全文获取类型
收费全文 | 1869篇 |
免费 | 79篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 97篇 |
综合类 | 12篇 |
化学工业 | 477篇 |
金属工艺 | 48篇 |
机械仪表 | 56篇 |
建筑科学 | 62篇 |
矿业工程 | 1篇 |
能源动力 | 59篇 |
轻工业 | 152篇 |
水利工程 | 7篇 |
石油天然气 | 15篇 |
武器工业 | 1篇 |
无线电 | 128篇 |
一般工业技术 | 348篇 |
冶金工业 | 242篇 |
原子能技术 | 93篇 |
自动化技术 | 157篇 |
出版年
2023年 | 8篇 |
2022年 | 28篇 |
2021年 | 48篇 |
2020年 | 33篇 |
2019年 | 37篇 |
2018年 | 31篇 |
2017年 | 43篇 |
2016年 | 43篇 |
2015年 | 41篇 |
2014年 | 57篇 |
2013年 | 106篇 |
2012年 | 76篇 |
2011年 | 101篇 |
2010年 | 87篇 |
2009年 | 90篇 |
2008年 | 111篇 |
2007年 | 89篇 |
2006年 | 63篇 |
2005年 | 57篇 |
2004年 | 57篇 |
2003年 | 56篇 |
2002年 | 54篇 |
2001年 | 40篇 |
2000年 | 41篇 |
1999年 | 47篇 |
1998年 | 112篇 |
1997年 | 67篇 |
1996年 | 45篇 |
1995年 | 44篇 |
1994年 | 26篇 |
1993年 | 31篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 14篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 7篇 |
1980年 | 13篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1969年 | 4篇 |
排序方式: 共有1955条查询结果,搜索用时 375 毫秒
61.
62.
63.
64.
Motoyasu Tanaka Kazuyuki Kon Mizuki Nakajima Nobutaka Matsumoto Shinnosuke Fukumura Kosuke Fukui 《Advanced Robotics》2020,34(2):70-88
AbstractIn this work, we develop an articulated mobile robot that can move in narrow spaces, climb stairs, gather information, and operate valves for plant disaster prevention. The robot can adopt a tall position using a folding arm and gather information using sensors mounted on the arm. In addition, this paper presents a stair climbing method using a single backward wave. This method enables the robot to climb stairs that have a short tread. The developed robot system is tested in a field test at the World Robot Summit 2018, and the lessons learned in the field test are discussed. 相似文献
65.
66.
67.
Operation Assist by Vibration Suppression Control Using Impulse‐Shaped Signals for Power Assist Conveyance System
下载免费PDF全文
![点击此处可从《Electrical Engineering in Japan》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yuichi Yamamoto Masaki Uchida Yoshifumi Morita Susumu Hara 《Electrical Engineering in Japan》2014,186(2):31-39
This paper presents an assist control method for a flexible parts conveyance task using a power assist conveyance system. The assist control method should be designed so as not only to suppress vibration but also to reduce the degradation of operating feel. For this purpose, multiple impulse‐shaped signals are used as feedforward signals in order to reduce the vibration of flexible parts during conveyance. In addition, the adjustment time is introduced to adjust the input timing of the impulse‐shaped signal and to suppress vibration. In order to improve the degradation of operating feel, the smaller amplitudes of the three impulse‐shaped signals are used and input repeatedly. The effectiveness of the proposed system was verified experimentally. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 31–39, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22476 相似文献
68.
