全文获取类型
收费全文 | 8658篇 |
免费 | 1105篇 |
国内免费 | 379篇 |
专业分类
电工技术 | 298篇 |
综合类 | 376篇 |
化学工业 | 3663篇 |
金属工艺 | 576篇 |
机械仪表 | 208篇 |
建筑科学 | 206篇 |
矿业工程 | 263篇 |
能源动力 | 878篇 |
轻工业 | 751篇 |
水利工程 | 38篇 |
石油天然气 | 931篇 |
武器工业 | 20篇 |
无线电 | 627篇 |
一般工业技术 | 773篇 |
冶金工业 | 322篇 |
原子能技术 | 70篇 |
自动化技术 | 142篇 |
出版年
2024年 | 20篇 |
2023年 | 301篇 |
2022年 | 293篇 |
2021年 | 370篇 |
2020年 | 419篇 |
2019年 | 341篇 |
2018年 | 281篇 |
2017年 | 326篇 |
2016年 | 354篇 |
2015年 | 376篇 |
2014年 | 478篇 |
2013年 | 486篇 |
2012年 | 619篇 |
2011年 | 689篇 |
2010年 | 527篇 |
2009年 | 524篇 |
2008年 | 436篇 |
2007年 | 534篇 |
2006年 | 392篇 |
2005年 | 312篇 |
2004年 | 276篇 |
2003年 | 321篇 |
2002年 | 262篇 |
2001年 | 240篇 |
2000年 | 190篇 |
1999年 | 165篇 |
1998年 | 119篇 |
1997年 | 90篇 |
1996年 | 80篇 |
1995年 | 54篇 |
1994年 | 60篇 |
1993年 | 49篇 |
1992年 | 33篇 |
1991年 | 41篇 |
1990年 | 22篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
31.
32.
Jale Müslehiddinolu Paul Lobben Simon Leung Lori Spangler San Kiang 《Catalysis Today》2007,123(1-4):164-170
Hydrogenolysis of a carbobenzyloxy group (CBz) was studied utilizing molecular hydrogen in the presence of carbon-supported palladium catalyst. It was demonstrated that the kinetics of the reaction are greatly influenced by the presence of the CO2 by-product. It was found out that the presence of CO2 determines whether the reaction is first or zero order since it causes deactivation of the catalyst via inhibition. The effect of potassium carbonate (K2CO3) and triethylamine (TEA) as additives was investigated. A considerable solvent effect was also observed that may be explained by the variation of dispersion of the catalyst from one solvent to another. 相似文献
33.
一氧化碳对聚丙烯收率、结构的影响 总被引:1,自引:0,他引:1
胡蔚鸽 《石油化工安全环保技术》2002,18(4):32-33
分析研究了Montell(Himont)聚丙烯工艺中CO对聚丙烯收率、产品结构的影响。 相似文献
34.
35.
36.
A novel annular reactor for kinetic studies at high temperature and flow conditions has been designed to keep eccentricity tolerances below 10%. In a previous work, we have shown that it is very important to keep such low eccentricity values in order to collect reliable kinetic data from this type of reactors. As proposed in this study, a modified reactor with the use of a spacer could guarantee an annular duct with low levels of eccentricity. Manufacturing tolerances or deformation effects giving rise to eccentricity can be significantly minimised when using this apparatus. The reactor has been both experimentally and theoretically characterised. Carbon monoxide oxidation was used as a model reaction under mass-transfer limited conditions revealing an eccentricity of ∼5%. With such small eccentricity levels, a concentric annular form can be assumed in the reactor analysis. Simple 1D or 2D models can therefore be inexpensively used in the evaluation of the kinetic data. Also, prior to the design of the annular reactor, a numerical investigation was carried out to clarify the effects of eccentricity, physical properties of the carrier gas and the annular aspect ratio on mass-transfer limitations. Contrary to expectations, a considerable increase in the fuel mass-diffusivity by carrier gas substitution did not change the mass-transfer rates for cases when eccentricity and aspect ratios were high. 相似文献
37.
38.
39.
In the pulp and paper industry, during major modernization projects the overall energy system consequences are often not estimated in detail, usually only local energy consequences are taken into account when evaluating possible projects. In this paper, the effects on the overall energy system when installing an advanced delignification process (i.e., a “state‐of‐the‐art” pulp digester and oxygen delignification process) will be presented. Also, the effect such an installation has on the potential for further energy integration is discussed. Furthermore, the CO2 consequences for both installing such a system and integrating the mill further energy‐wise are presented. 相似文献
40.
A spatially resolved infrared (IR) imaging technique to monitor the linear adsorbed CO coverage on supported catalyst surface combining an IR bandpass filter and an IR thermography camera has been developed. Images acquired during the CO adsorption/desorption and ignition indicate that the technique provides an excellent method to image the change of surface coverage with a spatial resolution. It is expected that the combination of infrared thermography with spatially resolved imaging of surface coverage will provide a deeper insight in the dynamics of spatio-temporal patterns on heterogeneous catalysts. 相似文献