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91.
Hisayasu Mitsui Ryoji Kumazawa Rie Aizawa Tatsuki Okamoto Tetsuo Ito Masaki Kanegami 《Electrical Engineering in Japan》1999,129(4):24-31
Experiments and investigations were carried out on the voltage life of a bar-coil model with a nickel-plated copper conductor covered with mica-alumina composite insulation at a temperature range of 550–850 °C. Diffusion of copper into the insulation layer was observed on the specimens aged for a long period. Insulation with mica paper gave faster diffusion speed and shorter voltage life than insulation with mica flake. The diffusion speed became higher with an increase in temperature. The ac current gradually increased with aging time and increased rapidly just before breakdown. There was the relationship I = aEn (a, n: constants) between ac current I and applied stress E, and n was approximately equal to 1 in the region where thermal unbalance did not occur. Arrhenius's law held in the relationship between ac current and aging time. Therefore, the breakdown mechanism might be that the effective insulation thickness decreased due to copper diffusion into the insulation layer and the ac current increased gradually until thermal breakdown in the last stage. If copper diffuses into the insulation layer, even with no voltage application, the aging time required to decrease the breakdown voltage to a certain level (the voltage life) obeys Arrhenius's law. If the voltage life is dominated by diffusion into the insulation layer, the activation energy for voltage life in the aging test becomes twice that for diffusion, both with and without voltage application. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 24–31, 1999 相似文献
92.
Ryo Miura Tetsuo Fujishima Hiromichi Uchimura Kensuke Toda Makoto Kobayashi Naoko Ashikawa Akio Sagara Naoaki Yoshida Yuji Hatano Yasuhisa Oya Kenji Okuno 《Fusion Engineering and Design》2013,88(9-10):1827-1830
The D2+ fluence dependence on deuterium (D) retention was studied to clarify the D retention mechanism in tungsten. The additional D desorption stage was observed around 660 K in the TDS spectrum for a sample implanted with D2+ up to the fluence of 1023 D+ m?2, which desorption stage was not observed the D2+ implanted sample with the fluence less than 1022 D+ m?2. The TEM observation showed that the highly dense voids were formed in tungsten by D2+ implantation with the fluence of 1023 D+ m?2, considering that the D would be trapped by voids. To understand the D trapping by voids in C+ implanted tungsten, C+–D2+ sequential implantation experiments at various C+ implantation temperatures were performed. It was found that the amount of D desorbed around 560 K was increased by increasing the C+ implantation temperature. The formation of the voids was observed with increasing the C+ implantation temperature by TEM, indicating that the increase of D desorption around 560 K was caused by the formation of voids. However, the desorption temperature of D trapped by voids in C+ implanted sample was lower than that in D2+ implanted one. TEM observation and XPS measurement indicated that this difference was caused by the increase of void size and/or the presence of implanted carbon. 相似文献
93.
94.
Tetsuo Matsumoto 《Progress in Nuclear Energy》2000,37(1-4):327-332
Neutron beam designs were studied for TRIGA reactor with a view to generating thermal, epithermal and fast neutron beams for both medical neutron capture therapy (NCT) and industrial neutron radiography (NR). The beams are delivered from thermal and thermalizing columns, and also horizontal beam hole. Several prospective neutron filters (high-density graphite (G), bismuth (Bi), single-crystal silicon (Si), aluminum (Al), aluminum oxide (Al2O3), aluminum fluoride (AlF3) and lead fluoride (PbF2)) were examined for obtaining sufficiently intense neutron beam for various applications. Monte Carlo calculations indicated that with a suitable neutron filter arrangement, thermal and epithermal neutron beams attaining 2×109 and 7×108 n cm−2S−1, respectively, could be obtainable from thermal and thermalizing columns with the reactor operating at 100 kW. These neutron beams could be adopted for boron neutron capture therapy. Compared with these columns, horizontal beam port would deliver neutron fluxes of 10−2 10−3 lower intensity, but produced thermal and neutron beams would be adequate for different application of nondestructive inspection by neutron radiography. 相似文献
95.
Transparent La0.33NbO3 flakes were fabricated by a rapid quenching technique. The quenched La0.33NbO3 phase takes a simple cubic perovskite structure and cation vacancies are randomly distributed on the A sites. The cubic La0.33NbO3 phase is a new modification which is different from the well-known orthorhombic phase with ordered A-site vacancies. Transparent flakes were found to show the predominant orientation of (110) and (220) planes. 相似文献
96.
