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941.
A. Modic Y.K. Sharma Y. Xu G. Liu A.C. Ahyi J.R. Williams L.C. Feldman S. Dhar 《Journal of Electronic Materials》2014,43(4):857-862
A nitrogen plasma annealing process for gate dielectric applications in 4H-SiC metal oxide semiconductor (MOS) technology has been investigated. This process results in substantially greater interfacial N coverage at the SiO2/4H-SiC interface and lower interface trap densities than the state-of-the-art nitric oxide (NO) annealing process. Despite these exciting results, the field-effect mobility of MOS field-effect transistors (MOSFETs) fabricated by use of this process is very similar to that of NO-annealed MOSFETs. These results emphasize the importance of understanding mobility-limiting mechanisms in addition to charge trapping in next-generation 4H-SiC MOSFETs. 相似文献
942.
Z. Zheng Y.F. Lu Z.Z. Ye H.P. He B.H. Zhao 《Materials Science in Semiconductor Processing》2013,16(3):647-651
The electrical and optical properties of zinc oxide (ZnO) films doped with different Na contents and grown by pulsed laser deposition were investigated. Hall measurements witnessed the conductivity conversion from n-type to p-type with targeted Na doping content increased up to more than 1%. The photoluminescence intensity first decreased as the targeted Na content increased to 1%, while non-degraded and even enhanced PL intensity was observed in p-type ZnO:Na0.02 film. This photoluminescence enhancement was ascribed to enhanced radiative recombination with more acceptor (NaZn) introduced. The band-gap shift of ZnO:Nax films was related to the variation of carrier type and concentration. Band-gap shrinkage was adopted to explain the carrier type- and concentration-dependent band-gap shift of ZnO:Nax films. 相似文献
943.
Secondary-arc suppression is necessary for successful fast, multiphase reclosing on UHV lines. Installation of a shunt reactor is one of the most effective methods of rapidly extinguishing the secondary arc. For multiphase reclosing on untransposed double-circuit UHV lines, a zero-sequence compensated balanced shunt reactor cannot suppress the secondary arc sufficiently. This is because of the imbalance in electrical couplings among phases. A zero-sequence compensated unbalanced shunt reactor is proposed to compensate for the imbalance in the electrostatic couplings. The effects of this reactor on suppressing the secondary arc can easily be analysed by the introduction of phase-to-phase compensation parameters. Such parameters can be used to decide on the optimum shunt reactor for secondary-arc extinction. 相似文献
944.
Microbial enhanced oil recovery (MEOR) applies biotechnology to improve residual crude oil production from substratum reservoir. MEOR includes in-situ MEOR and ex-situ MEOR. The former utilizes microbial growth and metabolism in the reservoir, and the latter directly injects desired active products produced by microbes on the surface. Taking biosurfactant-producing strain Pseudomonas aeruginosa WJ-1 for research objects, in-situ enhanced oil recovery and ex-situ enhanced oil recovery by biosurfactant-producing strain WJ-1 were comparatively investigated in sand-pack columns.The results showed that P.aeruginosa WJ-1 really proliferated in sand-pack columns, produced 2.66 g/L of biosurfactant, altered wettability, reduced oil-water interfacial tension (IFT) and emulsified crude oil under simulated in-situ process. Results also showed that higher biosurfactant concentration, lower IFT, smaller average diameters of emulsified crude oil were obtained in in-situ enhanced oil recovery experiment than those in ex-situ enhance oil recovery experiment. Similar wettability alteration was observed in both in-situ and ex-situ enhanced oil recovery experiment. The flooding experiments in sand-pack columns revealed that the recovery of in-situ was 7.46%/7.32% OOIP (original oil in place), and the recovery of the ex-situ was 4.64%/4.49% OOIP. Therefore, in-situ approach showed greater potential in enhancing oil recovery in contrast with ex-situ approach. It is recommended that the stimulation of indigenous microorganisms rather than injection of microbial produced active products should be applied when MEOR technologies were employed. 相似文献
945.
Y. Konishi S.T. Allen M. Reddy M.J.W. Rodwell R.P. Smith J. Liu 《Solid-state electronics》1993,36(12):1673-1676
The Schottky-collector resonant-tunnel-diode (SRTD) is an resonant-tunnel-diode with the normal N+ collector layer and ohmic contact replaced by direct Schottky contact to the space-charge layer, thereby eliminating the associated parasitic series resistance Rins. By scaling the Schottky collector contact to submicron dimensions, the device periphery-to-area ratio is increased, decreasing the periphery-dependent components of the parasitic resistance, and substantially increasing the device's maximum frequency of oscillation. We report measured d.c. and microwave parameters of planar SRTDs fabricated with 1 μm-geometries in AlAs/GaAs. 相似文献
946.
