全文获取类型
收费全文 | 506篇 |
免费 | 6篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 1篇 |
综合类 | 4篇 |
化学工业 | 70篇 |
金属工艺 | 5篇 |
能源动力 | 164篇 |
无线电 | 186篇 |
一般工业技术 | 97篇 |
冶金工业 | 3篇 |
自动化技术 | 2篇 |
出版年
2023年 | 20篇 |
2022年 | 33篇 |
2021年 | 45篇 |
2020年 | 33篇 |
2019年 | 21篇 |
2018年 | 16篇 |
2017年 | 21篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 21篇 |
2012年 | 23篇 |
2011年 | 26篇 |
2010年 | 10篇 |
2009年 | 24篇 |
2008年 | 21篇 |
2007年 | 10篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 12篇 |
1998年 | 14篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 14篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
排序方式: 共有532条查询结果,搜索用时 15 毫秒
1.
Kelin Hu Feipeng Wang Yuyang Yan Hongcheng Liu Zijia Shen 《Ceramics International》2021,47(11):15228-15236
In this paper, a novel hybrid structure of Pd doped ZnO/SnO2 heterojunction nanofibers with hexagonal ZnO columns was one step synthesized from electrospun precursor nanofibers. Due to the synergistic effect of hexagonal ZnO, SnO2 and Pd, the structure exhibited excellent hydrogen (H2) gas sensing properties. At low-temperature of 120 °C, the response (Ra/Rg) to 100 ppm H2 gas exceeded 160, the response/recovery time was only 20 s and 6 s respectively and the limit of detection was only 0.5 ppm. Meanwhile, it also had good selectivity for H2 gas and excellent linearity. In addition, the materials were characterized by XRD, FESEM, HRTEM, XPS, and the synthesis mechanism and gas sensing mechanism were proposed. 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(80):33955-33965
We report the study of conductive polyaniline (PANI) chain embedded Ti-MOF functionalized with CoS as a cocatalyst for hydrogen evolution reaction (HER) application. The post synthetically modified hybrid photocatalyst PANI/Ti-MOF/CoS greatly influences the redox and e? ? h+ separation process and exhibits an impressive rate of HER (~1322 μmol h?1g?1), suppressing the pristine Ti-MOF (~62 μmol h?1g?1) with apparent quantum yield (AQY) of ~3.2 and transient current response of ~46.4 μA cm?2. In this system, Ti-MOF provides the circulation of Ti3+ and Ti4+ to the reaction of photocatalytic H2 generation, where the additional PANI and CoS amended the performance of H2 production through electron enrichment and thereby improving the stability and integrity of Ti-MOF. The Electrochemical studies demonstrated increased photocurrent by interweaving Ti-MOF crystal with PANI through cation-π interaction thereby enhancing interface connection and then promoting electron transfers. The charge dynamics revealed the initial charge transfer from photoexcited PANI to encapsulated MOF framework to boost the photocatalytic performance of the system. Further, the electron movement at the Ti-MOF/CoS interface is investigated through work function and electrochemical potential of electrons (Fermi level). DFT results demonstrate the importance of CoS in improving the photocatalytic performance of hybrid Ti-MOF catalyst, which leads to superior catalytic behaviour. These results establish that the encapsulation of catalytic active sites inside MOFs with desirable energy band gaps would be an ideal choice for the production of solar fuels. 相似文献
3.
Sehar Tasleem Muhammad Tahir Wesam Alsayeh Khalifa 《International Journal of Hydrogen Energy》2021,46(27):14148-14189
Photocatalytic H2 generation using semiconductor photocatalysts is considered as a cost-effective and eco-friendly technology for solar to energy conversion; however, the present photocatalysts have been recognized to depict low efficiency. Currently, porous coordination polymers known as metal-organic frameworks (MOFs) constituting flexible and modifiable porous structure and having excess active sites are considered to be appropriate for photocatalytic H2 production. This review highlights current progress in structural development of MOF materials along with modification strategies for enhanced photoactivity. Initially, the review discusses the photocatalytic H2 production mechanism with the concepts of thermodynamics and mass transfer with particular focus on MOFs. Elaboration of the structural categories of MOFs into Type I, Type II, Type III and classification of MOFs for H2 generation into transition metal based, post-transition metal based, noble-metal based and hetero-metal based has been systematically discussed. The review also critically deliberate various modification approaches of band engineering, improvement of charge separation, efficient irradiation utilization and overall efficiency of MOFs including metal modification, heterojunction formation, Z-scheme formation, by introducing electron mediator, and dye based composites. Also, the MOF synthesized derivatives for photocatalytic H2 generation are elaborated. Finally, future perspectives of MOFs for H2 generation and approaches for efficiency improvement have been suggested. 相似文献
4.
Shuyi Fu Wenrui Feng Ying Jia Tielong Deng Wenzhong Wang Guling Zhang Junli Fu 《International Journal of Hydrogen Energy》2021,46(21):11544-11555
ZnO/Cu2S nanotube arrays are fabricated firstly by a facile and capping-agent-free method, and the photo-electrochemical performance has been studied systematically. The results show that ZnO/Cu2S nanotube arrays achieve enhanced photo-electrochemical water splitting performance and the photocurrent densities of ZnO/Cu2S are 7.9 times than that of ZnO at 0 V versus Ag/AgCl. The performance of the ZnO/Cu2S nanotube arrays can be adjusted by changing the amount of Cu2S microcrystals. The results confirm that the enhanced photo-electrochemical performance of ZnO/Cu2S is due to the significantly improved visible light absorption, effective separation of photo-induced carriers due to the well band energy match and the formed p-n junction between ZnO and Cu2S. 相似文献
5.
