排序方式: 共有50条查询结果,搜索用时 296 毫秒
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THE THERMAL BEHAVIOR OF TWO-COMPONENT PIEZOELECTRIC SINGLE CRYSTAL ALUMINIUM GALLIUM PHOSPHATE Al1-xGaxPO4 下载免费PDF全文
The temperature properties of elastic, piezoelectric and dielectric constants for the single crystal Al0.88Ga0.12PO4 have been studied in detail over a temperature range from 150 to 410K. And two crystal plates with different orientations which have zero temperature coefficient are introduced. As might have been expected, the single crystal Al1-xGaxPO4 is a new kind of materials applicable to the surface acoustic wave devices. 相似文献
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采用单晶提拉法成功生长出优质的Gd3+/Yb3+共掺铝酸钇晶体。对晶体的结构、分凝系数、光谱和激光性能进行了表征,结果表明:所生长的晶体空间群为Pnma,属于正交晶系,Yb3+的分凝系数为1.13。从偏振吸收和荧光光谱发现,b偏振方向时,晶体在980 nm处吸收截面为2.14×10-20 cm2,适用于InGaAs 激光二极管泵浦;在1 044 nm处的发射截面为0.39×10-20 cm2,荧光寿命为1.638 ms。此外,对b切向的Gd/Yb∶YAP晶体进行激光实验,在1 μm处实现连续激光输出,斜率效率为23.5%,最大输出功率可达0.51 W。 相似文献
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高效液相色谱法测定啤酒、发酵液和麦汁中的糖类和乙醇 总被引:7,自引:0,他引:7
Cheethan和Rajkyla提出以十八烷基修饰的硅胶作为固定相,以纯水作洗脱液,来分离单糖和寡糖,类似方法应用于啤酒工业分析的国内报道,仅见一篇文章,国外文献报道、美国酿造化学家协会(ASBC)和欧洲酿造协会(EBC)推荐的高效液相色谱法(HPLC),多采用阳离子交换柱分析酿造用辅料,麦汁,发酵液,啤酒中的糖类.目前国内大啤酒厂多采用啤酒分析仪测定乙醇,很少采用气相色谱法(GC)和液相色谱法(HPLC).采用GC直接测定乙醇含量,由于啤酒中乙醇含量远高于其它杂醇油,GC法测定杂醇油时,难以定量测定乙醇,除非采用填充柱,单独测定乙醇.本文方法采用Nucleosil C18柱,测定啤酒,发酵液和麦汁中的糖类时,同时测定乙醇. 相似文献
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Energy transfer processes between two aggregates in a coupled chromophoric-pigment(protein)system are studied via the standard master equation approach.Each pigment of the two aggregates is modeled as a two-level system.The excitation energy is assumed to be transferred from the donor aggregate to the acceptor aggregate.The model can be used to theoretically simulate many aspects of light-harvesting complexes(LHCs).By applying the real bio-parameters of photosynthesis,we numerically investigate the efficiency of energy transfer(EET)between the two aggregates in terms of some factors,e.g.,the initial coherence of the donor aggregate,the coupling strengthes between the two aggregates and between different pigments,and the effects of noise from the environment.Our results provide evidence for that the actual numbers of pigments in the chromophoric rings of LHCs should be the optimum parameters for a high EET.We also give a detailed analysis of the effects of noise on the EET. 相似文献
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THE THERMAL BEHAVIOR OF TWO-COMPONENT PIEZOELECTRIC SINGLE CRYSTAL ALUMINIUM GALLIUM PHOSPHATE Al1-xGaxPO4 下载免费PDF全文
The temperature properties of elastic, piezoelectric and dielectric constants for the single crystal Al0.88Ga0.12PO4 have been studied in detail over a temperature range from 150 to 410K. And two crystal plates with different orientations which have zero temperature coefficient are introduced. As might have been expected, the single crystal Al1-xGaxPO4 is a new kind of materials applicable to the surface acoustic wave devices. 相似文献
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在300—20K的温度范围内观测了用丘克拉斯基法生长的Li0.025Na0.975NbO3晶体的介电、铁电和热电特性。介电常数,极化强度和热电性的反常表示该晶体在低温时发生相变。此相变有特别大的热滞(约80K),降温时发生于180K附近,升温时发生于260K附近。测量了晶体的室温结构,指出了可能的低温相点群。观测了热电电荷的时间响应,报道了热电电荷随时间改变符号的特异现象,认为其起因是相变过程中两相共存。
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太阳能光催化水直接制氢被认为是未来解决全球能源危机和环境污染问题的有效途径之一.COFs是一类新兴的有机结晶多孔聚合物光催化剂,具有巨大的发展空间.当前研究最多的是亚胺键连接的COFs光催化剂,其骨架的π-共轭程度相对较低,且亚胺键上的氮容易受到质子攻击,会影响光化学过程和光催化性能.烯烃(C=C键)连接的COFs是全π-共轭的,具有促进的载流子迁移率和超高的化学稳定性,是极具潜力的光催化反应平台.然而,由于C=C键的不可逆特性,成功构筑具有高结晶度和孔隙率的烯烃连接的COFs仍极具挑战.构建D-A结构被认为是提升其光催化活性的有效策略之一,但目前具有D-A结构的烯烃连接的COFs光催化研究较少.本文提出了一种简单的分子工程策略来调控烯烃连接COFs的D-A相互作用以实现高效的光催化产氢.将2,4,6-三甲基1,3,5-三嗪(TM)分别与对苯二甲醛(TA)、 2,5-二甲基对苯二甲醛(MA)和3,3’-二甲基-4,4’-二醛基联苯(DMA)通过Knoevenagel聚合反应制备三种D-A型烯烃连接的COFs,即TM-TA-COF, TM-MA-COF和TM-DMA-COF,系统考察了引... 相似文献