全文获取类型
收费全文 | 171879篇 |
免费 | 1673篇 |
国内免费 | 223篇 |
专业分类
电工技术 | 2589篇 |
综合类 | 125篇 |
化学工业 | 27011篇 |
金属工艺 | 9554篇 |
机械仪表 | 5862篇 |
建筑科学 | 3110篇 |
矿业工程 | 1889篇 |
能源动力 | 3050篇 |
轻工业 | 9186篇 |
水利工程 | 2804篇 |
石油天然气 | 8720篇 |
武器工业 | 12篇 |
无线电 | 14917篇 |
一般工业技术 | 39021篇 |
冶金工业 | 28014篇 |
原子能技术 | 7007篇 |
自动化技术 | 10904篇 |
出版年
2021年 | 1815篇 |
2019年 | 1892篇 |
2018年 | 3327篇 |
2017年 | 3384篇 |
2016年 | 3658篇 |
2015年 | 1853篇 |
2014年 | 3258篇 |
2013年 | 6860篇 |
2012年 | 4604篇 |
2011年 | 5700篇 |
2010年 | 4683篇 |
2009年 | 5105篇 |
2008年 | 5069篇 |
2007年 | 4982篇 |
2006年 | 4243篇 |
2005年 | 3891篇 |
2004年 | 3682篇 |
2003年 | 3565篇 |
2002年 | 3377篇 |
2001年 | 3370篇 |
2000年 | 3210篇 |
1999年 | 3102篇 |
1998年 | 6941篇 |
1997年 | 5096篇 |
1996年 | 3728篇 |
1995年 | 2942篇 |
1994年 | 2597篇 |
1993年 | 2732篇 |
1992年 | 2264篇 |
1991年 | 2311篇 |
1990年 | 2421篇 |
1989年 | 2319篇 |
1988年 | 2315篇 |
1987年 | 2194篇 |
1986年 | 2255篇 |
1985年 | 2297篇 |
1984年 | 2228篇 |
1983年 | 2140篇 |
1982年 | 1977篇 |
1981年 | 2188篇 |
1980年 | 2058篇 |
1979年 | 2261篇 |
1978年 | 2435篇 |
1977年 | 2432篇 |
1976年 | 3094篇 |
1975年 | 2246篇 |
1974年 | 2300篇 |
1973年 | 2335篇 |
1972年 | 2155篇 |
1971年 | 1903篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
1.
Venhryn Yu. I. Popovych I. D. Serednytski A. S. Kolomys O. F. Luchechko A. P. Strelchuk V. V. 《Journal of Materials Science: Materials in Electronics》2022,33(14):10715-10722
Journal of Materials Science: Materials in Electronics - The ZnO and TiO2 nanopowders have been prepared by means of the pulsed laser reactive ablation of metallic (Zn, Ti) targets. The Structural,... 相似文献
2.
In the present work, the heating performance of a new system combined with a new modified baseboard radiator and fan coil is investigated. Using longitudinal fins with special geometry and also forced airflow at the end of the system causes that at the lower inlet water temperature compared with the conventional models, higher heat output rate be obtained. The heat output rate of the new modified system is obtained by experimental metrology based on the European Standard No. EN-442. Temperature and velocity distribution in the room space is done by simulation of the modified system in the Flovent software. Computational fluid dynamics (CFD) results are validated against experimental results and there is a good agreement between them. Also, the energy consumption of the system during the winter season is calculated in TRANSYS software. Experimental results show that the heat output rate of a new modified heating system with inlet water temperature in the range of 45–55°C is on average 4.17 times higher compared with the conventional model. CFD simulation also showed that the combined system provides good thermal comfort conditions. Energy consumption of the new system reduced about 13% compared with conventional models. 相似文献
3.
4.
Kuznetsov I. V. Budin O. N. Shchepin A. S. Kalenova M. Yu. Mel’nikova I. M. Saprykin R. V. Al’zhev N. I. 《Inorganic Materials》2022,58(6):651-660
Inorganic Materials - We have studied the effect of annealing on the chemical and physical properties of mineral-like host matrices for immobilization of the rare-earth–actinide fraction from... 相似文献
5.
Kalinina E. V. Kudoyarov M. F. Nikitina I. P. Dementyeva E. V. Zabrodskii V. V. 《Semiconductors》2022,56(3):184-188
Semiconductors - The results of the effect of irradiation with Ar ions on the structural, electrophysical, and optical characteristics of ultraviolet Cr/4H-SiC photodetectors in the spectral range... 相似文献
6.
Gerasimov Sergey I. Ilyushin Mikhail A. Putis Sergey M. Dushenok Sergey A. Shugalei Irina V. Sudarikov Andrey M. 《含能材料》2022,30(4):370-378
In the present work it is found that the pyrotechnic composition VS-2 can be initiated with flash lamps IFC-500 and EVIS. VS-2 pyrotechnic composition contains 90% of mercury(Ⅱ) 5-hydrazinotetrazolate perchlorate and 10% of optically transparent copolymer of 2-methyl-5-vinyltetrazole and methacrylic acid (PVMT). We have found that the flash lamps make it possible to initiate combustion of VS-2 composition with its transition to detonation both in cylindrical charges placed in brass caps of 5 mm diameter and 2 mm high, and film charges with 10 mm×80 mm in size and surface weights of 60 mg·cm-2 and 90 mg·cm-2, showing ignition delay times 10 μs and 3 μs, respectively. We also measured detonation velocities for VS-2 composition film charges, which were 4375-4505 m·s-1 (of the charge being surface mass 60 mg·cm-2) and 4221-4281 m·s-1 (of the charge being surface mass 90 mg·cm-2) and their blasting action on the aluminum plate. The depths of the normal shock wave imprints at the charge-barrier interface were 0.6-0.7 mm (for surface mass of the film charges 60 mg·cm-2) and 1.2-1.3 mm (for surface mass of the film charges 90 mg·cm-2). 相似文献
7.
Strength of Materials - The effect of the creep of materials of a structure on the nature of the contact interaction between its elements during long-term operation is investigated. The problem of... 相似文献
8.
Parkhomenko M. P. Kalenov D. S. Eremin I. S. Fedoseev N. A. Kolesnikova V. M. 《Journal of Communications Technology and Electronics》2022,67(9):1127-1133
Journal of Communications Technology and Electronics - A modified resonator method for determining the complex permittivity of materials based on the theory of small perturbations where a resonator... 相似文献
9.
Journal of Computer and Systems Sciences International - The replacement of complex technical system elements is optimized using a genetic algorithm. Its various operators are analyzed and modified... 相似文献
10.
Rukomoynikov A. A. Yuminov I. P. Khamitov A. I. Garifullin I. Sh. Agliullin Ya. F. 《Russian Engineering Research》2022,42(9):916-919
Russian Engineering Research - Systems are considered for the dehydration of petroleum so as to separate water–petroleum emulsions. In particular, the low-temperature microwave (UHF)... 相似文献