全文获取类型
收费全文 | 4817篇 |
免费 | 129篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 234篇 |
综合类 | 6篇 |
化学工业 | 1151篇 |
金属工艺 | 128篇 |
机械仪表 | 117篇 |
建筑科学 | 123篇 |
能源动力 | 158篇 |
轻工业 | 454篇 |
水利工程 | 19篇 |
石油天然气 | 3篇 |
无线电 | 433篇 |
一般工业技术 | 822篇 |
冶金工业 | 748篇 |
原子能技术 | 157篇 |
自动化技术 | 411篇 |
出版年
2023年 | 27篇 |
2022年 | 61篇 |
2021年 | 109篇 |
2020年 | 40篇 |
2019年 | 56篇 |
2018年 | 104篇 |
2017年 | 86篇 |
2016年 | 132篇 |
2015年 | 78篇 |
2014年 | 124篇 |
2013年 | 270篇 |
2012年 | 196篇 |
2011年 | 278篇 |
2010年 | 201篇 |
2009年 | 228篇 |
2008年 | 236篇 |
2007年 | 192篇 |
2006年 | 163篇 |
2005年 | 164篇 |
2004年 | 162篇 |
2003年 | 129篇 |
2002年 | 123篇 |
2001年 | 92篇 |
2000年 | 69篇 |
1999年 | 108篇 |
1998年 | 321篇 |
1997年 | 197篇 |
1996年 | 145篇 |
1995年 | 86篇 |
1994年 | 76篇 |
1993年 | 107篇 |
1992年 | 44篇 |
1991年 | 61篇 |
1990年 | 41篇 |
1989年 | 39篇 |
1988年 | 36篇 |
1987年 | 33篇 |
1986年 | 50篇 |
1985年 | 44篇 |
1984年 | 27篇 |
1983年 | 36篇 |
1982年 | 27篇 |
1981年 | 27篇 |
1980年 | 22篇 |
1979年 | 20篇 |
1978年 | 20篇 |
1977年 | 26篇 |
1976年 | 18篇 |
1975年 | 9篇 |
1973年 | 9篇 |
排序方式: 共有4964条查询结果,搜索用时 0 毫秒
71.
Ichikawa S Akita T Okumura M Haruta M Tanaka K Kohyama M 《Journal of electron microscopy》2003,52(1):21-26
Three-dimensional (3-D) nanostructures of gold catalysts supported on TiO2 were analysed by electron holography and high-resolution electron microscopy. The contact angle of the gold particle on TiO2 tended to be >90 degrees in the case of gold particles with a size (height) of >4 nm and it tended to be <90 degrees for gold particles with a height of <2 nm. The change in morphology increases the perimeter at the Au/TiO2 interface as the particle size decreases. This change in 3-D structure should be attributed to a change in electronic structure at the interface. It was found that electron holography enabled 3-D analysis at the atomic level and was effective for analysing nanostructured particles. 相似文献
72.
A new space-time turbo equalization algorithm is derived for frequency-selective multiple-input-multiple-output (MIMO) channels with unknown interference. The algorithm is an extension of our proposed MIMO equalization algorithm , which performs joint channel estimation, multiple users' signal detection, and decoding, all in an iterative manner. This paper's proposed algorithm uses estimates of the correlation matrix of composite unknown interference-plus-noise components to suppress the unknown interference while effectively separating multiple users' signals to be detected (referred to as "known user" later). The correlation matrix of the composite unknown interference-plus-noise components can be estimated by time averaging the instantaneous empirical correlation matrix over the training period. Since the iterative channel estimation yields better channel estimates as more iterations are performed, thereby the estimate of the correlation matrix of the unknown interference-plus-noise components also becomes more accurate. This results in better signal detection performances, even in the presence of unknown interferers. A series of computer simulations show that this paper's proposed algorithm can properly separate known users' signals while suppressing unknown interference. 相似文献
73.
3D Micromolding of Arrayed Waveguide Gratings on Upconversion Luminescent Layers for Flexible Transparent Displays without Mirrors,Electrodes, and Electric Circuits 下载免费PDF全文
Satoshi Watanabe Takeo Asanuma Takafumi Sasahara Hiroshi Hyodo Mutsuyoshi Matsumoto Kohei Soga 《Advanced functional materials》2015,25(28):4390-4396
A new technique for the fabrication of arrayed waveguide gratings on upconversion luminescent layers for flexible transparent displays is reported. Ho3+‐ and Yb3+‐codoped NaYF4 nanoparticles are synthesized by hydrothermal techniques. Transparent films consisting of two transparent polymers on the NaYF4 nanoparticle films exhibit mechanical flexibility and high transparence in visible region. Patterned NaYF4 nanoparticle films are fabricated by calcination‐free micromolding in capillaries. Arrayed waveguide gratings consisting of the two transparent polymers are formed on the patterned NaYF4 nanoparticle films by micromolding in capillaries. Green and red luminescence is observed from the upconversion luminescent layers of the NaYF4 nanoparticle films in the arrayed waveguide gratings under excitation at 980 nm laser light. Arrayed waveguide gratings on the upconversion luminescent layers are fabricated with Er3+‐doped NaYF4 nanoparticles which can convert two photons at 850 and 1500 nm into single photon at 550 nm. These results demonstrate that flexible transparent displays can be fabricated by constructing arrayed waveguide gratings on upconversion luminescent layers, which can operate in nonprojection mode without mirrors, transparent electrodes, and electric circuits. 相似文献
74.
