全文获取类型
收费全文 | 161篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 72篇 |
金属工艺 | 12篇 |
机械仪表 | 3篇 |
能源动力 | 17篇 |
轻工业 | 31篇 |
石油天然气 | 2篇 |
武器工业 | 2篇 |
无线电 | 11篇 |
一般工业技术 | 18篇 |
冶金工业 | 1篇 |
自动化技术 | 3篇 |
出版年
2023年 | 24篇 |
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 12篇 |
2019年 | 10篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 9篇 |
2014年 | 16篇 |
2013年 | 15篇 |
2012年 | 21篇 |
2011年 | 7篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 6篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1997年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有173条查询结果,搜索用时 15 毫秒
1.
采用固定床反应器分别探究了三类催化剂(固体磷酸催化剂、酸性阳离子交换树脂催化剂以及分子筛催化剂)对异丁烯齐聚过程的影响。实验结果表明:固体磷酸催化剂适用于C8烯烃的生产,酸性阳离子树脂催化剂及改性的分子筛催化剂(Hβ)适合生产C12烯烃。异丁烯齐聚产物C8~C16(清洁燃料油)因无芳烃、无硫,在石化工业中具有非常广泛的应用潜力;由三种类催化剂的评价结果来看,C8~C16的选择性最高时均能接近100%,但是固体磷酸催化剂和酸性阳离子树脂催化剂的异丁烯原料转化率比Hβ分子筛催化剂低,Hβ催化作用下异丁烯转化率可以达到88%。 相似文献
2.
《Carbon》2014
Ag nanoparticles (Ag NPs) supported on nitrogen-doped ordered mesoporous carbon (N-OMC) were fabricated by one-pot synthesis strategy, in which 2D hexagonally ordered mesoporous SBA-15 and aniline were used as template and carbon precursor, respectively. Furthermore, the as-prepared composite of Ag NPs supported on N-OMC (Ag NPs/N-OMC) as electrochemical sensor towards the reduction of nitrobenzene (NB) was investigated, which displayed high sensitivity, fast response and good stability. The peak current of NB increased linearly with the concentration of NB in the range from 6.62 × 10−8 to 2.60 × 10−7 mol/L and 7.97 × 10−7 to 1.12 × 10−6 mol/L, and the low detection limit of 6.61 × 10−9 mol/L (S/N = 3) was obtained. Therefore, this work provides a new pathway to design and fabricate novel N-OMC composites, which have unique characteristics and hold numerous applications in the fields of sensors, electrocatalysis and others. 相似文献
3.
4.
Shuo Li Jianlin Cao Xiang Feng Yupeng Du De Chen Chaohe Yang Wenhua Wang Wanzhong Ren 《中国化学工程学报》2022,47(7):174-184
Elucidating the confinement effect harbours tremendous significance for isobutane alkylation with C4 olefin. Herein, the confinement effect over zeolite catalysts was elucidated by combining DFT calculations, experiments (using the novel Beta zeolite exposing only external surfaces (Beta-E) and conventional Beta-I zeolite with both external and internal surfaces) and multi-techniques (e.g., TGA-DTG, HRTEM, SEM and XRD). It is found that the main active sites for C4 alkylation reaction are located on internal surface rather than external surface. On the external surface, the hydride transfer reaction does not occur because the H-shared intermediate cannot be formed without the confinement effect. Moreover, the external surface has stronger selectivity for C4 olefin adsorption than isobutane, leading to enhanced oligomerization reactions. Therefore, the suitable micropore with confinement effect is essential for zeolite-catalyzed C4 alkylation. The atomic-scale insights of this work are of great referential importance to the design of highly effective zeolite catalyst. 相似文献
5.
《Ceramics International》2016,42(3):4556-4561
Eu-doped Ca-α-SiAlON phosphors, featuring high phase purity, uniform particle size of 3–5 μm and good luminescent properties with a yellow emission spectrum under blue light excitation, were prepared by a highly efficient combustion synthesis (CS) method. A certain amount of NaCl was applied as an innovative additive to regulate and control the properties of synthesized phosphors. Further, the effects of NaCl additive in the CS system were systematically investigated and rational proposed. It was found that the effect on accelerating nitridation and crystallization played a dominant role in the reaction as the content of NaCl was less than 6 wt%, while the effect of absorbing reaction heat through vaporization was dominant with the further-increased content of NaCl. The intensity of the emission spectrum for the sample doped with 6 wt% of NaCl was remarkably enhanced, nearly 40% more than the sample which was not NaCl-doped. Moreover, a continuous blue-shift phenomenon in emission spectra was observed with the increased content of NaCl. 相似文献
6.
