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21.
22.
在分子束外延生长的InAs/In0.52Al0.48As/InP异质结体系中,形成InAs量子线.这些InAs量子线在生长和结构方面有一些独到的特性,并介绍了本实验室在研究InAs量子线的生长和结构方面所做的工作. 相似文献
23.
Molecular beam epitaxial HgCdTe material characteristics and device performance: Reproducibility status 总被引:1,自引:0,他引:1
J. Bajaj J. M. Arias M. Zandian J. G. Pasko L. J. Kozlowski R. E. De Wames W. E. Tennant 《Journal of Electronic Materials》1995,24(9):1067-1076
Extensive material, device, and focal plane array (FPA) reproducibility data are presented to demonstrate significant advances
made in the molecular beam epitaxial (MBE) HgCdTe technology. Excellent control of the composition, growth rate, layer thickness,
doping concentration, dislocation density, and transport characteristics has been demonstrated. A change in the bandgap is
readily achieved by adjusting the beam fluxes, demonstrating the flexibility of MBE in responding to the needs of infrared
detection applications in various spectral bands. High performance of photodiodes fabricated on MBE HgCdTe layers reflects
on the overall quality of the grown material. The photodiodes were planar p-on-n junctions fabricated by As ion-implantation
into indium doped, n-type, in situ grown double layer heterostructures. At 77K, diodes fabricated on MBE Hg1−xCdxTe with x ≈ 0.30 (λco
≈ 5.6 μm), x ≈ 0.26 (λco
≈ 7 μm), x ≈ 0.23 (λco ≈ 10 μm) show R0A products in excess of 1 x 106 ohm-cm2, 7 x 105 ohm-cm2, and 3 x 102 ohm-cm2, respectively. These devices also show high quantum efficiency. As a means to assess the uniformity of the MBE HgCdTe material,
two-dimensional 64 x 64 and 128 x 128 mosaic detector arrays were hybridized to Si multiplexers. These focal plane arrays
show an operability as high as 97% at 77K for the x ≈ 0.23 spectral band and 93% at 77K for the x ≈ 0.26 spectral band. The
operability is limited partly by the density of void-type defects that are present in the MBE grown layers and are easily
identified under an optical microscope. 相似文献
24.
Hall and drift mobilities in molecular beam epitaxial grown GaAs 总被引:1,自引:0,他引:1
V. W. L. Chin T. Osotchan M. R. Vaughan T. L. Tansley G. J. Griffiths Z. Kachwalla 《Journal of Electronic Materials》1993,22(11):1317-1321
A series of nominally undoped and Si-doped GaAs samples have been grown by molecular beam epitaxy (MBE) with Hall concentrations
ranging from 1015 to 1019 cm−3 and mobilities measured at 77 and 300K by Hall-van der Pauw methods. Drift mobilities were calculated using the variational
principle method and Hall scattering factors obtained from a relaxation-time approximation to permit cross-correlation of
experimental data with drift or Hall mobilities and actual or Hall electron concentrations. At 77K, both high purity and heavily
doped samples are well represented by either drift or Hall values since piezoelectric acoustic phonon scattering and strongly
screened ionized impurity scattering hold the Hall factor close to unity in the respective regimes. Between n≊1015 and 1017 cm−3, where lightly screened ionized impority scattering predominates, Hall mobility overestimates drift mobility by up to 50
percent and Hall concentration similarly underestimates n. At 300K, polar optical phonons limit mobility and a Hall factor
up to 1.4 is found in the lowest doped material, falling close to unity above about 1016 cm−3. Our calculation also agrees remarkably well with the Hall mobility of the highest purity MBE grown sample reported to date. 相似文献
25.
The surface growth kinetics of CdTe and HgTe have been investigated during molecular and metalorganic molecular beam epitaxy.
The surface growth kinetics was studied through in-situ measurements of the growth rate as a function of flux ratio and substrate
temperature on the (001), (111)B, and (211)B CdTe surface orientations. For the (001) and (111)B CdTe growth kinetics, the
existence of low binding energy surface precursor sites was proposed for both molecular and atomic growth species before lattice
incorporation. Intensity oscillations were observed during HgTe growth on misoriented (111)B surfaces and during CdTe growth
on the (211)B orientation. The (211)B surface reconstructions displayed both vicinal and singular surface characteristics,
depending on the growth flux ratio. 相似文献
26.