Soft errors in 16 Mbit dynamic random access memories (DRAMs) have been investigated using proton microprobes at 400 keV with a spot size of 1 × 1 μm2. The newly developed susceptibility mapping can reveal the correlation between the particle hit-position position and the susceptibility to soft errors in a DRAM. The cell-mode soft-errors were found to take place by the incidence of ions within 6 μm around a monitored cell. These errors would be induced by minority carrier diffusion in a lateral direction. This result manifests the possibility of multiple-bit errors by the incidence of an energetic particle. 相似文献
947.
Thin CdTe films were deposited by hot-wall epitaxy (HWE) on (111) HgCdTe and CdZnTe substrates at temperatures from about 140 to 335°C. X-ray rocking curves were used to show that crystal quality of the CdTe (111)B films improved as substrate temperature increased from 140 to about 250°C. Rocking curve values for full width at half maximum (FWHM) decreased from 2–4 degrees at 140–150°C to less than 100 arc-s at 250°C, and a FWHM of 59 arc-s was the lowest value observed near 250°C. The FWHM of the HWE CdTe was found to be insensitive to growth rate below about 400Å/min, but increased to four degrees at 1250Å/min. X-ray diffraction confirmed that films grown on the B-face at higher temperatures were epitaxial, but contained a significant volume fraction, 35% to 50%, of rotational in-plane twins. Electron microscopy confirmed a coarse twin density, and photoluminescence spectra showed an absence of excitonic emission in the HWE films. Simultaneous growth on two (111) HgCdTe substrates with different surface polarities between 230°C and 335°C showed that deposition rate on the A-face decreased relative to that on the B-face as temperature increased. Films grown on the B-face exhibited better surface morphologies than those grown on the A-face. 相似文献
948.
H. Fujiyasu Y. Takeuchi K. Hikida T. Kiichi K. Masuo Y. Gotou K. Ishino A. Ishida 《Journal of Electronic Materials》1993,22(5):545-550
CdSSe (manganese-doped, Eg = 1.9–2.5 eV, lattice constant a = 6.05–5.8A)-ZnS (Eg = 3.56 eV, a = 5.41A) superlattices, SrS (cerium-doped, E = 4.4 eV,
a = 6.02A) layers, and CdSSe-SrS (cerium-doped) superlattice layers nave been prepared by hot-wall epitaxy, and the properties
and the electroluminescent device characteristics of the active layers are reported. For the superlattices with ZnS, the maximum
luminance was 800 cd/m2 at an applied sinusoidal voltage (Vo-p = 200 V) with frequency 1kHz, and the wavelength of the spectral peak was 610 nm due to the large strain caused by the lattice
mismatch (8–15%) between the CdSSe and ZnS layers. The maximum luminance and Comisson Internationale de Enluminure (CIE) chromaticity
of CdS(Mn)-ZnS superlattices and CdSe(Mn)-ZnS superlattice devices were 557cd/m2 and (x,y) = (0.58,0.41) and 982 cd/m2 and (0.61, 0.38), respectively. For superlattices with SrS, the maximum luminance of the device with the SrS (cerium-doped)
active layer was nearly 700 cd/m2 at a voltage of 340V. Blue electroluminescent emission was observed in the photon wavelength region less than 450 nm, due
to carriers dropping into the quantum wells of the device with the CdSSe-SrS superlattice active layer. 相似文献
949.
The electron doped Ln2−xCexCuO4 (Ln=lanthanide) oxides have intergrowth structures consisting of superconductively active CuO2 sheets alternating with inactive (Ln, Ce)2O2 fluorite layers along the c-axis. Stabilization of such intergrowth structures requires bond length matching across the intergrowth
interface. The bond length matching criterion causes a monotonic decrease in the Ce solubility limit from x=0.24 to x=0.15
as the size of Ln3+ decreased from Ln=La0.5Nd0.5 to Ln=Gd. Annealing in N2 atm of Ln2−xCexCuO4 at temperatures above 900°C creates oxygen vacancies and the number of vacancies decreases with increasing Ce content. The
value of x at which a semiconductor to superconductor transition occurs in Ln2−xCexCuO4 increases with decreasing size of Ln3+ due to an increasing Madelung energy caused by a decreasing Cu−O bond length. 相似文献
950.
Thin epitaxial films of HgSe and Hg1−xCdxSe (x≤0.34) were successfully grown for the first time by molecular beam epitaxy. Film growth parameters are discussed, and
results of structural, electrical, and optical studies are reported. 相似文献