全文获取类型
收费全文 | 420篇 |
免费 | 115篇 |
国内免费 | 123篇 |
专业分类
化学 | 24篇 |
晶体学 | 4篇 |
力学 | 1篇 |
综合类 | 3篇 |
物理学 | 200篇 |
无线电 | 426篇 |
出版年
2024年 | 10篇 |
2023年 | 12篇 |
2022年 | 24篇 |
2021年 | 43篇 |
2020年 | 25篇 |
2019年 | 21篇 |
2018年 | 14篇 |
2017年 | 33篇 |
2016年 | 41篇 |
2015年 | 22篇 |
2014年 | 40篇 |
2013年 | 23篇 |
2012年 | 24篇 |
2011年 | 32篇 |
2010年 | 16篇 |
2009年 | 31篇 |
2008年 | 34篇 |
2007年 | 35篇 |
2006年 | 30篇 |
2005年 | 30篇 |
2004年 | 17篇 |
2003年 | 14篇 |
2002年 | 17篇 |
2001年 | 19篇 |
2000年 | 17篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
排序方式: 共有658条查询结果,搜索用时 15 毫秒
131.
132.
量子阱中能级位置的确定是获得量子阱红外探测器其它设计参数的基础。为了提供足够的载流子跃迁,阱层一般为重掺杂层。重掺杂使半导体材料禁带宽度变窄,从而改变量子阱中能级的位置。通过对不同温度、量子阱区不同掺杂浓度条件下的量子阱材料PL 谱进行测量,得出PL 谱峰值波长对应的电子跃迁峰值能量,它与阱中基态能级的位置有关。分别计算了考虑和不考虑禁带变窄效应时的电子跃迁峰值能量,并与实验结果相比较,可以看出考虑禁带变窄效应时与实验结果相吻合,因此掺杂量子阱区能级的计算需要考虑禁带变窄效应,这样可以较为精确的得出阱中能级的位置。 相似文献
133.
本文报道淀积条件对非晶态硒化镉(a-CdSe)薄膜微区结构的影响,并对利用a-CdSe为光敏介质的超快光电探测器的特性进行了比较深入的测试研究。 相似文献
134.
Zeyu He Jiayue Han Xiaoyang Du Luye Cao Jun Wang Caijun Zheng Hui Lin Silu Tao 《Advanced functional materials》2021,31(37):2103988
Emerging graphene/organic phototransistors are eye-catching technologies owing to their unique merits including easy/low-cost fabrication, temperature independent, and achieving various functions. However, their development in the near-infrared (NIR) region is experiencing a bottleneck of inferior sensitivity due to low exciton dissociation efficiency and inefficient charge extraction rate. Here, a novel-design solution-processed graphene/organic NIR phototransistor is reported, that is, creatively introducing electron extraction layer of ZnO on graphene channel and employing organic ternary bulk heterojunction as photosensitive layer, successfully breaking that bottleneck. The phototransistor exhibits a high responsivity of 6.1 × 106 A W−1, a superior detectivity of 2.4 × 1013 Jones, and a remarkable minimum detection power of 1.75 nW cm−2 under 850 nm radiation. Considering its excellent NIR detection performance, a noncontact transmission-type pulse monitoring is carried out with no external circuit support, from which human pulse signal and heart rate can be displayed in real time. The phototransistor, interestingly, can be switched into a photomemory function with a retention time of 1000 s in the atmosphere through a gate voltage of −20 V. The design takes the characteristics of graphene/organic phototransistors to a higher level, beyond the limit of sensitivity, and opens up a novel approach for developing multifunction devices. 相似文献
135.
Ningqin Deng He Tian Jian Zhang Jinming Jian Fan Wu Yang Shen Yi Yang Tian-Ling Ren 《半导体学报》2021,42(8):21-33
Black phosphorus(BP),an emerging two-dimensional material,is considered a promising candidate for next-genera-tion electronic and optoelectronic devices due to in-plane anisotropy,high mobility,and direct bandgap.However,BP devices face challenges due to their limited stability,photo-response speed,and detection range.To enhance BP with powerful electric-al and optical performance,the BP heterostructures can be created.In this review,the state-of-the-art heterostructures and their electrical and optoelectronic applications based on black phosphorus are discussed.Five parts introduce the perform-ance of BP-based devices,including black phosphorus sandwich structure by hBN with better stability and higher mobility,black phosphorus homojunction by dual-gate structure for optical applications,black phosphorus heterojunction with other 2D materials for faster photo-detection,black phosphorus heterojunction integration with 3D bulk material,and BP via As-doping tunable bandgap enabling photo-detection up to 8.2 μm.Finally,we discuss the challenges and prospects for BP electric-al and optical devices and applications. 相似文献
136.
