迁移率或少数载流子具有较高的迁移率时 ,有利于载流子的输运与复合 ,发光性能可得到较大提高。  相似文献   

4.
在分析提供手机白光二极管(LED)背光的DC2DC转换器应具有高效率、低功耗、低电流等特性的基础上,设计了一款芯片,集成PWM技术、同步整流技术、软启动技术的同时,利用与绝对温度成正比的电流源(PTAT电流源)和三极管、MOS管,设计实现了一具有迟滞功能的过温保护电路,同时工艺上采用了低阻抗版图设计.芯片采用0.5μm的P衬N阱数模混合1P3M BiCMOS工艺流片.测试结果表明,芯片开关频率可达到1 MHz,具有2.7~6.0 V的输入电压范围,实现了PWM亮度控制、过压保护和短路保护等功能,做到了高效率低功耗,转换效率高达86%,可稳定驱动多达5个白光LED,完全满足系统设计的需要.  相似文献   

5.
The sea is the cradle of photosynthesis on the Earth. Bio-utilization of light in the sea is usually thought to be carried out by light-harvesting pigments, such as normal chlorophyll, divinyl chlorophyll and bacterial chlorophyll, which exist correspondi…  相似文献   

6.
ICM7218A是通用数码管驱动器,控制方式简单灵活,并可与8位微处理器接口.可广泛应用于电源及仪器仪表的显示中;文中介绍了芯片的工作原理,并且给出了与AT89C51接口的应用电路.  相似文献   

7.
A new method for fabricating electroabsorption modulator integrated with a distributed feedback laser (EML) was proposed, With the method we fabricated a selective area growth double stack active layer EML (SAG-DSAL-EML), Through comparing with other fabrication methods of EMLs, the characters and the merits of the new method presented in this paper were discussed.  相似文献   

8.
提出了一种适用于动态环境下移动机器人路径规划的新方法.用栅格法对环境进行建模,从目标栅格点出发,各栅格中心点到目标栅格中心点的距离信息以每个时间步一个栅格的速度不断向外传播.经过足够多时间步的传播后,通过逐步寻找信息的传播来源,即可获得机器人的最短路径.仿真结果表明,该方法非常简单且高效,能快速规划出动态环境下移动机器人的最优路径.  相似文献   

9.
设G是有限无向简单图。{a,b}等于包含于V(G),N[a]=N(a)∪{a},令J(a,b)={u│u∈N(a)∩N(b)且N(u)等于包含于N[a]∪N[b]}。G^*称为G的部分平方图:V(G^*)=V(G),E(G^*)=E(G)∪{ab│ab不属于E(G),J(a,b)≠Φ}。设G是(k+1)-连通图(k≥2),{u1,u2}等于包含于V(G)。本文主要结论:(a)设Gw是G中添加新顶点  相似文献   

10.
以某新型半导体显示产业钢结构厂房备料区为工程背景,建立了厂房钢框架-支撑结构的非线性有限元模型,分别对多遇地震和罕遇地震下的结构抗震性能进行了分析。结果表明,结构整体指标均满足设计规范要求,第3层和第6层的层间位移角较大;罕遇地震下构件损伤主要集中在支撑,而结构底层角柱和中部楼层的边跨梁有轻微损伤;钢支撑能够有效提高结构刚度,减小梁柱的损伤。  相似文献   

11.
12.
监督分为基于权力的监督和基于权利的监督两种。随着网络的发展,网络舆论监督日益成为人民群众进行监督的手段之一。本文在对权力监督和网络舆论监督的分析之上,探讨把二者结合进行监督,开辟反腐新路径。  相似文献   

13.
Using monitored active layer thickness(ALT) and environmental variables of 10 observation fields along the Qinghai-Tibet Highway in permafrost region of the Qinghai-Tibetan Plateau(QTP),a model for ALT estimation was developed.The temporal and spatial characteristics of the ALT were also analyzed.The results showed that in the past 30 years ALT in the study region increased at a rate of 1.33 cm a-1.Temperatures at the upper limit of permafrost and at 50 cm depth,along with soil cumulative temperature at 5 cm depth also exhibited a rising trend.Soil heat flux increased at a rate of 0.1 Wm-2 a-1.All the above changes demonstrated that the degradation of permafrost happened in the study region on the QTP.The initial thawing date of active layer was advanced,while the initial freezing date was delayed.The number of thawing days increased to a rate of 1.18 da-1.The variations of active layer were closely related to the permafrost type,altitude,underlying surface type and soil composition.The variations were more evident in cold permafrost region than in warm permafrost region,in high-altitude region than in low-altitude region,in alpine meadow region than in alpine steppe region;and in fine-grained soil region than in coarse-grained soil region.  相似文献   

