全文获取类型
收费全文 | 1181篇 |
免费 | 121篇 |
国内免费 | 76篇 |
专业分类
电工技术 | 11篇 |
综合类 | 63篇 |
化学工业 | 206篇 |
金属工艺 | 120篇 |
机械仪表 | 63篇 |
矿业工程 | 1篇 |
能源动力 | 4篇 |
轻工业 | 1篇 |
武器工业 | 7篇 |
无线电 | 648篇 |
一般工业技术 | 190篇 |
冶金工业 | 45篇 |
原子能技术 | 11篇 |
自动化技术 | 8篇 |
出版年
2023年 | 15篇 |
2022年 | 14篇 |
2021年 | 21篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 30篇 |
2017年 | 29篇 |
2016年 | 23篇 |
2015年 | 27篇 |
2014年 | 38篇 |
2013年 | 57篇 |
2012年 | 84篇 |
2011年 | 69篇 |
2010年 | 66篇 |
2009年 | 61篇 |
2008年 | 83篇 |
2007年 | 74篇 |
2006年 | 85篇 |
2005年 | 69篇 |
2004年 | 74篇 |
2003年 | 77篇 |
2002年 | 62篇 |
2001年 | 66篇 |
2000年 | 45篇 |
1999年 | 34篇 |
1998年 | 27篇 |
1997年 | 24篇 |
1996年 | 27篇 |
1995年 | 12篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 3篇 |
排序方式: 共有1378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.
《Ceramics International》2021,47(21):30147-30155
Yttrium aluminum garnet (Y3Al5O12, YAG) is an important functional material. However, the strict and complicated preparation has limited its wide application. This study aimed to rapidly synthesize Y3Al5O12 by plasma electrolysis for the first time. The prepared powder was studied from topography, structure and elements by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The powder had a good crystal form with a spherical shape. The single kind of diffraction peak of Y3Al5O12 in XRD revealed the high purity of the synthesized powders. The study of the relationship between the applied voltage and the synthesized powder revealed a threshold voltage of 210 V under the present condition. The higher voltage led to the damage of the electrode due to excessive heat. The synthesis of the YAG powder had a melt-quench process. The two processes were carried out at the same time. 相似文献
3.
Yung-Tang Nien Chang-Han Tsai Rui-He Zheng Hong-Jun Ye 《Ceramics International》2021,47(13):18550-18556
Cerium-doped yttrium aluminum garnet (Y3Al5O12:Ce, YAG:Ce) was prepared using a sol-gel method and then fired for CO2 laser post-treatments. Phase transformations and formation of impurities were not observed in YAG:Ce after CO2 laser sintering. The shift of the diffraction peak and the appearance of another Raman peak indicate a more homogeneous distribution of Ce activators and enhanced crystallinity in laser-sintered YAG hosts. Larger spheres (100–200 μm) with tiny crystallites (<10 μm) were observed on the smoother surface in the laser-sintered YAG:Ce, unlike the irregular, porous, and layered powders in the sol-gel-derived YAG:Ce (1–100 μm). Photoluminescence (PL) measurements revealed an emission increase of 180% and a red shift of the emission peak for the laser-sintered YAG:Ce powders compared with the sol-gel-derived powders. Both have comparable thermal PL quenching behavior; however, the YAG:Ce powders with CO2 laser treatment exhibited a PL efficiency improvement of approximately 4%. 相似文献
4.
