全文获取类型
收费全文 | 91722篇 |
免费 | 6614篇 |
国内免费 | 2161篇 |
专业分类
电工技术 | 3177篇 |
技术理论 | 2篇 |
综合类 | 2565篇 |
化学工业 | 17793篇 |
金属工艺 | 4668篇 |
机械仪表 | 6120篇 |
建筑科学 | 4098篇 |
矿业工程 | 1321篇 |
能源动力 | 3300篇 |
轻工业 | 6572篇 |
水利工程 | 903篇 |
石油天然气 | 2565篇 |
武器工业 | 339篇 |
无线电 | 12919篇 |
一般工业技术 | 16143篇 |
冶金工业 | 6271篇 |
原子能技术 | 1122篇 |
自动化技术 | 10619篇 |
出版年
2024年 | 290篇 |
2023年 | 1392篇 |
2022年 | 2331篇 |
2021年 | 3564篇 |
2020年 | 2571篇 |
2019年 | 2567篇 |
2018年 | 2872篇 |
2017年 | 2853篇 |
2016年 | 3104篇 |
2015年 | 3091篇 |
2014年 | 4262篇 |
2013年 | 5627篇 |
2012年 | 5924篇 |
2011年 | 6913篇 |
2010年 | 5196篇 |
2009年 | 5249篇 |
2008年 | 5184篇 |
2007年 | 4334篇 |
2006年 | 4267篇 |
2005年 | 3498篇 |
2004年 | 2864篇 |
2003年 | 2668篇 |
2002年 | 2419篇 |
2001年 | 2088篇 |
2000年 | 1929篇 |
1999年 | 1909篇 |
1998年 | 2336篇 |
1997年 | 1679篇 |
1996年 | 1414篇 |
1995年 | 1070篇 |
1994年 | 852篇 |
1993年 | 685篇 |
1992年 | 519篇 |
1991年 | 474篇 |
1990年 | 421篇 |
1989年 | 394篇 |
1988年 | 305篇 |
1987年 | 257篇 |
1986年 | 172篇 |
1985年 | 166篇 |
1984年 | 129篇 |
1983年 | 99篇 |
1982年 | 66篇 |
1981年 | 63篇 |
1980年 | 57篇 |
1979年 | 48篇 |
1978年 | 45篇 |
1977年 | 43篇 |
1976年 | 77篇 |
1973年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Zhao Jiandong Lei Wei Li Zijian Zhao Dongfeng Han Mingmin Hou Xiaoqing 《Multimedia Tools and Applications》2022,81(4):4753-4780
Multimedia Tools and Applications - The crowding in bus is an important factor affecting passenger satisfaction and bus dispatching level. However, how to use video images to detect crowding... 相似文献
2.
3.
4.
5.
7.
Jiajia Suo Bowen Yang Edoardo Mosconi Hyeon-Seo Choi YeonJu Kim Shaik M. Zakeeruddin Filippo De Angelis Michael Grätzel Hui-Seon Kim Anders Hagfeldt 《Advanced functional materials》2021,31(34):2102902
Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI2. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions. 相似文献
8.
Chunsheng Wang Yishuang Wang Mingqiang Chen Defang Liang Zhonglian Yang Wen Cheng Zhiyuan Tang Jun Wang Han Zhang 《International Journal of Hydrogen Energy》2021,46(7):5852-5874
Given the continuing issues of environment and energy, methane dry reforming for syngas production have sparked interest among researchers, but struggled with the process immaturity owing to catalyst deactivation. This review summarizes the recent advances in the development of efficient and stable catalysts with strong resistance to coking and metal sintering, including the application of novel materials, the assessment of advanced characterizations and the compatibility to improved reaction system. One feasible option is the crystalline oxide catalysts (perovskite, pyrochlore, spinel and LDHs), which feature a fine metal dispersion and surface confinement effect via a metal exsolution strategy and exhibit superior reactivity and stability. Some new materials (h-BN, clays and MOFs) also extend the option because of their unique morphology and microstructure. It also is elaborated that progresses were achieved in advanced characterizations application, leading to success in the establishment of reaction mechanisms and attributions to the formed robust catalysts. In addition, the perspective described the upgrade of reaction system to a higher reaction efficiency and milder reaction conditions. The combination of efficient reaction systems and robust catalysts paves a way for a scaling-up application of the process. 相似文献
9.
John D. Rodney S. Deepapriya M. Cyril Robinson C. Justin Raj Suresh Perumal Byung Chul Kim S. Krishnan S. Jerome Das 《International Journal of Hydrogen Energy》2021,46(54):27585-27596
The production of hydrogen, a favourable alternative to an unsustainable fossil fuel remains as a significant hurdle with the pertaining challenge in the design of proficient, highly productive and sustainable electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, the dysprosium (Dy) doped copper oxide (Cu1-xDyxO) nanoparticles were synthesized via solution combustion technique and utilized as a non-noble metal based bi-functional electrocatalyst for overall water splitting. Due to the improved surface to volume ratio and conductivity, the optimized Cu1-xDyxO (x = 0.01, 0.02) electrocatalysts exhibited impressive HER and OER performance respectively in 1 M KOH delivering a current density of 10 mAcm?2 at a potential of ?0.18 V vs RHE for HER and 1.53 V vs RHE for OER. Moreover, the Dy doped CuO electrocatalyst used as a bi-functional catalyst for overall water splitting achieved a potential of 1.56 V at a current density 10 mAcm?2 and relatively high current density of 66 mAcm?2 at a peak potential of 2 V. A long term stability of 24 h was achieved for a cell voltage of 2.2 V at a constant current density of 30 mAcm?2 with only 10% of the initial current loss. This showcases the accumulative opportunity of dysprosium as a dopant in CuO nanoparticles for fabricating a highly effective and low-cost bi-functional electrocatalyst for overall water splitting. 相似文献
10.
Shuhai Liu Ming Han Xiaolong Feng Qiuhong Yu Long Gu Longfei Wang Yong Qin Zhong Lin Wang 《Advanced functional materials》2021,31(17):2010339
Utilizing inner-crystal piezoelectric polarization charges to control carrier transport across a metal-semiconductor or semiconductor–semiconductor interface, piezotronic effect has great potential applications in smart micro/nano-electromechanical system (MEMS/NEMS), human-machine interfacing, and nanorobotics. However, current research on piezotronics has mainly focused on systems with only one or rather limited interfaces. Here, the statistical piezotronic effect is reported in ZnO bulk composited of nanoplatelets, of which the strain/stress-induced piezo-potential at the crystals’ interfaces can effectively gate the electrical transport of ZnO bulk. It is a statistical phenomenon of piezotronic modification of large numbers of interfaces, and the crystal orientation of inner ZnO nanoplatelets strongly influence the transport property of ZnO bulk. With optimum preferred orientation of ZnO nanoplatelets, the bulk exhibits an increased conductivity with decreasing stress at a high pressure range of 200–400 MPa, which has not been observed previously in bulk. A maximum sensitivity of 1.149 µS m−1 MPa−1 and a corresponding gauge factor of 467–589 have been achieved. As a statistical phenomenon of many piezotronic interfaces modulation, the proposed statistical piezotronic effect extends the connotation of piezotronics and promotes its practical applications in intelligent sensing. 相似文献