全文获取类型
收费全文 | 321篇 |
免费 | 54篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 19篇 |
综合类 | 10篇 |
化学工业 | 63篇 |
金属工艺 | 6篇 |
机械仪表 | 4篇 |
建筑科学 | 1篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 4篇 |
石油天然气 | 1篇 |
无线电 | 151篇 |
一般工业技术 | 95篇 |
冶金工业 | 24篇 |
自动化技术 | 14篇 |
出版年
2023年 | 19篇 |
2022年 | 12篇 |
2021年 | 23篇 |
2020年 | 13篇 |
2019年 | 17篇 |
2018年 | 22篇 |
2017年 | 18篇 |
2016年 | 11篇 |
2015年 | 18篇 |
2014年 | 24篇 |
2013年 | 27篇 |
2012年 | 17篇 |
2011年 | 41篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 16篇 |
2007年 | 13篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有399条查询结果,搜索用时 15 毫秒
1.
Yuelong Ma Le Zhang Tianyuan Zhou Bingheng Sun Chen Hou Shunshun Yang Jin Huang Rui Wang Farida A. Selim Zhongying Wang Ming Li Hao Chen Yun Wang 《Journal of the European Ceramic Society》2021,41(4):2834-2846
Ce:Y3Al5O12 transparent ceramics (TCs) with appropriate emission light proportion and high thermal stability are significant to construct white light emitting diode devices with excellent chromaticity parameters. In this work, strategies of controlling crystal-field splitting around Ce3+ ion and doping orange-red emitting ion, were adopted to fabricate Ce:(Y,Tb)3(Al,Mn)5O12 TCs via vacuum sintering technique. Notably, 85.4 % of the room-temperature luminescence intensity of the TC was retained at 150 °C, and the color rendering index was as high as 79.8. Furthermore, a 12 nm red shift and a 16.2 % increase of full width at half maximum were achieved owing to the synergistic effects of Tb3+ and Mn2+ ions. By combining TCs with a 460 nm blue chip, a warm white light with a low correlated color temperature of 4155 K was acquired. Meanwhile, the action mechanism of Tb3+ ion and the energy transfer between Ce3+ and Mn2+ ions were verified in prepared TCs. 相似文献
2.
Zhiyong Fang Xiaohui Lai Jian Zhang Rui Zhang 《International Journal of Applied Ceramic Technology》2021,18(4):1106-1113
K2TiF6:Mn4+ is an attractive narrow-band red-emitting phosphor for warm white light-emitting diodes (LEDs). Nevertheless, the hexafluoride phosphor is liable to deliquesce in moist environments, which leads to a sharp deterioration performance of luminescence. Surface modification of K2TiF6:Mn4+ phosphor with SrF2 coating has been introduced, with the aid of KHF2 transition layer to moderate the lattice mismatch. The reaction mechanism is discussed in detail, as so as the influence of SrF2 coating on the luminescence intensity. The SrF2 coating is able to prevent the hydrolysis of internal [MnF6]2− group; thereby, the luminescence intensity retains over 90% of initial value after being immersed in distilled water for 2 h. The LED devices fabricated with commercial Y3Al5O12:Ce3+ and as-modified K2TiF6:Mn4+ phosphors exhibit bright white light with tunable chromaticity coordinate, correlated color temperature, and color rendering index. It enlightens a convenient method to enhance the moisture resistance of Mn4+ doped fluoride phosphors for commercial application in the field of white LEDs. 相似文献
3.
New luminescent copolyethers with diphenylanthracene‐emitting segments and electron‐transporting benzoxazole phenyl were successfully synthesized by aromatic nucleophilic substitution. The polymers, characterized by NMR and IR spectroscopy, were obtained in high yields, showed good solubility in various organic solvents, and had high thermal stability with high glass‐transition temperatures (125–129). The number‐average molecular weights of the polymers were 10,000–20,000, and they had polydispersity indices of 1.2–1.4. The optical and electrochemical properties of the polymers were also investigated. The pure blue emission for the polymers (maximum wavelength = 430–440 nm) was obtained with high photoluminescence quantum efficiency (76–78%) in a chloroform solution. The blue electroluminescence for the poly(TDPB) (maximum wavelength = 440 nm) was obtained with a turn‐on voltage of 15–20 V when simple light‐emitting diodes (indium tin oxide/polymer/Al) were fabricated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2151–2157, 2006 相似文献
4.
