全文获取类型
收费全文 | 746篇 |
免费 | 32篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 31篇 |
化学工业 | 200篇 |
金属工艺 | 23篇 |
机械仪表 | 18篇 |
建筑科学 | 37篇 |
能源动力 | 45篇 |
轻工业 | 51篇 |
水利工程 | 2篇 |
无线电 | 32篇 |
一般工业技术 | 162篇 |
冶金工业 | 101篇 |
原子能技术 | 16篇 |
自动化技术 | 67篇 |
出版年
2023年 | 10篇 |
2022年 | 12篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 17篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 15篇 |
2014年 | 17篇 |
2013年 | 46篇 |
2012年 | 31篇 |
2011年 | 41篇 |
2010年 | 34篇 |
2009年 | 41篇 |
2008年 | 34篇 |
2007年 | 30篇 |
2006年 | 34篇 |
2005年 | 30篇 |
2004年 | 16篇 |
2003年 | 29篇 |
2002年 | 27篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 17篇 |
1998年 | 42篇 |
1997年 | 23篇 |
1996年 | 28篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 9篇 |
1992年 | 9篇 |
1991年 | 2篇 |
1990年 | 11篇 |
1989年 | 2篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 7篇 |
1975年 | 2篇 |
1974年 | 4篇 |
排序方式: 共有785条查询结果,搜索用时 15 毫秒
61.
Haruhisa Kato Kohei Mizuno Manabu Shimada Ayako Nakamura Kayori Takahashi Kenji Hata Shinichi Kinugasa 《Carbon》2009,47(15):3434-3440
The slow diffusion of Tween80 surfactant molecules in a single-walled carbon nanotube (SWCNT) aqueous dispersion was directly observed using the pulsed field gradient nuclear magnetic resonance method. The slow diffusion of Tween80 molecules was attributed to the strongly adsorbed molecules on the SWCNTs in the aqueous dispersion. The amount of bound Tween80 molecules was estimated to be approximately 12% of the total amount of Tween80 molecules, contributing to the stability of the SWCNT aqueous dispersion. Using dynamic light scattering and total organic carbon measurements, this SWCNT/Tween80 aqueous dispersion was found to be very stable for at least 3 weeks. The observed zeta potentials of this SWCNT dispersion are between −10 and 0 mV, indicating that the stability of the SWCNTs in the Tween80 solution was maintained by steric interactions between the small amount of adsorbed Tween80 molecules on the SWCNTs, while the effect of electrostatic interactions between adsorbed Tween80 was minimal. This proposed method to investigate the amount of bound Tween80 molecules on SWCNTs has potential benefits in the field of the production of functional materials and nano-toxicity assessments. 相似文献
62.
Effect of heat treatment on precipitation behaviour and high temperature strength in a wrought Co-base superalloy 总被引:1,自引:0,他引:1
The effects of solution and ageing temperatures on the grain boundary reaction as well as on matrix precipitation in the interior of the grains were investigated using wrought Co-base superalloy HS-21. The grain boundary reaction occurred during furnace-cooling after solution-heating. The phase that precipitated in the grain boundary reactions nodule was M23C6 carbide. It also occurred during ageing after solution treatment, but the extent of it was considerably influenced by cooling procedure after solution heating. The activation energy of the grain boundary reaction was 244 kJ mol–1 for the early stage of the grain boundary reaction in HS-21 alloy, and was considered to be the activation energy of grain boundary diffusion of chromium. The extent of the matrix precipitation that occurred during ageing was also influenced by the cooling procedure. Creep rupture tests were carried out at 1088 K in air. An excellent combination of long rupture life and large ductility was attained on a specimen, which involved both the grain boundary reaction nodules (about 7% in area fraction) and the matrix precipitates. The improvement of creep rupture properties results from the retardation of brittle intergranular fracture, which is achieved by grain boundary serration owing to the grain boundary reaction and by the increase of strength in the interior of grain due to the matrix precipitation. 相似文献
63.
64.
