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41.
Rutherfordα-particles backscattering technique was employed for measurements of diffusion rates in metallic glasses. Effects of relaxation,
crystallization and plastic deformation on diffusion rates were also investigated.
It has been observed that the diffusion rates of a metallic solute are of the same orders of magnitude in both metal-metal
and metal-metalloid glasses. A higher diffusivity is likely if there is a large difference between melting points of the solute
and matrix. Relaxation has no effect on diffusion, however, diffusivity increases on crystallization. An increase in diffusivity
is also observed on plastic deformation of metallic glass. 相似文献
42.
Seong-Min Lee 《Metals and Materials International》2006,12(6):513-516
Based on empirical data, the present work provides a model to prevent filler-induced reliability degradation in plastic-encapsulated
LOC (lead-on-chip) packages. According to the model, the maximum size of the silica fillers included in the plastic package
body should be smaller than one half of the inter-distance between the device and its overlying lead-frame. In particular,
it is shown in the model that the spherical silica particles, which are sometimes trapped in the space between the top surface
of the device and the bottom of the lead-frame during the encapsulating process, can induce huge compressive stress on a specific
site of the integrated circuit pattern due to the thermal shrinkage of the plastic package body. Further, the present model
suggests that tiny fillers squeezed beneath a large trapping filler might directly attack the brittle layer of the device
pattern because the compressive force from the large filler particle can develop into huge compressive stress due to the reduced
load-carrying area. 相似文献
43.
44.
Microstructural change of ultrafine-grained aluminum during high-speed plastic deformation 总被引:5,自引:0,他引:5
N. Tsuji T. Toyoda Y. Minamino Y. Koizumi T. Yamane M. Komatsu M. Kiritani 《Materials Science and Engineering: A》2003,350(1-2):108-116
Effect of strain rate on microstructural change in deformation of the ultrafine grained (UFG) aluminum produced by severe plastic deformation (SPD) was studied. Commercial purity 1100 aluminum sheets were highly strained up to an equivalent strain of 4.8 by the Accumulative Roll-Bonding (ARB) process at ambient temperature. The ARB-processed sheets were found to be filled with pancake-shaped ultrafine grains surrounded by high-angle grain boundaries. The ultrafine grains had a mean grain thickness of 200 nm and a mean grain length of 1100 nm. The ultrafine-grained aluminum sheets were deformed at various strain rates ranging from 2 to 6.0×104 s−1 by conventional rolling, ultra-high-speed rolling, and impact compression. High-speed plastic deformation generates a large amount of heat, inducing coarsening of the ultrafine grains during and after deformation. On the other hand, it was also suggested that high-speed plastic deformation is effective for grain-subdivision, in other words, ultra-grain refinement, if the effect of heat generation is extracted. 相似文献
45.
M. M. I. HAMMOUDA I. G. EL-BATANONY H. E. M. SALLAM 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(7):627-639
An understanding into the macro kinetic and kinematic behaviour of fretted surfaces is provided. Making use of a modified version of a previously developed in‐house two‐dimensional elastic–plastic finite element analysis numerically simulates flat contact pad fretting fatigue tests. Basic macro mechanics concepts are adopted to idealise two bodies with rough contact surfaces and loaded at two different sites with arbitrary axial loading profiles. A time scale factor is devised to recognise the earliest candidate out of the events possibly accommodated at each loading increment. The present analysis utilises a relevant experimental set up developed in the Structural Integrity Research Institute of the University of Sheffield as an application. Computational results accurate to within 1.2% and corresponding to one contact pad span and six constant normal loads acting individually with four amplitudes of two sinusoidal axial load cycles are presented. The present computations include (1) the development of the global and local normal and tangential reactions and relative sliding displacement acting along the fretting surfaces and (2) contact pad deformation, generated stress fields and plasticity development within the neighbouring region of the fretted area. 相似文献
46.
河北省迁安市滦河生态防洪工程是河北省重点工程建设项目,在建设中采用土工格室生态护岸工程技术,不仅大大提高了工程建设的速度和质量,而且延长了堤坝使用寿命,减少了维护成本,收到了环保、生态等方面的综合效益。 相似文献
47.
48.
49.
Mitsutoshi Miyasaka 《Journal of the Society for Information Display》2007,15(7):479-484
Abstract— Suftla is a technology that is used to transfer polycrystalline silicon (polysilicon) thin‐film‐transistor (TFT) circuits from an original glass substrate to a plastic sheet. The electronic devices in the next generation will be thin, lightweight, and will handle huge amounts of data, yet consume less energy. Suftla technology, together with high‐performance polysilicon TFTs, meets all these requirements because we have developed a variety of smart flexible electronic devices, such as thin paperback‐sized displays and microprocessors. Suftla will usher in a new era of life‐enhancing flexible microelectronics. 相似文献
50.
Exact solution of elasto-plastic stresses in a metal-matrix composite beam of arbitrary orientation subjected to transverse loads 总被引:1,自引:0,他引:1
An analytical elasto-plastic stress analysis is presented for a metal-matrix composite beam of arbitrary orientation subjected to a single transverse force applied to the free end of the beam and a uniformly distributed load. The material is assumed to be perfectly plastic in the elasto-plastic solution. A composite consisting of stainless-steel-reinforced aluminum was produced for this work. Sample problems are given for various orientation angles. Elastic, elastoplastic and residual normal and shear stresses are calculated. The location of the elasto-plastic boundary of the beam is obtained according to the x coordinates of the beam. 相似文献