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排序方式: 共有9193条查询结果,搜索用时 15 毫秒
31.
研究了热丝CVD金刚石薄膜的红外反射吸收谱,讨论了金刚石薄膜中H、N等杂质和晶粒晶型、晶粒尺度对膜红外透过率的影响。 相似文献
32.
高精密度可互换NTC热敏电阻器的设计 总被引:1,自引:0,他引:1
以高稳定,易重现瓷料为基础,运用特性互补偿原理和集成组装技术,设计高精密度可互换NTC热敏电阻器。着重阐述了互换精度达0.2级的高精密可互换NTC热敏电阻的设计要点及质控技术。 相似文献
33.
Xiaoyang Chen Xuejun Qian Kwok‐Ho Lam Chi Tat Chiu Ruimin Chen Zeyu Chen K. Kirk Shung Ping Yu Qifa Zhou 《Advanced functional materials》2019,29(32)
The developments of personalized medicine, ultrasound imaging, and contactless “microscopic handle” techniques are pushing ultrasonic transducers toward features of high frequency, device miniaturization, and even novel function. However, the conventional ultrasonic transducer has severely limited the development of novel ideas for applications due to its ordinary ultrasonic field. Although transducer arrays and monolithic acoustic holograms are capable of producing the complicated ultrasonic field, it is still difficult to achieve high frequency, device miniaturization, and novel function simultaneously. Here, a simple but effective approach is introduced that aims at reconstructing the complicated and high‐frequency ultrasonic field via a compact single‐element ultrasonic transducer. The 3D ultrathin piezoelectric element with a complex configuration is demonstrated theoretically and experimentally to produce the desired complicated ultrasonic field. With helical‐like configuration, the single‐element ultrasonic transducer offers efficient noncontact trapping and manipulation of suspended microparticles and biological cells. Moreover, its strong trapping capability leads to the 3D stacking of microparticles, which is a novel and interesting phenomenon achieved by a single‐element ultrasonic transducer. This work brings the possibility of a complicated ultrasonic field for achieving novel high‐frequency ultrasound applications through the design of smart structure ultrathin piezoelectric materials. 相似文献
34.
Jun-ichi Nishizawa Akihiko Murai Hiroki Makabe Osamu Ito Tomoyuki Kimura Ken Suto Yutaka Oyama 《Solid-state electronics》2004,48(12):2251-2254
The tunnel injection transit time (TUNNETT) diodes with p+p+n+n−n+ structure were fabricated by liquid phase epitaxy (LPE). About 100 Å tunnel junction (p+n+) was successfully prepared by the double impurity diffusion of Ge and S during LPE growth. Continuous wave (CW) oscillation was realized at 51.520 GHz in the V-band cavity with the phase noise of −60 dBc/Hz at 1 kHz bandwidth. 相似文献
35.
S. Miya S. Muramatsu N. Kuze K. Nagase T. Iwabuchi A. Ichii M. Ozaki I. Shibasaki 《Journal of Electronic Materials》1996,25(3):415-420
InAs/AlGaAsSb deep quantum well was successfully formed on GaAs substrate and examined for two electron devices, Hall elements
(HEs), and field-effect transistors (FETs). With a thin buffer layer of 600 nm AIGaAsSb on GaAs substrate, we observed high
electron mobility more than 23000 cm2/Vs and extrinsic effective electron velocity of 2.2 x 107 cm/s for a 15 nm thick InAs channel at room temperature. AIGaAsSb lattice matched to InAs was discussed from the view points
of insulating property, carrier confinement, and oxidization rate. Reliability data good enough for practical use were also
obtained for HEs. We demonstrated AIGaAsSb as a promising buffer/barrier layers for InAs channel devices on GaAs substrate,
and we discussed the possible advantages of AIGaAsSb also for InGaAs FETs. 相似文献
36.
Third generation multi-layer tandem solar cells for achieving high conversion efficiencies 总被引:1,自引:0,他引:1
Different ways of connecting solar cell structures to form multi-layer tandem solar cells have been considered by re-visiting relevant device designs. It is found that the present use of a series connection or tunnel junction approach is detrimental to charge-carrier collection in the tandem cells. Each tunnel junction introduced to the solar cell structure decelerates the charge carriers and allows them to recombine at the vicinity of the tunnel junction. The adoption of parallel connections has several advantages over series connections and there is high potential for achieving enhanced efficiencies in third generation tandem solar cells. In these devices, charge carriers are continuously accelerated across the whole device and collected in the external circuit. Multi charge-carrier production and impurity photo-voltaic mechanisms are also built into this system to enhance its performance by increasing the short-circuit current density. 相似文献
37.
Patrick B Milimo 《Journal of the science of food and agriculture》1994,64(3):365-370
Results of chemical analyses of some nutritional characteristics of Melia volkensii browse, important for large wild and domestic herbivores in East Africa, are presented. Seeds, fruit pulp, leaves and twigs had high levels of crude protein, crude fat, minerals and fibre. Newly coppiced shoots (leaves and twigs), old shoots, fruit pulp and seed contained 230, 190, 130 and 320 g kg-1 dry weight crude protein, respectively. The essential amino acid profile compared well with the FAO scoring pattern. Tyrosine was the first limiting amino acid in the coppice leaves and twigs, lysine in the cotyledons, and threonine and lysine in the endosperm. The concentrations of crude fat in the seed, fruit pulp, coppice shoots and old shoots were 480, 100, 80 and 50 g kg-1, respectively. The fatty acids in the cotyledon and endosperm were mainly palmitic (110 and 109 g kg-1, respectively), oleic (327 and 252 g kg-1, respectively) and linoleic (487 and 573 g kg-1, respectively). The levels of P, Na, K, Ca, Mg and the Ca/P ratio per kg dry weight were on average higher than the optimum recommended for ruminants. These results demonstrate that M volkensii browse, especially coppice leaves and twigs, have a high index for nutrient content, and the planting of this species should be promoted in the semi-arid areas to supplement senescent grasses and cereal crop residues. 相似文献
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本文对具有两组压电陶瓷激励元件的夹心式功率超声压电换能器进行了理论及实验研究.当换能器中的两组压电陶瓷元件分别被激励时,换能器可以产生两组不同的共振及反共振频率.利用换能器的梅森等效电路,得出了其频率方程.探讨了换能器的共振频率及反共振频率与其几何尺寸及电学边界条件的依赖关系.研究表明,换能器的共振频率不仅与其几何形状和尺寸有关,而且与电学边界条件有关.在同样的几何尺寸下,电端开路时的共振及反共振频率大于电端短路时的共振及反共振频率.在两种电学边界条件下,换能器的共振及反共振频率与几何尺寸之间的依赖关系是相似的,即当换能器圆锥前盖板的半径比增大时,换能器的共振及反共振频率总是降低的. 相似文献