全文获取类型
收费全文 | 268860篇 |
免费 | 2064篇 |
国内免费 | 1008篇 |
专业分类
电工技术 | 4561篇 |
综合类 | 256篇 |
化学工业 | 39852篇 |
金属工艺 | 18199篇 |
机械仪表 | 11344篇 |
建筑科学 | 5033篇 |
矿业工程 | 2615篇 |
能源动力 | 4653篇 |
轻工业 | 12101篇 |
水利工程 | 3961篇 |
石油天然气 | 10519篇 |
武器工业 | 12篇 |
无线电 | 23950篇 |
一般工业技术 | 64140篇 |
冶金工业 | 39027篇 |
原子能技术 | 8321篇 |
自动化技术 | 23388篇 |
出版年
2021年 | 1874篇 |
2019年 | 1922篇 |
2018年 | 10749篇 |
2017年 | 11279篇 |
2016年 | 8212篇 |
2015年 | 2651篇 |
2014年 | 3778篇 |
2013年 | 8628篇 |
2012年 | 7790篇 |
2011年 | 14151篇 |
2010年 | 12708篇 |
2009年 | 12230篇 |
2008年 | 12161篇 |
2007年 | 13967篇 |
2006年 | 5497篇 |
2005年 | 7850篇 |
2004年 | 6474篇 |
2003年 | 6006篇 |
2002年 | 5036篇 |
2001年 | 4554篇 |
2000年 | 4397篇 |
1999年 | 4166篇 |
1998年 | 8958篇 |
1997年 | 6676篇 |
1996年 | 5195篇 |
1995年 | 3821篇 |
1994年 | 3327篇 |
1993年 | 3454篇 |
1992年 | 2810篇 |
1991年 | 2843篇 |
1990年 | 2847篇 |
1989年 | 2721篇 |
1988年 | 2633篇 |
1987年 | 2524篇 |
1986年 | 2518篇 |
1985年 | 2596篇 |
1984年 | 2445篇 |
1983年 | 2361篇 |
1982年 | 2215篇 |
1981年 | 2399篇 |
1980年 | 2326篇 |
1979年 | 2514篇 |
1978年 | 2639篇 |
1977年 | 2755篇 |
1976年 | 3605篇 |
1975年 | 2465篇 |
1974年 | 2492篇 |
1973年 | 2546篇 |
1972年 | 2332篇 |
1971年 | 2070篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Semiconductors - In this work, we discuss for the first time the principle of rotation in the constant electric field of a conducting particle with participation of the Lorentz force, which ensures... 相似文献
2.
Zienko S. I. Zhbanova V. L. 《Journal of Communications Technology and Electronics》2022,67(4):395-402
Journal of Communications Technology and Electronics - A quantitative comparison of the spectral characteristics of the human visual system and matrix photodetectors is carried out. Criteria for a... 相似文献
3.
Journal of Signal Processing Systems - 相似文献
4.
Kuznetsov Yu. A. Markov M. A. Kravchenko I. N. Krasikov A. V. Bykova A. D. 《Refractories and Industrial Ceramics》2021,62(4):421-425
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized... 相似文献
5.
To investigate the evolution of the structural and enhanced magnetic properties of GdMnO3 systems induced by the substitution of Mn with Cr, polycrystalline GdMn1-xCrxO3 samples were synthesized via solid-state reactions. XRD characterization shows that all GdMn1-xCrxO3 compounds with single-phase structures crystallize well and that Cr3+ ions entering the lattice sites of GdMnO3 induce structural distortion. SEM results indicate that the grain size of the synthesized samples (a few microns) decreases as the Cr substitution concentration increases. Positron annihilation lifetime spectroscopy reveals that vacancy-type defects occur in GdMn1-xCrxO3 ceramics and that the vacancy size and concentration clearly change with the Cr content. The temperature and field dependence of the magnetization curves show that Cr substitution significantly influences the magnetic ordering of the gadolinium sublattice, improving the weak ferromagnetic transition temperature and magnetization of GdMn1-xCrxO3. The enhanced magnetization of GdMn1-xCrxO3 is closely related to the vacancy defect concentration. 相似文献
6.
Seredin P. V. Radam Ali Obaid Goloshchapov D. L. Len’shin A. S. Buylov N. S. Barkov K. A. Nesterov D. N. Mizerov A. M. Timoshnev S. N. Nikitina E. V. Arsentyev I. N. Sharafidinov Sh. Kukushkin S. A. Kasatkin I. A. 《Semiconductors》2022,56(4):253-258
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid... 相似文献
7.
Boltar K. O. Burlakov I. D. Iakovleva N. I. Vlasov P. V. Lazarev P. S. 《Journal of Communications Technology and Electronics》2022,67(9):1175-1184
Journal of Communications Technology and Electronics - In recent years, there has been a rapid improvement in photonics products due to the use of multilayer heterostructures grown on the basis of... 相似文献
8.
Glass and Ceramics - Ceramic bricks based on low-melting clay and ferro-dust from self-disintegrating, low-carbon, ferrochrome slags, graded from M100 to M175, respectively, were obtained in the... 相似文献
9.
Automation and Remote Control - A linear-quadratic positional differential game of three persons is considered. Coefficient criteria are established under which there is no Nash equilibrium... 相似文献
10.
A. Nakano T. Shimazaki M. Sekiya H. Shiozawa K. Ohtsuka A. Aoyagi T. Iwakiri Z. Mikami M. Sato Y. Sugino K. Kinoshita T. Matsuoka T. Imamura Y. Takayama K. Yamamoto 《International Journal of Hydrogen Energy》2021,46(29):15649-15659
Monitoring the temperature in liquid hydrogen (LH2) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa. 相似文献