全文获取类型
收费全文 | 460457篇 |
免费 | 5242篇 |
国内免费 | 1404篇 |
专业分类
电工技术 | 8864篇 |
综合类 | 394篇 |
化学工业 | 66824篇 |
金属工艺 | 21913篇 |
机械仪表 | 17541篇 |
建筑科学 | 9495篇 |
矿业工程 | 2737篇 |
能源动力 | 12028篇 |
轻工业 | 29394篇 |
水利工程 | 5116篇 |
石油天然气 | 8820篇 |
武器工业 | 17篇 |
无线电 | 54422篇 |
一般工业技术 | 97647篇 |
冶金工业 | 79119篇 |
原子能技术 | 9863篇 |
自动化技术 | 42909篇 |
出版年
2022年 | 2550篇 |
2021年 | 3882篇 |
2020年 | 2942篇 |
2019年 | 3803篇 |
2018年 | 12830篇 |
2017年 | 13233篇 |
2016年 | 10623篇 |
2015年 | 4717篇 |
2014年 | 7206篇 |
2013年 | 20071篇 |
2012年 | 13442篇 |
2011年 | 21740篇 |
2010年 | 18427篇 |
2009年 | 18945篇 |
2008年 | 19285篇 |
2007年 | 20637篇 |
2006年 | 12462篇 |
2005年 | 13887篇 |
2004年 | 12018篇 |
2003年 | 11687篇 |
2002年 | 10362篇 |
2001年 | 9779篇 |
2000年 | 9253篇 |
1999年 | 9532篇 |
1998年 | 24329篇 |
1997年 | 16709篇 |
1996年 | 12810篇 |
1995年 | 9526篇 |
1994年 | 8384篇 |
1993年 | 8398篇 |
1992年 | 6069篇 |
1991年 | 5716篇 |
1990年 | 5679篇 |
1989年 | 5317篇 |
1988年 | 5050篇 |
1987年 | 4419篇 |
1986年 | 4299篇 |
1985年 | 4812篇 |
1984年 | 4421篇 |
1983年 | 3994篇 |
1982年 | 3654篇 |
1981年 | 3730篇 |
1980年 | 3429篇 |
1979年 | 3326篇 |
1978年 | 3334篇 |
1977年 | 3750篇 |
1976年 | 4847篇 |
1975年 | 2850篇 |
1974年 | 2663篇 |
1973年 | 2730篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
The separation of iron oxide from banded hematite jasper(BHJ) assaying 47.8% Fe, 25.6% Si O2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite,jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. Beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade BHJ iron ore under appropriate conditions. 相似文献
52.
53.
54.
55.
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
56.
57.
58.
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
59.
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
60.