Flexible semitransparent photodetectors based on perovskites provide merits in terms of light weight and bifacial advantages but suffer from poor stability. To simultaneously enhance the performance and stability of flexible perovskite photodetectors (PPDs), silver (Ag) nanoparticles are incorporated to improve the responsiveness through the surface plasmon resonance (SPR) effect in the bulk of perovskite layer, and block copolymer F68 is employed to increase the surface hydrophobicity of perovskite film to keep long-term stable devices. Ag@polyvinyl pyrrolidone (PVP) core shell structure enables the sufficiently enhanced film light absorption and device quantum efficiency following the SPR response curve, the amphiphilic F68 make the perovskite less vulnerable to humid ambient exposure. Moreover, the sputtered transparent indium tin oxide back electrode enables the double facial operability of our flexible self-powered photodetectors with a bifacial factor of 80% and improved stability as well. Addressing the poor responsiveness and instability issues extends the potential broad applications of our bifacial flexible perovskite photodetectors. 相似文献
137.
本文提出了一种基于新型非周期高对比度亚波长 光栅(High Contrast Subwavelength Grating,HCSG)的谐振腔 增强型(Resonant Cavity Enhanced,RCE)光电探测器(Photodetector,PD),该器件是由顶 部光栅型上反射镜、PIN光探 测结构和分布式布拉格下反射镜(Distributed Bragg Reflectors,DBR)组成。新型非周期HC SG上反射镜是由局部湿法 氧化后形成的Al2O3间隔层和非周期GaAs光栅组成,实现了850 n m波段TM模式偏振光的高反射会聚特性,反射 率达到了86.5%且在1.5 μm焦距处实现了光束 会聚。下反射镜是由周期GaAs光栅和GaAs/Al0.9Ga0.1As DBR组成, 周期GaAs光栅对入射光有偏振选择特性,对TM模式的偏振光透射率为96.1%,而对TE模式的偏振光透射率仅有 3.7%。该器件利用了传输矩阵理论方法仿真模拟了其量子效率,量子 效率达到了71.8%,半高全宽接近于0.1 nm。 有效的解决了光电探测器的高量子效率和高响应带宽相互制约的问题,为下一代光通信系统 的发展提供了良好的基础。 相似文献
138.
Guoqing Tong Maowei Jiang Dae‐Yong Son Luis K. Ono Yabing Qi 《Advanced functional materials》2020,30(34)
A large number of derivative phases in inorganic perovskites are reported with special structures and extraordinary performances in photoelectronic device applications. The reverse phase transition between derivative phases and perovskites usually induces recrystallization or forms mixed components. In this work, derivative phase‐induced growth of the CsPbBr3 micro–nanowire (MW) array by utilizing phase transition of the 2D CsPb2Br5 phase is reported. Owing to its layered structure and phase transition, annealing of CsPb2Br5 at a temperature of 550 °C combined with solvent quenching leads to a templating effect to form a high‐quality CsBr MW array. Subsequent PbBr2 deposition and the second annealing are employed to form aligned CsPbBr3 MW arrays. Based on this method, a CsPbBr3 MW array‐based photodetector is fabricated. The large grain size, less grain boundaries, and lower surface potential of the CsPbBr3 MW array lead to high device performance with a responsivity of 7.66 A W?1, a detectivity of ≈1012 Jones, and long‐term operational stability over 1900 min. 相似文献
139.
Optoelectronic devices on silicon substrates are essential not only to the optoelectronic integrated circuit but also to low-cost lasers,large-area detectors,and so forth.Although heterogeneous integration of III-V semiconductors on Si has been welldeveloped,the thermal dissipation issue and the complicated fabrication process still hinders the development of these devices.The monolithic growth of III-V materials on Si has also been demonstrated by applying complicated buffer layers or interlayers.On the other hand,the growth of lattice-matched B-doped group-III-V materials is an attractive area of research.However,due to the difficulty in growth,the development is still relatively slow.Herein,we present a comprehensive review of the recent achievements in this field.We summarize and discuss the conditions and mechanisms involved in growing B-doped group-III-V materials.The unique surface morphology,crystallinity,and optical properties of the epitaxy correlating with their growth conditions are discussed,along with their respective optoelectronic applications.Finally,we detail the obstacles and challenges to exploit the potential for such practical applications fully. 相似文献
140.
Fei Ye Hong Lin Haodi Wu Lu Zhu Zhanfeng Huang Dan Ouyang Guangda Niu Wallace C. H. Choy 《Advanced functional materials》2019,29(6)
Organic–inorganic halide hybrid perovskite materials are promising materials for X‐ray and photon detection due to their superior optoelectronic properties. Single‐crystal (SGC) perovskites have increasingly attracted attention due to their substantially low crystal defects, which contribute to improving the figures of merit of the devices. Cuboid CH3NH3PbI3 SGC with the naturally favorable geometry for device fabrication is rarely reported in X‐ray and photon detection application. The concept of seed dissolution‐regrowth to improve crystal quality of cuboid CH3NH3PbI3 SGC is proposed and a fundamental understanding of the nucleation and growth is provided thermodynamically. The X‐ray detector fabricated from cuboid CH3NH3PbI3 SGC demonstrates the firstly reported high sensitivity of 968.9 µC?1 Gy?1 cm?2 under ?1 V bias. The results also show that the favorable crystal orientation and high quality of cuboid CH3NH3PbI3 leads to better responsivity and faster response speed than the more common dodecahedral CH3NH3PbI3 in photodetection. Consequently, the work paves a way to synthesize high‐quality perovskite SGCs and benefits the application of MAPbI3 SGCs with preferred crystal orientation and favorable crystal geometry for emerging device applications. 相似文献