全文获取类型
收费全文 | 2587篇 |
免费 | 108篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 147篇 |
综合类 | 10篇 |
化学工业 | 684篇 |
金属工艺 | 75篇 |
机械仪表 | 74篇 |
建筑科学 | 91篇 |
矿业工程 | 8篇 |
能源动力 | 100篇 |
轻工业 | 219篇 |
水利工程 | 9篇 |
石油天然气 | 15篇 |
无线电 | 203篇 |
一般工业技术 | 513篇 |
冶金工业 | 335篇 |
原子能技术 | 90篇 |
自动化技术 | 146篇 |
出版年
2024年 | 8篇 |
2023年 | 33篇 |
2022年 | 45篇 |
2021年 | 85篇 |
2020年 | 40篇 |
2019年 | 39篇 |
2018年 | 47篇 |
2017年 | 45篇 |
2016年 | 73篇 |
2015年 | 43篇 |
2014年 | 55篇 |
2013年 | 168篇 |
2012年 | 109篇 |
2011年 | 149篇 |
2010年 | 103篇 |
2009年 | 117篇 |
2008年 | 110篇 |
2007年 | 114篇 |
2006年 | 94篇 |
2005年 | 82篇 |
2004年 | 68篇 |
2003年 | 78篇 |
2002年 | 80篇 |
2001年 | 52篇 |
2000年 | 66篇 |
1999年 | 56篇 |
1998年 | 144篇 |
1997年 | 87篇 |
1996年 | 80篇 |
1995年 | 55篇 |
1994年 | 44篇 |
1993年 | 52篇 |
1992年 | 26篇 |
1991年 | 10篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 18篇 |
1986年 | 20篇 |
1985年 | 15篇 |
1984年 | 27篇 |
1983年 | 21篇 |
1982年 | 6篇 |
1981年 | 18篇 |
1980年 | 7篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1976年 | 18篇 |
1973年 | 5篇 |
排序方式: 共有2719条查询结果,搜索用时 15 毫秒
1.
A method for estimating the sway angle using an observer has already been proposed. The state observer estimates the sway angle accurately and must use the detected sway angle value. However, the estimated sway angle has an error owing to rope length error, friction force, and wind. Moreover, the container mass cannot be determined, and therefore the observer parameter is not suitable. We already proposed robust antisway control for overcoming rope length error without adding a new sensor. Further, we designed a friction disturbance observer to cancel out the influence of the friction force. In this paper, we first propose a container mass estimation method when a crane system performs rolling up control. The observer parameter can be selected using the estimated mass value. Second, in crane parallel shift control, we propose a robust antisway control even when there is a wind disturbance. We design a wind disturbance observer and propose a wind disturbance estimator to separate the friction observer output from the wind disturbance observer output. We confirm through experiments that the proposed method can reduce vibration. 相似文献
2.
Joon‐Young Jun Sosuke Nakajima Koji Yamazaki Yuji Kawai Hajime Yasui Yasuyuki Konishi 《International Journal of Food Science & Technology》2015,50(4):871-877
Cystoseira hakodatensis is an unutilised brown algae belonging to family Sargassaceae. A crude methanol extract from the algae showed inhibitory effects on the growths of Bacillus cereus and Bacillus licheniformis. To isolate the major antimicrobial agent, a sequential active‐guided isolation procedure was applied: liquid–liquid extraction, column chromatography and bio‐autography. A marked antimicrobial agent (active α) was isolated in hydrophobic fraction and was determined to phenolics without carbohydrates and proteins by phytochemical test. Regarding the antimicrobial potential, the isolated active α showed better inhibitory effects against B. cereus and B. licheniformis at 2 and 4 times of lower concentrations (62.5 and 31.3 μg mL?1) in comparison with epigallocatechin gallate. These results showed that C. hakodatensis is a potential source of antimicrobial agent capable of preventing the growth of the two bacteria. 相似文献
3.
Sawao Honda Shinobu Hashimoto Benoît Nait-Ali David S. Smith Yusuke Daiko Yuji Iwamoto 《Journal of the American Ceramic Society》2022,105(10):6335-6344
Porous alumina with a highly textured microstructure was fabricated by pulse electric current sintering (PECS) using alumina platelets. Highly oriented porous alumina with a porosity of 3%–50% was obtained by a pressure-controlled method of PECS. The properties of the highly textured porous alumina were measured in two directions. The nitrogen gas permeance and thermal conductivity at room temperature were higher in the direction along the platelet length due to the higher continuity of pores and the connectivity of alumina platelets, respectively. The anisotropy of the thermal conductivity at room temperature was investigated and explained by the effect of grain size of platelets as well as morphology and orientation of pores. The bending strength was higher with the loading direction along the platelet thickness. The thermal shock strength was clearly different in the two directions. The difference in the thermal shock strength was investigated by the measurement of properties and thermal stress analysis. 相似文献
4.
