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排序方式: 共有398条查询结果,搜索用时 15 毫秒
251.
252.
The effect of periodic delta-doping and modulation-doping on high Al content n-AlxGa1-xN(x = 0.55) epilayers grown by MOCVD has been investigated.Measured by XRD,AFM,contactless sheet resistance, and Hall-effect tests,δ-doped and modulation-doped n-AlxGa1-xN have better crystal quality,surface morphology and electrical properties as compared with uniformly-doped n-AlxGa1-xN.These improvements are attributed to the SiNx growth mask induced by 5-doping layers and the dislocation-blocking effect induced by both growth techniques.In addition,due to the broadened doping profile ascribed to enhanced dopant diffusion at high growth temperatures(1150℃) of n-Al0.55Ga0.45N,modulation-doped n-Al0.55Ga0.45N has similar properties asδ-doped n-Al0.55Ga0.45N. 相似文献
253.
A 5.35-μm-thick ZnO film is grown by chemical vapour deposition technique on a sapphire (0001) substrate with a GaN buffer layer. The surface of the ZnO film is smooth and shows many hexagonal features. The full width at half maximum of ZnO (0002) u-rocking curve is 161 arcsec, corresponding to a high crystal quality of the ZnO film. From the result of x-ray diffraction 0 - 20 scanning, the stress status in ZnO film is tensile, which is supported by Raman scattering measurement. The reason of the tensile stress in the ZnO film is analysed in detail. The lattice mismatch and thermal mismatch are excluded and the reason is attributed to the coalescence of grains or islands during the growth of the ZnO film. 相似文献
254.
在低温强磁场条件下,对In0.53 Ga0.47 As/In0.52AI0.48As量子阱中的二维电子气进行了磁输运测试.在低磁场范围内观察到正磁电阻效应,在高磁场下这一正磁电阻趋于饱和,分析表明这一现象与二维电子气中的电子占据两个子带有关.在考虑了两个子带之间的散射效应后,通过分析低磁场下的正磁电阻,得到了每个子带电子的迁移率,结果表明第二子带电子的迁移率高于第一子带电子的迁移率.进一步分析表明,这主要是由两个子带之间的散射引起的. 相似文献
255.
Dependence of current-voltage characteristics of pseudomorphic AlAs/In0.53a0.47s/InAs resonant tunneling diodes on quantum well widths 下载免费PDF全文
This paper studies the dependence of I-V characteristics on
quantum well widths in AlAs/In0.53Ga0.47As and
AlAs/In0.53Ga0.47As/InAs resonant tunneling structures
grown on InP substrates. It shows that the peak and the valley
current density in the negative differential resistance region are
closely related with quantum well width. The measured peak current
density, valley current densities and peak-to-valley current ratio
of resonant tunneling diodes are continually decreasing with
increasing well width. 相似文献
256.
溶胶-凝胶法制备ZnO纳米薄膜的工艺和应用 总被引:5,自引:0,他引:5
ZnO是一种重要的功能材料和新型的Ⅱ-Ⅵ族宽禁带半导体材料.采用溶胶-凝胶(Sol-gel)工艺在Si(100)、Si(111)和c面蓝宝石衬底上成功制备出高质量的ZnO纳米薄膜,并用XRD、SEM、AFM等方法研究了薄膜的特性.首次以制备的ZnO纳米薄膜为缓冲层,在n型Si(100)衬底上采用低压化学气相沉积(LPCVD)工艺外延生长了SiC薄膜,得到了低载流子浓度、高电子迁移率和高空穴迁移率的两种SiC薄膜样品,分析了该薄膜的性能. 相似文献
257.
高剂量的磷离子注入4H-SiC(0001)晶面,注入速率从1.0×1012到4.0×1012 P+ cm-2s-1变化,而注入剂量固定为2.0×1015 P+ cm-2。室温注入,1500oC的高温下退火。利用光荧光和拉曼谱分析注入产生的晶格损伤以及退火后的残余缺陷。通过霍耳测试来分析注入层的电学性质。基于上述测试结果,发现通过减小磷离子的注入速率,极大地减少了注入层的损伤及缺陷。考虑到室温注入以及相对较低的退火温度(1500 oC),在注入速率为1.0×1012 P+ cm-2s-1及施主浓度下为4.4×1019 cm-3的条件下,获得了非常低的方块电阻106 Ω/sq。 相似文献
258.
259.
The influence of AlN/GaN superlattice intermediate layer on the properties of GaN grown on Si(111) substrates 下载免费PDF全文
AlN/GaN superlattice buffer is inserted between GaN epitaxial layer
and Si substrate before epitaxial growth of GaN layer. High-quality
and crack-free GaN epitaxial layers can be obtained by inserting
AlN/GaN superlattice buffer layer. The influence of AlN/GaN
superlattice buffer layer on the properties of GaN films are
investigated in this paper. One of the important roles of the
superlattice is to release tensile strain between Si substrate and
epilayer. Raman spectra show a substantial decrease of in-plane
tensile strain in GaN layers by using AlN/GaN superlattice buffer
layer. Moreover, TEM cross-sectional images show that the densities
of both screw and edge dislocations are significantly reduced. The
GaN films grown on Si with the superlattice buffer also have better
surface morphology and optical properties. 相似文献
260.