全文获取类型
收费全文 | 268篇 |
免费 | 17篇 |
国内免费 | 27篇 |
学科分类
工业技术 | 312篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 9篇 |
2013年 | 39篇 |
2012年 | 14篇 |
2011年 | 13篇 |
2010年 | 13篇 |
2009年 | 19篇 |
2008年 | 14篇 |
2007年 | 36篇 |
2006年 | 35篇 |
2005年 | 24篇 |
2004年 | 22篇 |
2003年 | 8篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 1篇 |
排序方式: 共有312条查询结果,搜索用时 0 毫秒
1.
低温烧结Dy-B-Si-O系玻璃介质掺杂Ba_(0.6)Sr_(0.4)TiO_3陶瓷 总被引:1,自引:1,他引:0
采用溶胶-凝胶法制备了Dy-B-Si-O系玻璃介质掺杂Ba0.6Sr0.4TiO3(BST)陶瓷粉体,并烧结成瓷。探讨了玻璃介质对BST陶瓷密度、烧结温度和介电性能的影响,利用扫描电子显微镜(SEM)、自动元件分析仪测试了BST陶瓷的显微结构和介电性能。研究结果表明,添加Dy-B-Si-O系玻璃介质降低了陶瓷烧结温度,提高了陶瓷致密度;随着Dy-B-Si-O系玻璃介质中Dy2O3组分含量的增加,介电常数增大;介电损耗先增大后减小,介电损耗最小值约为0.01,可满足在电压可调电容器上的使用要求。 相似文献
2.
D. Y. Wang Y. Wang J. Y. Dai H. L. W. Chan C. L. Choy 《Journal of Electroceramics》2006,16(4):587-591
Heteroepitaxial Ba0.7Sr0.3TiO3 thin films were grown on (LaAlO3)0.3(Sr2AlTaO6)0.35 (001) (LSAT) and SrTiO3 (001) (STO) single crystal substrates using pulsed laser deposition (PLD). X-ray diffraction characterization revealed a
good crystallinity and a pure perovskite structure for films grown on both LSAT and STO substrates. The in-plane ferroelectric
and dielectric properties of the films were studied using interdigital electrodes (IDE). The film grown on LSAT substrate
exhibited an enhanced in-plane ferroelectricity, including a well-defined P-E hysteresis loop with the remnant polarization
P
r
= 10.5 μC/cm2 and a butterfly-shaped C-V curve. Nevertheless, only a slim hysteresis loop was observed in the film grown on STO substrate. Curie temperature T
c
of the film grown on LSAT substrate was found to be ∼105∘C, which is nearly 70∘C higher than that of the bulk Ba0.7Sr0.3TiO3 ceramics. T
c
of the film grown on STO substrate has almost no change compared to the bulk Ba0.7Sr0.3TiO3 ceramics. The dielectric tunabilities were found to be 64% and 52% at 1 MHz for the films grown on LSAT and STO substrates,
respectively. 相似文献
3.
4.
5.
采用新型的Sol-gel工艺制备了Ba0.6Sr0.4TiO3(BST)超细粉体,将BST粉体进行压制和烧结,获得了晶粒尺寸在1μm以内的BST陶瓷块体.观察了BST陶瓷块体的结晶情况并测定了其电学性能.在Sol-gel工艺中,加入了有机大分子量聚乙烯吡咯烷酮(polyvinyl pyrrolidone,PVP)制备BST前驱体.实验结果表明:PVP的加入可有效增加前驱体的稳定性和分散性,降低BST陶瓷的预烧温度约250℃,并在1200℃获得晶粒细小、致密的BST陶瓷.BST陶瓷,显示弥散相变特征. 相似文献
6.
衬底同步加热溅射BST薄膜的研究 总被引:1,自引:0,他引:1
介绍了一种衬底同步加热射频磁控溅射制备BST(BaxSr1-xTiO3)薄膜的新方法,讨论了BST薄膜的晶化效果对介电常数的影响,分析了薄膜的居里温度和εr-V铁电性能.XRD测试结果表明制备的BST薄膜具有完整的钙钛矿晶体结构,相对介电常数超过150,介质击穿强度大于1.3 MV/cm.使用这种方法不需要专门的退火工艺,就可以制备晶体结构完整的高介电常数BST薄膜. 相似文献
7.
8.
Ba0.7Sr0.3TiO3薄膜的制备、结构及性能研究 总被引:2,自引:0,他引:2
研究了一种以乙二醇为稳定剂的新的BST前驱液,用sol-gel法在Pt/Ti/SiO2/Si(100)基底上成功地制备出具有优良电学性能的Ba0.7Sr0.3 TiO3薄膜.乙二醇的加入有效地增加了前驱液的稳定性,并降低薄膜的结晶温度.利用XRD、DTA等技术分析了凝胶热处理过程中相变化情况及薄膜厚度与成相的关系.厚度 200nm,O2气氛中 700℃处理 15min后的 BST薄膜具有良好的介电性能,100kHz时介电常数ε>400,介电损耗 D<0.02;P—E电滞回线说明薄膜具有良好的铁电性能,剩余极化只约为1.4μC/cm2,矫顽场强 Ec约为 48kV/cm. 相似文献
9.
Fe-doped Ba0.65Sr0.35TiO3 (BST) thin films have been fabricated on Pt/Ti/SiO2/Si substrate using the sol–gel method. The structural and surface morphology, dielectric, and leakage current properties of undoped and 1 mol% and 2 mol% Fe-doped BST thin films have been studied in detail. The results demonstrate that the Fe-doped BST films exhibit improved dielectric loss, tunability, and leakage current characteristics as compared to the undoped BST thin films. The improved figure of merit (FOM) of Fe-doped BST thin film suggests a strong potential for utilization in microwave tunable devices. 相似文献
10.
A novel sandwich structure of Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) was sputtered onto Pt/Ti/SiO2/Si substrate. With the insertion of a Cr layer, the leakage currents are decreased and the thermal stability of the specimens is enhanced. Temperature coefficient of capacitance (TCC) of specimens with BST(200 nm)/Cr(2 nm)/BST(200 nm) multifilms can achieve about 83% lower than those with BST (400 nm) monolayer. However, the dielectric constant of the BST(200 nm)/Cr(2 nm)/BST(200 nm) multifilms decreases to about 37% of that BST monolayer. The leakage current densities under an electric field of 125 kV/cm at 90 °C are 4 × 10− 4 A/cm2 and 9 × 10− 1 A/cm2 for BST (200 nm)/Cr (2 nm)/BST (200 nm) and monolayer BST (400 nm), respectively. X-ray diffraction results indicate the formation of a CrO3 secondary phase after annealing at 700 °C or above in O2 atmosphere. The root causes for the improvement of leakage currents and thermal stability with the insertion of nano-Cr interlayer are explored. The results show the insertion of Cr-nanolayer improves the electric properties for application in capacitors. 相似文献