全文获取类型
收费全文 | 12302篇 |
免费 | 214篇 |
国内免费 | 190篇 |
专业分类
电工技术 | 145篇 |
技术理论 | 1篇 |
综合类 | 248篇 |
化学工业 | 4453篇 |
金属工艺 | 576篇 |
机械仪表 | 257篇 |
建筑科学 | 237篇 |
矿业工程 | 133篇 |
能源动力 | 989篇 |
轻工业 | 741篇 |
水利工程 | 37篇 |
石油天然气 | 312篇 |
武器工业 | 22篇 |
无线电 | 414篇 |
一般工业技术 | 2819篇 |
冶金工业 | 229篇 |
原子能技术 | 723篇 |
自动化技术 | 370篇 |
出版年
2024年 | 3篇 |
2023年 | 120篇 |
2022年 | 156篇 |
2021年 | 218篇 |
2020年 | 228篇 |
2019年 | 273篇 |
2018年 | 228篇 |
2017年 | 224篇 |
2016年 | 205篇 |
2015年 | 204篇 |
2014年 | 538篇 |
2013年 | 1124篇 |
2012年 | 575篇 |
2011年 | 1225篇 |
2010年 | 755篇 |
2009年 | 793篇 |
2008年 | 688篇 |
2007年 | 669篇 |
2006年 | 604篇 |
2005年 | 531篇 |
2004年 | 487篇 |
2003年 | 435篇 |
2002年 | 377篇 |
2001年 | 244篇 |
2000年 | 244篇 |
1999年 | 215篇 |
1998年 | 199篇 |
1997年 | 190篇 |
1996年 | 151篇 |
1995年 | 150篇 |
1994年 | 102篇 |
1993年 | 95篇 |
1992年 | 72篇 |
1991年 | 59篇 |
1990年 | 44篇 |
1989年 | 44篇 |
1988年 | 46篇 |
1987年 | 36篇 |
1986年 | 27篇 |
1985年 | 21篇 |
1984年 | 19篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 22篇 |
1980年 | 14篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1972年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
A.L. Pan H.G. ZhengZ.P. Yang F.X. Liu Z.J. Ding Y.T. Qian 《Materials Research Bulletin》2003,38(5):789-796
Small Ag particles or clusters dispersed mesoporous SiO2 composite films were prepared by a new method: First the matrix SiO2 films were prepared by sol-gel process combined with the dip-coating technique, then they were soaked in AgNO3 solutions followed by irradiation of γ-ray at room temperature and in ambient pressure. The structures of these films were examined by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and optical absorption spectroscopy. It has been shown that the Ag particles grown within the porous SiO2 films are very small, and they are isolated and dispersed from each other with very narrow size distributions. With increasing the soaking concentration and an additional annealing, an opposite peakshift effect of the surface plasmon resonance (SPR) was observed in the optical absorption measurements. 相似文献
3.
CMP系统技术与市场 总被引:3,自引:1,他引:2
葛劢冲 《电子工业专用设备》2003,32(1):17-24
概述了CMP系统技术的发展历史、发展趋势以及在IC生产中的重要性,介绍了国外CMP设备主要制造厂家的设备型号和性能及CMP设备市场分布和需求,阐述了CMP系统技术的基础研究、关键技术和国内研究概况。 相似文献
4.
Over the last five years, many activities have focused on the unexploited field of carrying out reactions on small scales. Due to the rapid development of new components, this paper deals with recent developments only in a compressed form. An important point is the analysis of possible plant concepts for microreactors and whether these are a sensible option. Due to the enormous difference in size between the microchannels and the fluid periphera of possible components this is not just a technical question. It touches on the microtechnology concept as a whole. The direction in which the field should be developed and which measures can be taken to influence its development are questions that are addressed here with respect to the big industrial interest in microreactors. 相似文献
5.
Particles and gases can deposit from the atmosphere to polar snow by several mechanisms. Dry deposition can be considered to consist of three steps: aerodynamic transport from the free atmosphere to the viscous sublayer near the surface, boundary layer transport across the sublayer, and interactions with the surface. The particle dry deposition mass flux is dominated by the largest particles present in a size distribution. Wet deposition includes in-cloud and below-cloud scavenging, where the former refers to uptake of particles during nucleation of cloudwater as well as scavenging of particles and gases by existing droplets and ice crystals. Of all the wet deposition mechanisms, nucleation scavenging is often the most important mechanism for particles in the polar regions. Finally, incorporation of particles and gases into fog droplets and subsequent settling of the fog to the snow surface can be an important removal process in regions of frequent fog. For Summit, Greenland, the total deposition of MSA, SO42-, Na+, K+, and Ca2+ during May 24-July 13, 1993 was dominated by wet deposition: this mechanism accounted for an average of 62% of the total deposition for these species. Fog and dry deposition accounted for 21% and 17% of the total, respectively. These results suggest that all three mechanisms may need to be considered when estimating total deposition of certain chemical species to polar snow. 相似文献
6.
腈纶纤维上油率的稳定控制 总被引:1,自引:0,他引:1
从油剂泵、皮辊和钢罗拉等设备构件运行状态考虑,探讨了腈纶纤维上油率的稳定控制问题。 相似文献
7.
In order to enhance product yields in selective oxidation reactions, numerous reaction engineering concepts are being studied worldwide. Periodic operation has been investigated for decades, yet its application is limited to a few examples, such as the butane oxidation after DuPont or reverse-flow reactors for VOC removal. The use of microchannel reactors is a younger field, but it has already yielded promising results for process optimization. Catalytic wall reactors have proved to be a helpful tool for kinetic studies. On the laboratory scale, membrane reactors have displayed favorable behavior in selective oxidation. The Na vapor-catalyzed dehydrogenation of methanol to formaldehyde is a final example of an unusual new concept for selective oxidation. 相似文献
8.
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
9.
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
10.
C. Athanassiou G. Pekridis N. Kaklidis K. Kalimeri S. Vartzoka G. Marnellos 《International Journal of Hydrogen Energy》2007
In the present work, the prospects and trends of solid electrolyte membrane reactors (SEMRs) towards hydrogen production, are discussed. Initially, an overview of the principles, the properties and the techniques related to the usage of the SEMRs, are presented. In the following, a literature survey covering earlier and recent developments of the various methods (e.g. reforming or partial oxidation or dehydrogenation of hydrocarbons, steam electrolysis) employed in the SEMRs for the production of hydrogen, is performed. Finally, the current status of this research field is analyzed and future research topics are proposed. 相似文献