全文获取类型
收费全文 | 359817篇 |
免费 | 4687篇 |
国内免费 | 1005篇 |
专业分类
电工技术 | 7370篇 |
综合类 | 1600篇 |
化学工业 | 55597篇 |
金属工艺 | 12791篇 |
机械仪表 | 11055篇 |
建筑科学 | 9867篇 |
矿业工程 | 1484篇 |
能源动力 | 9215篇 |
轻工业 | 33526篇 |
水利工程 | 3189篇 |
石油天然气 | 4888篇 |
武器工业 | 24篇 |
无线电 | 45940篇 |
一般工业技术 | 67136篇 |
冶金工业 | 62068篇 |
原子能技术 | 5935篇 |
自动化技术 | 33824篇 |
出版年
2022年 | 4512篇 |
2021年 | 5975篇 |
2020年 | 4455篇 |
2019年 | 5667篇 |
2018年 | 4882篇 |
2017年 | 4291篇 |
2016年 | 4124篇 |
2015年 | 3071篇 |
2014年 | 5044篇 |
2013年 | 15509篇 |
2012年 | 8330篇 |
2011年 | 12173篇 |
2010年 | 9547篇 |
2009年 | 10878篇 |
2008年 | 10750篇 |
2007年 | 10719篇 |
2006年 | 9607篇 |
2005年 | 9064篇 |
2004年 | 9962篇 |
2003年 | 9568篇 |
2002年 | 9461篇 |
2001年 | 9192篇 |
2000年 | 8314篇 |
1999年 | 8466篇 |
1998年 | 18469篇 |
1997年 | 13584篇 |
1996年 | 10666篇 |
1995年 | 8388篇 |
1994年 | 7827篇 |
1993年 | 7376篇 |
1992年 | 5747篇 |
1991年 | 5375篇 |
1990年 | 5271篇 |
1989年 | 5248篇 |
1988年 | 5049篇 |
1987年 | 4158篇 |
1986年 | 4424篇 |
1985年 | 5093篇 |
1984年 | 4543篇 |
1983年 | 4409篇 |
1982年 | 3920篇 |
1981年 | 4027篇 |
1980年 | 3642篇 |
1979年 | 3599篇 |
1978年 | 3480篇 |
1977年 | 4112篇 |
1976年 | 5071篇 |
1975年 | 3033篇 |
1974年 | 2855篇 |
1973年 | 2812篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Fischer-Tropsch synthesis of the CO2 in biogas aims at producing light hydrocarbons and increasing its calorific value for feeding into the grid. Fe catalysts with Mn and K as promoters are supposed to yield high amounts of light hydrocarbons. Using a Fe-Mn-K/MgO catalyst, a parameter screening and long-term experiments were carried out. The catalyst shows, within the examined range, the highest selectivity to C2–C4 hydrocarbons at 450 °C, 8 bar(a), and a gas hourly space velocity of 350 h−1. Calcination of the catalyst resulted in a significant drop of activity and an almost complete loss of selectivity to hydrocarbons. Admixture of steam to the reactant gas lowers the tendency to carbon deposition but also promotes the water-gas shift reaction and results in lower yields of hydrocarbons. 相似文献
2.
Ivashchuk O. A. Ivashchuk O. D. Fedorov V. I. Shtana A. I. 《Russian Engineering Research》2020,40(11):970-972
Russian Engineering Research - Models based on regression analysis for predicting the operational efficiency of high-pressure roller crushers are considered. A systematized and structured... 相似文献
3.
Popov N. N. Presnyakov D. V. Lar’kin V. F. 《Journal of Machinery Manufacture and Reliability》2020,49(3):232-236
Journal of Machinery Manufacture and Reliability - A device based on smart alloys has been designed for use in machine building items, in particular, in nuclear engineering, for preventing... 相似文献
4.
Bakirov Zh. B. Tanirbergenova A. A. 《Journal of Machinery Manufacture and Reliability》2020,49(3):263-271
Journal of Machinery Manufacture and Reliability - The problem of calculating the reliability and fatigue life of machine parts by the fatigue failure under random changes in the actual and limit... 相似文献
5.
6.
One specific class of non-linear evolution equations, known as the Tzitzéica-type equations, has received great attention from a group of researchers involved in non-linear science. In this article, new exact solutions of the Tzitzéica-type equations arising in non-linear optics, including the Tzitzéica, Dodd–Bullough–Mikhailov and Tzitzéica–Dodd–Bullough equations, are obtained using the expa function method. The integration technique actually suggests a useful and reliable method to extract new exact solutions of a wide range of non-linear evolution equations. 相似文献
7.
Salim Hengky K. Padfield Rory Lee Chew Tin Syayuti Khadijah Papargyropoulou Effie Tham Mun Hou 《Clean Technologies and Environmental Policy》2018,20(3):529-538
Clean Technologies and Environmental Policy - Food production and consumption is one of the major causes of global environmental degradation. One way to address environmental impacts in the food... 相似文献
8.
Kobrakov K. I. Kurnetsov D. N. Ruchkina A. G. Sharpar N. M. 《Theoretical Foundations of Chemical Engineering》2020,54(5):1052-1056
Theoretical Foundations of Chemical Engineering - New research results, as well as those published earlier by the authors, on the synthesis of azo compounds based on nitroanilines obtained by the... 相似文献
9.
Gomes A. C. S. A. Costa L. C. Brito D. C. Frana R. J. Marques Mnica R. C. 《Polymer Bulletin》2020,77(4):1969-1981
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with... 相似文献
10.
Theoretical Foundations of Chemical Engineering - The extraction of nitric and oxalic acids by neutral compounds TBP, DBBP, and TBPO have been studied. The optimal conditions of their separation... 相似文献