全文获取类型
收费全文 | 20851篇 |
免费 | 1656篇 |
国内免费 | 877篇 |
专业分类
电工技术 | 1111篇 |
综合类 | 1364篇 |
化学工业 | 3615篇 |
金属工艺 | 1424篇 |
机械仪表 | 1165篇 |
建筑科学 | 1538篇 |
矿业工程 | 771篇 |
能源动力 | 489篇 |
轻工业 | 1344篇 |
水利工程 | 359篇 |
石油天然气 | 1521篇 |
武器工业 | 198篇 |
无线电 | 2162篇 |
一般工业技术 | 2744篇 |
冶金工业 | 1146篇 |
原子能技术 | 188篇 |
自动化技术 | 2245篇 |
出版年
2024年 | 108篇 |
2023年 | 355篇 |
2022年 | 651篇 |
2021年 | 905篇 |
2020年 | 706篇 |
2019年 | 593篇 |
2018年 | 606篇 |
2017年 | 720篇 |
2016年 | 604篇 |
2015年 | 866篇 |
2014年 | 1082篇 |
2013年 | 1183篇 |
2012年 | 1277篇 |
2011年 | 1472篇 |
2010年 | 1244篇 |
2009年 | 1202篇 |
2008年 | 1075篇 |
2007年 | 1184篇 |
2006年 | 1129篇 |
2005年 | 973篇 |
2004年 | 609篇 |
2003年 | 545篇 |
2002年 | 545篇 |
2001年 | 458篇 |
2000年 | 469篇 |
1999年 | 539篇 |
1998年 | 406篇 |
1997年 | 367篇 |
1996年 | 317篇 |
1995年 | 292篇 |
1994年 | 250篇 |
1993年 | 171篇 |
1992年 | 131篇 |
1991年 | 82篇 |
1990年 | 62篇 |
1989年 | 47篇 |
1988年 | 54篇 |
1987年 | 31篇 |
1986年 | 21篇 |
1985年 | 11篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Jian‐Peng Cui Feng Zhou Chengqun Song Quan‐Min Zhong Qiong‐Hua Wang 《Journal of the Society for Information Display》2012,20(6):347-350
Abstract— A low‐voltage (~10 Vrms) and high‐transmittance (~90%) polymer‐stabilized blue‐phase liquid‐crystal (BPLC) device with a slanted‐electrodes structure is proposed. Unlike the vertical‐field‐switching (VFS) mode in which oblique incident light and a vertical field are employed, the proposed device utilizes normal incident light and an oblique field. The slanted electrodes generate a strong and uniform oblique electric field, which contributes in obtaining low voltage and high transmittance. Moreover, no couple films or prism sheets are needed, which helps to enhance the optical efficiency and simplify of the device structure. This device has great potential application for emerging BPLC displays and photonic devices. 相似文献
102.
本文阐述了充分考虑矿石性质,探索出混合浮选的分步流程,恰当的施用多元扑收剂所产出的“协同效应”,稳定和强化选别工艺,收到提高选金技术指标的效果。 相似文献
103.
104.
Journal of Porous Materials - Aiming at the poor heat conduction performance of porous MIL-101 applied in adsorption cooling process, few layer graphene (FLG) was selected as a promising thermal... 相似文献
105.
Qiu Jun Wang Yueting Wu Peng Jiang Shan Cui Kaibo Chen Guowei Liu Dongliang Cui Guangwen 《Journal of Porous Materials》2021,28(6):1675-1687
Journal of Porous Materials - The dynamics and thermodynamics of adsorption of hexadecyl ammonium with different numbers of carbon chains in montmorillonite (Mt) with different layer charge density... 相似文献
106.
107.
Jia Zhu Fangpei Zhang Yuanhao Cui Junsheng Mu Ronghui Zhang Xiaojun Jing 《北京理工大学学报(英文版)》2021,30(1):60-68
Joint radar and communication(JRC) technology is gradually becoming an essential approach to alleviating spectral congestion. Radar and communications systems were designed with common spectral and hardware resources to reduce size, improve performance, reduce cost, and decongest the spectrum. Various approaches have been proposed to achieve the coexistence of radar and communication systems. This paper mainly focuses on the research directions of radar communication coexistence(RCC) and dual-function radar communication systems(DFRC) in JRC technology. We summarize and analyze the existing research problems in the JRC era. According to the characteristics and advantages of JRC technology, we highlight several potentials in military and commercial applications. 相似文献
108.
This paper develops a new transmit beamforming for an integrated mechanical and electrical scanning dual-function radar-communication(DFRC) system. Differing from the related some works using beampattern sidelobe level to communication, we exploit the fact that transmit beamforming weight vector u k in direction θ and weight vector u *k in direction-θ can achieve the same spatial power distribution, and formulate a new transmit beamforming vector design problem accounting for some extra sidelobe level constraints. By doing so, the number of the transmit beamforming weight vectors and the computing demand in the multi-user communication(MUC) scenario can be reduced. Finally, the numerical examples are designed to verify the effectiveness of the proposed design strategy in comparison with the existing method. 相似文献
109.
介绍了2002年国内高碳铬轴承钢的产量及品种结构,评述了国内轴承钢生产工艺装备、质量状况和发展方向。 相似文献
110.
Yan Cui Zequan Zeng Jianfeng Zheng Zhanggen Huang Jieyang Yang 《Frontiers of Chemical Science and Engineering》2021,15(5):1125
To realize the utilization of visible light and improve the photocatalytic efficiency of organic pollutant degradation in wastewater, a nitrogen-doped titanium-carbon composite (N-TiO2/AC) prepared by sol-gel methods was applied in the photodegradation of phenol assisted by persulfate under visible light irradiation (named N-TiO2/AC/PS/VIS). The results show that a synergistic effect exists between visible-light photocatalysis and persulfate activation. Compared with TiO2/PS/VIS, the phenol degradation rate was found to be observably improved by 65% in the N-TiO2/AC/PS/VIS system. This significant increase in degradation rate was mainly attributed to the following two factors: 1) The N and C doping can change the crystal structure of TiO2, which extends the TiO2 absorption wavelength range to the visible light region. 2) As an electron acceptor, PS can not only prevent electrons and holes from recombining with each other but can also generate strong oxidizing radicals such as ∙SO4– and ∙OH to accelerate the reaction dynamics. The process of phenol degradation was found to be consistent with the Langmuir pseudo-first-order kinetic model with an apparent rate constant k of 1.73 min–1. The N-TiO2/AC/PS/VIS process was proven to be a facile method for pollutant degradation with high pH adaptability, excellent visible-light utilization and good application prospects. 相似文献