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281.
282.
The chemical composition, morphology, selective absorber characteristics, and degradation of selective absorber characteristics at high temperatures of black chrome solar selective coating are influenced by various substrate pre-treatments like mechanical polishing, chemical etching, and electropolishing prior to film deposition. The major oxide content in the deposit is formed as Cu2(OH)2CrO4 (JCPDS 38-0230), which on high temperature annealing decomposes to CuCrO4 (JCPDS 34-0507), CuO (JCPDS 41-0254), and Cu2O (JCPDS 5-0667). Formation of the oxides of Cu at high temperatures retains the high optical absorption characteristics of the coating even after high temperature degradation. 相似文献
283.
Various dual-converter configurations operating in the circulating current mode are compared for use in constant-voltage DC regenerative power-supply applications. Three types of dual-converter configurations are discussed. The design of these systems, including the circulating current limiting inductors, is provided. System components were designed using the three dual-converter configurations with the following specifications: (1) AC supply, three-phase, 115 V, 60 Hz; (2) DC output voltage 135 V; (3) maximum DC load current, 100 A; and (4) ratio of the allowable average circulating current to the maximum DC load current=0.2. The results are experimentally verified 相似文献
284.
The electrical conductivity and stability in resistance of CdSe0.2Te0.8 thin films in different ambients and deposited at different substrate temperatures were investigated. A reduction in conduction activation energy with increase in film thickness and deposition temperature is accounted for by the fact that in CdSe
x
Te1–x
inhomogeneous semiconductor thin films, the potential relief inhomogeneity may be reduced with increase in film thickness and substrate temperature, which results in the decrease of conduction activation energy of the films. 相似文献
285.
Daijiro Nozaki Jens Kunstmann Felix Zörgiebel Sebastian Pregl Larysa Baraban Walter M. Weber Thomas Mikolajick Gianaurelio Cuniberti 《Nano Research》2014,7(3):380-389
For the development of ultra-sensitive electrical bio/chemical sensors based on nanowire field effect transistors (FETs), the influence of the ions in the solution on the electron transport has to be understood. For this purpose we establish a simulation platform for nanowire FETs in the liquid environment by implementing the modified Poisson-Boltzmann model into Landauer transport theory. We investigate the changes of the electric potential and the transport characteristics due to the ions. The reduction of sensitivity of the sensors due to the screening effect from the electrolyte could be successfully reproduced. We also fabricated silicon nanowire Schottky-barrier FETs and our model could capture the observed reduction of the current with increasing ionic concentration. This shows that our simulation platform can be used to interpret ongoing experiments, to design nanowire FETs, and it also gives insight into controversial issues such as whether ions in the buffer solution affect the transport characteristics or not. 相似文献
286.
Ultrasmall silicon (Si) nanoelectronic devices require an energy shift of electronic states for n‐ and p‐conductivity. Nanocrystal self‐purification and out‐diffusion in field effect transistors cause doping to fail. Here, it is shown that silicon dioxide (SiO2) and silicon nitride (Si3N4) create energy offsets of electronic states in embedded Si quantum dots (QDs) in analogy to doping. Density functional theory (DFT), interface charge transfer (ICT), and experimental verifications arrive at the same size of QDs below which the dielectric dominates their electronic properties. Large positive energy offsets of electronic states and an energy gap increase exist for Si QDs in Si3N4 versus SiO2. Using DFT results, the SiO2/QD interface coverage is estimated with nitrogen (N) to be 0.1 to 0.5 monolayers (ML) for samples annealed in N2 versus argon (Ar). The interface impact is described as nanoscopic field effect and propose the energy offset as robust and controllable alternative to impurity doping of Si nanostructures. 相似文献
287.
288.
