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排序方式: 共有193条查询结果,搜索用时 156 毫秒
51.
T. TSURU S. KOBAYASHI T. AKIYAMA H. FUKUSHIMA S. K. GOGIA R. KAMMEL 《Journal of Applied Electrochemistry》1997,27(2):209-214
Electrodeposition of zinc–iron-group metal alloys is carried out in a methanol bath. The effects of different parameters, such as bath composition and current density on current efficiency and alloy composition are investigated. Partial polarization curves of zinc and nickel are measured for both alloy and single metal deposition to evaluate the codeposition behaviour of zinc–iron-group metal alloys. Attempts are also made to confirm the proposed hydroxide suppression mechanism explaining the anomalous type of codeposition of zinc–iron-group metal alloys by investigating the role of water in the electroreduction process of zinc and iron-group metal ions. 相似文献
52.
The response of a current induced by sinusoidal stress within an elastic deformation was measured during corrosion fatigue tests to monitor the course of corrosion fatigue cracking and to evaluate corrosion fatigue damage. The test material was an iron bar subjected to a passive potential in borate buffer solution containing 5 mM NaCl. Harmonic analysis was used to analyze the current response and to extract valuable parameters that were associated with crack initiation and corrosion fatigue damage. The current response before crack initiation consisted of only the fundamental current without any harmonics. Higher harmonic amplitudes of the current response, especially the second and third harmonics, appeared and increased after crack initiation. In addition, the phase shift between the strain and the fundamental current response to the sinusoidal stress decreased from nearly 90° towards 0° as harmonic amplitudes of the current response increase. The results indicate that the amplitudes of the harmonic current response and the phase shift are the optimal parameters for detecting crack initiation and evaluating corrosion fatigue damage. 相似文献
53.
54.
Degradation mechanism of galvanized steel in wet-dry cyclic environment containing chloride ions 总被引:2,自引:0,他引:2
The wet-dry cyclic test of a galvanized steel (GI) and pure zinc (ZN), which simulates marine atmospheric environment, has been conducted to clarify the degradation mechanism of galvanized steel. The samples were exposed to alternate conditions of 1 h-immersion in a 0.05 M NaCl solution and 7 h-drying at 25 °C and 60%RH, and the corrosion was monitored for 10 days (30 cycles) using a two-electrode type probe. Simultaneously, the corrosion potential was measured every three cycles only during the immersed conditions. The reciprocal of polarization resistance Rp−1 was taken as an index of the corrosion rate. Several sample plates of GI and ZN were exposed, together with the monitoring probes. They were removed from the test chamber at the end of 1st, 3rd, 9th, 18th, and 30th cycles of exposure and were analyzed for the corrosion products with XRD and laser Raman spectroscopy. Further, their cross sections were analyzed with FESEM-EDS. The FESEM photographs and elemental analysis of cross sections confirmed that the Rp−1 value commences to decrease when the corrosion front reaches Zn-Fe alloy layers (boundary layers of zinc coating and steel substrate) due to localized nature of attack. A schematic model of degradation mechanism and the role of galvanic protection have been discussed. 相似文献
55.
ALBERT S. KOBAYASHI ASHLEY F. EMERY BEEN MING LIAW 《Journal of the American Ceramic Society》1983,66(2):151-155
Dynamic fracture toughness specimens consisting of 5.1-mm thick, modified wedge-loaded, tapered double-cantilever-beam (WL-MTDCB) specimens, which are side-grooved on one side, were used to establish the room-temperature dynamic fracture toughness, K ID vs crack velocity, a , relations of two reaction-bonded silicon nitrides. The measured dynamic crack extension histories were then used to drive a dynamic finite-element code in its generation mode which computes the dynamic stress intensity factors for a given crack extension. Results indicate that the K ID vs a relations of reaction-bonded silicon nitrides do not follow the general trend in those relations of brittle polymer and steel. The slow initial crack velocity which was reported for glass was observed again in silicon nitride and resulted in a nonunique K ID vs a relation, in contrast to the unique K ID vs a material properties reported for brittle polymers and metals. 相似文献
56.
