全文获取类型
收费全文 | 2600篇 |
免费 | 52篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 214篇 |
综合类 | 2篇 |
化学工业 | 477篇 |
金属工艺 | 78篇 |
机械仪表 | 54篇 |
建筑科学 | 43篇 |
矿业工程 | 1篇 |
能源动力 | 138篇 |
轻工业 | 129篇 |
水利工程 | 15篇 |
石油天然气 | 9篇 |
无线电 | 224篇 |
一般工业技术 | 543篇 |
冶金工业 | 442篇 |
原子能技术 | 120篇 |
自动化技术 | 171篇 |
出版年
2022年 | 26篇 |
2021年 | 35篇 |
2020年 | 9篇 |
2019年 | 21篇 |
2018年 | 26篇 |
2017年 | 22篇 |
2016年 | 36篇 |
2015年 | 25篇 |
2014年 | 41篇 |
2013年 | 93篇 |
2012年 | 86篇 |
2011年 | 109篇 |
2010年 | 97篇 |
2009年 | 110篇 |
2008年 | 112篇 |
2007年 | 109篇 |
2006年 | 82篇 |
2005年 | 75篇 |
2004年 | 77篇 |
2003年 | 80篇 |
2002年 | 73篇 |
2001年 | 62篇 |
2000年 | 83篇 |
1999年 | 70篇 |
1998年 | 204篇 |
1997年 | 114篇 |
1996年 | 89篇 |
1995年 | 75篇 |
1994年 | 52篇 |
1993年 | 57篇 |
1992年 | 35篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 26篇 |
1988年 | 28篇 |
1987年 | 21篇 |
1986年 | 30篇 |
1985年 | 36篇 |
1984年 | 28篇 |
1983年 | 26篇 |
1982年 | 37篇 |
1981年 | 32篇 |
1980年 | 29篇 |
1979年 | 19篇 |
1978年 | 24篇 |
1977年 | 18篇 |
1976年 | 19篇 |
1975年 | 14篇 |
1974年 | 10篇 |
1973年 | 8篇 |
排序方式: 共有2660条查询结果,搜索用时 343 毫秒
81.
82.
Hideo Yoshioka 《Journal of Low Temperature Physics》2006,142(3-4):507-510
The magnetic susceptibility χ(T) in normal states of the quasi-one-dimensional (Q1D) superconductor is calculated by using
the N-chain renormalization group technique developed newly. For temperatures above T
cross
being of the order of the interchain hopping t┴, χ(T) of QID system agrees with that of one-dimensional systems. For temperatures
below T
cross
where the Fermi liquid state is expected, it is found that dχ(T)/dT>0 in contrast to the case of the normal Fermi liquid, i.e., dχ(T)/dT=0. The origin of such a “pseudo-gap like” behavior is discussed in terms of antiferromagnetic spin fluctuations. 相似文献
83.
Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and their basic optical and electrical properties were examined. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were examined by normal/inverse photoemission spectroscopy and energy band calculations. The results of the examinations suggested that these materials possess unique features more than simple wide-gap semiconductors. Namely, the layered oxychalcogenides are considered to be extremely thin quantum wells composed of the oxide and chalcogenide layers or 2D chalcogenide crystals/molecules embedded in an oxide matrix. Observation of step-like absorption edges, large band gap energy and large exciton binding energy demonstrated these features originating from 2D density of states and quantum size effects in these layered materials. 相似文献
84.
Youichi Ogo Kenji Nomura Hiromichi Ohta Masahiro Hirano Hideo Hosono 《Thin solid films》2006,496(1):64-69
A reactive solid-phase epitaxy (R-SPE) method combines deposition of a thick amorphous or polycrystalline layer with a desired chemical composition and post-deposition solid-phase epitaxial growth. The solid-phase epitaxial growth is invoked by thermal annealing with an assistance of a sacrificial layer working as an epitaxial template. Thereby it enables us to grow high-quality epitaxial films of complex oxides whose epitaxial films are not grown by conventional high-temperature growth techniques. It was reported that 2-nm-thick ZnO layers worked as template for growing InGaO3(ZnO)m (m = integer) epitaxial films. The present study extended the R-SPE technique to growth of various complex oxides with chemical compositions of RAO3(MO)m and to use of various epitaxial template layers. We found that mono oxide epitaxial layers such as In2O3 and Ga2O3 work as template layers as well. Alternatively, a ZnO epitaxial layer is also applicable to ZnO-free compounds. The films obtained were grown heteroepitaxially on YSZ(111) and single-crystalline when the fabrication conditions are optimized. 相似文献
85.
M. Raburn M. Takenaka K. Takeda Xueliang Song J.S. Barton Y. Nakano 《Photonics Technology Letters, IEEE》2006,18(13):1421-1423
A novel fully integrable all-optical flip-flop has been created using distributed Bragg reflector multimode interference bistable laser diodes. The single metal-organic vapor phase epitaxy regrowth offset quantum well structure active/passive integrated flip-flop lases in single mode at 1554 nm and is compatible with standard fabrication methods of InP photonic integrated circuits (PICs). All-optical reset switching through cross-gain saturation was demonstrated over a 52-nm range, at 1522-1574 nm. An optical set has been achieved with -3 dBm and optical reset with less than -5-dBm external light injection. The flip-flop will be useful for integration in PICs of future photonic systems for self-routing and optical memories or buffers. 相似文献
86.
