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61.
Grinding force, which is a representative factor of the grindability of a workpiece, is discussed in this study. The metallurgical structures of different carbon steels were classified into two groups according to the magnitude of their grinding force. For each group, the fracture toughness (Jc), was measured. The method used for this measurement was to mount a strain gauge on the hammer of a Charpy impact test machine. The strain at impact fracture was measured and the fracture toughness was calculated, with the results shown on a load-displacement diagram.A comparison of the fracture toughness (Jc) of each material and its grinding force was done. It was found that the fracture toughness (Jc) can be used in estimating the grinding force. 相似文献
62.
Effect of Substrate Temperature on Deposition Behavior of Copper Particles on Substrate Surfaces in the Cold Spray Process 总被引:2,自引:0,他引:2
M. Fukumoto H. Wada K. Tanabe M. Yamada E. Yamaguchi A. Niwa M. Sugimoto M. Izawa 《Journal of Thermal Spray Technology》2007,16(5-6):643-650
The deposition behavior of sprayed individual metallic particles on the substrate surface in the cold spray process was fundamentally
investigated. As a preliminary experiment, pure copper (Cu) particles were sprayed on mirror-polished stainless steel and
aluminum (Al) alloy substrate surfaces. Process parameters that changed systematically were particle diameter, working gas,
gas pressure, gas temperature, and substrate temperature, and the effect of these parameters on the flattening or adhesive
behavior of an individual particle was precisely investigated. Deposition ratio on the substrate surface was also evaluated
using these parameters. From the results obtained, it was quite noticeable that the higher substrate temperature brought about
a higher deposition rate of Cu particles, even under the condition where particles were kept at room temperature. This tendency
was promoted more effectively using helium instead of air or nitrogen as a working gas. Both higher velocity and temperature
of the particles sprayed are the necessary conditions for the higher deposition ratio in the cold spraying. However, instead
of particle heating, substrate heating may bring about the equivalent effect for particle deposition.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
63.
Matsumura Y. Fukumoto M. Hayashi S. Kasama A. Iwanaga I. Tanaka R. Narita T. 《Oxidation of Metals》2004,61(1-2):105-124
A β-NiAl coating with or without a Re-base alloy layer was formed on a Nb–5Mo–15W alloy. The coated alloys were oxidized isothermally in air at 1373 and 1473 K. Electroplating of a high (more than 70at.%)-Re–Ni film, Cr-pack cementation, Ni plating, and then Al-pack cementation, in this sequence, formed a coating structure with Re-base alloy and β-NiAl layers. The Re-base alloy layers were comprised of an outer σ-phase in the Re–Cr(Ni) system and an inner χ-phase in the Re–Nb(Cr) system. It was found that reaction between the β-NiAl and the alloy substrate was significantly suppressed when the Re-base alloy layers were present. The Re-base σ and χ phases were found to be good candidates for a diffusion barrier against inward-Al diffusion because they have very low solubilities for Al. 相似文献
64.
Hideaki Itoh Yoshitaka Sakai Toru Kadoya Hisao Fukumoto Hiroshi Wakuya Tatsuya Furukawa 《Artificial Life and Robotics》2017,22(3):327-335
Recently, the optimization-by-inference approach has been proposed as a new means for solving high-dimensional optimization problems quickly. Approximate Inference COntrol (AICO) is one of the most successful and promising methods that implement the optimization-by-inference approach. AICO is able to solve stochastic optimal control problems and has already been successfully used in many applications. However, it is known that the iterative inference of AICO sometimes fails to converge to the optimal solution. To make the optimization more robust, in this paper, we propose to take model uncertainty into account. In AICO, the cost function to be minimized is accurate around a particular state of a given stochastic system, but the accuracy is uncertain in regions far from that state. Because using such an uncertain function is harmful to the convergence, we modify AICO, so that it does not use the function in uncertain regions. Our method is easy to implement and does not add much computational time to the original AICO. Experiments using two different scenarios show that our method substantially improves AICO in terms of the rate at which the algorithm produces convergent results. 相似文献
65.
