共查询到20条相似文献，搜索用时 62 毫秒
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张艺 《内江师范学院学报》2014,(12):27-29
用溶剂热法、150℃反应12h成功合成了分散性良好的LaP04：Ce^3＋/Tb^3＋荧光晶体.XRD数据表明,合成了六方晶系的LaP04：Ce^3＋/Tb^3＋晶体（PDF 84-0600）.pH为9.0时,合成晶体的离子最佳摩尔比为nLa^3＋∶nCe^3＋∶nTb^3＋=6∶3∶1.根据荧光光谱可知,LaP04：Ce^3＋/Tb^3＋在270nm处有最强激发峰,在545nm处有最强发射峰,对应于Tb^3＋的5 D4→7F5跃迁. 相似文献
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合成了一系列Eu^3 (Tb^3 )和phen共掺杂的杂化材料，并对其发光性能进行了考察。在所有样品中除了掺杂浓度为1％的样品外，其余材料均为透明块状且无裂纹。所有材料在紫外灯照射下，发出明亮的红光（Eu^3 掺杂）和绿光（Tb^3＋掺杂）。 相似文献
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测量了1．62at％-Er^3＋ Y0.5Gd0．5，VO4晶体的吸收光谱和荧光发射谱，光谱显示该晶体在382、525、1536nm有很强的偏振光吸收峰，且偏振光（E∥C）吸收远强于σ偏振光（E⊥C）吸收；通过计算可得，吸收截面分别为2．95013×10^-20cm^2、2．57757×10^20cm^2和1．15504×10^-20cm^2；其荧光发射（^4I15／2→^4I11／2跃迁）峰值波长在1524nm，半高宽度为72nm；415/2^I→^4I11/2跃迁的荧光寿命为3．1ms,光谱特性表明Er3^＋：Y0．5，Gd0．5，VO4晶体是潜在的高效率激光晶体材料． 相似文献
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采用水热法,结合后续的热处理,制备了Eu^3＋掺杂的ZnF2-ZnO纳米结构材料,利用X-射线衍射仪（XRD）、扫描电子显微镜（SEM）和荧光光谱仪对样品结构、形貌及发光性能进行表征．结果表明,以NaF为原料得到的样品为正方体状,长为220-400nm;以NH4F为原料得到的样品呈棒状,长约为1．2μm,直径为110nm左右．紫外光激发下,棒状样品发光性能强于立方体状的样品,表现为掺杂Eu^3＋的特征发射．光催化脱色实验表明,两种形貌样品的光催化活性差别不大,150min对甲基橙的脱色率达70％左右． 相似文献
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将功率为30W．波长为1064nm的YAG激光束（束斑直径0．045mm）照射在硅样品表面打出小孔，在孔内的侧壁上有很特殊的网孔状结构，其中的网孔壁厚为纳米尺度，解释孔侧壁网孔状结构的机理．孔侧壁上的网孔状结构有很强的受激荧光发光效应，发光峰中心约在700nm处．当样品在加工和检查过程中保持脱氧状态时，其样品几乎没有发光，证实了氧在PL发光增强上起着重要作用．我们用量子受限及其纳晶与氧化硅界面态复合的综合模型来解释其光致发光的增强机理 相似文献
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采用荧光光度法测定了鸡肉和鱼肉肌肉中洛美沙星药物的残留量．样品用酸性乙腈提取,正己烷脱脂,水相在B—R（pH3．0）缓冲溶液中,激发波长λex=275nm,荧光波长λem=450nm下用荧光光度法测定其中的洛美沙星含量,洛美沙星线性范围是10~120μg／mL,相关系数r=0．9958,检出限为0．005μg／mL．样品回收率为76．0％-94．5％,日内变异系数为2．14％~6．50％,日间变异系数为3．02％～9．78％． 相似文献
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以聚乙烯基吡咯烷酮（PVP）为表面包覆剂，在室温大气条件下的水溶液中制备了ZnS：Mn^2＋和ZnS：Mn^2＋、Pb^2＋纳来晶．XRD分析表明纳米尺寸的平均直径为2-4nm，TEM分析表明纳米尺寸均一，用荧光光谱检测到其激发波长（λexc≈410nm）和发射波长（λem≈510～560nm）都在可见光范围以内，显示出一种新颖的光致发光性质，并对这一性质作出了适当的解释．这些结果表明共掺杂的纳米晶代表了一种新型的发光材料． 相似文献
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采用X射线衍射、红外光谱和荧光光谱研究了Ca1-xCdxTiO3：Pr^3＋的物相组成及发光性质。X射线衍射和红外光谱研究表明掺入适量的Cd^2＋物相组成为CaTiO2。激发光谱是峰值位于330nm附近的宽带谱，发射光谱是峰值在625nm半宽度为20nm的带谱。对应Pr^3＋的ID2-3H4跃迁发射。发光强度随基质组分Cd／Ca摩尔比和合成温度而变化。Cd^2＋的最佳含量在15％～20％. 相似文献
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在77K测定了标题配合的激发光谱和荧光光谱，在配合物的^7F→^D0激发光谱里，580．14nm和580．68nm处呈现两个锐锋，说明在该配合物中存在两种Eu^3 格位，选择激发配合物的^5D0能级，得到两组完全不同的^5D→^7FJ(J=1,2）荧光光谱，表明配合物中Eu^3＋离子具有不同的化学环境，两种格位的可能点群是C1，C2或Cs，可能具有与Y2（P－CH3C6H4COO）6（C12H8N2）2类似的晶体结构。 相似文献
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对钝顶螺旋藻藻胆体在解离过程中77K荧光发射光谱与光能传递途径进行了研究．在77K荧光发射光谱中，完整藻胆体只有一个峰，位于682nm，这是藻胆体核心一类囊体膜连接多肽的荧光峰；随着藻胆体逐渐解离，首先在649nm出现一个小峰，之后，在661nm又出现一个荧光发射肩，前者是C-藻蓝蛋白的荧光，后者是别藻蓝蛋白的荧光；随着藻胆体解离程度的加重，C-藻蓝蛋白的荧光逐渐加强并成为主峰，别藻蓝蛋白的荧光也逐渐加强，但随后又逐渐减弱，直至消失；682nm主峰逐渐减弱并消失，但在679nm却出现另一个荧光峰，这是别藻蓝蛋白-B的荧光，当别藻蓝蛋白的荧光消失后，679nm荧光峰减弱为荧光发射肩，但仍然有很强的荧光。这表明：C-藻蓝蛋白不但与别藻蓝蛋白相连接，而且还与别藻蓝蛋白-B相连，在钝顶螺旋藻藻胆体中，光能是沿着两条途径传递给光系统Ⅱ的。 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献