全文获取类型
收费全文 | 299952篇 |
免费 | 5080篇 |
国内免费 | 2549篇 |
专业分类
电工技术 | 6378篇 |
技术理论 | 5篇 |
综合类 | 1554篇 |
化学工业 | 48033篇 |
金属工艺 | 13588篇 |
机械仪表 | 9084篇 |
建筑科学 | 7753篇 |
矿业工程 | 2036篇 |
能源动力 | 6865篇 |
轻工业 | 27855篇 |
水利工程 | 3301篇 |
石油天然气 | 7309篇 |
武器工业 | 260篇 |
无线电 | 31649篇 |
一般工业技术 | 58063篇 |
冶金工业 | 53718篇 |
原子能技术 | 6267篇 |
自动化技术 | 23863篇 |
出版年
2021年 | 2942篇 |
2020年 | 2027篇 |
2019年 | 2552篇 |
2018年 | 4051篇 |
2017年 | 3994篇 |
2016年 | 4402篇 |
2015年 | 3428篇 |
2014年 | 5470篇 |
2013年 | 13571篇 |
2012年 | 9057篇 |
2011年 | 11983篇 |
2010年 | 9545篇 |
2009年 | 10332篇 |
2008年 | 11016篇 |
2007年 | 11215篇 |
2006年 | 9754篇 |
2005年 | 8609篇 |
2004年 | 7752篇 |
2003年 | 7208篇 |
2002年 | 7214篇 |
2001年 | 7343篇 |
2000年 | 6810篇 |
1999年 | 6824篇 |
1998年 | 14802篇 |
1997年 | 11043篇 |
1996年 | 8600篇 |
1995年 | 6445篇 |
1994年 | 5779篇 |
1993年 | 5656篇 |
1992年 | 4493篇 |
1991年 | 4269篇 |
1990年 | 4291篇 |
1989年 | 4201篇 |
1988年 | 3860篇 |
1987年 | 3370篇 |
1986年 | 3365篇 |
1985年 | 3727篇 |
1984年 | 3577篇 |
1983年 | 3310篇 |
1982年 | 2934篇 |
1981年 | 3131篇 |
1980年 | 2940篇 |
1979年 | 3097篇 |
1978年 | 2964篇 |
1977年 | 3180篇 |
1976年 | 4232篇 |
1975年 | 2703篇 |
1974年 | 2529篇 |
1973年 | 2569篇 |
1972年 | 2188篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
S. V. Yakubovskaya L. V. Kul'bitskaya N. L. Budeiko A. A. Korbit 《Inorganic Materials》2004,40(3):221-226
The effect of the composition of sensitizing–activating solutions on the activation efficiency and the chemical coppering of diamond powders is studied. The results demonstrate that stabilizing additives improve the stability of the solutions, influence the average coppering rate, and play a key role in determining the morphology and quality of the resultant coatings. The most effective stabilizing additive is synthamid-10, which ensures the deposition of high-quality copper coatings. 相似文献
72.
V. N. Perevezentsev M. Yu. Shcherban’ M. Yu. Murashkin R. Z. Valiev 《Technical Physics Letters》2007,33(8):648-650
The structure and mechanical properties of nanocrystalline aluminum alloy 1570 obtained by means of severe plastic deformation have been studied. Being tested in a temperature range from 300 to 400°C, the alloy exhibits high-strain-rate superplasticity. At 400°C, the superplasticity is manifested in a very broad range of strain rates, extending from 5 × 10?3 to 1 s?1. 相似文献
73.
74.
O Bernard B Chachuat A Hélias B Le Dantec B Sialve J-P Steyer L Lardon P Neveu S Lambert J Gallop M Dixon P Ratini A Quintabà S Frattesi J M Lema E Roca G Ruiz J Rodriguez A Franco P Vanrolleghem U Zaher D J W De Pauw K De Neve K Lievens D Dochaine O Schoefs H Fibrianto R Farina V Alcaraz Gonzalez V Gonzalez Alvarez P Lemaire J A Martinez F Esandi O Duclaud J F Lavigne 《Water science and technology》2005,52(1-2):457-464
The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem. 相似文献
75.
Polystyrene packaging material taint was sensorily evaluated in cocoa powder for drinks and chocolate flakes using short-cut signal detection measures on differences between control and test samples and on recognition of styrene. No differences were observed in cocoa powder for drinks and plain chocolate flakes treated with 0.5 dm2 polystyrene of 1 mm thickness. However, differences were detected in milk chocolate flakes and plain chocolate flakes, which were in contact with a larger area or thicker polystyrene packaging material. The latter results were confirmed by the styrene recognition test, so polystyrene is a potential source of off-flavour for chocolate products. The amount of residual styrene in the polystyrene used was about 320 ppm, while the amounts of styrene ranged from 7 to 132 ppb in cocoa drinks and from 414 to 1447 ppb in chocolate flakes. 相似文献
76.
77.
Zhang Z.G. Chan S.C. Tsui K.M. 《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(6):576-580
This paper proposes a new Kalman-filter-based recursive frequency estimator for discrete-time multicomponent sinusoidal signals whose frequencies may be time-varying. The frequency estimator is based on the linear prediction approach and it employs the Kalman filter to track the linear prediction coefficients (LPCs) recursively. Frequencies of the sinusoids can then be computed using the estimated LPCs. Due to the coloredness of the linear prediction error, an iterative algorithm is employed to estimate the covariance matrix of the prediction error and the LPCs alternately in the Kalman filter in order to improve the tracking performance. Simulation results show that the proposed Kalman-filter-based iterative frequency estimator can achieve better tracking results than the conventional recursive least-squares-based estimators. 相似文献
78.
Oxide films were deposited on different substrates by laser molecular beam epitaxy. Reflection high-energy electron diffraction was performed to in situ investigate the change of growth mode and the lattice relaxation during the growth. An asymmetrical phenomenon was found in the two kinds of strain states, compressive stress and tensile stress of heterostructures with different lattice mismatch. In the case of BaTiO3/SrTiO3 (2.2%), 2D layer-by-layer growth mode without lattice relaxation can be maintained for a longer period for BTO films on STO with compressive stress, comparing to STO films on BTO with tensile stress. When MgO films were deposited on SrTiO3 with a large mismatch of 7.8%, compressive stress leads to rapid lattice relaxation with a very thin wet layer, and 3D strained island were observed. As a comparison, SrTiO3 films on MgO with tensile stress were configured. No RHEED patterns can be observed duo to a large tensile stress. 相似文献
79.
L. M. Aksel’rod V. I. Rumyantsev N. Yu. Korableva N. V. Belykh Ya. G. Dyatlova 《Refractories and Industrial Ceramics》2008,49(2):116-119
Technology is developed for preparing refractory components made of partially stabilized zirconium dioxide using an isostatic
compaction press. Technology is provided for manufacturing dispensing nozzles using combined and separately stabilized zirconium
dioxide, and also indices of the refractories obtained and imported materials are compared.
__________
Translated from Novye Ogneupory, No. 3, pp. 127–131, March 2008. 相似文献
80.
I. D. Kashcheev S. N. Sychev M. N. Dunaeva L. A. Karpets P. A. Emel’yanov O. S. Ryakhova 《Refractories and Industrial Ceramics》2008,49(2):131-134
Compositions have been developed for nonshrinking vibrocast thermally insulating light refractory concretes with densities
of 1.0, 1.3, 1.5, and 1.8 g/cm3 for temperatures of use up to 1400°C. The structure and properties have been examined for the concrete of density 1.3 g/cm3.
__________
Translated from Novye Ogneupory, No. 4, pp. 29–32, April, 2008. 相似文献