Takami Kai Norihide Okada Manabu Baba Takeshige Takahashi Masaki Misawa Ion Tiseanu Naoki Ichikawa 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2007,130(2-3):119-124
In a fluidized catalyst bed, the reactant gas transfers from the bubble phase to the emulsion phase and reactions proceed in the emulsion phase. The catalyst particles around the bubbles should contact the gases containing a high concentration of the reactants. Therefore, the effect of the catalysts around the bubbles is very important for estimating the conversion and selectivity in the reactor. In order to study the role of these catalysts, the hydrogenation of carbon dioxide was carried out in a fluidized catalyst bed. Based on the results, the amount of the catalyst that was effective for the reaction was calculated. In addition, the shape of the bubbles ascending in the fluidized catalyst bed was observed using a fast X-ray computer tomography (CT) scanner. The structure of the bubbles in the fluidized catalyst bed was very complicated and the surface area of the bubbles was much greater than the obtained when assuming spherical shaped bubble. By assuming that effective catalysts existed around the bubbles, the thickness of catalyst layer was obtained. Finally, the 3-dimensional images of the catalyst layers around the bubbles were reconstructed. 相似文献
65.
Kimihiro Yamanaka Teruya Fujisaki Manabu Ichinose Takafumi Ooyoshi 《Journal of Materials Science: Materials in Electronics》2010,21(9):943-949
Build-up substrates have been preferable solutions for small and high performance systems for more than a few decades. Micro-vias
need to be smaller to realize ever higher wiring density in build-up substrates, but there has been concern on the reliability.
This paper focuses on Cu filled micro-vias of 25 μm in diameter and investigates the strain on micro-vias using a finite element
method for varying geometric parameters and material properties. The strain becomes smaller with shrinking micro-vias, and
a prediction equation for the strain is developed as a function of the aspect ratio and material properties for both single
and stacked micro-vias. 相似文献
66.
Independent component analysis (ICA) is a technique of transforming observation signals into their unknown independent components; hence, ICA has often been applied to blind signal separation problems. In this application, it is expected that the obtained independent components extract essential information of independent signal sources from input data in an unsupervised fashion. Based on such characteristics, ICA is currently utilized as a feature extraction method for images and sounds for recognition purposes. However, since ICA is an unsupervised learning, the obtained independent components are not always useful in recognition. To overcome this problem, we propose a supervised approach to ICA using category information. The proposed method is implemented in a conventional three‐layered neural network, but its objective function to be minimized is defined not only for the output layer but also for the hidden layer. The objective function consists of the following two terms: one evaluates the kurtosis of hidden unit outputs and the other evaluates the error between output signals and their teacher signals. The experiments are performed using several standard datasets to evaluate performance of the proposed algorithm. It is confirmed that a higher recognition accuracy is attained by the proposed method as compared with a conventional ICA algorithm. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 25–32, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20522 相似文献
67.
Carminati Maria Nella; van Gompel Roger P. G.; Scheepers Christoph; Arai Manabu 《Canadian Metallurgical Quarterly》2008,34(5):1098
Two visual-world eye-movement experiments investigated the nature of syntactic priming during comprehension--specifically, whether the priming effects in ditransitive prepositional object (PO) and double object (DO) structures (e.g., "The wizard will send the poison to the prince/the prince the poison?") are due to anticipation of structural properties following the verb (send) in the target sentence or to anticipation of animacy properties of the first postverbal noun. Shortly following the target verb onset, listeners looked at the recipient more (relative to the theme) following DO than PO primes, indicating that the structure of the prime affected listeners' eye gazes on the target scene. Crucially, this priming effect was the same irrespective of whether the postverbal nouns in the prime sentences did ("The monarch will send the painting to the president") or did not ("The monarch will send the envoy to the president") differ in animacy, suggesting that PO/DO priming in comprehension occurs because structural properties, rather than animacy features, are being primed when people process the ditransitive target verb. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
68.
