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991.
The large-scale commercialization of aluminum-matrix composites 总被引:2,自引:0,他引:2
Thomas F. Klimowicz M.S. 《JOM Journal of the Minerals, Metals and Materials Society》1994,46(11):49-53
The successful commercialization of aluminum composites depends on much more than just the development of the material and the discovery of suitable applications. In order for large potential users to consider a new material adequate production capacity must be demonstrated and costs must be reduced to levels consistent with the products targeted. For all potential applications, appropriate secondary fabrication techniques must be developed. Recycling and reclamation assume a special importance in particularly cost-sensitive markets, such as automobiles, as they have a sizable impact on the final cost of a component. Finally, suitable analytical techniques are required by all parties, including the material producer, secondary fabricators, and end-users. While many of these enabling technologies will eventually be further developed and refined by fabricators and end-users, the initial development, in most cases, has been left to the materials producer. 相似文献
992.
993.
Richard Thomas Lermen Ivan Guerra Machado 《Journal of Materials Processing Technology》2012,212(11):2371-2379
The main objectives of this study were to construct a plasma generator device and to investigate its applications in welding, cutting, and surface hardening. The device was derived from the union of two plasma-generating technologies, non-transferred-arc plasma and magnetoplasmadynamic thruster (MPDT), and characterised by the simultaneous formation of two plasma arcs in one device, generating a plasma jet with high energy density. Initially, trials were conducted to analyse the influence of the physical variables (gas flow rate and electric current intensities – primary and secondary) on the plasma jet, for which the thruster and the length of the plasma jet expulsed from the chamber were determined. The relevant parameters for welding, cutting and surface hardening were determined by trial and error, in which the trials were conducted using various plate thicknesses and materials. The results have shown that this device can be used for welding, cutting and surface hardening. 相似文献
994.
Mathias Breimesser Stefan Ritter Hans-Peter Seifert Sannakaisa Virtanen Thomas Suter 《Corrosion Science》2012
The electrochemical microcapillary technique was applied for the first time to study the electrochemical dissolution signals from single growing cracks due to stress corrosion cracking of thermally sensitised AISI 304 stainless steel in potassium tetrathionate solution. Potentiostatic current measurements on initiating cracks along grain boundaries were performed. Typical current signals of potentiostatic and potentiodynamic measurements consisted of a series of current peaks showing fast rise and exponential decay, sometimes interrupted by passive phases. The results indicate that stress corrosion crack growth is a discontinuous process of passive and active phases, which might be explained by the film rupture model. 相似文献
995.
996.
997.
Thomas J. Hill John J. Mecholsky Kenneth J. Anusavice 《Journal of the American Ceramic Society》2000,83(3):545-552
The objective of this paper was to analyze the crystal aspect ratio (AR), the fracture toughness, and the fractal dimension of 3BaO. 5SiO2 glass-ceramics and to relate the topography of fracture surfaces to fractal behavior. These analyses demonstrate that crystal morphology strongly affects the fracture path, the fracture toughness, and the fractal dimension. Fracture toughness increased from 0.7 ± 0.1 MPa. m1/2 for the glass to 2.2 ± 0.6 MPa. m1/2 for the glass-ceramic with an AR of 8.1 while the fractal dimensional increment ( D *) for the glass and the glass-ceramic increased from 0.10 ± 0.01 to 0.25 ± 0.02, respectively. The materials with lower aspect ratios (AR = 1.4 and 3.6) exhibited the predicted relationship between toughness and D * while the glass-ceramic with an aspect ratio of 8.1 did not satisfy the expected relationship because of multiple toughening mechanisms. 相似文献
998.
Crystal Structure and Related Properties of Manganese-Doped Barium Titanate Ceramics 总被引:1,自引:0,他引:1
Hans Theo Langhammer Thomas Müller Karl-Heinz Felgner Hans-Peter Abicht 《Journal of the American Ceramic Society》2000,83(3):605-611
The influence of manganese on the crystallographic phase and the microstructure of BaTi1− x Mn x O3 ceramics (0 ≤ x ≤ 0.05) is investigated. The crystal structure at room temperature changes from tetragonal to hexagonal between x = 0.005 and 0.017, which causes a drastic change in the microstructure. The Jahn_Teller distortion caused by the MnTi 3+ ions is proposed as the driving force for the phase transition. Annealing of the as-fired samples in both a reducing and oxidizing atmosphere restores the tetragonal phase, which is accompanied by a change in the microstructure based on the percentage of tetragonal phase. 相似文献
999.
Effect of the Interfacial Transition Zone on the Conductivity of Portland Cement Mortars 总被引:3,自引:0,他引:3
John D. Shane Thomas O. Mason Hamlin M. Jennings Edward J. Garboczi Dale P. Bentz 《Journal of the American Ceramic Society》2000,83(5):1137-1144
The electrical conductivity of portland cement mortars was determined experimentally as a function of the volume fraction of sand and the degree of hydration. The results were analyzed using theoretical models that represent the mortars as three-phase, interactive composites. The three phases are the matrix paste, the aggregate, and the thin interfacial transition zone between the two. The microstructure and properties of the conductive phases (the transition zone and the matrix paste) were determined by a micrometer-scale microstructural model, and were used in conjunction with random-walk algorithms and differential-effective medium theory to determine the overall mortar conductivities. The presence of the transition zone was not found to significantly affect the global electrical conductivity of the mortar. However, there were significant differences in conductivity between the transition zone and matrix pastes when examined on a local level. These differences were found to vary with hydration and were most significant when the degree of hydration was between 0.5 and 0.8. 相似文献
1000.
Rainer Mü ller Klaus Heckmann Manfred Habermann Thomas Paul Martin Stratmann 《The Journal of Adhesion》2000,72(1):65-83
New primer molecules have been synthesized to increase the adhesion strength between a copper leadframe and an epoxy molding compound in microelectronical devices. The coupling agents were preliminarily chemisorbed at the surface of copper plates via special binding groups like thiol, disulfide, ethylene diamine and phthalocyanine. Binding to the epoxy resin was performed via an hydroxyl group. Linear hydrocarbon spacers with various chain lengths connected the copper- and epoxy-binding groups. The self-assembled layers of the organic coupling agents at the metal surface were characterized by X-ray photoelectron spectroscopy. Thermogravimetric analysis was used to study the coating with respect to its corrosion oxidation inhibition. Shear tests clearly indicated that the coupling agents increase adhesion strength and are stable even in extreme humidity and thermal conditions in analogy to IPC-Level-1 pretreatment. Thus, delamination of the microelectronical packages was prevented. 相似文献