全文获取类型
收费全文 | 1830篇 |
免费 | 60篇 |
国内免费 | 109篇 |
专业分类
电工技术 | 21篇 |
综合类 | 74篇 |
化学工业 | 357篇 |
金属工艺 | 261篇 |
机械仪表 | 91篇 |
建筑科学 | 10篇 |
矿业工程 | 10篇 |
能源动力 | 51篇 |
轻工业 | 40篇 |
石油天然气 | 8篇 |
武器工业 | 5篇 |
无线电 | 295篇 |
一般工业技术 | 699篇 |
冶金工业 | 26篇 |
原子能技术 | 27篇 |
自动化技术 | 24篇 |
出版年
2024年 | 5篇 |
2023年 | 18篇 |
2022年 | 21篇 |
2021年 | 18篇 |
2020年 | 23篇 |
2019年 | 39篇 |
2018年 | 32篇 |
2017年 | 33篇 |
2016年 | 43篇 |
2015年 | 42篇 |
2014年 | 59篇 |
2013年 | 83篇 |
2012年 | 73篇 |
2011年 | 146篇 |
2010年 | 88篇 |
2009年 | 127篇 |
2008年 | 134篇 |
2007年 | 91篇 |
2006年 | 129篇 |
2005年 | 90篇 |
2004年 | 120篇 |
2003年 | 80篇 |
2002年 | 76篇 |
2001年 | 73篇 |
2000年 | 77篇 |
1999年 | 44篇 |
1998年 | 50篇 |
1997年 | 35篇 |
1996年 | 37篇 |
1995年 | 24篇 |
1994年 | 19篇 |
1993年 | 14篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 1篇 |
1988年 | 9篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有1999条查询结果,搜索用时 171 毫秒
131.
Sachio Okada Takeyuki Kikuchi Masafumi Kobune Tetsuo Yazawa 《Thin solid films》2007,515(18):7342-7346
A mixed ionic and electronic conducting hydrogen separation membrane, which consisted of proton-conductive oxide and metallic palladium, was fabricated. A porous alumina tube was employed as a support, and proton-conductive oxide particles were introduced into a microporous top layer of the support by an impregnation method. Palladium particles were deposited into the same porous layer by chemical vapor deposition. Hydrogen permeated preferentially via the membrane thus obtained with a hydrogen permeance (PH2) of 1.2 × 10− 9 mol·m− 2·s− 1·Pa− 1 at 873 K. Selectivity for hydrogen (PH2/PN2) increased with the operating temperature due to an increase in proton conductivity of the membrane, and PH2/PN2 = 5.7 was attained at 873 K. 相似文献
132.
Govindhan Dhanaraj Yi Chen Hui Chen Dang Cai Hui Zhang Michael Dudley 《Journal of Electronic Materials》2007,36(4):332-339
A chemical vapor deposition (CVD) system was designed and fabricated in our laboratory and SiC homo-epitaxial layers were
grown in the CVD process using silicon tetrachloride and propane precursors with hydrogen as a carrier gas. The temperature
field was generated using numerical modeling. Gas flow rates, temperature field, and the gradients are found to influence
the growth rates of the epitaxial layers. Growth rates were found to increase as the temperature increased at high carrier
gas flow rate, while at lower carrier gas flow rate, growth rates were observed to decrease as the temperature increased.
Based on the equilibrium model, “thermodynamically controlled growth” accounts for the growth rate reduction. The grown epitaxial
layers were characterized using various techniques. Reduction in the threading screw dislocation (SD) density in the epilayers
was observed. Suitable models were developed for explaining the reduction in the SD density as well as the conversion of basal
plane dislocations (BPDs) into threading edge dislocations (TEDs). 相似文献
133.
134.
Yoshimasa Kondo Takao Saito Tatsuya Terazawa Naoto Ohtake 《Electrical Engineering in Japan》2007,159(4):1-7
Diamondlike carbon (DLC) films show high hardness, high electric resistivity, and the self‐lubricant characteristic, and many applications and synthesis methods have been reported. Pulse plasma chemical vapor deposition (CVD) is one of the synthesis methods suitable for DLC films on complicated form work, such as molding and extruding die. Ordinary, microsecond‐order pulse is used in this method. This paper describes the development of the synthesis method using nanosecond‐order pulse plasma CVD for DLC films. To realize this process, a static induction (SI) thyristor with an inductive energy storage (IES) circuit was used. Compared with microsecond, nanosecond‐order pulse plasma CVD method shows the characteristics of high electron temperature and exponential relationship between pulse frequency and growth rate. The characteristics of the thus‐obtained DLC films show two broad peaks of the disordered band at 1360 cm?1 and the graphitic band at 1580 cm?1 by Raman spectroscopy and hardness of 16.0 GPa and elastic modulus of 170 GPa. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(4): 1–7, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20341 相似文献
135.