Synthesis and luminescence properties of LiInO2 nanocrystals by the sol–gel process were investigated. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectroscopy and absorption spectra. The well-crystallized tetragonal LiInO2 can be obtained by heat treatment above 600 °C from XRD. The excitation wavelengths at about 246 nm were associated with charge transfer between In and O with In3+ ions in octahedral coordination. The PL spectra excited at 246 nm have a broad and strong emission band maximum at 391 nm, corresponding to the self-activated luminescence. The optical absorption spectra of the 600 °C sample exhibited the band gap energies of 3.7 eV. 相似文献
7.
Y. Balcaen N. Radutoiu J. Alexis J.-D. Beguin L. Lacroix D. Samélor C. Vahlas 《Surface & coatings technology》2011,206(7):1684-1690
This study focuses on the implementation of different aluminum oxide coatings processed by metal-organic chemical vapor deposition from aluminum tri-isopropoxide on commercial Ti6Al4V titanium alloy to improve its high temperature corrosion resistance. Films grown at 350 °C and at 480 °C are amorphous and correspond to formulas AlOOH, and Al2O3, respectively. Those deposited at 700 °C are composed of γ-Al2O3 nanocrystals dispersed in a matrix of amorphous alumina. Their mechanical properties and adhesion to the substrates were investigated by indentation, scratch and micro tensile tests. Hardness and rigidity of the films increase with increasing deposition temperature. The hardness of the coatings prepared at 350 °C and 480 °C is 5.8 ± 0.7 GPa and 10.8 ± 0.8 GPa respectively. Their Young's modulus is 92 ± 8 GPa (350 °C) and 155 ± 6 GPa (480 °C). Scratch tests cause adhesive failures of the films grown at 350 °C and 480 °C whereas cohesive failure is observed for the nanocrystalline one, grown at 700 °C. Micro tensile tests show a more progressive cracking of the latter films than on the amorphous ones. The films allow maintaining good mechanical properties after corrosion with NaCl deposit during 100 h at 450 °C. After corrosion test only the film deposited at 700 °C yields an elongation at break comparable to that of the as processed samples without corrosion. The as established processing–structure–properties relation paves the way to engineer MOCVD aluminum oxide complex coatings which meet the specifications of the high temperature corrosion protection of titanium alloys with regard to the targeted applications. 相似文献
8.
Ternary alloys of CdS1−xSex (x=0, x=0.2, x=0.4, x=0.6, x=0.8, x=1) thin films were prepared on to glass substrates by a simple and economical soft chemical route (chemical bath deposition) at 50° to 80 °C in air. The as-grown films were characterized by optical and electrical measurement systems, X-ray diffraction (XRD), Energy dispersive X-ray analysis (EDAX) and SEM (scanning electron microscopy). The optical study reveals shift in the absorption edge towards the higher wavelengths, i.e. the band gap decreases as a function of ‘x’ (quantity of selenium in the bath). I–V measurement of CdS (resulted when x=0), CdS1−xSex (x=0.2, x=0.4, x=0.6, x=0.8) and CdSe (resulted when x=1) thin films under dark and illumination conditions (60 W) were measured. Increase in photoconductivity is observed, suggesting its applicability in photosensor devices. Electrical resistivity shows semiconducting behavior and activation energy decreases. The XRD patterns reveals that deposited thin films have hexagonal mixed structure. EDAX confirmed the compositional parameters. SEM images showed uniform deposition of the material over the entire glass substrate. 相似文献
9.
Interfacial lubrication plays an important role in the functional performance of nanoelectrome-chanical (NEMS) systems. Here, we used molecular dynamics simulation to analyze the lubricating effect of a perfluoropolyether (PFPE) film to reveal the mechanism behind our experimental observations and understand the performance of the film. There was good agreement in the trends of the coefficients of friction between our simulation results and experimental characterizations. By studying the atomic motion, interfacial mechanics and polymer chain deformation, we found that PFPE films provide good lubrication because their linear flowability promotes surface reconstruction. Our simulations suggest that a high performance lubricant film needs to have low resistance to shear deformation, possess high linear flowability, promote surface reconstruction and adhere effectively to the substrates. 相似文献
10.