全文获取类型
收费全文 | 1022篇 |
免费 | 99篇 |
国内免费 | 51篇 |
专业分类
电工技术 | 9篇 |
综合类 | 35篇 |
化学工业 | 413篇 |
金属工艺 | 23篇 |
机械仪表 | 61篇 |
建筑科学 | 32篇 |
矿业工程 | 6篇 |
能源动力 | 84篇 |
轻工业 | 111篇 |
水利工程 | 2篇 |
石油天然气 | 81篇 |
武器工业 | 2篇 |
无线电 | 67篇 |
一般工业技术 | 65篇 |
冶金工业 | 12篇 |
原子能技术 | 1篇 |
自动化技术 | 168篇 |
出版年
2024年 | 1篇 |
2023年 | 33篇 |
2022年 | 47篇 |
2021年 | 56篇 |
2020年 | 71篇 |
2019年 | 53篇 |
2018年 | 37篇 |
2017年 | 28篇 |
2016年 | 44篇 |
2015年 | 79篇 |
2014年 | 138篇 |
2013年 | 146篇 |
2012年 | 189篇 |
2011年 | 153篇 |
2010年 | 28篇 |
2009年 | 14篇 |
2008年 | 2篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1982年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有1172条查询结果,搜索用时 31 毫秒
1.
Mixed reality can overlay and display 3D digital content in the real world, convey abstract concepts to users, and promote the understanding of complex tasks. However, the abstract graphics overlaid on the physical space may cause a certain cognitive load for local users and reduce the efficiency of collaboration. To improve the efficiency of remote collaboration, we conducted an elicitation study on assembly tasks, explored the user needs for collaboration, and defined the design goals of our remote collaboration method. Inspired by the mirror-neuron mechanism, we present an imitative collaboration method that allows local users to imitate the interaction behavior of remote users to complete tasks. We also propose a series of interaction methods for remote users to select, copy, and interact with the local point clouds to facilitate the expression of collaboration intentions. Finally, the results of a user study evaluating our imitative collaboration method on assembly tasks are reported, confirming that our method improves collaboration efficiency while reducing the cognitive load of local users. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(8):5064-5073
Reasonable construction of heterostructure is of significance yet a great challenge towards efficient pH-universal catalysts for hydrogen evolution reaction (HER). Herein, a facial strategy coupling gas-phase nitridation with simultaneous heterogenization has been developed to synthesize heterostructure of one-dimensional (1D) Mo3N2 nanorod decorated with ultrathin nitrogen-doped carbon layer (Mo3N2@NC NR). Thereinto, the collaborative interface of Mo3N2 and NC is conducive to accomplish rapid electron transfer for reaction kinetics and weaken the Mo–Hads bond for boosting the intrinsic activity of catalysts. As expected, Mo3N2@NC NR delivers an excellent catalytic activity for HER with low overpotentials of 85, 129, and 162 mV to achieve a current density of 10 mA cm?2 in alkaline, acidic, and neutral electrolytes, respectively, and favorable long-term stability over a broad pH range. As for practical application in electrocatalytic water splitting (EWS) under alkaline, Mo3N2@NC NR || NiFe-LDH-based EWS also exhibits a low cell voltage of 1.55 V and favorable durability at a current density of 10 mA cm?2, even surpassing the Pt/C || RuO2-based EWS (1.60 V). Consequently, the proposed suitable methodology here may accelerate the development of Mo-based electrocatalysts in pH-universal non-noble metal materials for energy conversion. 相似文献
3.
Propylene molecule owns two active sites, the direct epoxidation of propylene by dioxygen is still a challenge due to the limitation of selectivity. In this work, the direct liquid-phase propylene aerobic epoxidation protocol by chloride manganese meso-tetraphenylporphyrin (MnTPPCl) was developed. The conversion of propylene was 12.7%, and the selectivity towards PO (propylene oxide) reached up to 80.5%. The formation of PO was attributed to the mechanism via high-valent Mn species, which was confirmed by means of in situ UV–vis spectrum. 相似文献
4.
Catalysts for the desulfurization of gasoline samples were synthesized via the immobilization of well-dispersed phosphotungstic acid (HPW) on Mobil composition of matter-twenty-two (MWW) zeolite. Characterization results indicated that these catalysts possess a mesoporous structure with the retention of the Keggin structure of immobilized HPW. Relevant reaction parameters influencing sulfur removal were systematically investigated, including HPW loading, catalyst dosage, temperature, initial S-concentration, molar ratio of oxidant to sulfide (O/S), volume ratio of MeCN to model oil (Ext./oil), and sulfide species. The 40 wt-% HPW/MWW catalyst exhibited the highest catalytic activity with 99.6% dibenzothiophene sulfur removal from prepared samples. The 40 wt-% HPW/MWW catalyst was recycled four times and could be easily regenerated. Finally, as an exploratory study, straight-run-gasoline and fluid catalytic cracking gasoline were employed to accurately evaluate the desulfurization performance of 40 wt-% HPW/MWW. Our research provides new insights into the development and application of catalysts for desulfurization of gasoline. 相似文献
5.