Shuai Huang Lixin Yu Kangliang Peng Youjun Zhao Jindi Wang Mengmeng Shang 《Journal of the American Ceramic Society》2021,104(11):5848-5858
To enhance the display quality of light-emitting diodes (LEDs), it is of great significance to exploit green/yellow-emitting phosphors with narrow emission band, high quantum yield, and excellent color purity to satisfy the application. Herein, orthophosphate-based green/yellow-emitting Na3Tb(PO4)2:Ce3+/Eu2+ (NTPO:Ce3+/Eu2+) phosphors have been successfully synthesized by a facile solid-state reaction method. The absorption band of NTPO samples was extended to the near-ultraviolet region and the absorption efficiency was significantly improved owing to a highly efficient energy transfer from Ce3+/Eu2+ ion to Tb3+ ion in NTPO host certified by time-resolved PL spectra. Upon 300 nm excitation, the NTPO:Ce3+ is characterized by ultra-narrow-band green emission of Tb3+ with an absolute quantum yield of 94.5%. Unexpectedly, NTPO:Eu2+ emits bright yellow light with a color purity of 73% as a result of the blending of green light emission from Tb3+ and red light emission from Eu3+. The thermal stability has been improved by controlling the stoichiometric ratio of Na+. The prototype white LED used yellow-emitting NTPO:Eu2+ phosphor has higher color-rendering index (Ra = 83.5), lower correlated color temperature (CCT = 5206 K), and closer CIE color coordinates (0.338, 0.3187) to the standard white point at (0.333, 0.333) than that used green-emitting NTPO:Ce3+ phosphor, indicating the addition of the yellow light component improved the Ra of the trichromatic (RGB) materials. 相似文献
5.
Masoud Alahbakhshi Aditya Mishra Grigorii Verkhogliadov Emigdio E. Turner Ross Haroldson Austen C. Adams Qing Gu Jeffrey J. Rack Jason D. Slinker Anvar A. Zakhidov 《Advanced functional materials》2023,33(28):2214315
Perovskite light-emitting diodes (PeLEDs) are advancing because of their superior external quantum efficiencies (EQEs) and color purity. Still, additional work is needed for blue PeLEDs to achieve the same benchmarks as the other visible colors. This study demonstrates an extremely efficient blue PeLED with a 488 nm peak emission, a maximum luminance of 8600 cd m−2, and a maximum EQE of 12.2% by incorporating the double-sided ethane-1,2-diammonium bromide (EDBr2) ligand salt along with the long-chain ligand methylphenylammonium chloride (MeCl). The EDBr2 successfully improves the interaction between 2D perovskite layers by reducing the weak van der Waals interaction and creating a Dion–Jacobson (DJ) structure. Whereas the pristine sample (without EDBr2) is inhibited by small stacking number (n) 2D phases with nonradiative recombination regions that diminish the PeLED performance, adding EDBr2 successfully enables better energy transfer from small n phases to larger n phases. As evidenced by photoluminescence (PL), scanning electron microscopy (SEM), and atomic force microscopy (AFM) characterization, EDBr2 improves the morphology by reduction of pinholes and passivation of defects, subsequently improving the efficiencies and operational lifetimes of quasi-2D blue PeLEDs. 相似文献
6.
Decoupling Charge Transport and Electroluminescence in a High Mobility Polymer Semiconductor 下载免费PDF全文
7.
8.
低色温高显色性大功率白光LED的制备及其发光特性研究 总被引:2,自引:3,他引:2
用GaN基大功率蓝光LED芯片作为激发光源,分别用荧光粉转换法和红光LED补偿法制备了不同相关色温及显色指数的白光LED。对器件的发光特性研究表明,采用监光LED芯片激发单一黄色荧光粉,虽可以获得光通量和发光效率较高的白光LED,但其色温较高,显色性较差;在黄色荧光粉中添加红色荧光粉,由于光谱中红色成分的增加,可降低器件的色温,并提高器件的显色性,但由于目前红色荧光粉的转换效率较低,致使器件的整体发光效率不高;采用蓝光LED芯片激发黄色荧光粉,同时用红光LED进行补偿,通过调整蓝光和红光LED芯片的工作电流以及荧光粉的用量,可获得低色温和高显色性白光LED,而且整体发光效率较高。 相似文献
9.
本文回顾了近年来照明光源与技术的研究、开发的主要成果,提出了近期的主要研究热点和需要解决的问题.其中照明光源主要讨论了半导体发光二极管、金属卤化物灯、荧光灯等. 照明技术讨论了视觉研究、照明质量评价、照明的光生物效应、天然采光技术和节能照明器材等. 相似文献
10.
Yen‐Ting Lin Ting‐Wei Yeh Yoshitake Nakajima P. Daniel Dapkus 《Advanced functional materials》2014,24(21):3162-3171
GaN nanorod formation on Ga‐polar GaN by continuous mode metalorganic chemical vapor deposition selective area growth (MOCVD SAG) is achieved under a relatively Ga‐rich condition. The Ga‐rich condition, provided by applying a very low V/III ratio, alters the growth rates of various planes of the defined nanostructure by increasing relative growth rate of the semi‐polar tilted m‐plane {1–101} that usually is the slowest growing plane under continuous growth conditions. This increased growth rate relative to the non‐polar m‐plane {1–100} and even the c‐plane (0001), permits the formation of GaN nanorods with nonpolar sidewalls. In addition, a new growth mode, called the NH3‐pulsed mode, is introduced, utilizing the advantages of both the continuous mode and the lower growth rate pulsed mode to form nanorods. Finally, nanorods grown under the different growth modes are compared and discussed. 相似文献