全文获取类型
收费全文 | 14189篇 |
免费 | 1207篇 |
国内免费 | 486篇 |
专业分类
电工技术 | 764篇 |
综合类 | 710篇 |
化学工业 | 2425篇 |
金属工艺 | 660篇 |
机械仪表 | 664篇 |
建筑科学 | 1053篇 |
矿业工程 | 292篇 |
能源动力 | 643篇 |
轻工业 | 1276篇 |
水利工程 | 276篇 |
石油天然气 | 578篇 |
武器工业 | 48篇 |
无线电 | 1569篇 |
一般工业技术 | 1922篇 |
冶金工业 | 792篇 |
原子能技术 | 118篇 |
自动化技术 | 2092篇 |
出版年
2024年 | 39篇 |
2023年 | 207篇 |
2022年 | 404篇 |
2021年 | 568篇 |
2020年 | 453篇 |
2019年 | 396篇 |
2018年 | 462篇 |
2017年 | 463篇 |
2016年 | 505篇 |
2015年 | 543篇 |
2014年 | 640篇 |
2013年 | 966篇 |
2012年 | 896篇 |
2011年 | 1046篇 |
2010年 | 891篇 |
2009年 | 869篇 |
2008年 | 772篇 |
2007年 | 752篇 |
2006年 | 701篇 |
2005年 | 569篇 |
2004年 | 417篇 |
2003年 | 383篇 |
2002年 | 413篇 |
2001年 | 313篇 |
2000年 | 294篇 |
1999年 | 279篇 |
1998年 | 286篇 |
1997年 | 219篇 |
1996年 | 194篇 |
1995年 | 169篇 |
1994年 | 140篇 |
1993年 | 120篇 |
1992年 | 82篇 |
1991年 | 57篇 |
1990年 | 45篇 |
1989年 | 45篇 |
1988年 | 39篇 |
1987年 | 31篇 |
1986年 | 24篇 |
1985年 | 22篇 |
1984年 | 29篇 |
1983年 | 16篇 |
1982年 | 16篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1977年 | 10篇 |
1976年 | 14篇 |
1975年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
As a solid state joining process, ultrasonic spot welding has been proven to be a promising technique for joining copper alloys. However, challenges still remain in employing ultrasonic spot welding to join copper alloys. This article comprehensively reviews the current state of ultrasonic spot welding of copper alloys with a number of critical issues including materials flow, plastic deformation, temperature distribution, vibration, relative motion, vertical displacement, interface friction coefficient, online monitoring technique, coupled with the macrostructure and microstructure, the mechanical properties and electrical conductivity. In addition, the future trends in this field are provided. 相似文献
3.
4.
5.
Yingcai Bi Menglu Lan Jiaxin Li Shupeng Lai Ben M. Chen 《Asian journal of control》2019,21(4):1732-1744
Micro Aerial Vehicles (MAVs) have great potentials to be applied for indoor search and rescue missions. In this paper, we propose a modular lightweight design of an autonomous MAV with integrated hardware and software. The MAV is equipped with the 2D laser scanner, camera, mission computer and flight controller, running all the computation onboard in real time. The onboard perception system includes a laser‐based SLAM module and a custom‐designed visual detection module. A dual Kalman filter design provides robust state estimation by multiple sensor fusion. Specifically, the fusion module provides robust altitude measurement in the circumstance of surface changing. In addition, indoor‐outdoor transition is explicitly handled by the fusion module. In order to efficiently navigate through obstacles and adapt to multiple tasks, a task tree‐based mission planning method is seamlessly integrated with path planning and control modules. The MAV is capable of searching and rescuing victims from unknown indoor environments effectively. It was validated by our award‐winning performance at the 2017 International Micro Air Vehicle Competition (IMAV 2017), held in Toulouse, France. The performance video is available on https://youtu.be/8H19ppS_VXM . 相似文献
7.
Qinhua Wang Xiaofeng Pan Xinpin Wang Shilin Cao Lihui Chen Xiaojuan Ma Liulian Huang Yonghao Ni 《Ceramics International》2021,47(4):4398-4403
Ti3C2Tx (MXene), a new kind of 2D ceramic nanosheets, is receiving more and more attention in the fields of medicine, biology, energy, electronics, etc. However, the preparation and application of MXene in hydrogel is still in its infancy period. Here, we review the latest progress (after 2018) related to MXene hydrogels in time. Aiming at the key issue of the dispersion stability of MXene in hydrogel systems, the preparation strategy, mechanism, advantages and disadvantages of MXene hydrogels are sorted out in detail, and the potential application prospects of MXene composite hydrogel are introduced. Finally, future viewpoints are put forward for the dispersion stability challenges that need solving in the design of MXene hydrogel. 相似文献
8.
Biyun Fang Chuanfeng Zhang Zeliang Qi Chunyan Li Jun Ni Xiuyun Wang Jianxin Lin Chak-Tong Au Bingyu Lin Lilong Jiang 《American Institute of Chemical Engineers》2022,68(11):e17849
The design of an efficient non-noble metal catalyst is of burgeoning interest for ammonia synthesis. Herein, we report a Mo2C/CeO2 catalyst that is superior in ammonia synthesis activity. In this catalyst, molybdenum carbide coexisted with the ceria overlayers which is from the ceria support as the strong metal–support interaction. There is a high proportion of low-valent Mo species, as well as high concentration of Ce3+ and surface oxygen species. The presence of Mo2C and CeO2 overlayers not only leads to enhancement of hydrogen and nitrogen adsorption, but also facilitates the desorption and exchange of adsorbed species with the gaseous reagents. Compared with the Mo/CeO2 catalyst prepared without carbonization, the Mo2C/CeO2 catalyst is more than sevenfold higher in ammonia synthesis rate. This work not only presents an explicit example of designing Mo-based catalyst that is highly efficient for ammonia synthesis by tuning the adsorption and desorption properties of the reactant gases, but opens a perspective for other elements in ammonia synthesis. 相似文献
9.
The Journal of Supercomputing - Data center network virtualization is being considered as a promising technology to provide a performance guarantee for cloud computing applications. One important... 相似文献
10.
Zhang Huawei Yang Zhi Wu Zhaoyu Hong Xiaoyu Li Zhong Xu Yulai Li Jun Ni Gaojin Xiao Xueshan 《Oxidation of Metals》2019,92(1-2):49-65
Oxidation of Metals - The isothermal oxidation behavior and oxide-scale evolution on a newly developed Ni–Fe-based superalloy were investigated. Three oxidation stages were generally... 相似文献