全文获取类型
收费全文 | 97208篇 |
免费 | 7716篇 |
国内免费 | 3679篇 |
专业分类
电工技术 | 5209篇 |
技术理论 | 7篇 |
综合类 | 5886篇 |
化学工业 | 16568篇 |
金属工艺 | 5376篇 |
机械仪表 | 6275篇 |
建筑科学 | 7176篇 |
矿业工程 | 3117篇 |
能源动力 | 2968篇 |
轻工业 | 6521篇 |
水利工程 | 1445篇 |
石油天然气 | 6425篇 |
武器工业 | 662篇 |
无线电 | 10337篇 |
一般工业技术 | 12462篇 |
冶金工业 | 4930篇 |
原子能技术 | 1084篇 |
自动化技术 | 12155篇 |
出版年
2024年 | 298篇 |
2023年 | 1641篇 |
2022年 | 2500篇 |
2021年 | 3905篇 |
2020年 | 3028篇 |
2019年 | 2589篇 |
2018年 | 2960篇 |
2017年 | 3390篇 |
2016年 | 2854篇 |
2015年 | 3720篇 |
2014年 | 4645篇 |
2013年 | 5712篇 |
2012年 | 5903篇 |
2011年 | 6559篇 |
2010年 | 5604篇 |
2009年 | 5313篇 |
2008年 | 5125篇 |
2007年 | 4909篇 |
2006年 | 4978篇 |
2005年 | 4596篇 |
2004年 | 3010篇 |
2003年 | 2722篇 |
2002年 | 2432篇 |
2001年 | 2115篇 |
2000年 | 2303篇 |
1999年 | 2654篇 |
1998年 | 2327篇 |
1997年 | 1855篇 |
1996年 | 1889篇 |
1995年 | 1580篇 |
1994年 | 1268篇 |
1993年 | 962篇 |
1992年 | 737篇 |
1991年 | 586篇 |
1990年 | 440篇 |
1989年 | 346篇 |
1988年 | 314篇 |
1987年 | 203篇 |
1986年 | 145篇 |
1985年 | 122篇 |
1984年 | 90篇 |
1983年 | 47篇 |
1982年 | 54篇 |
1981年 | 40篇 |
1980年 | 31篇 |
1979年 | 22篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 13篇 |
1975年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
随着FPGA技术和电力电机技术的发展,FPGA+ARM的集成方式已经成为FPGA的发展方向.针对一体化多轴运动控制与驱动的特点,选用了集成双核ARM CPU与FPGA结合的Xilinx Zynq-7020全可编程System-on-chip(SoC)作为硬件平台,一个ARM CPU完成多轴的位置环、速度环和电流环的算法以及多轴轨迹生成,能同时完成伺服高级算法如谐振等,另一个ARM CPU完成交互功能,发挥FPGA高速运算的功能,完成6轴电流环流水线控制以及双采样双更新电流环算法.提高了系统整体带宽,实现多轴ns级同步精度以实现更精确的位置轨迹,驱控一体内部数据通过共享内存以及高速内部总线的方式进行交换,其传输速度更快、传输信息更加丰富. 相似文献
54.
56.
Ming-Puu Chen Asta Y. Z. Lord Yu-Yao Cheng Ku-Chou Tai Wen-Harn Pan 《Journal of Computer Assisted Learning》2020,36(3):383-396
Reflective judgement is crucial for medical-related practitioners in dealing with controversial issues. However, the conformity phenomenon is likely to occur and interfere with reflective judgement learning during interactive activities. Effective strategies are required to moderate the conformity behaviour tendency (CBT) and improve reflective judgement performance (RJP). This study demonstrates two significant results: (a) Compared with the guided self-reflection learning strategy, the online collective reflection (OCR) learning strategy effectively weakened the learners' general CBT while dealing with professional controversial issues; and (b) a significantly negative correlation between the RJP achieved and the change of CBT in online environment was detected in the OCR group. The implications and potential applications in higher education were discussed. Further studies are needed to confirm the long-term effects and the extending application to other professional studies. 相似文献
57.
Yong Xu Yun Li Songlin Li Francis Balestra Gerard Ghibaudo Wenwu Li Yen‐Fu Lin Huabin Sun Jing Wan Xinran Wang Yufeng Guo Yi Shi Yong‐Young Noh 《Advanced functional materials》2020,30(20)
Unreliable mobility values, and particularly greatly overestimated values and severely distorted temperature dependences, have recently hampered the development of the organic transistor field. Given that organic field‐effect transistors (OFETs) have been routinely used to evaluate mobility, precise parameter extraction using the electrical properties of OFETs is thus of primary importance. This review examines the origins of the various mobilities that must be determined for OFET applications, the relevant extraction methods, and the data selection limitations, which help in avoiding conceptual errors during mobility extraction. For increased precision, the review also discusses device fabrication considerations, calibration of both the specific gate‐dielectric capacitance and the threshold voltage, the contact effects, and the bias and temperature dependences, which must actually be handled with great care but have mostly been overlooked to date. This review serves as a systematic overview of the OFET mobility extraction process to ensure high precision and will also aid in improving future research. 相似文献
58.
Wei Mengnan Ban Boyuan Li Jingwei Sun Jifei Li Feifei Jiang Xuesong Chen Jian 《SILICON》2020,12(2):327-338
Silicon - A novel green cationic surfactant Poly (propylene glycol) bis (2-aminopropyl ether) (PEA) with multiple amine groups was utilized as a collector for flotation separation of quartz from... 相似文献
59.
60.
Mineralization of Para-Chlorobenzoic Acid in Water by Cobalt-Incorporated MCM-41 Catalyzed Ozonation
Cobalt-incorporated MCM-41(Co-MCM-41) was used as a heterogeneous catalyst for the ozonation of para-chlorobenzoic acid (p-CBA) in aqueous solution. Cobalt oxide supported on MCM-41(Co/MCM-41) was synthesized for comparison. Their textural properties were elucidated by various characterization techniques to understand the relationship between surface texture and catalytic activity. TOC removal at 60 min reached 91% with Co-MCM-41, 83% with Co/MCM-41 and only 52% with ozone alone, respectively. Observations from diffuse reflection spectroscopy demonstrated that different metal phases were formed in these cobalt-modified molecular sieves samples. Radical scavenger experiments indicated the formation of hydroxyl radicals that were responsible for the effective degradation of p-CBA. An integrated approach to the catalytic mechanism was proposed by considering the variation of pH in the course of ozonation as well as its subsequent influence on the dissociation of targeted compounds and surface charge of the catalyst. In the reusability experiments, the reused Co-MCM-41 was able to regain the same catalytic capability as the fresh one within 5 cycles. X-ray photoelectron spectroscopy results indicated that a part of Co2+ was oxidized to Co3+ after oxidation reaction. 相似文献