Tatsuro Ouchi Tooru Katsuura Masaya Inaba Taiji Azuma Yoshifumi Hosaka Minoru Imoto 《Polymer》1984,25(3):412-416
The polymerization of vinyl monomer initiated by an aqueous solution of poly(N,N,N-trimethyl-N-2-methacryloxyethyl)ammonium chloride (poly(Q-DMAEM-CI) has been carried out at 85°C. The effects of the amounts of vinyl monomer, poly(Q-DMAEM-CI) and water on the conversion of vinyl monomer have been studied. The overall activation energy in the polymerization of MMA is estimated as 41.9 kJ mol?1. The polymerization proceeds through a radical mechanism. The location in which the polymerization occurs is discussed. The selectivity for vinyl monomer is explained by ‘the concept of hard and soft hydrophobic areas and monomers’. 相似文献
57.
The effect of γ‐irradiation on thermal strain of high strength polyethylene fiber at low temperature
Atsuhiko Yamanaka Yoshinobu Izumi Tooru Kitagawa Takaya Terada Hiroshi Hirahata Kimiko Ema Hiroyuki Fujishiro Shigehiro Nishijima 《应用聚合物科学杂志》2006,102(1):204-209
To understand the contribution to negative thermal expansion by the length of the molecular chains in high‐strength ultra‐high‐molecular‐weight polyethylene (UHMW‐PE) fiber, the thermal expansion coefficient in the range of low temperature was investigated for high‐strength UHMW‐PE fiber (Toyobo, Dyneema®; hereinafter abbreviated to DF), irradiated by γ‐rays (γ‐rays treatment) that induce the molecular scission. The molecular weight of DF decreased by γ‐ray treatment. X‐ray diffraction behavior did not change by γ‐ray treatment. The melting behavior observed by DSC showed the main chain scission of DF by γ‐ray treatment. The DFs, with and without γ‐ray treatment, expand by cooling down (negative thermal expansion). The change of negative thermal expansion of DF by γ‐ray treatment was small. It is suggested that negative thermal expansion does not change by only the molecular chain scission. These results suggested that the effect of negative thermal expansion of DF in the temperature range from 213 to 303 K by the molecular chain scissions is small and that the length of extended molecular chains contributes to a negative thermal expansion a little. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 204–209, 2006 相似文献
58.
TOSHIHIRO KOBAYASHI 《International journal of control》2013,86(5):1511-1523
In this paper, we investigate a model reference adaptive control problem for the class of distributed parameter systems generated by spectral operators. First we present an equivalent static input-output representation for the spectral system using filtered values generated from the inputs and the outputs. Next, we design and analyse a model reference adaptive control system for systems with unknown input and output distribution functions. 相似文献
59.
This study concerns with analysis of water inside a poly‐p‐phenylenebenzobisoxazole (PBO) fiber. It is important to analyze the state of water attached to polymer, because it may affect properties of fibers as the increase of drying speed of water from the fiber. To carry out such observation, differential scanning calorimetry and nuclear magnetic resonance spectroscopy were applied. They reveal the large freezing point depression and the state of water inside wet PBO fiber. It shows extraordinary low crystallization temperature. The reason may be that the water is packed into capillary voids whose diameter is around 2–3 nm. Proton NMR analysis also suggests the above result. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1030–1036, 2001 相似文献
60.
KAORU KOHYAMA SATOKO KOBAYASHI EIKO HATAKEYAMA TATEO SUZUKI 《Journal of texture studies》2000,31(5):577-590
Electromyograms (EMGs) of mastication of kelp snack were compared with the physical properties measured by a tensile test and sensory assessment. The number of chewing strokes, masticatory time, total muscle activities and total duration for whole mastication agreed with the breaking force in the tensile test and with sensory difficulty of mastication. Amplitude, EMG activity, and duration per chew also showed the same tendency. In the masticatory cycle, significant differences among the samples were not observed. As mastication proceeded, the amplitude and EMG activity decreased, and the EMG-duration shortened. The EMG activity, amplitude, and masticatory rhythm changed significantly, and sample differences decreased from the middle to the late stage of mastication. Just before swallowing, the chewing cycle was lengthened, and no significant difference was observed among samples at the last chew. 相似文献