LIULu FANGuang-han LIAOChang-jun 《半导体光子学与技术》2004,10(2):86-92
A simple model of the graded heterojunction in AIGalnP compound semiconductors was introduced to analyze the band profile. The band profiles are analyzed with the different grading ways but the same grading length and under the different doping densities. The effect of the different grading lengths on the surplus of the potential of the spike to the potential of N region are also analyzed under the different doping densities. Through the experiments, it proves that the performances of high brightness light emitting diodes can be improved by the effects of the graded heterojunction. 相似文献
6.
Yan Huang Honggang Lu Bingnan Wang Wenbo He Hongzhou Dong Lina Sui Zhixing Gan Shuai Ma Beili Pang Lifeng Dong Liyan Yu 《International Journal of Hydrogen Energy》2021,46(5):3530-3538
As a promising catalyst for solar hydrogen production, black phosphorus (BP) has received widespread attention due to variable band gaps, high carrier mobility, and strong light absorption performance. Herein, we use MoS2 as a cocatalyst to synthesize BP/MoS2 catalyst with polycrystalline BP to improve photocatalytic performance under visible light irradiation. A small amount of MoS2 can reduce the recombination of electron-hole pairs in the composite, increase carrier transport efficiency, and then improve photocatalytic performance. As expected, the 10/0.5 ratio of BP/MoS2 catalyst exhibits the highest photocatalytic hydrogen evolution performance with a hydrogen evolution rate of 575.4 μmol h?1 g?1, which is 2.5 times of pure BP. Based on the results above, a simple method is provided to synthesize low-cost black phosphorus-based photocatalysts. 相似文献
7.
《International Journal of Hydrogen Energy》2019,44(10):4821-4831
Construction of semiconductor heterojunctions can effectively accelerate the separation of photo-induced charge carriers and thereby enhance photocatalytic activity. Here, NiSe was used as an effective co-catalyst to construct an active NiSe/TiO2 heterojunction for improving the photocatalytic H2 production of TiO2. The resultant 10%NiSe/TiO2 heterojunction exhibited 11 times higher photocatalytic H2-production activity than that of bare TiO2. The NiSe/TiO2 heterojunction and the photo-reduction of partial Ni2+ to Ni0 notably accelerated the separation and transfer of photo-excited electron-hole pairs, and thus resulted in obvious improvement of H2-evolution activity. This work holds promise for the application of NiSe in photocatalysis as a high-efficiency photocatalytic cocatalyst. 相似文献
8.
《International Journal of Hydrogen Energy》2019,44(33):17611-17621
Constructing heterojunction was an efficient way to promote photoelectrochemical (PEC) water splitting performance of TiO2-based nano-photoanode. In this work, we demonstrated the feasible preparation of oxygen vacancies-induced In2O3 (In2O3-x) nanorods/black Si-doped TiO2 (Ti–Si–O) nanotubes heterojunction photoanode for enhanced PEC water splitting. Black Ti–Si–O nanotubes were fabricated through Zn reduction of the as-annealed Ti–Si–O nanotubes, followed by In2O3-x nanorods coupling by a facile electrodepositing and Ar heat treatment. Solar to hydrogen conversion efficiency of the heterojunction photoanode reached as high as 1.96%, which was almost 10 times that of undoped TiO2. The improved PEC properties were mainly attributed to co-doping effects of Si and Ti3+/oxygen vacancy as well as In2O3-x decoration, which resulted in enhanced optical absorption and facilitated separation-transport process of photogenerated charge carriers. Charge transfer process in the composite system and hydrogen production mechanism were proposed. This work will facilitate designing TiO2-based nano-photoanodes for promoting water splitting by integrating with elements doping, oxygen vacancies self-doping and semiconductors coupling. 相似文献
9.
Using nonequilibrium Green's function in combination with the density functional theory, we investigate the spin-dependent transport properties of three silicene-based heterojunctions. The calculated results show that the heterojunctions are promising multifunctional devices in spintronics due to their nearly perfect bipolar spin-filter effect and high rectification ratio. Also shown are the obvious negative differential resistance behaviors for both spin channels. By analyzing the spin-resolved transmission spectra and the band structure of ZSiNR electrodes, as well as the spatial resolved local density of states, the mechanisms for these intriguing properties are demonstrated in detail. 相似文献
10.
《Ceramics International》2021,47(22):31302-31310
Control of Nitrogen dioxide (NO2) byproducts is of great importance for the photocatalytic NO removal and environmental remedy. However, individual semiconductor photocatalysts generally show limited capabilities for selective NO removal due to severe charge recombination and inadequate redox potentials. Herein, the cotton-like g-C3N4 was modified with Ti3C2@TiO2 to construct a heterojunction photocatalyst Ti3C2@TiO2/g-C3N4, which showed outperformed photocatalytic NO removal and MB degradation abilities compared to the individual photocatalysts under visible light irradiation. The UV–vis absorption spectra and photoluminescence (PL) spectra confirmed that Ti3C2@TiO2/g-C3N4 photocatalyst was endowed with superior light utilization and separation/transfer ability of charge carriers due to the presence of n-n heterojunction and Schottky barrier. Furthermore, the g-C3N4, Ti3C2, and TiO2 were closely contacted showing a high specific surface area, which promoted the charge transfer and the exposure of more active sites, further inducing the formation of more active species. Therefore, the designed photocatalyst delivered a high removal rate of NO and a suppressed discharge of NO2. Notably, the photocatalyst Ti3C2@TiO2/g-C3N4 also presented superior NO removal ability during the cycling experiment, indicating their outstanding stability and recyclability. Besides, the effects of active species were monitored using a trapping experiment to propose probable photocatalytic mechanism. This study could shed a new light to the design of photocatalyst for air purification in the future. 相似文献