Liquid Crystals: Liquid‐Crystalline Electrolytes for Lithium‐Ion Batteries: Ordered Assemblies of a Mesogen‐Containing Carbonate and a Lithium Salt (Adv. Funct. Mater. 8/2015) 下载免费PDF全文
75.
76.
Flexible Electronics: 3D Micromolding of Arrayed Waveguide Gratings on Upconversion Luminescent Layers for Flexible Transparent Displays without Mirrors,Electrodes, and Electric Circuits (Adv. Funct. Mater. 28/2015) 下载免费PDF全文
77.
Zilong Zhang Wen Zhao Guo Chen Masaya Toda Satoshi Koizumi Yasuo Koide Meiyong Liao 《Advanced functional materials》2023,33(27):2300805
Electrically integrable, high-sensitivity, and high-reliability magnetic sensors are not yet realized at high temperatures (500 °C). In this study, an integrated on-chip single-crystal diamond (SCD) micro-electromechanical system (MEMS) magnetic transducer is demonstrated by coupling SCD with a large magnetostrictive FeGa film. The FeGa film is multifunctionalized to actuate the resonator, self-sense the external magnetic field, and electrically readout the resonance signal. The on-chip SCD MEMS transducer shows a high sensitivity of 3.2 Hz mT−1 from room temperature to 500 °C and a low noise level of 9.45 nT Hz−1/2 up to 300 °C. The minimum fluctuation of the resonance frequency is 1.9 × 10−6 at room temperature and 2.3 × 10−6 at 300 °C. An SCD MEMS resonator array with parallel electric readout is subsequently achieved, thus providing a basis for the development of magnetic image sensors. The present study facilitates the development of highly integrated on-chip MEMS resonator transducers with high performance and high thermal stability. 相似文献
78.
Tomohiro Kasakawa Hiroki Tabata Ryo Onodera Hiroki Kojima Mutsumi Kimura Hiroyuki Hara Satoshi Inoue 《Solid-state electronics》2011,56(1):207-210
We propose degradation evaluation of poly-Si TFTs by comparing normal and reverse characteristics. Since symmetrical normal and reverse characteristics indicate Joule-heating degradation whereas asymmetrical characteristics indicate hot-carrier degradation, they can be clearly and easily classified. Moreover, degradation occurrence is contrasted between standard and fine TFTs. Finally, behavior of the hot-carrier degradation is analyzed. 相似文献
79.
Koh Matsumoto Kazutada Ikenaga Jun Yamamoto Kazuki Naito Yoshiki Yano Akinori Ubukata Hiroki Tokunaga Tadanobu Arimura Katsuaki Cho Toshiya Tabuchi Akira Yamaguchi Yasuhiro Harada Yuzaburo Ban Kousuke Uchiyama 《半导体学报》2011,32(1):21-23
Growth rate has a direct impact on the productivity of nitride LED production.Atmospheric pressure growth of GaN with a growth rate as high as 10μm/h and also Al0.1Ga0.9N growth of 1μm/h by using 4 inch by 11 production scale MOVPE are described.XRD of(002) and(102) direction was 200 arcsec and 250 arcsec, respectively.Impact of the growth rate on productivity is discussed. 相似文献
80.
Hashimoto K. Nagano I. Yamamoto M. Okada T. Kimura I. Matsumoto H. Oki H. 《Geoscience and Remote Sensing, IEEE Transactions on》1997,35(2):278-286
The Akebono (EXOS-D) satellite has been successfully observing the Earth's magnetosphere since it was launched on February 21, 1989. The objectives of VLF instruments on board the satellite were to investigate the behavior of plasma waves associated with accelerated auroral particles, wave-particle interaction mechanisms, and propagation characteristics of whistler-mode waves in the magnetosphere. The instruments measured not only the dynamic spectra of VLF waves up to 15 kHz by a wideband receiver, but also their absolute field intensities, wave normal vectors, and Poynting vectors. Two electric and three magnetic components with a bandwidth of about 50 Hz up to 12.5 kHz are sent to measure the wave normal vectors and Poynting vectors. The antenna impedance is measured to determine the correct absolute electric field intensities. The instruments have successfully measured the wave spectra, the wave normal vectors. Poynting vectors, the precise wave intensities, the antenna impedance, etc. The present paper describes the unique features of the instruments, especially the Poynting flux analyzers in more detail. Obtained scientific results are also reviewed 相似文献