The electrocatalytic activities of various metals and alloys in the anodic oxidation of hydrazine in alkaline solution have been studied by means of palladium membrane method in which the contact side of the membrane was electrodeposited with a thin layer of the electrocatalytic metals. The electrode materials studied can be divided into two groups. In the first group, platinum, rhodium, cobalt, cobalt—phosphor and cobalt—boron, anodic current of hydrogen oxidation on the diffusion side decreased remarkably with an increase of the electro-oxidation of hydrazine on the contact side. The anodic oxidation of hydrazine occurs through the preliminary stepwise dehydrogenation on this group metals.On the other hand, the amount of sorbed hydrogen in the palladium, gold, nickel and nickel—phosphor electrodes increased with an increase of the electro-oxidation of hydrazine on the contact side. Thus, the anodic oxidation of hydrazine on the latter group metals may proceed through the anodic formation of the intermediate radicals which readily decompose into hydrogen and the related compounds. 相似文献
66.
Effect of fiber compression on flexural modulus of the natural fiber composites was examined. The kenaf, bagasse, and polypropylene were mixed into pellets, and composites were fabricated by injection molding. To predict flexural modulus of the composites, the Young's modulus of kenaf and bagasse fiber were measured. Using the obtained Young's modulus, the flexural modulus of the composites was predicted by Cox's model that incorporates the effect of fiber compression. It was found that those fibers with high Young's modulus were more compressed than that with low Young's modulus. Moreover, the distribution of fiber length and orientation in the composites were also investigated. To calculate the orientation factor for the prediction model, the distribution function of fiber orientation was determined to a triangular function. The flexural modulus of the composites increased with increase of volume fraction. The predicted values were in good agreement with the experimental values. Furthermore, it was revealed by SEM that the porous structure of the natural fibers was compressed. The fiber compression ratio (3.6) in bagasse was higher than that in kenaf (1.4) due to the difference in porous structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 911–917, 2006 相似文献
67.
Hideyuki Azegami Shota Fukumoto Taiki Aoyama 《Structural and Multidisciplinary Optimization》2013,47(2):247-258
The present paper introduces a numerical solution to shape optimization problems of domains in which boundary value problems of partial differential equations are defined. In the present paper, the finite element method using NURBS as basis functions in the Galerkin method is applied to solve the boundary value problems and to solve a reshaping problem generated by the H1 gradient method for shape optimization, which has been developed as a general solution to shape optimization problems. Numerical examples of linear elastic continua illustrate that this solution works as well as using the conventional finite element method. 相似文献
68.
Fukumoto K Matsushita T Osawa H Nakamura T Muro T Arai K Kimura T Otani Y Kinoshita T 《The Review of scientific instruments》2008,79(6):063903
A femtosecond pulsed laser system has been installed at the BL25SU soft x-ray beamline at SPring-8 for time-resolved pump-probe experiments with synchronization of the laser pulses to the circularly polarized x-ray pulses. There are four different apparatuses situated at the beamline; for photoemission spectroscopy, two-dimensional display photoelectron diffraction, x-ray magnetic circular dichroism (XMCD) with electromagnetic coils, and photoelectron emission microscopy (PEEM). All four can be used for time-resolved experiments, and preliminary investigations have been carried out using the PEEM apparatus to observe magnetization dynamics in combination with XMCD. In this article, we describe the details of the stroboscopic pump-probe XMCD-PEEM experiment, and present preliminary data. The repetition rate of the laser pulses is set using a pulse selector to match the single bunches of SPring-8's hybrid filling pattern, which consists of several single bunches and a continuous bunch train. Electrons ejected during the bunch train, which do not provide time-resolved signal, are eliminated by periodically reducing the channel plate voltage using a custom-built power supply. The pulsed laser is used to create 300 ps long magnetic field pulses, which cause magnetic excitations in micron-sized magnetic elements which contain magnetic vortex structures. The observed frequency of the motion is consistent with previously reported observations and simulations. 相似文献
69.
Local stresses at the intersection of a top flange of a cross beam with a box-girder web are investigated analytically and experimentally. Finite element analyses of a T-shaped welded joint and a loading test of a cantilever beam of acrylic material reveal that a local stress which is different from the one caused by the stress concentrations at a weld toe is developed at the intersection. Finite element analyses of an I-section beam show that the restraint of the vertical deformation of the cross beam at the box-girder web induces the local stress. It is pointed out that the local stress must be considered in fatigue design. A method of determining the local stress is proposed. 相似文献
70.