Zhou Wenhui Wu Jie Zhong Weifeng Zhang Haochuan Shu Lei Yu Rong 《Mobile Networks and Applications》2019,24(3):950-961
Mobile Networks and Applications - Energy trading mechanism for microgrids has an inherent two-layer architecture, in which the energy trading at the first layer is between a microgrid aggregator... 相似文献
6.
7.
Olusola Bamisile Mustapha Mukhtar Nasser Yimen Qi Huang Olamide Olotu Victor Adebayo Mustafa Dagabsi 《International Journal of Hydrogen Energy》2021,46(52):26272-26288
CO2 based power and refrigeration cycles have been developed and analyzed in different existing studies. However, the development of a CO2 based comprehensive energy system and its performance analysis have not been considered. In this study, the integration of a CO2 based solar parabolic trough collector system, a supercritical CO2 power cycle, a transcritical CO2 power cycle, and a CO2 based cascade refrigeration system for hydrogen production and multigeneration purpose is analyzed thermodynamically. This study aims to analyze and compare the difference in the thermodynamic performance of comprehensive energy systems when CO2 is used as the working fluid in all the cycles with a system that uses other working fluids. Therefore, two comprehensive energy systems with the same number of subsystems are designed to justify the comparison. The second comprehensive energy system uses liquid potassium instead of CO2 as a working fluid in the solar parabolic trough collector and a steam cycle is used to replace the transcritical CO2 power cycle. Results of the energy and exergy performance analysis of two comprehensive energy systems showed that the two systems can be used for the multigeneration purpose. However, the use of a steam cycle and potassium-based solar parabolic trough collector increases the comprehensive energy systems’ overall energy and exergy efficiency by 41.9% and 26.7% respectively. Also, the use of liquid potassium as working fluid in the parabolic trough collectors increases the absorbed solar energy input by 419 kW and 2100 kW thereby resulting in a 23% and 90.7% increase in energetic and exergetic efficiency respectively. The carbon emission reduction potential of the two comprehensive energy systems modelled in this study is also analyzed. 相似文献
8.
9.
Yurong Liu Zongqiang Zhang Tianyu Wang 《International Journal of Hydrogen Energy》2018,43(24):11120-11131
Three-dimensional hierarchical porous graphene with nickel nanoparticles (3DHPG-Ni) was synthesized through electrostatic assembly method with the assistance of poly (methyl methacrylate) (PMMA) template and subsequent removal of PMMA template by calcination. The morphology, microstructure and hydrogen adsorption properties of 3DHPG-Ni nanocomposites were examined in detail. The obtained 3DHPG-Ni nanocomposite exhibited hierarchical porous structure composed of macro-, meso- and micropores, high specific surface area (925 m2 g?1), large pore volume (0.58 cm3 g?1) and excellent hydrogen storage capacity. Under the pressure of 5 bar, 3DHPG-Ni nanocomposite showed a maximum hydrogen capacity of 4.22 wt% and 1.95 wt% at 77 K and 298 K, respectively, demonstrating that the as-prepared 3DHPG-Ni nanocomposite was supposed to be a promising material with outstanding properties for practical applications in the field of hydrogen storage. The three-dimensional hierarchical porous structure, evenly distributed Ni nanoparticles and hydrogen spillover effect were responsible for the enhanced hydrogen storage capacities. 相似文献
10.
《International Journal of Hydrogen Energy》2020,45(59):34494-34502
The multifunctional potential of a catalyst previously synthesised for thermal processes is explored by investigating its activity for photocatalytic production of H2 from glycerol, a by-product from the manufacture of bio-diesel. The studied catalyst contains TiO2 doped with Al2O3 that was derived from aluminum foil waste. This catalyst showed higher photocatalytic activity than the analogous catalyst prepared with a commercial Al2O3. Pt and Pd act as electron traps while the Al2O3 demonstrated a promotional effect, partially through proton donation. Under optimum conditions, a steady-state of 4.2 mmol H2 gTiO2−1 hr−1 was produced, which is comparable to the 4.7 mmol H2 gTiO2−1 hr−1 obtained with Pt–TiO2, which is a standard photocatalytic material. It should be noted that the reported Pt/Pd/TiO2-ANFL catalyst has not yet been optimised and so this result is encouraging. It is hoped that these findings can inspire more sustainable and less expensive hydrogen production, including from biomass feedstocks such as glycerol. 相似文献