14.
东北地区打造对外开放新前沿是国家完善改革开放格局的重大战略部署.在新形势下,东北地区构建对外开放新前沿,需要增强东北地区对外开放的国家战略认识,推动扩大开放与区域振兴的战略协同,以深化东北亚经济贸易合作为突破口,强化自由贸易试验区的平台功能.  相似文献   

15.
E S Levitan  R H Kramer 《Nature》1990,348(6301):545-547
Calcium channel activity is crucial for secretion and synaptic transmission, but it has been difficult to study Ca2+ channel modulation because survival and regulation of some of these channels require cytoplasmic constituents that are lost with the formation of cell-free patches. Here we report a new patch clamp configuration in which activity and regulation of channels are maintained after removal from cells. A pipette containing the pore-forming agent nystatin is sealed onto a cell and withdrawn to form an enclosed vesicle. The resulting perforated vesicle, formed from pituitary tumour cells, contains Ca2+ and K+ channels. Ca2(+)-activated K+ channels in the vesicle are activated by cyclic AMP analogues, and by a neuropeptide (thyrotropin-releasing hormone) that stimulates phosphatidylinositol turnover and inositol trisphosphate-gated Ca2+ release from intracellular organelles. Thus, the perforated vesicle retains signal transduction systems necessary for ion channel modulation. Functional dihydropyridine-sensitive Ca2+ channels (L-type) are maintained in the vesicle, and their gating is inhibited by thyrotropin-releasing hormone. Hence, this new patch clamp configuration has allowed a direct detection of the single-channel basis of transmitter-induced inhibition of L-type Ca2+ channels. The modulation of Ca2(+)-channel gating may be an important mechanism for regulating hormone secretion from pituitary cells.  相似文献   

16.
This review summarizes the role of catalysts with highly dispersed and isolated active sites (active sites: supported atoms f≤0.5%) in the selective oxidation of light hydrocarbons, such as methane, ethane and propane, into oxygenates and the epoxidation of olefins. The plausible structures of the highly dispersed and isolated active species, as well as their effects on the catalytic performances are discussed. The special physico-chemical properties and the functional mechanism of the catalysts with highly dispersed and isolated active sites, as well as the preparation, characterization of the catalysts with highly dispersed and isolated active sites and their applications in other types of reactions of lower hydrocarbons are summarized.  相似文献   

17.
Hardin’s "The Tragedy of the Commons" prophesies the inescapable collapse of many human enterprises.The emergence and abundance of cooperation in animal and human societies is a challenging puzzle to evolutionary theory.In this work,we introduce a new decision-making criterion into a voluntary public goods game with incomplete information and choose successful strategies according to previous payoffs for a certain strategy as well as the risk-averse benefit.We find that the interest rate of the common pool and the magnitude of memory have crucial effects on the average welfare of the population.The appropriate sense of individuals’ innovation also substantially influences the equilibrium strategies distribution in the long run.  相似文献   

18.
研究了具有非线性恶化函数的加工时间,同时工件的安装时间与已加工完工件的实际加工时间有关(即p-s-d)的单机排序问题.证明了极小化最大完工时间,极小化完工时间和是多项式时间可解的.另外极小化加权完工时间和,极小化总延误以及极小化最大延误在一定的条件下是多项式时间可解的.  相似文献   

19.
新疆蝗虫——新属新种(蝗总科:槌角蝗科)   总被引:1,自引:0,他引:1  
记述了采自新疆的拟槌角蝗 Gomphoceroides 新属及新疆拟槌角蝗Gomphoceroides xingangensis 新种.该新属近似于 Gomphocerippus Rob.和Gomphocerus Thunberg.其区别于两者为前胸背板后横沟雄性在背板中部穿过,雌性在中后部穿过;前翅前缘基部在雌性明显扩大,雄性不明显;缘前脉域端部明显超过前翅中部.其区别于前者为前翅前、后肘脉接近、合并;中脉域宽为肘脉域5~6倍.而区别于后者为雄性前足胫节不膨大.  相似文献   

20.
研究了在污染环境中具有捕获及扩散的单种群在两斑块之间扩散后,种群的持久性和灭绝性问题.一个斑块是保护区,另一个斑块是污染区,在两个斑块内都进行捕获.通过对右端函数的分析,得到种群持久和灭绝的充分条件,并指出捕获及扩散对种群的影响.  相似文献   

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