Tetsuo Fukuchi Takayuki Ozeki Mitsutoshi Okada Tomoharu Fujii 《IEEJ Transactions on Electrical and Electronic Engineering》2016,11(4):391-400
A thermal barrier coating (TBC) is applied to high‐temperature components in gas turbines, and consists of a ceramic topcoat and a metallic bondcoat. Various kinds of TBC degradation and damage occur in high‐temperature components during service, such as topcoat thinning, topcoat delamination, and formation of a thermally grown oxide (TGO) layer below the topcoat, each of which can be examined using a suitable nondestructive inspection technique. Topcoat thinning can be detected by topcoat thickness measurement using terahertz waves, which are electromagnetic waves in the frequency region between optical and radio waves. The measurement resolution is about 10 μm, which is comparable to microscopic observation of the cross section in destructive inspection. Topcoat delamination can be detected by active thermography, in which the topcoat surface is scanned by a heating laser and the surface temperature distribution is measured by a thermal infrared camera. The combination of temperature peak and residual thermal image detection is effective in eliminating false detection. The TGO layer can be detected using photoluminescence, in which the Cr3+ ions included as an impurity in Al2O3 are detected. Since delamination tends to occur at locations at which the TGO layer has grown, TGO layer detection provides an effective method to select regions where delamination has occurred or is likely to occur. An inspection flow based on these techniques is proposed, which is expected to aid the establishment of condition‐based maintenance strategies of high‐temperature components. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
97.
In this article, we propose MAC protocols based on our infrared-space division transceiver (IR-SDT) for mobile robots. The IR-SDT has eight communication modules, so it can communicate with a maximum of eight other nodes simultaneously. The number of parallel multiple accesses will be improved by using this transceiver and its specialized protocol. In addition, we consider situations in which a packet collision occurs, and propose a protocol that resolves communication conflicts using the signal collision-detection function of IR-SDT. Finally, we consider the performance of these protocols, and discuss the influence of signal collision-detection accuracy. 相似文献
98.
Katsunori Takeda Tetsuo Hattori Tetsuya Izumi Hiromichi Kawano Shinichi Masuda 《Artificial Life and Robotics》2010,15(4):421-424
Recently, remote monitoring camera systems have been widely used for security. In such systems, one important function is that the system automatically detects any change in the scenes from the monitoring cameras. In wireless remote monitoring camera systems, the images of the scenes are generally transmitted as compressed data (e.g., JPEG file), because of the capacity of the wireless channel. This article shows the automated detection of the change point in time-series data of compressed JPEG file quantity (Kbytes) from the monitoring camera by applying the sequential probabilistic ratio test (SPRT) and the Chow test, which is well known as a standard method for detecting structural change in time-series data. 相似文献
99.
1H and 13C n.m.r. chemical shifts and also spin-lattice relaxation times of phospholipids, mainly egg yolk lecithin, were measured in organic solvents, especially aromatic solvents. The use of aromatic solvents promotes the difference in the magnetic shielding environment of the internal methylene protons of the fatty acyl chains and as a result, a doublet peak for the methylene groups was observed in the solvents, especially mesitylene. The 1H and 13C n.m.r. T1 measurements indicate the remarkable gradient in the motional freedom along the fatty acyl chains as well as the marked decrease in the motional freedom of the polar head group and also, the high-field component of the doublet peak for internal methylene protons has a shorter T1 value than the low-field component. Thus, it was concluded that the low-field component in the doublet comes from the methylene protons located relatively in the neighbourhood of the carbonyl groups and the high-field component the methylene protons located relatively in the neighbourhood of the terminal methyl groups of the fatty acyl chains. 相似文献
100.
Dilute solution behaviour of poly(maleic anhydride-co-ethyl vinyl ether) and poly(maleic acid-co-ethyl vinyl ether) has been investigated by light scattering, osmotic pressure, and viscosity measurements. The molecular weights ( and ), the second virial coefficients A2, and the intrinsic viscosities [η] have been determined for three states of this copolymer: anhydride-form, H-form, and Na-salt independently. The constants in the Mark-Houwink relations were obtained for the above three states under different solvent conditions. The molecular weight of the anhydride-form is found to be higher than that of the acid-form or the Na-salt, suggesting the degradation in a process of hydrolysis. The second virial coefficient A2 as well as the Mark-Houwink relation indicates that the anhydride-form and H-form behave as flexible polymer chains in good solvents. However, the polymer coil of Na-salt is highly expanded even at saturated NaCl concentration. 相似文献