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991.
运用光学传输矩阵和有限元方法对波长可调谐垂直腔面发射激光器(VCSELs)的波长调谐范围进行了研究.对中心波长为980nm的可调谐VCSELs的波长调谐特性和微电子机械系统(MEMS)悬臂梁结构进行了设计,并进行了实验研究.结果表明,MEMS可调谐VCSELs调谐特性同时受到光波谐振腔结构和悬臂梁最大位移的共同影响.在悬臂梁几何尺寸和激光器有源区结构一定的条件下,通过优化可调谐VCSELs的牺牲层厚度可实现大范围波长调谐.同时,对可调谐VCSELs整体结构进行了设计,计算结果显示波长调谐范围达到30nm以
关键词:
悬臂梁
可调谐垂直腔面发射激光器 相似文献
992.
993.
由于宏观的对称性,导致了某些量间的等值关系,从而可将实际问题简单化.本文利用这种特性,把它应用到具有对称性的曲线运动上,取得复杂问题简单处理的效果. 相似文献
994.
介绍了一种新的制备纳米石墨粉的方法——炸药爆轰法.通过对爆轰合成的黑色粉末进行x射线衍射分析,确认其为六方结构的纳米石墨,平均晶粒度为1.86—2.61nm.用BET气体吸附仪测试纳米石墨粉的比表面积约为500—650m2/g,由比表面积计算得到的纳米石墨粒度为4.41—6.85nm.在室温(≈290K)和12MPa压力条件下对纳米石墨粉进行储放氢气性能测试,结果表明纳米石墨粉样品的储放氢量为0.33wt%—0.37wt%.在相同实验条件下,纳米石墨粉原始样品的储放氢能力较原始纳米炭纤维(0.15wt%—0.35wt%)和多壁碳纳米管(0.15wt%—0.20wt%)的储放氢能力略强,但低于超级活性炭(0.92wt%—0.98wt%).纳米碳材料的比表面积在其储放氢实验中起关键作用.
关键词:
爆轰
纳米石墨粉
比表面积
储放氢量 相似文献
995.
996.
Exploration of α,α-dibromo-β-dicarbonyl compounds as novel organic oxidants for the mild Cu(I)-catalyzed Glaser-type homo-coupling reaction has been achieved, which provides an alternatively efficient pathway for the construction of 1,3-conjugated structures. In addition, the mechanism of this reaction was investigated. 相似文献
997.
Dioxomolybdenum(VI) complex covalently attached to amino‐modified graphene oxide: heterogeneous catalyst for the epoxidation of alkenes 下载免费PDF全文
Zhifang Li Shujie Wu Dafang Zheng Jiayin Liu Heng Liu Haiming Lu Qisheng Huo Jingqi Guan Qiubin Kan 《应用有机金属化学》2014,28(5):317-323
Transition metal salen complex MoO2–salen was successfully tethered onto amino‐functionalized graphene oxide (designated as MoO2–salen–GO), which was tested in the epoxidation of various alkenes using tert‐butylhydroperoxide or H2O2 as oxidant. Characterization results showed that dioxomolybdenum(VI) complex was successfully grafted onto the amino‐functionalized graphene oxide and the structure of the graphene oxide was well preserved after several stepwise synthesis procedures. Catalytic tests showed that heterogeneous catalyst MoO2–salen–GO was more active than its homogeneous analogue MoO2–salen in the epoxidation of cyclooctene due to site isolation. In addition, the MoO2–salen–GO catalyst could be reused three times without significant loss of activity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
998.
'Nafion®‐supported oxovanadium‐catalyzed hydrophosphonylation of aldehydes under solventless conditions', Applied Organometallic Chemistry,v. 26, issue 9, September 2012, pages 455–460 下载免费PDF全文
Shiue‐Shien Weng Guan‐Ying Lin Hsin‐Chun Li Kuo‐Chen Yang Teng‐Mao Yang Hui‐Chi Liu Syuan‐Hua Sie 《应用有机金属化学》2014,28(11):852-852
999.
Yan Wen Fang Lian Yan Ren Hong‐Yan Guan 《Journal of Polymer Science.Polymer Physics》2014,52(8):572-577
Polyvinyl formal (PVFM)‐based dense polymer membranes with nano‐Al2O3 doping are prepared via phase inversion method. The membranes and also their performances as gel polymer electrolytes (GPEs) for lithium ion battery are studied by field emission scanning electron microscope, X‐ray diffraction, differential scanning calorimetry, mechanical strength test, electrolyte uptake test, electrochemical impedance spectroscopy, cyclic voltammetry, and charge–discharge test. The polymer membrane with 3 wt % nano‐Al2O3 doping shows the improved mechanical strength of 12.16 MPa and electrolyte uptake of 431.25% compared with 10.47 MPa and 310.59% of the undoped sample, respectively. The membrane absorbs and swells liquid electrolyte to form stable GPE with ionic conductivity of 4.92 × 10?4 S cm?1 at room temperature, which is higher than 1.77 × 10?4 S cm?1 of GPE from the undoped membrane. Moreover, the Al2O3‐modified membrane supporting GPE exhibits wide electrochemical stability window of 1.2–4.8 V (vs. Li/Li+) and good compatibility with LiFePO4 electrode, which implies Al2O3‐modified PVFM‐based GPE to be a promising candidate for lithium ion batteries. © 2014 Wiley Periodicals, Inc. J. Polym. Sci. Part B: Polym. Phys. 2014 , 52, 572–577 相似文献
1000.
Hongyan Yao Yunhe Zhang Yu Liu Kaiyuan You Shanyou Liu Baijun Liu Shaowei Guan 《Journal of polymer science. Part A, Polymer chemistry》2014,52(3):349-359
A series of novel high molecular weight fluorinated co‐polyimides (Co‐PIs) containing styryl side chain based on 1,3‐bis(2‐trifluoromethyl‐4‐aminophenoxy)‐5‐(2,3,4,5‐tetrafluorophenoxy)benzene (6FTFPB) were successfully synthesized. The weight‐average molecular weights (Mws) and polydispersities of the co‐polyimides were in the range 8.93–10.81 × 104 and 1.33–1.82, respectively. The co‐polyimide film showed excellent solubility in organic solvents, high tensile properties (tensile strength exceeded 91 MPa), excellent optical transparency (cutoff wavelength at 332–339 nm and light transparencies above 89% at a wavelength of 550 nm), and high thermal stability (5% thermal weight‐loss temperature up to 510 °C). The casting and spinning films could be cross‐linked by thermal curing. The cured films show better combination property (including excellent resistance to solvents) than that of co‐polyimides. For instance, the glass transition temperature of Co‐PI‐1 (the molar weight ratio of 6FTFPB was 30%) increased from 217 to 271 °C, the tensile strength enhanced from 94 to 96 MPa, the 5% thermal weight‐loss temperature improved from 514 to 525 °C. Moreover, after cured, Co‐PI‐1 film also has a coefficient of thermal expansion (CTE) value of 60.3 ppm °C?1, low root mean square surface roughness (Rq) at 4.130 nm and low dielectric constant of 2.60. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 349–359 相似文献