Xu Wang Yujie Zhong Qian Sun Dongqing Qi Fuxue Yan Quangang Xian Dong Wang Kui Du Jingyang Wang 《Journal of the American Ceramic Society》2019,102(4):2176-2186
The microstructure evolution and growth behavior of the Al2O3/Y3Al5O12(YAG)/ZrO2 ternary eutectic ceramics during directional solidification were well investigated. During directional solidification of the Al2O3/YAG/ZrO2 ternary eutectic ceramics, {} Al2O3 paralleled with {001}ZrO2 while they did not parallel with {001}YAG at the same time in the competitive growth stage. All of the interfaces parallel to each other finally. The area percentage of the Al2O3/ZrO2 and YAG/ZrO2 interfaces are 40.4 ± 0.2% and 30.8 ± 0.1%, respectively, higher than that of the Al2O3/YAG (28.8 ± 0.2%). The content of Al2O3 and YAG phases are 39.9% and 41.1%, respectively, almost double of that of ZrO2. The interfaces of Al2O3/ZrO2 and YAG/ZrO2 are shorter and more dispersed than that of the Al2O3/YAG. It was found that the interfacial energy of Al2O3/ZrO2 and YAG/ZrO2 interfaces are lower than that of Al2O3/YAG. It can be concluded that interfacial energy plays a decisive role in affecting the crystallographic orientation and interfaces distribution in the Al2O3/YAG/ZrO2 eutectic since the interfaces of Al2O3/ZrO2 and YAG/ZrO2 with lower interfacial energy can be formed more easily during directional solidification. Therefore, the contents of Al2O3/ZrO2 and YAG/ZrO2 interfaces are higher. This study can provide theoretical guidance for interface design of multi-phase materials. 相似文献
5.
Meiling He Yinzi Cheng Linli Shen Huiling Zhang Chenyang Shen Weidong Xiang Xiaojuan Liang 《Journal of the American Ceramic Society》2019,102(3):1090-1100
CsPbX3 (X = Cl, Br, I) perovskite quantum dots (QDs) represent bright and tunable photoluminescence, it is regrettable that the air instability and poor water resistant properties prevent their application in optoelectronic devices. At the same time, the toxicity of lead is also a major factor restricting its development. As a consequence, we demonstrate the partial replacement of Pb with Mn through conventional melt-quenching and heat-treatment method preparation of Mn-doped CsPb(Cl/Br)3 QD glass. Mn-doped CsPb(Cl/Br)3 QD glass exhibits high luminescent intensity like QDs. It is important that Mn-doped CsPb(Cl/Br)3 QD glass with Dual-Color maintained the same lattice structure like Mn-doped CsPb(Cl/Br)3 QDs, and highly homogeneous spectral characteristics of Mn luminescence. The intensity and position of this Mn-related emission are also tunable by altering the experimental parameters, such as the Pb-to-Mn feed ratio, annealing temperature. More importantly, the as-prepared orange Mn-doped CsPb(Cl/Br)3 QD glass was employed to fabricate white LEDs combined with a commercial Ce3+:Y3Al5O12 phosphor-in-glass (Ce-PiG) on top of a InGaN blue chip. And the constructed WLEDs generate a warm white with an optimal luminous efficacy (LE) of 67.00 lm/W, a high CRI of 81.4, and a low CCT of 4902 K. 相似文献
6.
Xiaoyun Li Jian Chen Zhuguang Liu Zhonghua Deng Qiufeng Huang Jiquan Huang Wang Guo 《Journal of the European Ceramic Society》2021,41(8):4590-4597
(Y1-x%Cex%)3Al5O12 (x = 0.2,0.4,0.6,0.8,1.0) transparent ceramics were fabricated by vacuum sintering technology, followed by air annealing at different temperatures. Transmittance of ceramics, valence of cerium, and luminescent properties with varying annealing temperatures are studied in detail. The negative effect of Ce3+ oxidation induced by annealing gets increasingly evident when Ce concentration increases. Collaborating Ce:YAG ceramics with InGaN blue chips, light-emitting diodes (LEDs) with superior performance were constructed. The relationships between Ce concentration, annealing temperature, and luminous flux of LEDs are elucidated, showing that the optimized annealing temperature of Ce:YAG ceramics decreases from 1200 °C to 900 °C as Ce concentration increases from 0.2 at% to 1.0 at%. The luminous fluxes of optimized LEDs increase by ~10 % compared with that of unannealed LEDs. 相似文献
7.