Takashi Hayashita Hiroaki Noguchi Hisashi Oka Manabu Igawa Makoto Takagi 《应用聚合物科学杂志》1990,39(3):561-569
The sorption behavior of heavy metal thiocyanate complexes was investigated for dibenzo-18-crown-6 (DB18C6) resin and bis[2-(o-methoxyphenoxy)ethyl]ether (BMPE) resin. The DB18C6 resin showed a high sorption ability and the degree of zinc sorption increased significantly with thiocyanate concentration. This behavior was not observed for BMPE resin. The sorption behavior was influenced by the countercation species, and the degree of sorption of zinc ions showed the maximum when the potassium thiocyanate was used as a complexing salt. The sorbed species appear to be KZn(SCN)3, K2Zn(SCN)4 in the potassium thiocyanate system, and Zn(SCN)2 in the lithium thiocyanate system, respectively, according to analysis of the sorption equilibrium. Sodium and ammonium thiocyanate systems show an intermediate behavior of the two. The sorption selectivity for DB18C6 resin depended not only on the hydrophobic nature of heavy metal thiocyanate complexes but also on the stabilization of counter cation species with crown ether matrix, and the sorption selectively was found to be effectively controlled by countercation species according to the cation-chelation mechanism. 相似文献
69.
SETO Masaru AOKI Atsuhito TANAKA Manabu TASHIRO Shinichi ERA Tetsuo 《Welding International》2018,32(5):312-320
Gas metal arc welding (GMAW) under pure argon shielding gas atmosphere (pure argon-GMAW) is suitable to obtain a high-strength and high toughness welded joint. However, it is difficult that pure argon-GMA welding is applied practically welding structure because of arc instability. In order to perform stable pure argon-GMA welding, duplex current feeding GMAW (DCF-GMAW) has been developed. The DCF-GMAW consists of primary GMA welding current and secondary welding current by constant-current power resource. DFC-GMAW can feed larger current near wire tip. This effect makes that weld penetration depth is deeper, weld bead shape is improved using DCF-GMAW. 相似文献
70.
Takejiro Takamatsu Mirai Watanabe Masami K. Koshikawa Shigeki Yamamura 《The Science of the total environment》2010,408(8):1932-1942
Soil cores and rainwater were sampled under canopies of Cryptomeria japonica in four montane areas along an atmospheric depositional gradient in Kanto, Japan. Soil cores (30 cm in depth) were divided into 2-cm or 4-cm segments for analysis. Vertical distributions of elemental enrichment ratios in soils were calculated as follows: (X/Al)i/(X/Al)BG (where the numerator and denominator are concentration ratios of element-X and Al in the i- and bottom segments of soil cores, respectively). The upper 14-cm soil layer showed higher levels of Cu, Zn, As, Sb, and Pb than the lower (14-30 cm) soil layer. In the four areas, the average enrichment ratios in the upper 6-cm soil layer were as follows: Pb (4.93) ≥ Sb (4.06) ≥ As (3.04) > Zn (1.71) ≥ Cu (1.56). Exogenous elements (kg/ha) accumulated in the upper 14-cm soil layer were as follows: Zn (26.0) > Pb (12.4) > Cu (4.48) ≥ As (3.43) ≥ Sb (0.49). These rank orders were consistent with those of elements in anthropogenic aerosols and polluted (roadside) air, respectively, indicating that air pollutants probably caused enrichment of these elements in the soil surface layer. Approximately half of the total concentrations of As, Sb, and Pb in the upper 14-cm soil layer were derived from exogenous (anthropogenic) sources. Sb showed the highest enrichment factor in anthropogenic aerosols, and shows similar deposition behavior to NO3−, which is a typical acidic air pollutant. There was a strong correlation between Sb and NO3− concentrations in rainfall (e.g., in the throughfall under C. japonica: [NO3−] = 21.1 [dissolved Sb], r = 0.938, p < 0.0001, n = 182). Using this correlation, total (cumulative) inputs of NO3− were estimated from the accumulated amounts of exogenous Sb in soils, i.e., 16.7 t/ha at Mt. Kinsyo (most polluted), 8.6 t/ha at Mt. Tsukuba (moderately polluted), and 5.8 t/ha at the Taga mountain system (least polluted). There are no visible ecological effects of these accumulated elements in the Kanto region at present. However, the concentrations of some elements are within a harmful range, according to the Ecological Soil Screening Levels determined by the U.S. Environmental Protection Agency. 相似文献