Fujiyoshi T. Shiratake S. Nomura S. Nishikawa T. Kitasho Y. Arakida H. Okuda Y. Tsuboi Y. Hamada M. Hara H. Fujita T. Hatori F. Shimazawa T. Yahagi K. Takeda H. Murakata M. Minami F. Kawabe N. Kitahara T. Seta K. Takahashi M. Oowaki Y. Furuyama T. 《Solid-State Circuits, IEEE Journal of》2006,41(1):54-62
A single-chip H.264 and MPEG-4 audio-visual LSI for mobile applications including terrestrial digital broadcasting system (ISDB-T / DVB-H) with a module-wise, dynamic voltage/frequency scaling architecture is presented for the first time. This LSI can keep operating even during the voltage/frequency transition, so there is no performance overhead. It is realized through a dynamic deskewing system and an on-chip voltage regulator with slew rate control. By the combination with traditional low power techniques such as embedded DRAM and clock gating, it consumes only 63 mW in decoding QVGA H.264 video at 15 frames/sec and MPEG-4 AAC LC audio simultaneously. 相似文献
87.
随着常规粉末冶金产业发展,像锻轧粉末冶金铝合金、超塑性高温合金、机械合金化氧化物弥散强化(ODS)合金之类的先进粉末冶金工艺,引起了人们的注意。受先进粉末冶金工艺启发,开发了适应日本汽车与家电产业的新材料与生产工艺,开发了适合于钢铁结构的粉末冶金Al-Si-X合金。为了改进经济性与近终形(NNS)成形性,开发了无包套粉末挤压工艺与精压式粉末锻造工艺。基于这些工艺,还开发了比单一结构材料具有较多功能的新材料,诸如轻量散热器(heat sink)与高性能发动机气缸内衬。 相似文献
88.
Nobuo Takeda Yoji Okabe Junichiro Kuwahara Seiji Kojima Toshimichi Ogisu 《Composites Science and Technology》2005,65(15-16):2575
The authors and Hitachi Cable, Ltd. have recently developed small-diameter optical fiber and its fiber Bragg grating (FBG) sensor for embedment inside a lamina of composite laminates without strength reduction. The outside diameters of the cladding and polyimide coating are 40 and 52 μm, respectively. First, a brief summary is presented for applications of small-diameter FBG sensors to damage monitoring in composite structures. Then, we propose a new damage detection system for quantitative evaluation of delamination length in CFRP laminates using Lamb wave sensing. In this system, a piezo-ceramic actuator generates Lamb waves in a CFRP laminate. After the waves propagate in the laminate, transmitted waves are received by an FBG sensor attached on or embedded in the laminate using a newly developed high-speed optical wavelength interrogation system. This system was applied to detect interlaminar delamination in CFRP cross-ply laminates. When the Lamb waves passed through the delamination, the amplitude decreased and a new wave mode appeared. These phenomena could be well simulated using a finite element analysis. From the changes in the amplitude ratio and the arrival time of the new mode depending on the delamination length, it was found that this system could evaluate the delamination length quantitatively. Furthermore, small-diameter FBG sensors were embedded in a double-lap type coupon specimen, and the debonding progress could be evaluated using the wavelet transform. 相似文献
89.
Yukio Tachibana Shigeaki Nakagawa Takeshi Takeda Akio Saikusa Takayuki Furusawa Kuniyoshi Takamatsu Kazuhiro Sawa Tatsuo Iyoku 《Nuclear Engineering and Design》2003,224(2):1010-197
Safety demonstration tests using the High Temperature Engineering Test Reactor (HTTR) will be conducted for the purpose of demonstrating inherent safety features of High Temperature Gas-cooled Reactors (HTGRs) as well as providing the core and plant transient data for validation of HTGR safety analysis codes. The first phase safety demonstration test items include the reactivity insertion test and the coolant flow reduction test. In the reactivity insertion test, which is the control rod withdrawal test, one pair out of 16 pairs of control rods is withdrawn, simulating a reactivity insertion event. The coolant flow reduction test consists of the partial loss of coolant flow test and the gas circulators trip test. In the partial loss of coolant flow test, primary coolant flow rate is slightly reduced by control system. In the gas circulators trip test one and two out of three gas circulators are run down, simulating coolant flow reduction events. The gas circulators trip tests, in which position of control rods are kept unchanged, are simulation tests of anticipated transients without scram (ATWS). 相似文献
90.
Permanent magnet linear synchronous motors have been developed for factory automation, transportation applications, and so on. In the rotary-type permanent magnet synchronous machines, the wide speed and constant power operation are realized by using the reluctance torque due to the saliency and the flux-weakening control. In this paper, we examine the effect of the interior permanent magnet arrangement for wide speed operation and the end effect in the linear structure 相似文献