Wei Jing Fang Li Shengquan Yu Xiangbo Ji Tao Xu Jian Zhang Zhongben Pan Zerui Yuan Bin Kang Jianguo Deng Wenlong Yin Hui Huang 《Journal of the European Ceramic Society》2018,38(5):2454-2461
A spray co-precipitation method was developed to efficiently synthesize Nd:YAG nano-powders. The effects of spray speeds and solution concentrations on the crystallization processes of calcined precursors have been studied. The results indicated that the pure phase of YAG could be obtained by three different crystallization processes owing to different homogeneity levels of Y and Al mixing. Pure YAG powder was obtained at 850?°C and the phase purity persisted to 1600?°C. Using the obtained powders, transparent ceramics with the in-line transmittance up to 80.2%@400 nm and 83.1%@1064?nm were fabricated by gel-casting method and hot isostatic pressing sintering. Furthermore, the microstructure and laser properties of the transparent ceramics have been measured. The maximum laser output of 7.015?W has been obtained with an oscillation threshold and a slope efficiency of 0.235?W and 59.4%, respectively. 相似文献
8.
Guosheng An Wensheng Li Li Feng Bo Cheng Zhiping Wang Ziyu Li Yi Zhang 《Ceramics International》2021,47(17):24320-24330
In this study, yttrium aluminum garnet/yttria-stabilized zirconia (YAG/YSZ) double-ceramic-layer thermal barrier coatings (DCL TBC) and yttria-stabilized zirconia (YSZ) single-ceramic-layer thermal barrier coatings (SCL TBC) were deposited by atmosphere plasma spray (APS) on the Inconel 738 alloy substrate, and isothermal oxidation tests were performed to investigate the formation and growth behavior of thermally grown oxide (TGO). Results showed that the Al2O3 TGO thickness of both TBC groups increased by increasing the isothermal oxidation time,and then slowly decreased with the appearance and growth of the adverse multilayer structure comprising CoCr2O4, (Ni,Co)Al2O4, NiCr2O4, and NiO mixed oxides. However, since the significant inhibition effect of the YAG coating to oxygen ionic diffusion, the mixed oxides appearance time and TGO growth behaviors were delayed in the DCL TBC. As a result, the TGO thickness of the DCL TBC was always smaller than that of the SCL TBC in the entire oxidation process. And the Al2O3 layer thickness proportion in the total TGO of the DCL TBC was greater than or equal to that of the SCL TBC after oxidation for the same period. The results of weight gain showed that compared with the SCL TBC, the parabolic oxidation rate of the DCL TBC was decreased approximately 35%. Consequently, the DCL TBC has better high-temperature oxidation resistance than the SCL TBC. 相似文献
9.
《Ceramics International》2022,48(7):9658-9666
Polycrystalline Nd:YAG materials have wide applications in solid-state lasers. In this study, micro hole drilling experiments were performed on polycrystalline Nd:YAG using a polycrystalline diamond micro drill. The hole diameter, edge chipping, and hole wall surface quality were examined in detail. The results showed that the hole diameter was slightly larger than tool diameter. A diameter error of less than 5.5% was achieved. The edge chipping at the entry hole was formed by the encircled petal shape exfoliations, which were produced by the indentation and rotation movement in the drilling entry stage. Edge chipping at the exit hole was generated by an entire piece of exfoliation, which was produced by a circle of microcracks around the tool tip propagating to the bottom surface in the drilling exit stage. The edge chipping width at the entry hole was smaller than that at the exit hole. Based on different material removal modes, the hole surface morphology was classified into three types: ductile removal, coexisting ductile and brittle removal, and brittle removal. The hole surface quality mainly depended on the proportion of the brittle fracture to ductile removal surface. 相似文献
10.
《Journal of the European Ceramic Society》2014,34(15):3827-3833
A freeze casting process with gelatine as gelling agent is presented to manufacture novel oxide fiber composites. The growth of ice crystals causes an in situ densification of the green matrix when the composite is frozen after the lamination of 2D-fabrics. This freeze casting process leads to a porous matrix with a cellular morphology, showing no shrinkage during sintering. The porous structure is suitable for a subsequent infiltration with a precursor to densify the matrix. As the matrix is crack-free, the sintered composites have high mechanical properties. The processing is demonstrated by manufacturing laminated Nextel™610/YAG-ZrO2 oxide fiber composites. 相似文献