全文获取类型
收费全文 | 38755篇 |
免费 | 2641篇 |
国内免费 | 1557篇 |
专业分类
电工技术 | 650篇 |
技术理论 | 1篇 |
综合类 | 2593篇 |
化学工业 | 21472篇 |
金属工艺 | 1479篇 |
机械仪表 | 812篇 |
建筑科学 | 460篇 |
矿业工程 | 417篇 |
能源动力 | 849篇 |
轻工业 | 1551篇 |
水利工程 | 113篇 |
石油天然气 | 2099篇 |
武器工业 | 398篇 |
无线电 | 1815篇 |
一般工业技术 | 5217篇 |
冶金工业 | 839篇 |
原子能技术 | 172篇 |
自动化技术 | 2016篇 |
出版年
2024年 | 61篇 |
2023年 | 395篇 |
2022年 | 579篇 |
2021年 | 879篇 |
2020年 | 800篇 |
2019年 | 725篇 |
2018年 | 745篇 |
2017年 | 928篇 |
2016年 | 1105篇 |
2015年 | 1153篇 |
2014年 | 1951篇 |
2013年 | 1959篇 |
2012年 | 2466篇 |
2011年 | 2961篇 |
2010年 | 2258篇 |
2009年 | 2476篇 |
2008年 | 2082篇 |
2007年 | 2707篇 |
2006年 | 2456篇 |
2005年 | 2256篇 |
2004年 | 1845篇 |
2003年 | 1744篇 |
2002年 | 1552篇 |
2001年 | 1307篇 |
2000年 | 1119篇 |
1999年 | 922篇 |
1998年 | 753篇 |
1997年 | 548篇 |
1996年 | 463篇 |
1995年 | 378篇 |
1994年 | 343篇 |
1993年 | 252篇 |
1992年 | 185篇 |
1991年 | 129篇 |
1990年 | 124篇 |
1989年 | 64篇 |
1988年 | 53篇 |
1987年 | 43篇 |
1986年 | 27篇 |
1985年 | 31篇 |
1984年 | 35篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1981年 | 14篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1975年 | 2篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
71.
论述了负压法(射流法)回收治理液氨尾气的环保安全工艺技术、原理;解决了目前一直沿用的正压法无法解决的棘手问题。 相似文献
72.
73.
场激活加压燃烧合成WC-Ni复合材料的工艺参数研究 总被引:1,自引:0,他引:1
以钨、碳和镍为原料,在电场激活下,材料的燃烧合成和致密化同时进行,短时间内完成了碳化钨镍复合材料的制备。研究了场激活 加压燃烧合成中的工艺参数,如脉冲电流、能量控制模式、升温速率、最高温度和压力对反应的影响。测量了在反应合成和致密化前后的样品 收缩率。所制备的复合材料的相对密度,490N载荷下Vickers硬度和断裂韧性分别为99.2%,13.965GPa和5.9MP·m1/2。 相似文献
74.
A novel milk-like Cu-thiourea colloid has been synthesized. Nanocrystalline quaternary copper sulfide Cu2FeSnS4 was obtained through the Cu-thiourea colloidal precursor cooperative conversion route at low temperature. The samples were characterized by means of X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, and X-ray energy dispersive spectroscopy techniques. The reaction details and features were described and discussed. 相似文献
75.
Thin layers of ceria were deposited on the surface of mica platelets in solution. The reaction of such particles with hydrogen sulfide yields a red colored special effect pigment. The ceria layer reacts with H2S to produce a variety of sulfide and oxysulfide phases. The reaction path discovered in situ by time and temperature resolved X-ray diffraction is CeO2→CeS2→C-Ce2S3→Ce10S14O. The reaction itself is extremely variable depending on gas flow, heating rates and decomposition atmospheres. Effects on the thin film are recorded by scanning electron microscopy (SEM) and revealed a destruction of the layer once red Ce10S14O was formed. The product layer then reveals the typical nonwetting behaviour of a liquid on a surface. 相似文献
76.
K Madhusudan Reddy Sunkara V Manorama R.D.K Misra 《Materials Research Bulletin》2004,39(10):1491-1498
A comparative study of gas sensing behavior of nanocrystalline nickel ferrite synthesized by micro-emulsion and hydrothermal method to liquefied petroleum gas (LPG) is presented. Nanocrystalline nickel ferrite synthesized by hydrothermal method indicated higher electrical conductivity and gas sensitivity at low operating temperature compared to nanocrystalline nickel ferrite synthesized by reverse micelle technique. This difference in the gas sensing behavior can be attributed to the presence of more oxygen vacancies (i.e. non-stoichiometry) in the hydrothermally synthesized nickel ferrite. Incorporation of palladium had a catalytic effect and the operating temperature was significantly reduced in both the samples. The higher operating temperature of the reverse micelle nickel ferrite material makes the sensor response speed faster (∼10 s) compared to the hydrothermally synthesized material (∼1 min). 相似文献
77.
The thick film of Zn-Sb-O was prepared by coating the paste of nanoparticles mixture (Sb2O3:ZnO=1:3) on the alumina substrate, followed by sintering at 500-900 °C for 2 h in air. The electrical resistance and gas-sensing properties to benzene, alcohol and acetone of Zn-Sb-O films were found to be dependent on the change of phase structure caused by sintering temperature. 相似文献
78.
G. N. Churilov R. B. Weisman N. V. Bulina N. G. Vnukova A. P. Puzir L. A. Solovyov S. M. Bachilo D. A. Tsyboulski G. A. Glushenko 《Fullerenes, Nanotubes and Carbon Nanostructures》2003,11(4):371-382
The addition of metallic Ir and Pt to a fullerene-forming, atmospheric-pressure plasma reactor was found to influence the generation of carbonaceous products. It was observed that the added metals were efficiently dispersed into the plasma and that their presence increased the yield of fullerenes. The addition of Ir led to a noticeable shift in the fullerene distribution towards C60, whereas the addition of Pt increased the proportion of C60 oxides and decreased the proportion of higher fullerenes. Addition of Ir also caused a reduction of the soot particle size and the formation of a considerable quantity of carbon nanotubes. 相似文献
79.
80.
高纯铝箔通常通过电化学扩面后用作铝电解电容器的阳极材料。利用铝箔(100)面隧道孔制备纳米模板。这种纳米模板的特点是制作简单、模板面积大,纳米阵列材料形状可控性强。还利用两步电化学侵蚀铝箔的特殊工艺,研制出纵横交错的TiO2纳米有序阵列材料。 相似文献