全文获取类型
收费全文 | 1871篇 |
免费 | 70篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 19篇 |
综合类 | 2篇 |
化学工业 | 417篇 |
金属工艺 | 65篇 |
机械仪表 | 33篇 |
建筑科学 | 37篇 |
矿业工程 | 1篇 |
能源动力 | 96篇 |
轻工业 | 118篇 |
水利工程 | 5篇 |
石油天然气 | 2篇 |
无线电 | 247篇 |
一般工业技术 | 500篇 |
冶金工业 | 164篇 |
原子能技术 | 7篇 |
自动化技术 | 236篇 |
出版年
2023年 | 23篇 |
2022年 | 24篇 |
2021年 | 48篇 |
2020年 | 32篇 |
2019年 | 38篇 |
2018年 | 53篇 |
2017年 | 43篇 |
2016年 | 46篇 |
2015年 | 38篇 |
2014年 | 73篇 |
2013年 | 119篇 |
2012年 | 83篇 |
2011年 | 96篇 |
2010年 | 71篇 |
2009年 | 87篇 |
2008年 | 87篇 |
2007年 | 77篇 |
2006年 | 51篇 |
2005年 | 52篇 |
2004年 | 38篇 |
2003年 | 53篇 |
2002年 | 41篇 |
2001年 | 40篇 |
2000年 | 36篇 |
1999年 | 40篇 |
1998年 | 40篇 |
1997年 | 33篇 |
1996年 | 25篇 |
1995年 | 38篇 |
1994年 | 31篇 |
1993年 | 30篇 |
1992年 | 24篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 23篇 |
1987年 | 15篇 |
1986年 | 17篇 |
1985年 | 31篇 |
1984年 | 26篇 |
1983年 | 20篇 |
1982年 | 20篇 |
1981年 | 18篇 |
1980年 | 15篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 9篇 |
1976年 | 15篇 |
1975年 | 10篇 |
1971年 | 7篇 |
排序方式: 共有1949条查询结果,搜索用时 15 毫秒
21.
In this paper a micromechanics model using the concentric cylinder assemblage model and the Mori-Tanaka average stress scheme is used to predict the static strength of unidirectional angle ply laminates. The predicted strengths agree with experimental results for Glass/Epoxy and Graphite/Epoxy systems. 相似文献
22.
Anne Venu Gopal Research Scholar P. Venkateswara Rao Associate Professor 《The International Journal of Advanced Manufacturing Technology》2004,24(11-12):816-820
The chip-thickness models, used to assess the performance of grinding processes, play a major role in predicting the surface quality. In the present paper, an attempt has been made to develop a new chip-thickness model for the performance assessment of silicon carbide grinding by incorporating the modulus of elasticities of the grinding wheel and the workpiece in the existing basic chip-thickness model to account for elastic deformation. The new model has been validated by conducting experiments, taking the surface roughness as a parameter of evaluation . 相似文献
23.
Room temperature synthesis of crystalline metal oxides 总被引:6,自引:0,他引:6
Crystalline titanium dioxide powders have been synthesized as either rutile or anatase from aqueous solutions at low temperatures
(T≤100°C) and atmospheric pressure. First, a sol is prepared by the hydrolysis of a titanium alkoxide in an acidic solution.
The sol is subsequently heated at different rates to produce the different crystalline phases of titanium dioxide. Powder
characterization was carried out using X-ray diffraction, scanning electron microscopy and high resolution transmission electron
microscopy. In general, the precipitate size was observed to be between 50 and 100 nm. Possible mechanisms involved in determining
the crystal variants are discussed.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
24.
25.
In single photon emission computed tomography (SPECT), every reconstruction algorithm must use some model for the response of the gamma camera to emitted gamma-rays. The true camera response is both spatially variant and object dependent. These two properties result from the effects of scatter, septal penetration, and attenuation, and they forestall determination of the true response with any precision. This motivates the investigation of the performance of reconstruction algorithms when there are errors between the camera response used in the reconstruction algorithm and the true response of the gamma camera. In this regard, the authors compare the filtered backprojection algorithm, the expectation-maximization maximum likelihood algorithm, and the generalized expectation maximization (GEM) maximum a posteriori (MAP) algorithm, a Bayesian algorithm which uses a Markov random field prior. 相似文献
26.
