全文获取类型
收费全文 | 72898篇 |
免费 | 8771篇 |
国内免费 | 5849篇 |
专业分类
电工技术 | 6507篇 |
综合类 | 7277篇 |
化学工业 | 9351篇 |
金属工艺 | 5406篇 |
机械仪表 | 5400篇 |
建筑科学 | 5519篇 |
矿业工程 | 2947篇 |
能源动力 | 2150篇 |
轻工业 | 7407篇 |
水利工程 | 2194篇 |
石油天然气 | 2942篇 |
武器工业 | 1172篇 |
无线电 | 8058篇 |
一般工业技术 | 6474篇 |
冶金工业 | 2660篇 |
原子能技术 | 1142篇 |
自动化技术 | 10912篇 |
出版年
2024年 | 214篇 |
2023年 | 1198篇 |
2022年 | 2933篇 |
2021年 | 3761篇 |
2020年 | 2799篇 |
2019年 | 1984篇 |
2018年 | 2140篇 |
2017年 | 2303篇 |
2016年 | 2094篇 |
2015年 | 3407篇 |
2014年 | 4207篇 |
2013年 | 4794篇 |
2012年 | 6119篇 |
2011年 | 6400篇 |
2010年 | 5958篇 |
2009年 | 5632篇 |
2008年 | 5630篇 |
2007年 | 5513篇 |
2006年 | 4658篇 |
2005年 | 3839篇 |
2004年 | 2749篇 |
2003年 | 1930篇 |
2002年 | 1818篇 |
2001年 | 1613篇 |
2000年 | 1335篇 |
1999年 | 735篇 |
1998年 | 305篇 |
1997年 | 307篇 |
1996年 | 227篇 |
1995年 | 186篇 |
1994年 | 153篇 |
1993年 | 114篇 |
1992年 | 89篇 |
1991年 | 56篇 |
1990年 | 62篇 |
1989年 | 62篇 |
1988年 | 35篇 |
1987年 | 21篇 |
1986年 | 23篇 |
1985年 | 12篇 |
1984年 | 13篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1979年 | 17篇 |
1978年 | 3篇 |
1959年 | 18篇 |
1956年 | 1篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
2.
3.
Yunyan Liu Ning Jiang Yao Liu Dawei Cui Chang-Feng Yu Huiqiang Liu Zhao Li 《Ceramics International》2021,47(16):22416-22423
Pulsed laser deposition (PLD) was used to prepare tungsten trioxide (WO3) films on ITO substrates with a varying laser power density of 4.0–5.5 W/cm2. XPS indicated that when the laser power density decreased, the peak positions of the W 4f and O 1s orbits shifted slightly to low energy due to the difference in oxygen vacancies. As the laser power density decreased, W6+ gradually replaced the lattice position of O2?, increasing oxygen vacancies in the lattice. The transmittance modulated values (ΔT) were over 44% at 830 nm, indicating strong absorption by the WO3 thin films in the near-infrared ray. The switching time of the WO3 thin films between bleached states and coloured states decreased as the laser power density increased due to the amorphous structure, morphology, and lower oxygen deficiency at a high power density. The high ΔT and very fast switching time of tb (1.09 s) and tc (6.01 s) demonstrated the excellent electrochromic (EC) properties of the WO3 films prepared by PLD. 相似文献
4.
为了解决机器人辅助在线检测系统示教过程中效率低、人为干预多的问题,针对孔类特征,提出一种通过处理光刀图像获取机器人位姿纠正参数的方法。在该方法中,纠偏过程按照将图像光刀线调整为水平方向、将被测特征调整至图像中央、根据不同特征调整最优扫描方向3个步骤进行。根据光刀图像可以求出测量坐标系与被测特征的位姿关系,并得到该位姿与理想测量位姿的偏差。经过坐标变换即可得到在机器人基坐标系下的调整参数。另外,可利用电脑控制机器人运动,从而实现了纠偏过程的自动化。实验结果表明,该方法可将初始的示教位姿修正为理想位姿,且比传统方式效率更高。 相似文献
5.
近年来,随着国民经济的快速增长,人们的生活质量得到进一步提升,基于此,新媒体行业得到快速发展.对此,基于VR、AR技术特点,探析"5G+4K/8K+AR/VR"新技术在广电新媒体制播领域的实践应用. 相似文献
6.
A novel CdS/CaFe2O4 (CS/CFO) heterogeneous p-n junction was created by thermal deposition of CaFe2O4 nanoparticles on CdS rods. The CS/CFO hetero-structured photocatalysts exhibited increasingly efficient visible light harvesting compared to the bare CdS. The CS/CFO composites also presented higher photocurrent and slower decay of photoluminescence, suggesting a better separation of the photo-generated electrons and holes. The photocatalytic H2 evolution quantity on the optimized CS/CFO composite from water in the presence of ethanol was up to 2200 μmol after 3-h visible light illumination, which is more than twice that of the pristine CdS. The chemical interaction between CdS and CaFe2O4 was confirmed by the shifts in the XPS peaks, which made it possible for the charge carriers to transfer across the p-n junction interface. This research highlights the importance of forming an interfacial p-n heterojunction between two semiconductors for efficient charge separation and improved photocatalytic performance. 相似文献
7.
8.
Changbai Long Ning Ji Li Yang Wenjie Zhou Kun Zheng Wei Ren Laijun Liu 《Journal of the European Ceramic Society》2021,41(6):3369-3378
With co-substitution of (Li0.5Sm0.5) at A site and W at B site, the electrical properties of modified Ca0.92(Li0.5Sm0.5)0.08Bi2Nb2-xWxO9 [(CLS)BN-xW, x = 0, 0.015 and 0.03] piezoceramics with ultrahigh Curie temperature (TC) of > 930 °C were enhanced dramatically. The increased resistivity induced by the co-substitution ensure them to be polarized under an enough high field. Combined with the increase of spontaneous ferroelectric polarization (PS), the significant enhancements in the piezoelectric, dielectric and ferroelectric properties can be obtained in the composition x = 0.015. Furthermore, the piezoelectric activity (d33) and bulk resistivity (ρb) of (CLS)BN-0.015 W can be further enhanced at an appropriate sintering temperature. This optimum composition sintered at 1170 °C shows ultrahigh TC of ~948 °C, d33 of ~17.3 pC/N and ρb of ~6.9 MΩ cm at 600 °C, which are comparable to those of the reported high-temperature Aurivillius piezoceramics with TC > 850 °C. 相似文献
9.
10.
Xinyao Xie Xiaoqiong Wang Xiufang Bi Nan Ning Mingyuan Li Yage Xing Zhenming Che 《International Journal of Food Science & Technology》2022,57(7):4368-4379
This study investigated the effect of ultrafiltration (UF) combined with high-pressure processing (HPP) at 550 MPa, 25 °C for 5 min, ultrasound (US) at 520 W, 40 °C for 10 min and heat treatment (HT) at 90 °C for 3 min on the microbial, physicochemical and sensory properties of a blueberry–grape–pineapple–cantaloupe juice blend during 104 days of storage at 4 °C. After UF, the shelf life of the HPP- and US-treated clear juice blends were 104 and 72 days during the storage at 4 °C respectively. HPP, US and HT treatment minimally affected the anthocyanin and total phenol contents, while HPP better maintained the ascorbic acid levels and sensory properties in the clear juice blend during the storage. Therefore, HPP combined with UF was identified as a prospective processing technique in the fruit juice industry. 相似文献