Sebastian NeubertDamian Pliszka Velmurugan ThavasiErich Wintermantel Seeram Ramakrishna 《Materials Science and Engineering: B》2011,176(8):640-646
The integration of electrospinning and electrospraying to prepare the fibrous catalytic filter membrane is demonstrated. The non-conductive polyethylene oxide (PEO) is blended with (±)-camphor-10-sulfonic acid (CSA) doped conductive polyaniline (PANi) for electrospinning. The conductive CSA/PANi-PEO composite fibers are produced upon electrospinning, which are used as the conductive collector for electrospraying process by which titanium dioxide (TiO2) nanoparticles (NPs) are sprayed and allowed to adsorb on the fibers. The degree of adsorption and dispersion of nano TiO2 catalysts on the surface of the CSA/PANi-PEO fibers exhibit a stronger dependence on weight percentage (wt%) of PANi in PEO solution and the strength of electrical conductivity of the fibers used during electrospraying. CSA/PANi-PEO fibers as collector reduce the wastage of TiO2 NPs during electrospraying to lesser than 5%. Among the three different composition of PANi studied, PEO with 12 wt% PANi yields very uniform diameter and beads-free fibrous structure with higher electrical conductivity. 12 wt% CSA/PANi-PEO fibrous membrane is found to support for greater dispersion of TiO2 NPs. The photocatalytic activity of the as-prepared TiO2-PANi-PEO catalytic membrane is tested against the toxicant simulant 2-chloroethyl phenyl sulfide (CEPS) under the ultraviolet light irradiation. It is observed that the TiO2 nanoparticles catalysts embedded PANi-PEO fibrous membrane decontaminated the toxicant CEPS significantly, which is due to uniform dispersion of the catalysts produced by the methodology. 相似文献
289.
T. Joseph S. Uma J. Philip M. T. Sebastian 《Journal of Materials Science: Materials in Electronics》2011,22(8):1000-1009
A new polymer-ceramic composite was prepared using PTFE and low loss Sr2ZnSi2O7. The dielectric properties of the composite were studied in the microwave and radiofrequency ranges. The relative permittivity
(εr) and dielectric loss (tan δ) increased with the filler loading from 0.10 to 0.50 volume fractions (vf). The observed values of εr, thermal conductivity and coefficient of thermal expansion (CTE) were compared with the corresponding theoretical predictions.
The ability of the composite towards moisture absorption resistance was studied as a function of filler loading. It was also
found that the variation of εr was less than 2% in the temperature range 25–90 °C, at 1 MHz. For a filler content of 0.50 vf, the PTFE/Sr2ZnSi2O7 composite exhibited εr = 4.4, tan δ = 0.003 (at 4–6 GHz), CTE = 38.3 ppm/°C, thermal conductivity = 2.1 W/mK and moisture absorption = 0.09 wt%. 相似文献
290.
Santucci SC Cojoc D Amenitsch H Marmiroli B Sartori B Burghammer M Schoeder S DiCola E Reynolds M Riekel C 《Analytical chemistry》2011,83(12):4863-4870
Investigations of single fragile objects manipulated by optical forces with high brilliance X-ray beams may initiate the development of new research fields such as protein crystallography in an aqueous environment. We have developed a dedicated optical tweezers setup with a compact, portable, and versatile geometry for the customary manipulation of objects for synchrotron radiation applications. Objects of a few micrometers up to a few tens of micrometers size can be trapped for extended periods of time. The selection and positioning of single objects out of a batch of many can be performed semi-automatically by software routines. The performance of the setup has been tested by wide-angle and small-angle X-ray scattering experiments on single optically trapped starch granules, using a synchrotron radiation microbeam. We demonstrate here for the first time the feasibility of microdiffraction on optically trapped protein crystals. Starch granules and insulin crystals were repeatedly raster-scanned at about 50 ms exposure/raster-point up to the complete loss of the structural order. Radiation damage in starch granules results in the appearance of low-angle scattering due to the breakdown of the polysaccharide matrix. For insulin crystals, order along the densely packed [110] direction is preferentially maintained until complete loss of long-range order. 相似文献