Tetsuya Ōgushi Gopal N. Suresha Yutaka Honjo Yoshihisa Ōzono Iwazo Kawano Tadashi Numata Yoshinori Hakuraku 《Journal of Low Temperature Physics》1987,69(5-6):451-457
We prepared La-Sr-Nb-O system samples both in bulk form and as a film, with sharp resistive transitions at temperatures of 228–323 K, depending on the annealing conditions. The sharp resistive transitions might be attributable to superconductivity. Magnetic ordering was observed over a narrow temperature range around 40 K for some of the samples. 相似文献
27.
Satya Gopal Rao P. Venkatehwarlu K. Siripuram Rajesh Sripada Suresh 《Glass Physics and Chemistry》2021,47(4):308-320
Glass Physics and Chemistry - The growth of nanocrystalization in TeO2–SeO2–Na2O glasses is achieved by the conventional heat treatment method. The influence of Na2O concentration on... 相似文献
28.
Silicon - This research aims at optimum utilization of waste recycled submerged arc welding slag along with virgin flux in place of pure virgin flux without compromising the quality of welding and... 相似文献
29.
This paper reports fabrication of 2-DOF vibratory gyroscope using SU-8 based UV-LIGA process. The device structure is designed to be symmetrical in order to match the resonance frequencies of drive and sense mode oscillators and also to minimize their relative temperature dependent drift. The overall arrangement is such that the two vibration modes do not affect each other and therefore, mechanical decoupling is achieved which helps in minimizing bias drift. The design is optimized to be compatible with the UV-LIGA process having 10 μm thick electroformed nickel as structural layer. Photolithography to create 11 μm thick SU-8 molds for electroforming sacrificial copper and structural nickel layer is optimized using multiple exposure technique that ensures near vertical side walls. Since the highly cross-linked SU-8 remaining after development is difficult to remove reliably from high aspect ratio structures without damage or alteration to the electroformed metals, a 2.45 GHz MW plasma etching process is developed with CF4/O2 mixes. The fabricated device is checked for off-plane misalignment between the stationary and movable comb fingers using white light interferometry and it is found to be almost negligible. Also, the prototype device is characterized for amplitude and phase spectral responses using Polytec MSA-500 Micro System Analyzer. The drive and sense mode resonance frequencies are observed at 7.3 and 7.1 kHz respectively against the mode matched designed frequency of 7.5 kHz. 相似文献
30.
Electrochemical cell current requirements for toxic organic waste destruction in Ce(IV)-mediated electrochemical oxidation process 总被引:1,自引:0,他引:1
Vasily V. Kokovkin Sang Joon Chung Subramanian Balaji Manickam Matheswaran Il-Shik Moon 《Korean Journal of Chemical Engineering》2007,24(5):749-756
The electrochemical cell for cerium oxidation and reactor for organic destruction are the most important operation units for
the successful working mediated electrochemical oxidation (MEO) process. In this study, electrochemical cells with DSA electrodes
of two types, single stack and double stack connected in series, were used. The performances towards the electrochemical generation
of Ce(IV) in nitric acid media at 80 °C were studied. The current-voltage curves and cerium electrolysis kinetics showed the
dependence on number of cell stacks needed to be connected in series for the destruction of a given quantity of organic pollutant.
The presence of an optimum region for Ce(III) oxidation with a contribution of oxygen evolution, especially at low Ce(III)
concentration (high conversion ratios), was found. The cells were applied for the Ce(IV) regeneration during the organic destruction.
The cell and reactor processes were fitted in a simple model proposed and used to calculate the current needed in terms of
Ce(III) oxidation rate and the number of cell stacks required for maintaining Ce(IV)/Ce(III) ratio at the same level during
the organic destruction. This consideration was based on the kinetic model previously developed by us for the organic destruction
in the MEO process. 相似文献