The future prospect of remote Cat-CVD, in which the decomposition and the deposition chambers are separated, is discussed on the basis of the absolute density measurements of H atoms. It is now well recognized that uniform deposition is possible on a large area without plasma damages by Cat-CVD. However, we may not overlook the demerits in Cat-CVD. One of the demerits is the poisoning of the catalyzer surfaces by the material gases, both temporary and permanent. One technique to overcome this problem is remote Cat-CVD. The question is how to separate the decomposition and deposition areas. If the separation is not enough, there should be back diffusion of the material gases, which will poison the catalyzers. If the separation is too tight, radicals may not effuse out from the decomposition chamber. These problems are discussed and it is shown that SiO2 coating to reduce the radical recombination rates on walls is promising. The possibility of the polytetrafluoroethene coating by Cat-CVD is also discussed. 相似文献
136.
Efforts of industrial application of Cat-CVD technology are surveyed. Recent movement of industrial implementation is also reviewed by showing examples in Japanese industry. Cat-CVD technology is originally developed as a new tool for fabricating semiconductor devices, however, recently, use of the technology is attempted in various fields such as chemical, mechanical and bio-technical engineering. It is shown that Cat-CVD has high feasibility as a fundamental technology of modern industries. 相似文献
137.
Atsushi Hibi 《Thin solid films》2008,516(5):856-858
Gaseous copper chlorides can be employed as precursors in a newly developed Cu-CVD method called metal chloride reduction-chemical vapor deposition (MCR-CVD). More than one species exists in the gas phase of copper chloride. We studied the gas phase composition of copper chlorides generated by etching of copper surface by electron impact-mass spectrometry. The composition of gaseous species can change because of gas phase reactions. After desorbing from the copper surface, copper chloride reached equilibrium composition immediately. 相似文献
138.
Interconnections between semiconductor devices in integrated circuits continue to present difficult problems in the tradeoffs
between RC time constants, production worthiness, reliability, structural complexity, and compactibility for any single technology.
A process and structure has been demonstrated for integrated circuit interconnections which uses a conformai tungsten layer
deposited by chemical vapor deposition to provide step coverage into via holes of variable height. The film is then patterned
with a via interconnect pattern designed for liftoff processing, layers of chromium copper and chromium are then depositedinsitu on the wafers by way of evaporation. The undesired material is lifted off in a solvent process and the resulting metal pattern
is used as the mask for the reactive ion etching of CVD tungsten. This combination of materials and process allows for high
conductivity reliable interconnections with negligable step coverage problems. Processing and test information will be presented
in the paper. 相似文献
139.
Nanofilamentous carbon was grown on a carbon foam by catalytic chemical vapour deposition (CVD) using the decomposition of ethylene/hydrogen mixtures over Ni. The carbon foam was obtained from a coal by a two-stage thermal process, with the first stage taking place at a temperature within the plastic region of the precursor coal. The extent of porosity and the pore size of the foam were mainly influenced by the pressure reached in the reactor during the first stage. In the CVD process, 700 °C was the optimum temperature for obtaining good yields of nanofilaments. A low ethylene/hydrogen ratio (1/4) in the reactive gas gave rise to almost only short and thin carbon nanostructures. A higher proportion of C2H4 (4/1, C2H4/H2) gave better yields of nanofilaments, with good proportions of higher-length and higher-diameter (up to around 0.5 μm) structures. Among the carbon forms produced, transmission electron microscopy revealed the predominance of fishbone-type nanofibres, with some bamboo-like nanotubes being also observed. 相似文献
140.
H. Reiss F. Schmaderer G. Wahl B. Ziegenbein R. Caps 《International Journal of Thermophysics》1987,8(2):263-280
This paper describes first experimental steps of an attempt to replace evacuated multifoils by metal-coated dielectric fibers as a new superisolation. Calculations of the Rosseland mean of spectral extinction coefficients for thin highly relective fibers show that radiation transport can be reduced to the same extent that is achievable with multifoils. Experimental results of extinction coefficients and thermal conductivity of Al-coated glass fibers are reported. Apparently, the metal coating does not increase seriously the small solid thermal conductivity of pure glass fibers. The procedure for optimizing this insulation is thus reduced to an optimization of its extinction properties. 相似文献