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Owing to unsaturated coordination environment,quantum size effect and metal-support interaction,single-or dual-atom metal sites,such as Mn,Fe,Co,Ni,Cu,Zn,Mo,Ru,Rh,Pd,Ag,Sn,Ir,Pt,Au,Bi,and Er coordinated with nonmetallic elements such as O,N,P,and S,exhibit different electronic configurations,which endow them with high catalytic performances in multiple redox reactions and versatile applications in organic synthesis,environmental remediation,energy conversion,and biomedicine.Despite intense research,the relation of structure-activity for single-atom catalysts(SACs)still bedazzles researchers,since diversified configurations of active sites would bring about difficulty in structural identification and theoretical simulations.Here,recent results on the applications of SACs are reviewed with an emphasis on identifying the active sites and discussing the relation between structure and property. 相似文献
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“我睡觉的时候,只要一关灯,抱抱就会出现在枕头边上,我掀开被子,抱抱就钻进来,转个身,紧紧靠着我睡,脑袋枕在我胳搏上,两手还伸开,跟我睡得一模一样。大冷天的,这样的肉麻很让人陶醉。有一次,我躺下的时候抱抱在吃夜宵,等他反应过来,我已经躺踏实了。他跑过来,仔细看了看我,确认我双眼紧闭呼吸均匀,以为我睡着了——其实我是故意的,要搁以前,他会叫两声,把我喊醒重睡。可这次,他竟然没言声,自己在被子上踩了个坑,躺下了。这不就是懂事么?我忍都忍不住,伸手就把他薅进被窝。” 相似文献
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一、结构设计总说明
主要是设计依据,抗震等级,人防等级,地基概况及其承载力,防潮层做法,活荷载取值,材料强度等级,施工中的注意事项,选用详图,通用详图或节点,以及在施工图中未画出而通过说明文字来表达的信息.…… 相似文献
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“风在吼,马在叫,黄河在咆哮,黄河在咆哮……” 太熟悉了,这气势磅礴的呐喊,这昂扬斗志的旋律,早在1939年春天就已经响彻云霄,传遍弥漫着抗日烽火的中华大地。由光未然作词、人民音乐家冼星海作曲的《黄河大合唱》,曾激励过多少抗日儿女奔赴前线,浴血奋战,保卫家乡,保卫黄河。 相似文献
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Ghasemi SH Hantehzadeh MR Sabbaghzadeh J Dorranian D Lafooti M Vatani V Rezaei-Nasirabad R Hemmati A Amidian AA Alavian SA 《Applied optics》2011,50(18):2927-2930
A beam shaping technique that rearranges the beam for improving the beam symmetry and power density of a ten-bar high power diode laser stack is simulated considering a stripe mirror plate and a V-Stack mirror in the beam shaping system. In this technique, the beam of a high power diode laser stack is effectively coupled into a standard 550 μm core diameter and a NA=0.22 fiber. By this technique, compactness, higher efficiency, and lower cost production of the diode are possible. 相似文献
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沙维 《材料科学与工程学报》1993,(2)
本文简要介绍激光沉积技术的原理、特点及国外科研机构采用这种方法制作陶瓷氧化物高温超导薄膜的技术参数等。本文还探讨了激光沉积超导薄膜的形貌及激光束与靶材的交互作用情况,并展望了这种技术的应用前景。 相似文献
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论述了激光准直技术的发展及共性的技术关键问题,系统介绍了对单位在高精度激光准直技术方面的研究成果,从理论到实践较好地克服激光漂移,大气环境对激光准直的严重影响。研制成功的激光光纤准直仪,激光双频同轴度仪及激光旋光准直仪具有当前高精度激光准直技术的代表性,并且均达到国内外先进水平。 相似文献
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A real-time, in situ fixing method by use of heating with a CO(2) laser beam is suggested for thermal fixing of a small local hologram in the bulk of a Fe:LiNbO(3) photorefractive crystal. For heating up to 100 degrees C-200 degrees C a volume with a shape similar to that of the laser beam a heat-guiding technique is developed. On the basis of the heat-transfer equations, different heating modes-with or without metal absorbers for heat guiding-obtained by use of a continuous or pulsed laser beam are analyzed. The optimal mode may be pulsed heating with absorbers. On this basis experiments have been designed and demonstrated. It is seen that the fixing process with CO(2) laser beam is short compared with the process by use of an oven, and the fixing efficiency is quite high. 相似文献
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In this letter we report a novel technique to measure small laser beam spot sizes. We use the open aperture z-scan technique as a tool to measure the laser beam spot size. This technique measures small spot sizes with accuracy better than 10%. 相似文献
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Toshiki Yamada Hidenori Shinohara Toshiya Kamikado Yoshishige Okuno Hitoshi Suzuki Shinro Mashiko Shiyoshi Yokoyama 《Thin solid films》2008,516(9):2522-2526
The spray-jet molecular beam apparatus enabled us to produce a molecular beam of non-volatile molecules under high vacuum from a sprayed mist of sample solutions. The apparatus has been used in spectroscopic studies and as a means of molecular beam deposition. We analyzed the molecular beam, consisting of non-volatile, solvent, and carrier-gas molecules, by using femtosecond- and nanosecond- laser mass spectroscopy. The information thus obtained provided insight into the molecular beam produced by the spray-jet technique. 相似文献
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A technique for transmitting a narrow laser beam from a ground station to a satellite has been developed. The principle of pointing a laser beam to a distant target in a scattering medium by use of a backscattered laser beam image is described. We calculated the intensity distribution of the image by using a typical model of atmospheric coefficients. The method was applied to transmit a laser beam from a ground station to Engineering Test Satellite-VI. The accuracy of pointing the laser beam to the satellite was approximately 10 murad in this experiment. 相似文献
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Highly efficient diode-stack, end-pumped Nd:YAG slab laser with symmetrized beam quality 总被引:1,自引:0,他引:1
An efficient high-power cw Nd:YAG slab laser, partially end pumped by diode-laser stacks, and a novel beam-shaping technique are reported. The optical efficiency amounted to 44 %, and the slope efficiency amounted to 55 %. Introducing an intracavity Brewster plate to polarize the laser beam, we obtained an optical efficiency of 35 % and a slope efficiency of 41 %. The output beam was rectangular and the beam quality asymmetric in two orthogonal directions. To equalize the beam quality, we introduced a step-mirror beam-shaping technique. The beam-shaping technique and the results obtained are discussed. 相似文献
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Optimal laser light delivery into turbid biological tissues was studied by using Monte Carlo simulations based on the delta-scattering technique. The goal was to deliver efficiently the maximum amount of optical power into buried tumors being treated while avoiding potential damage to normal tissue caused by strong optical power deposition underneath the tissue surface illuminated by the laser beam. The buried tumors were considered to have much higher absorption than the surrounding normal tissue because of selective uptake of the absorption-enhancement dye. The power delivering efficiency to buried tumors was investigated for various diameters of the laser beam. An optimal beam diameter was estimated to achieve the maximum product of the power coupling efficiency and the power delivered to the buried tumor. The distribution of power deposition was simulated for single-beam delivery and multiple-beam delivery as well. The simulated results showed that with an appropriate dye enhancement and an optimal laser delivery configuration, a high selectivity for laser treatment of tumor could be achieved. 相似文献