全文获取类型
收费全文 | 65831篇 |
免费 | 5322篇 |
国内免费 | 2925篇 |
专业分类
电工技术 | 3895篇 |
技术理论 | 7篇 |
综合类 | 4349篇 |
化学工业 | 11258篇 |
金属工艺 | 3619篇 |
机械仪表 | 3981篇 |
建筑科学 | 5579篇 |
矿业工程 | 1898篇 |
能源动力 | 1906篇 |
轻工业 | 4168篇 |
水利工程 | 1203篇 |
石油天然气 | 4590篇 |
武器工业 | 461篇 |
无线电 | 7222篇 |
一般工业技术 | 8121篇 |
冶金工业 | 3166篇 |
原子能技术 | 729篇 |
自动化技术 | 7926篇 |
出版年
2024年 | 242篇 |
2023年 | 1088篇 |
2022年 | 1836篇 |
2021年 | 2553篇 |
2020年 | 1969篇 |
2019年 | 1701篇 |
2018年 | 1921篇 |
2017年 | 2137篇 |
2016年 | 1955篇 |
2015年 | 2421篇 |
2014年 | 3259篇 |
2013年 | 3715篇 |
2012年 | 4143篇 |
2011年 | 4507篇 |
2010年 | 3933篇 |
2009年 | 3771篇 |
2008年 | 3674篇 |
2007年 | 3586篇 |
2006年 | 3654篇 |
2005年 | 3129篇 |
2004年 | 2144篇 |
2003年 | 1927篇 |
2002年 | 1696篇 |
2001年 | 1648篇 |
2000年 | 1690篇 |
1999年 | 1804篇 |
1998年 | 1419篇 |
1997年 | 1189篇 |
1996年 | 1078篇 |
1995年 | 963篇 |
1994年 | 792篇 |
1993年 | 572篇 |
1992年 | 452篇 |
1991年 | 344篇 |
1990年 | 318篇 |
1989年 | 232篇 |
1988年 | 175篇 |
1987年 | 113篇 |
1986年 | 110篇 |
1985年 | 65篇 |
1984年 | 43篇 |
1983年 | 31篇 |
1982年 | 34篇 |
1981年 | 22篇 |
1980年 | 15篇 |
1979年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
对上海市地铁列车中的三种不同车型的微机控制系统的总线进行分析与研究,并针对近年总线通信中出现的问题,提出改进方法。 相似文献
132.
133.
A method for observing the three-dimensional morphologies of inclusions by deeply eroding a steel sample with a kind of organic solution composed of bromine water,acetone,and HC1 (volume ratio,45∶45∶10... 相似文献
134.
In this paper, we consider the partial pole assignment problem (PPAP) for high order control systems. It is shown that solving the PPAP is essentially solving a pole assignment for a linear system of a much lower order, and the robust PPAP is then concerning the robust pole assignment problem for this linear system. Based on this theory, a rather simple algorithm for solving the robust PPAP is proposed, and numerical examples show that this algorithm does lead to comparable results with earlier algorithms, but at much lower computational cost. 相似文献
135.
Jun-Qiu Jiang Kun Wang Xue-Xuan Peng Qing-Liang Zhao Yun-Shu Zhang Xiu-Dong Zhou 《哈尔滨工业大学学报(英文版)》2013,20(4):1-6
This paper compared the degradation efficiency of sludge organic matters and electric-production by two typical microbial fuel cells——dual-chamber microbial fuel cell(DMFC)and single chamber air cathode microbial fuel cell(SAMFC),and the variations of sludge protein,polysaccharide and ammonia nitrogen within the systems were also investigated.The results showed that the concentration of sludge soluble chemical oxygen demand,protein and carbohydrate of DMFC are higher than these of SAMFC during the systems operation,while DMFC can achieve a better ammonia nitrogen removal than SAMFC.Under the same operation condition,the stable voltage output of DMFC and SAMFC is 0.61 V and 0.37 V;the maximum power density of DMFC and SAMFC is 2.79 W/m3and 1.25 W/m3;TCOD removal efficiency of DMFC and SAMFC is 34.14%and 28.63%for 12 d,respectively.Meanwhile,DMFC has a higher coulomb efficiency than SAMFC,but both are less than5%.The results showed that DMFC present a better performance on sludge degradation and electric-production. 相似文献
136.
孟政 《武汉理工大学学报(材料科学英文版)》2013,28(1):79-81
The oxidation state of sulfur is detected in Na2O-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure (XANES) spectra at the sulfur K edge. The measured spectra show the only presence of S6+ in the Na2O-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S6+ is the dominant species, but S2- is also present on both surfaces. It is not certain whether cation bonds to S2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated. 相似文献
137.
138.
应用Menke条件,在改性高岭土固体酸催化下,甲苯能被浓硝酸对位选择性硝化,表现在对邻硝化产物比例达到1.5。 相似文献
139.
Obituaries
Grigorii Valentinovich Samsonov 相似文献140.
Yun Ye Yadong Jiang Junsheng Yu Zhiming Wu Hongjuan Zeng 《Journal of Materials Science: Materials in Electronics》2006,17(12):1005-1009
Interface changes induced by electric poling treatment between an Ag electrode deposited by vacuum thermal evaporation and a polymer thin film have been investigated. The polymer film poly (vinylidene fluoride) (PVDF), a fluoropolymer of repeat unit (–CH2–CF2–) was treated under electric poling at high temperature of 90°C. The characterization was accomplished using X-ray photoelectron spectroscopy (XPS) as a primary tool. The results indicate that the piezoelectricity of PVDF thin films and adhesion force between polymer thin film and metallic electrode are improved by electric poling and chemical bond joint. 相似文献