全文获取类型
收费全文 | 391000篇 |
免费 | 5687篇 |
国内免费 | 2224篇 |
专业分类
电工技术 | 7467篇 |
技术理论 | 5篇 |
综合类 | 3468篇 |
化学工业 | 58289篇 |
金属工艺 | 20364篇 |
机械仪表 | 15572篇 |
建筑科学 | 9459篇 |
矿业工程 | 2813篇 |
能源动力 | 7169篇 |
轻工业 | 29419篇 |
水利工程 | 4741篇 |
石油天然气 | 7546篇 |
武器工业 | 243篇 |
无线电 | 41341篇 |
一般工业技术 | 78433篇 |
冶金工业 | 54012篇 |
原子能技术 | 6766篇 |
自动化技术 | 51804篇 |
出版年
2021年 | 2474篇 |
2019年 | 2121篇 |
2018年 | 22717篇 |
2017年 | 22254篇 |
2016年 | 15989篇 |
2015年 | 3763篇 |
2014年 | 4841篇 |
2013年 | 11579篇 |
2012年 | 12374篇 |
2011年 | 24816篇 |
2010年 | 21483篇 |
2009年 | 19024篇 |
2008年 | 20414篇 |
2007年 | 22967篇 |
2006年 | 8597篇 |
2005年 | 11522篇 |
2004年 | 9216篇 |
2003年 | 8560篇 |
2002年 | 7206篇 |
2001年 | 6461篇 |
2000年 | 6168篇 |
1999年 | 5943篇 |
1998年 | 12913篇 |
1997年 | 9573篇 |
1996年 | 7326篇 |
1995年 | 5553篇 |
1994年 | 5118篇 |
1993年 | 4985篇 |
1992年 | 3968篇 |
1991年 | 3797篇 |
1990年 | 3827篇 |
1989年 | 3774篇 |
1988年 | 3538篇 |
1987年 | 3019篇 |
1986年 | 3053篇 |
1985年 | 3409篇 |
1984年 | 3323篇 |
1983年 | 3074篇 |
1982年 | 2700篇 |
1981年 | 2902篇 |
1980年 | 2643篇 |
1979年 | 2840篇 |
1978年 | 2737篇 |
1977年 | 2843篇 |
1976年 | 3697篇 |
1975年 | 2458篇 |
1974年 | 2290篇 |
1973年 | 2321篇 |
1972年 | 1982篇 |
1971年 | 1786篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
A. A. Babenko V. I. Zhuchkov L. A. Smirnov A. V. Sychev A. A. Akberdin A. S. Kim M. F. Vitushchenko A. A. Dobromilov 《Steel in Translation》2015,45(11):883-886
A technology for slag formation in the ladle–furnace unit is considered; the slag is based on the CaO–SiO2–MgO–Al2O3–B2O3 system. This technology permits both microalloying of the steel with boron (reduced from the oxide phase) and desulfurization of the steel. The resulting boron content in the steel is 0.001–0.008%; the sulfur content in low-alloy steel and pipe steel is low (0.004–0.010%); and the consumption of manganese ferroalloys is reduced to 0.5 kg/t for 08кп steel and 1.4 kg/t for 09Г2C steel. In addition, the proposed technology increases the strength of the rolled steel, without loss in its plasticity; and reduces the environmental impact thanks to the replacement of fluorspar by colemanite. 相似文献
94.
D. Solís-Cortés E. Navarrete-Astorga J.L. Costa-Krämer J. Salguero-Fernandez R. Schrebler D. Leinen E.A. Dalchiele J.R. Ramos-Barrado F. Martín 《Ceramics International》2019,45(5):5577-5587
C-axis textured thin films of gallium-doped indium zinc oxide (GIZO) with a 2% ratio of Ga/Zn, were obtained via RF-magnetron sputtering with high transparency and electrical conductivity. A Box-Behnken response surface design was used to evaluate the effects of the deposition parameters (In2O3 target power, deposition time, and substrate temperature) on the chemical composition, optical, electrical, and structural properties of the GIZO films. The optical constants and the electrical properties were obtained using optical models. The GIZO stoichiometry, and therefore the In/Zn atomic ratio, affected the crystallinity, crystalline parameters, band gap, and charge carrier mobility of the GIZO films. The charge carrier density was related to the change in the crystalline parameters of the hexagonal structure and the In/Zn atomic ratio. The best electrical conductivity values (1.75?×?103 Ω?1 cm?1) were obtained for GIZO films with In/Zn ratio ≥?1. Several figures of merit (FOM) defined for the visible and solar regions were comparatively used to select the optimal In/Zn atomic ratio that provided the best balance between the conductivity and the transparency. The optimal In/Zn ratio was in a range of 0.85–0.90 for the GIZO films. 相似文献
95.
Journal of Computer and Systems Sciences International - We consider a controlled mechanical system with one degree of freedom described by an angular coordinate. The system is under the action of... 相似文献
96.
97.
98.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
99.
A. M. Mirzabaev V. P. Kanonerov T. A. Makhkamov O. R. Sytdykov Sh. M. Mirzabekov 《Applied Solar Energy》2018,54(3):224-226
The data on the use of solar photovoltaic plants (PVPs) for providing a reliable and guaranteed power supply to telecommunication systems and cellular communication systems in the conditions prevalent in Uzbekistan are given. The research-based structures developed by OOO MIR SOLAR and the selection of PVP elements ensuring their reliable operation are described. The main influencing factors are discussed, and the use of effective combinations of different types of panels (from monocrystalline and polycrystalline silicon) and a specially developed controller are considered. 相似文献
100.
C. G. Prosgolitis S. G. Lambrakos A. D. Zervaki 《Journal of Materials Engineering and Performance》2018,27(10):5102-5113
This work presents simulation of microstructure evolution in the nugget zone (NZ) of a AZ31-Mg-alloy friction stir weld. The process parameters (tool geometrical characteristics, rotational speed, travel speed, applied load) have been correlated with the resulting microstructural features in the NZ of the weld (grain size and population) with the aid of the MICRESS software, which provides the ability to simulate both nucleation and grain growth during dynamic recrystallization phenomena evolving in the NZ during the weld thermal cycle. The input parameters of the developed model include the tool geometry, the welding conditions as well as the recrystallization energy, the grain boundary mobility and specific material properties. NZ microstructure obtained by simulation shows good agreement with experimental measurements for both grain population and size. 相似文献