Genki Saito Yuji Kunisada Takumi Watanabe Xuemei Yi Takahiro Nomura Norihito Sakaguchi Tomohiro Akiyama 《Journal of the American Ceramic Society》2019,102(1):524-532
Carbon-and-oxygen-doped AlN specimens were prepared by combustion synthesis using Al, graphite, and AlN. Graphite addition changed the product color from white to blue. By XRD, the lattice constant increased slightly with increasing carbon content. Blue AlN powder was synthesized with a molar ratio of the diluent AlN of 0.2-0.5 with a fixed graphite content of 0.05. At an AlN molar ratio exceeding 0.6, carbon was not successfully incorporated due to the lower reaction temperature. Calcination at 800°C in air removed residual graphite without changing the crystal structure or product color. Oxygen, nitrogen, and carbon analyses revealed that blue AlN powders contained 0.45-0.54 mass% carbon and 1.4-1.6 mass% oxygen, while the undoped AlN contained 0.021 mass% carbon and 0.94 mass% oxygen. The origin of the white-to-blue color change was investigated via reflection measurements. Blue AlN exhibits an absorption peak at 634 nm (1.96 eV). From first-principles electronic structure calculations, the C-doped AlN and carbon-and-oxygen-doped AlN with a 1:1 ratio could be classified as p-type, whereas the O-doped AlN and 1:3 carbon-and-oxygen-doped AlN were n-type. One reason for the absorption peak at 634 nm may be a transition from the conduction band to an upper unoccupied state. These results suggest the possible control of optical and electronic properties of AlN via carbon-and-oxygen doping. 相似文献
5.
Tomonari Tanaka Ayane Matsuura Yuji Aso Hitomi Ohara 《Journal of Applied Glycoscience》2020,67(4):119
Glycopolymers have attracted increased attention as functional polymeric materials, and simple methods for synthesizing glycopolymers remain needed. This paper reports the aqueous one-pot and chemoenzymatic synthesis of four types of glycopolymers via two reactions: the β-galactosidase-catalyzed glycomonomer synthesis using 4,6-dimetoxy triazinyl β-D-galactopyranoside and hydroxy group-containing (meth)acrylamide and (meth)acrylate derivatives as the activated glycosyl donor substrate and as the glycomonomer precursors, respectively, followed by radical copolymerization of the resulting glycomonomer and excess glycomonomer precursor without isolating the glycomonomers. The resulting glycopolymers bearing galactose moieties exhibited specific and strong interactions with the lectin peanut agglutinin as glycoclusters. 相似文献
6.
Iwao Shimizu Yuji Naito Iwao Yamaguchi Katsuyuki Kaiho Hitoshi Mizoguchi Satoru Yanabu 《Electrical Engineering in Japan》2008,164(1):52-61
Using conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20315 相似文献
7.
Polyacrylate gels containing Ag+ and TiO2 nanoparticles are shown to swell under UV light and shrink under visible light in water. In work reported by Tetsu Tatsuma and co‐workers on p. 1249, the TiO2 absorbs UV light and reduces the Ag+, whereas the deposited Ag absorbs visible light and dissolves itself. These redox reactions change the interactions between the polymer chains and eventually the volume of the gel, as shown on the cover. 相似文献
8.
Theoretical analysis based on the calculation of phase diagrams was employed for Fe-Si-Co and Fe-Si-Al ordering systems to
clarify the necessity for the occurrence of phase separation in Fe-base ternary ordering systems. The free energy of Fe-base
ternary ordering alloys where B2 and D03 ordered structures are formed is evaluated statistically using a pairwise interaction approximation up to second nearest
neighbours, taking into account not only the atomic interaction but also the magnetic interaction, based on the Bragg-Williams-Gorsky
model. The calculated phase diagrams are consistent with the experimentally obtained ones. The phase diagram calculation in
this work is useful to predict the equilibrium states of the ternary ordering systems. The phase separation in ordering alloys
is caused by the contribution of excess free energies due to ordering. The influences of ferromagnetism on the two-phase regions
are also demonstrated. 相似文献
9.
Kazuhiko Miyazaki Hirofumi Kasada Masayuki Ohtsuka 《Journal of Infrared, Millimeter and Terahertz Waves》1994,15(10):1669-1674
We succeeded in observing the continuously tunable, pulsed InSb SFR (Spin-Flip Raman) laser emission in the infrared region of 11~16µm (11.4~16.3µm) from only one InSb device, merely by adjusting the pumping wavelength (11 lines from the infrared NH3 laser) and the applied magnetic field (0~80 kGauss). 相似文献
10.