全文获取类型
收费全文 | 66041篇 |
免费 | 6485篇 |
国内免费 | 3581篇 |
专业分类
电工技术 | 4462篇 |
技术理论 | 1篇 |
综合类 | 6256篇 |
化学工业 | 10652篇 |
金属工艺 | 3721篇 |
机械仪表 | 3863篇 |
建筑科学 | 5352篇 |
矿业工程 | 1719篇 |
能源动力 | 1533篇 |
轻工业 | 7933篇 |
水利工程 | 1461篇 |
石油天然气 | 2785篇 |
武器工业 | 652篇 |
无线电 | 7042篇 |
一般工业技术 | 6584篇 |
冶金工业 | 2569篇 |
原子能技术 | 714篇 |
自动化技术 | 8808篇 |
出版年
2024年 | 326篇 |
2023年 | 1089篇 |
2022年 | 2182篇 |
2021年 | 2771篇 |
2020年 | 2144篇 |
2019年 | 1710篇 |
2018年 | 1779篇 |
2017年 | 2040篇 |
2016年 | 1907篇 |
2015年 | 2721篇 |
2014年 | 3604篇 |
2013年 | 4079篇 |
2012年 | 4797篇 |
2011年 | 5238篇 |
2010年 | 4817篇 |
2009年 | 4634篇 |
2008年 | 4722篇 |
2007年 | 4329篇 |
2006年 | 4055篇 |
2005年 | 3313篇 |
2004年 | 2356篇 |
2003年 | 1956篇 |
2002年 | 1997篇 |
2001年 | 1666篇 |
2000年 | 1354篇 |
1999年 | 1071篇 |
1998年 | 702篇 |
1997年 | 523篇 |
1996年 | 518篇 |
1995年 | 427篇 |
1994年 | 304篇 |
1993年 | 223篇 |
1992年 | 167篇 |
1991年 | 128篇 |
1990年 | 109篇 |
1989年 | 81篇 |
1988年 | 74篇 |
1987年 | 44篇 |
1986年 | 26篇 |
1985年 | 25篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 3篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1959年 | 4篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
Wireless Personal Communications - The existing long term evolution networks originally designed for human-to-human communications are hard to tackle numerous and bursty random access requests from... 相似文献
12.
13.
14.
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
15.
Junling Guo Huayu Pei Ying Dou Siyuan Zhao Guosheng Shao Jinping Liu 《Advanced functional materials》2021,31(18):2010499
Lithium-sulfur batteries (LSBs) are considered a promising next-generation energy storage device owing to their high theoretical energy density. However, their overall performance is limited by several critical issues such as lithium polysulfide (PS) shuttles, low sulfur utilization, and unstable Li metal anodes. Despite recent huge progress, the electrolyte/sulfur ratio (E/S) used is usually very high (≥20 µL mg−1), which greatly reduces the practical energy density of devices. To push forward LSBs from the lab to the industry, considerable attention is devoted to reducing E/S while ensuring the electrochemical performance. To date, however, few reviews have comprehensively elucidated the possible strategies to achieve that purpose. In this review, recent advances in low E/S cathodes and anodes based on the issues resulting from low E/S and the corresponding solutions are summarized. These will be beneficial for a systematic understanding of the rational design ideas and research trends of low E/S LSBs. In particular, three strategies are proposed for cathodes: preventing PS formation/aggregation to avoid inadequate dissolution, designing multifunctional macroporous networks to address incomplete infiltration, and utilizing an imprison strategy to relieve the adsorption dependence on specific surface area. Finally, the challenges and future prospects for low E/S LSBs are discussed. 相似文献
16.
A microchannel heat exchanger with a triangular wave and symmetrical triangular wave structure was proposed in this paper. In addition, a new N-type microchannel heat exchanger was developed to balance the heat transfer performance and pressure drop. The relationship between different configurations of the N structure of the microchannel and the heat transfer performance was analyzed. The results showed that, at a high inlet flow rate, the symmetrical triangular wave microchannel had the best heat transfer performance, followed by the triangular wave microchannel and the straight channel. At the same flow rate, the degree of disturbance of the fluid was highest in the symmetrical N-structure microchannel, and an excellent heat transfer effect was observed. 相似文献
17.
18.
19.
Ying Chen HuiLi Zhang YuNing Liang YanHua Gao Yongchao Li 《Petroleum Science and Technology》2019,37(7):787-795
In this study, a simple hydrothermal synthesis method was adapted for the preparation of Co-doping Co2+/F-/TiO2 nanotubes photocatalyst, and the micro-nano structure of catalysts prepared by biomimetic technology which makes the catalyst have super-oleophilicity property. Co2+/F-/TiO2 revealed improved photocatalytic performance for denitrification of light oil compared to single TiO2 photocatalysts. The enhance of photocatalytic activity can be attributed to narrowing the band gap, increasing the light response wavelength and exposing more highly active crystal surfaces due to synergistic effects of Co2+ and F? in the photocatalyst. 相似文献
20.