Phase Relations and Volume Changes of Hafnia under High Pressure and High Temperature 总被引:1,自引:0,他引:1
Osamu Ohtaka Hiroshi Fukui Taichi Kunisada Tomoyuki Fujisawa Kenichi Funakoshi Wataru Utsumi Tetsuo Irifune Koji Kuroda Takumi Kikegawa 《Journal of the American Ceramic Society》2001,84(6):1369-1373
Using multi-anvil high-pressure devices and synchrotron radiation, X-ray in situ observations of HfO2 under high pressure and high temperature have been performed to investigate its phase relations and compression behavior. An orthorhombic phase (orthoI) is stable from 4 to 14.5 GPa below 1250°–1400°C and transforms to a tetragonal phase, which is one of the high-temperature forms of HfO2 , above these temperatures. Another orthorhombic phase (orthoII) with a cotunnite-type structure appears above 14.5 GPa. OrthoII is stable up to 1800°C at 21 GPa. OrthoII is quenchable to ambient conditions. The orthoI-to-orthoII transition is accompanied by ∼8 vol% decrease. The bulk moduli of orthoI and orthoII at room temperature are 220 and 312 GPa, respectively. This low compressibility of orthoII indicates that it is a potential candidate for very hard materials. 相似文献
69.
Effects of Atmospheric Composition on the Molecular Structure of Synthesized Silicon Oxycarbides
下载免费PDF全文
![点击此处可从《Journal of the American Ceramic Society》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Masaki Narisawa Fuji Funabiki Akihiro Iwase Fumihiro Wakai Hideo Hosono 《Journal of the American Ceramic Society》2015,98(10):3373-3380
The dependence of silicon oxycarbides' chemical composition and molecular structure on their reaction conditions was tested by varying the atmosphere under which pyrolysis was performed. To obtain the silicon oxycarbides, densely cross‐linked silicone resin particles with an averaged diameter of 2 μm were pyrolyzed in various atmospheres of H2, Ar, and CO2, in the temperature range 700°C–1100°C. The residual mass of resin after pyrolysis was almost constant at 700°C, although their apparent colors varied distinctly. The sample obtained from the H2 atmosphere was white, whereas that obtained from the CO2 atmosphere was dark brown. Fourier‐transform infrared (FT‐IR) spectra of the residues suggested that the Si–O–Si network evolution was accelerated in the CO2 atmosphere. Beyond 800°C, the chemical compositions of the compounds obtained from a H2 atmosphere increasingly approached near‐stoichiometric SiO2–xSiC composition with increasing the pyrolysis temperature. Compounds from a CO2 atmosphere approached a composition of SiO2–xC with no free SiC as the pyrolysis temperature increased. In the products from an Ar atmosphere, SiO2–xSiC–yC compositions were typically obtained. The observed effects of the pyrolysis atmosphere on the resulting chemical compositions were analyzed in terms of thermodynamic calculations. Electron spin resonance (ESR) spectra revealed broad and intense signals from products obtained from either Ar or CO2. Estimating from the signal intensity, the residual spin concentrations were in the range 1018–1019 g?1. Meanwhile, the spectra from the samples obtained in H2 showed weak and sharp signals with estimated spin concentrations ranging from 1016–1017 g?1. This signal attenuation may have been due to the hydrogen capping of dangling bond formed during pyrolysis. 相似文献
70.
Hiroyuki Yamada Atsushi Tsurumaki‐Fukuchi Masaki Kobayashi Takuro Nagai Yoshikiyo Toyosaki Hiroshi Kumigashira Akihito Sawa 《Advanced functional materials》2015,25(18):2708-2714
Tunnel electroresistance in ferroelectric tunnel junctions (FTJs) has attracted considerable interest, because of a promising application to nonvolatile memories. Development of ferroelectric thin‐film devices requires atomic‐scale band‐structure engineering based on depolarization‐field effects at interfaces. By using FTJs consisting of ultrathin layers of the prototypical ferroelectric BaTiO3, it is demonstrated that the surface termination of the ferroelectric in contact with a simple‐metal electrode critically affects properties of electroresistance. BaTiO3 barrier‐layers with TiO2 or BaO terminations show opposing relationships between the polarization direction and the resistance state. The resistance‐switching ratio in the junctions can be remarkably enhanced up to 105% at room temperature, by artificially controlling the fraction of BaO termination. These results are explained in terms of the termination dependence of the depolarization field that is generated by a dead layer and imperfect charge screening. The findings on the mechanism of tunnel electroresistance should lead to performance improvements in the devices based on nanoscale ferroelectrics. 相似文献