全文获取类型
收费全文 | 750篇 |
免费 | 16篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 43篇 |
综合类 | 1篇 |
化学工业 | 219篇 |
金属工艺 | 20篇 |
机械仪表 | 26篇 |
建筑科学 | 22篇 |
能源动力 | 36篇 |
轻工业 | 79篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 43篇 |
一般工业技术 | 121篇 |
冶金工业 | 36篇 |
原子能技术 | 38篇 |
自动化技术 | 84篇 |
出版年
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 16篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 14篇 |
2015年 | 14篇 |
2014年 | 15篇 |
2013年 | 68篇 |
2012年 | 34篇 |
2011年 | 51篇 |
2010年 | 34篇 |
2009年 | 38篇 |
2008年 | 37篇 |
2007年 | 34篇 |
2006年 | 34篇 |
2005年 | 30篇 |
2004年 | 28篇 |
2003年 | 30篇 |
2002年 | 22篇 |
2001年 | 15篇 |
2000年 | 17篇 |
1999年 | 10篇 |
1998年 | 17篇 |
1997年 | 24篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 6篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有771条查询结果,搜索用时 15 毫秒
151.
In situ measurement of tip-enhanced near-field Raman spectra of an isolated single-wall carbon nanotube (SWNT) bundle has been demonstrated by applying a uniaxial pressure up to approximately 2 GPa to the bundle via a metal-coated atomic force microscope tip. We investigated the pressure dependences of Raman frequencies and the intensity of the radial breathing mode bands, the D-band and the G-band, which were related to deformation of SWNTs caused by the tip pressure. 相似文献
152.
Kiguchi M Nakashima S Tada T Watanabe S Tsuda S Tsuji Y Terao J 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(5):726-730
An electronic conductance with small fluctuations, which is stipulated in single-molecule junctions, is necessary for the precise control of single-molecule devices. However, the suppression of conductance fluctuations in conventional molecular junctions is intrinsically difficult because the fluctuations are related to the contact fluctuations and molecular motion. In the present study involving experimental and theoretical investigations, it is found that covering a single π-conjugated wire with an α-cyclodextrin molecule is a promising technique for suppressing conductance fluctuations. The conductance histogram of the covered molecular junction measured with the scanning tunneling microscope break-junction technique shows that the conductance peak for the covered junction is sharper than that of the uncovered junction. The covering technique thus has two prominent effects: the suppression of intramolecular motion, and the elimination of intermolecular interactions. Theoretical calculations of electronic conductance clearly support these experimental observations. 相似文献
153.
Ichikawa T Bando M Kondo Y Nakahara M 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2012,370(1976):4671-4689
Unitary operations acting on a quantum system must be robust against systematic errors in control parameters for reliable quantum computing. Composite pulse technique in nuclear magnetic resonance realizes such a robust operation by employing a sequence of possibly poor-quality pulses. In this study, we demonstrate that two kinds of composite pulses-one compensates for a pulse length error in a one-qubit system and the other compensates for a J-coupling error in a two-qubit system-have a vanishing dynamical phase and thereby can be seen as geometric quantum gates, which implement unitary gates by the holonomy associated with dynamics of cyclic vectors defined in the text. 相似文献
154.
Naoomi Yamada Taro Hitosugi Ngoc Lam Huong Hoang Shoichiro Nakao Yasushi Hirose Toshihiro Shimada Tetsuya Hasegawa 《Thin solid films》2010,518(11):3101-3104
Transparent conducting Nb-doped anatase TiO2 (TNO) epitaxial films were sputtered from TiO2-, Ti2O3-, and Ti-based targets at various oxygen partial pressures (Po2). Using the TiO2- and Ti2O3-based targets, highly conductive films showing a resistivity (ρ) of ~ 3 × 10− 4 Ω cm could be formed without postdeposition treatment. In the case of the TNO films formed from the Ti-based target, reductive annealing had to be carried out at a temperature of 600 °C to achieve similar resistivity values. Thus, the use of oxide targets is preferable to obtain as-grown transparent conducting TNO films. In particular, the Ti2O3-based target is practically advantageous, because it offers a wide range of optimal Po2 values at which ρ values of the order of 10− 4 Ω cm are achievable. 相似文献
155.
