全文获取类型
收费全文 | 242355篇 |
免费 | 2643篇 |
国内免费 | 427篇 |
专业分类
电工技术 | 4304篇 |
综合类 | 261篇 |
化学工业 | 39602篇 |
金属工艺 | 9394篇 |
机械仪表 | 7411篇 |
建筑科学 | 5478篇 |
矿业工程 | 1398篇 |
能源动力 | 5178篇 |
轻工业 | 24883篇 |
水利工程 | 2488篇 |
石油天然气 | 5098篇 |
武器工业 | 32篇 |
无线电 | 25116篇 |
一般工业技术 | 44940篇 |
冶金工业 | 45657篇 |
原子能技术 | 5959篇 |
自动化技术 | 18226篇 |
出版年
2021年 | 2114篇 |
2019年 | 2020篇 |
2018年 | 3500篇 |
2017年 | 3438篇 |
2016年 | 3690篇 |
2015年 | 2248篇 |
2014年 | 3918篇 |
2013年 | 10232篇 |
2012年 | 6174篇 |
2011年 | 8334篇 |
2010年 | 6580篇 |
2009年 | 7267篇 |
2008年 | 7618篇 |
2007年 | 7753篇 |
2006年 | 6923篇 |
2005年 | 6075篇 |
2004年 | 5839篇 |
2003年 | 5618篇 |
2002年 | 5705篇 |
2001年 | 5585篇 |
2000年 | 5400篇 |
1999年 | 5325篇 |
1998年 | 12627篇 |
1997年 | 8937篇 |
1996年 | 6898篇 |
1995年 | 5350篇 |
1994年 | 4760篇 |
1993年 | 4649篇 |
1992年 | 3685篇 |
1991年 | 3407篇 |
1990年 | 3622篇 |
1989年 | 3502篇 |
1988年 | 3330篇 |
1987年 | 2911篇 |
1986年 | 2947篇 |
1985年 | 3392篇 |
1984年 | 3235篇 |
1983年 | 2903篇 |
1982年 | 2756篇 |
1981年 | 2843篇 |
1980年 | 2730篇 |
1979年 | 2634篇 |
1978年 | 2700篇 |
1977年 | 2957篇 |
1976年 | 3824篇 |
1975年 | 2378篇 |
1974年 | 2251篇 |
1973年 | 2384篇 |
1972年 | 1974篇 |
1971年 | 1865篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
H. W. Mead C. E. Birchenall 《JOM Journal of the Minerals, Metals and Materials Society》1957,9(7):874-877
The self-diffusion coefficients of gold in pure gold and alloys of gold and silver have been measured over a range of temperatures. Chemical interdiffusion coefficients have been measured on pure metal and incremental couples, but are of lower accuracy because of the development of porosity. The results are compared with earlier work and internally on the basis of Darken’s equations. 相似文献
992.
993.
Gnevko A. I. Kazakov N. A. Sultanovskii V. I. Zubov O. E. 《Metal Science and Heat Treatment》2002,44(1-2):94-94
Metal Science and Heat Treatment - 相似文献
994.
The wear resistance of corundum milling bodies developed by the authors is estimated compared to foreign analogs. It is established that domestic ceramics, with respect to its abrasion rate in milling electrocorundum and quartz sand, is not inferior to foreign ceramics. The kinetics of milling the specified materials is analyzed.__________Translated from Steklo i Keramika, No. 1, pp. 17 – 18, January, 2005. 相似文献
995.
996.
997.
Kester Bruce E. Gilliland J. L. Fritts Stewart S. Bell Zeb G. Smith Hubert Berby Richard H. 《Industry Applications, IEEE Transactions on》1972,(1):8-18
MAN is but a part of the universe; his capabilities make him a significant link, in the cycle of life. To ensure this life, man must live in harmony with his environment. Recently, a disharmony has been discovered which could have grave effects upon the existence of man. It appears that man in his great thrust forward is destroying his own environment. The gravity of this threat to man's own existence carries some intrinsic problems of its own: man must allow his reason rather than his emotion to take command. 相似文献
998.
S. Feliu Jr. J. M. Bastidas J. C. Galvan J. Simancas M. Morcillo E. Almeida 《Journal of Applied Electrochemistry》1993,23(2):157-161
The stability of a rusted steel surface exposed to a 0.11 M sodium sulphate solution has been studied. Electrochemical impedance spectroscopy, polarization resistance and atomic absorption analysis techniques were used in conjunction with mild steel specimens rusted in a rural atmosphere and treated with different concentrations of phosphoric acid. Since most of the impedance diagrams obtained differ from the typical semicircle, it is not clear how to obtain kinetic information on the corrosion process. The polarization resistance technique gives more useful data. 相似文献
999.
A. Domingue K. Piyakis E. Sacher M. Di Renzo S. D nomm e T. H. Ellis 《The Journal of Adhesion》1993,40(2):151-162
The irreversibly bound interfacial layer deposited by the γ-aminopropysilanetriol adhesion promoter onto a crystalline silicon substrate, which remains even after profuse washing, was found by XPS to have resulted from the fragmentation and rearrangement of the original γ-aminopropylsilanetriol molecule. A mechanism is proposed, involving the homolytic scission of the terminal N-C bond. One of the subsequent reactions is believed to involve hydrogen loss by abstraction and the formation of a terminal vinyl group, which bonds to the substrate. Support for this mechanism is found in IR spectroscopy of this layer. 相似文献
1000.
Tin electrodeposition in its initial stages in acid sulfate/gluconate baths was studied with varying tin and gluconate concentrations using potential-controlled electrochemical techniques. The deposit morphology was observed by scanning electron microscopy (SEM). A comparison with tin electrodeposition from acid sulfate baths in the absence of gluconate was also carried out. Use of a highly acidic bath leads to nonuniform deposits, even in the presence of gluconate; at pH 4 deposits are uniform, brilliant and suitable for finishing applications. Tin crystallites have a well defined morphology which depends on bath agitation conditions. In the absence of agitation, the crystallites have the same tetragonal shape as in a sulfate bath without gluconate. 相似文献