Sridhar Govindaraju Jason M. Reifsnider Michael M. Oye Archie L. HolmesJr. 《Journal of Electronic Materials》2004,33(8):851-860
This article describes the effects of rapid thermal annealing (RTA) on the photoluminescence (PL) emission from a series of GaIn(N)As quantum wells. Indium compositions of both 20% and 32% were examined with nominal N compositions of 1% or 2%. The N location was varied within our quantum structure, which can be divided into three regions: (1) quantum well, (2) Ga(N)As spacer layers at the barrier-to-well interface and well-to-barrier interface, and (3) barriers surrounding each quantum well. Eight combinations of samples were examined with varying In content, Ga(N)As spacer layer thickness, N content, and N location in the structure. In the best cases, the presence of these Ga(N)As spacer layers improves the PL properties, due to annealing, with a reduction in the emission wavelength blueshift by ~400 Å, a reduction of the decrease in the full-width at half-maximum (FWHM) by ~5 meV, and a threefold reduction of the increase in integrated intensity. It was also observed that relocating N from the quantum wells to the barriers produces a comparable emission wavelength both before and after annealing. Our results further show that the composition of incorporated N in the material is most influential during the stages of RTA in which relatively small amounts of thermal energy is present from our lower annealing times and temperatures. Hence, we believe a low thermal-energy anneal is responsible for the recovery of the plasma-related crystal damage that was incurred during its growth. However, the In composition in the quantum well is most influential during the latter stages of thermal annealing, at increased times and temperatures, where the wavelength blueshift was roughly independent of the amount of incorporated N. As a result, our investigations into the effects of RTA on the PL properties support other reports that suggest the wavelength blueshift is not due to N diffusion. 相似文献
27.
J.G.A. Wehner R.H. Sewell C.A. Musca J.M. Dell L. Faraone 《Journal of Electronic Materials》2007,36(8):877-883
Investigation into resonant-cavity-enhanced (RCE) HgCdTe detectors has revealed a discrepancy in the refractive index of the
CdTe layers grown by molecular beam epitaxy (MBE) for the detectors, compared with the reported value for crystalline CdTe.
The refractive index of the CdTe grown for RCE detectors was measured using ellipsometry and matches that of CdTe with an
inclusion of approximately 10% voids. X-ray measurements confirm that the sample is crystalline and strained to match the
lattice spacing of the underlying Hg(1−x)Cd(x)Te, while electron diffraction patterns observed during growth indicate that the CdTe layers exhibit some three-dimensional
structure. Secondary ion mass spectroscopy results further indicate that there is enhanced interdiffusion at the interface
between Hg(1−x)Cd(x)Te and CdTe when the Hg(1−x)Cd(x)Te is grown on CdTe, suggesting that the defects are nucleated within the CdTe layers. 相似文献
28.
Brian R. Bennett J. Brad Boos Mario G. Ancona N. A. Papanicolaou Graham A. Cooke H. Kheyrandish 《Journal of Electronic Materials》2007,36(2):99-104
Heterostructures for InAs-channel high-electron-mobility transistors (HEMTs) were investigated. Reactive AlSb buffer and barrier
layers were replaced by more stable Al0.7Ga0.3Sb and In0.2Al0.8Sb alloys. The distance between the gate and the channel was reduced to 7–13 nm to allow good aspect ratios for very short
gate lengths. In addition, n+-InAs caps were successfully deposited on the In0.2Al0.8Sb upper barrier allowing for low sheet resistance with relatively low sheet carrier density in the channel. These advances
are expected to result in InAs-channel HEMTs with enhanced microwave performance and better reliability. 相似文献
29.
Chun-Yuan Huang Tzu-Min Ou Cheng-Shuan Tsai Shih-Yen Lin Bang-Yu Hsu 《Thin solid films》2007,515(10):4459-4461
We have investigated the effects of silicon doping concentration within thirty-period self-assembled quantum dot (QD) layers on quantum dot infrared photodetectors (QDIPs). The lens-shaped quantum dots with the dot density of 1 × 1011 cm− 2 were observed by atomic force microscope (AFM). From the high ratio of photoluminescence (PL) peak intensities from dot layer to that from wetting layer, we have concluded that high dot density caused the short diffusion length for carriers to be easily captured by QDs. Moreover, the Si-doped samples exhibited the multi-state transitions within the quantum dots, which were different to the single level transition of undoped sample. Besides, the dominant PL peaks of Si-doped samples were red-shifted by about 25 meV compared to that of the undoped sample. It should result from the dopant-induced lowest transition state and therefore, the energy difference should be equal to the binding energy of Si in InAs QDs. 相似文献
30.
The growth of high quality multicomponent oxide thin films by reactive molecular beam epitaxy (MBE) requires precise composition control. We report the use of in situ reflection high-energy electron diffraction (RHEED) for the stoichiometric deposition of SrTiO3 (1 0 0) from independent strontium and titanium sources. By monitoring changes in the RHEED intensity oscillations as monolayer doses of strontium and titanium are sequentially deposited, the Sr:Ti ratio can be adjusted to within 1% of stoichiometry. Furthermore, the presence of a beat frequency in the intensity oscillation envelope allows the adjustment of the strontium and titanium fluxes so that a full monolayer of coverage is obtained with each shuttered dose of strontium or titanium. RHEED oscillations have also been employed to determine the doping concentration in barium- and lanthanum-doped SrTiO3 films. 相似文献