A novel technique of spectroscopic imaging using a near-infrared (NIR) laser sheet beam was developed for visualization of liquid water in a proton-exchange membrane (PEM) sandwiched between two opaque electrodes set in a polymer electrolyte fuel cell (PEFC). In-plane two-dimensional distribution of water in the thin membrane was clearly visualized during the fuel cell operation. Under the condition of fuel feeding into the PEFC without humidification, water was generated by the fuel cell reaction in the whole electrode area. In contrast, under the condition of fuel feeding with humidification, the PEM got wet in the vicinity of a gas flow field locally. 相似文献
156.
Yasushi Abe Kunio Matsubara Kiyoaki Sasagawa Kouki Matsuse 《IEEJ Transactions on Electrical and Electronic Engineering》2008,3(1):113-119
This paper presents a medium‐voltage inverter applying series connected general‐purpose 1.2 kV insulated gate bipolar transistors (IGBTs) as a switching device to achieve low switching losses compared to inverters applying high‐voltage IGBTs with over 3 kV rating. Gate signal synchronization, which is essential to keep the balance of collector‐emitter voltages across the IGBTs, is achieved by magnetically coupling all gate lines using a simple two‐windings transformer. In order to obtain better voltage balancing, influence of stray capacitance distribution associated with an insulating substrate in a two‐in‐one IGBT module on the voltage sharing is investigated, and an optimized layout of heat sinks for the IGBT modules is proposed. To validate some performances concerning the device losses and the voltage sharing, a 170 kVA inverter based on three 1.2 kV IGBTs connected in series is built and evaluated. The experimental results are shown. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
157.
Hiroko Ohuchi-Yoshida Yuji Hatano Yasushi Kino Yasuhiro Kondo 《Fusion Engineering and Design》2012,87(5-6):423-426
A method to detect tritium non-destructively in regions deeper than the escape depth of beta rays is being developed using bremsstrahlung induced by beta rays with an imaging plate (IP). An IP made of europium-doped BaFBr(I), a photostimulated luminescence (PSL) material, is a two-dimensional radiation sensor. The bremsstrahlung energy spectrum is a continuum with photon energies, varying based on the atomic number and thickness of the target (or absorbing) material. When tritium migrates into matter, the bremsstrahlung energy spectrum distribution would change. The PSL intensity of the IP is affected by this energy spectrum variation. In order to quantify the amount of tritium in deeper regions with the IP technique, a tritium depth profile is required.In this study, a new method of obtaining a tritium depth profileusing the combined technique of the IP and thin absorbers is presented. 相似文献
158.
159.
Wang Lin Zhang Chen Cai Dexiang Zhang Jianqiang Sasaki Yasushi Ostrovski Oleg 《Metallurgical and Materials Transactions B》2017,48(1):516-526
Metallurgical and Materials Transactions B - This paper investigated the effects of CaO/SiO2 ratio (0.8 to 1.5) and Na2O concentration (6 to 9 wt pct) on melting properties and viscosity... 相似文献
160.
Abstract Some properties of fields diffracted in the Fraunhofer region by apertures bounded by regular fractals are investigated. A recursion relation describing such apertures is introduced and the associated relation in the Fourier transform domain is described. For a triadic Koch aperture whose edge has the fractal dimension of Ds = 1·262, the recursion relation is numerically evaluated. Self-similar structures of intensity distributions in the Fraunhofer region are verified for the present objects. The relationship of the fractal dimension D s of the fractal edge with the power-law decay of the Fraunhofer diffraction intensities is also verified. 相似文献