全文获取类型
收费全文 | 286475篇 |
免费 | 2272篇 |
国内免费 | 914篇 |
专业分类
电工技术 | 4997篇 |
综合类 | 242篇 |
化学工业 | 41589篇 |
金属工艺 | 17607篇 |
机械仪表 | 11731篇 |
建筑科学 | 5492篇 |
矿业工程 | 2847篇 |
能源动力 | 4904篇 |
轻工业 | 15324篇 |
水利工程 | 4326篇 |
石油天然气 | 10969篇 |
武器工业 | 51篇 |
无线电 | 26058篇 |
一般工业技术 | 66220篇 |
冶金工业 | 42783篇 |
原子能技术 | 9514篇 |
自动化技术 | 25007篇 |
出版年
2021年 | 2150篇 |
2019年 | 2131篇 |
2018年 | 10890篇 |
2017年 | 11392篇 |
2016年 | 8588篇 |
2015年 | 2815篇 |
2014年 | 4217篇 |
2013年 | 9289篇 |
2012年 | 8240篇 |
2011年 | 14396篇 |
2010年 | 12912篇 |
2009年 | 12447篇 |
2008年 | 12553篇 |
2007年 | 14138篇 |
2006年 | 5995篇 |
2005年 | 8047篇 |
2004年 | 6835篇 |
2003年 | 6427篇 |
2002年 | 5226篇 |
2001年 | 4706篇 |
2000年 | 4597篇 |
1999年 | 4347篇 |
1998年 | 10115篇 |
1997年 | 7280篇 |
1996年 | 5376篇 |
1995年 | 4250篇 |
1994年 | 3780篇 |
1993年 | 3888篇 |
1992年 | 3087篇 |
1991年 | 3178篇 |
1990年 | 3258篇 |
1989年 | 3121篇 |
1988年 | 3050篇 |
1987年 | 2859篇 |
1986年 | 2930篇 |
1985年 | 3031篇 |
1984年 | 2820篇 |
1983年 | 2716篇 |
1982年 | 2497篇 |
1981年 | 2730篇 |
1980年 | 2574篇 |
1979年 | 2753篇 |
1978年 | 2904篇 |
1977年 | 3046篇 |
1976年 | 3855篇 |
1975年 | 2679篇 |
1974年 | 2704篇 |
1973年 | 2728篇 |
1972年 | 2528篇 |
1971年 | 2260篇 |
排序方式: 共有10000条查询结果,搜索用时 15 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.
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
3.
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
4.
The thermodynamics modeling of a Reiner–Philippoff-type fluid is essential because it is a complex fluid with three distinct probable modifications. This fluid model can be modified to describe a shear-thinning, Newtonian, or shear-thickening fluid under varied viscoelastic conditions. This study constructs a mathematical model that describes a boundary layer flow of a Reiner–Philippoff fluid with nonlinear radiative heat flux and temperature- and concentration-induced buoyancy force. The dynamical model follows the usual conservation laws and is reduced through a nonsimilar group of transformations. The resulting equations are solved using a spectral-based local linearization method, and the accuracy of the numerical results is validated through the grid dependence and convergence tests. Detailed analyses of the effects of specific thermophysical parameters are presented through tables and graphs. The study reveals, among other results, that the buoyancy force, solute and thermal expansion coefficients, and thermal radiation increase the overall wall drag, heat, and mass fluxes. Furthermore, the study shows that amplifying the space and temperature-dependent heat source parameters allows fluid particles to lose their cohesive force and, consequently, maximize flow and heat transfer. 相似文献
5.
Dobrydnev S. V. Alexandrova O. A. Rezvov Yu. G. 《Theoretical Foundations of Chemical Engineering》2022,56(3):362-366
Theoretical Foundations of Chemical Engineering - The reaction of nickel(II) hydroxide and a mixed ammonia–carbonate solution to form nickel(II) aqua–ammonia complexes is studied in the... 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.
Potomkin M. M. Sedliar A. A. Sirchenko R. S. Ishchenko O. M. 《Cybernetics and Systems Analysis》2022,58(3):392-398
Cybernetics and Systems Analysis - It is noted that fuzzy methods are widely used to substantiate rational decisions in multi-criteria analysis of complex systems since the operating conditions of... 相似文献
8.
Kulikova M. V. Krylova A. Yu. Zhagfarov F. G. Krysanova K. O. 《Chemistry and Technology of Fuels and Oils》2022,58(2):327-332
Chemistry and Technology of Fuels and Oils - The review examines biomass of animal origin in terms of a potential renewable raw material for obtaining CO2-neutral fuel unaffecting the carbon... 相似文献
9.
Strength of Materials - Methods of elastic solutions and interchangeable elasticity parameters for solving nonlinear boundary value problems of mechanics are considered, making it possible to... 相似文献
10.
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