全文获取类型
收费全文 | 1957篇 |
免费 | 107篇 |
国内免费 | 77篇 |
专业分类
电工技术 | 226篇 |
综合类 | 44篇 |
化学工业 | 294篇 |
金属工艺 | 115篇 |
机械仪表 | 61篇 |
建筑科学 | 20篇 |
矿业工程 | 7篇 |
能源动力 | 107篇 |
轻工业 | 18篇 |
水利工程 | 2篇 |
石油天然气 | 10篇 |
武器工业 | 6篇 |
无线电 | 583篇 |
一般工业技术 | 437篇 |
冶金工业 | 11篇 |
原子能技术 | 21篇 |
自动化技术 | 179篇 |
出版年
2024年 | 1篇 |
2023年 | 49篇 |
2022年 | 39篇 |
2021年 | 55篇 |
2020年 | 53篇 |
2019年 | 47篇 |
2018年 | 47篇 |
2017年 | 56篇 |
2016年 | 35篇 |
2015年 | 56篇 |
2014年 | 79篇 |
2013年 | 91篇 |
2012年 | 92篇 |
2011年 | 168篇 |
2010年 | 113篇 |
2009年 | 121篇 |
2008年 | 120篇 |
2007年 | 114篇 |
2006年 | 92篇 |
2005年 | 74篇 |
2004年 | 58篇 |
2003年 | 76篇 |
2002年 | 62篇 |
2001年 | 69篇 |
2000年 | 58篇 |
1999年 | 63篇 |
1998年 | 55篇 |
1997年 | 26篇 |
1996年 | 56篇 |
1995年 | 23篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 21篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有2141条查询结果,搜索用时 109 毫秒
1.
Chenglai Xin Rong Yuan Jiang Wu Qingyuan Wang Yanan Zhou 《Ceramics International》2021,47(3):3411-3420
A novel method for fabricating a nano-Cu/Si3N4 ceramic substrate is proposed. The nano-Cu/Si3N4 ceramic substrate is first fabricated using spark plasma sintering (SPS) with the addition of nanoscale multilayer films (Ti/TiN/Ti/TiN/Ti) as transition layers. The microstructures of the nano-Cu metal layer and the interface between Cu and Si3N4 are investigated. The results show that a higher SPS temperature increases the grain size of the nano-Cu metal layer and affects the hardness. The microstructure of the transition layer evolves significantly after SPS. Ti in the transition layer can react with Si3N4 and with nano-Cu to form interfacial reaction layers of TiN and Ti–Cu, respectively; these ensure stronger bonding between nano-Cu and Si3N4. Higher SPS temperatures improve the diffusion ability of Ti and Cu, inducing the formation of Ti3Cu3O compounds in the nano-Cu metal layer and Ti2Cu in the transition layer. This study provides an important strategy for designing and constructing a new type of ceramic substrate. 相似文献
2.
《Journal of the European Ceramic Society》2020,40(15):5475-5482
The lead-free Ba0.53Sr0.47TiO3 (BST) thin films buffered with La0.67Sr0.33MnO3 (LSMO) bottom electrode of different thicknesses were fabricated by pulsed laser deposition method on a (001) SrTiO3 substrate. It was found that the roughness of electrode decreases and substrate stress relaxes gradually with the increase of LSMO thickness, which is beneficial for weakening local high electric field and achieving higher Eb. Therefore, the recoverable energy density (Wrec) of BST films can be greatly improved up to 67.3 %, that is, from 30.6 J/cm3 for the LSMO thickness of 30 nm up to 51.2 J/cm3 for the LSMO thickness of 140 nm after optimizing the LSMO thickness. Furthermore, the thin film capacitor with a 140 nm LSMO bottom electrode shows an outstanding thermal stability from 20 °C to 160 °C and superior fatigue resistance after 108 electrical cycles with only a slightly decrease of Wrec below 1.6 % and 3.7 %, respectively. Our work demonstrates that optimizing bottom electrodes thickness is a promising way for enhancing energy storage properties of thin-film capacitors. 相似文献
3.
《Journal of the European Ceramic Society》2020,40(14):4792-4798
The multilayer ceramic composites (MLC) consist of two ceramic materials insoluble in each other and sequentially piled in a symmetric manner whereas they can be divided into two groups: multilayer composites with weak interfaces and composites with strong interfaces. The graphene added multilayer ceramic sandwich (GMCS) composite was developed. The multilayer stack of Si3N4 with 5 and 30 wt% graphene addition were stratified in sandwich structure. So formed multilayer stacks with 5 and 7 layers were sintered by hot issostatic pressing (HIP). The homogenity of graphene addition, the effect of layered structures and the position of layers with lower and higher graphene content on the final properties were studied. 相似文献
4.
《Ceramics International》2019,45(10):13409-13413
We report an industrially viable promising approach to produce micrometer-sized multilayer graphene nanoplatelet powder (MGNP) in a scalable quantity via microwave-assisted exfoliation of graphite (MEG) and fragmented into MGNP through liquid-phase exfoliation in the co-solvent mixture by kitchen mixer (KM). KM allows rapid delaminating MEG into MGNP by shear force dominated exfoliation. Majority of MGNPs are with a diameter of few micrometers and thickness is in nanometers. MGNP are crystalline with very limited defects was confirmed by Raman measurements and transmission electron microscopy. This process transforms, more than 86% of graphite flakes into MGNP. This advanced approach opens a new pathway to produce MGNP in bulk quantity as it is feasible, rapid, and cost-effective. 相似文献
5.
6.
7.
ZHAOJi-jun JIYue-feng XUDa-xiong 《半导体光子学与技术》2003,9(3):141-147
In last decade,due to that the popularity of the internet, data--central traffic kept growing, some emerging networking requirements have been posed on the today‘s telecommunication networks,especially in the area of network survivability. Obviously, as a key networking problem, network reliability will be more and more important. The integration of different technologies such as ATM, SDH, and WDM in multilayer transport networks raises many questions regarding the coordination of the individual network layers.This problem is referred as multilayer network survivability. The integrated multilayer network survivability is investingated as well as the representation of an interworking strategy between different single layer survivability schemes in IP via generalized multiprotocol label switching over ootical netwnrk 相似文献
8.
X-ray diffraction analysis shows that the transformation during heat treatment from amorphous to crystalline phases of bismuth-borate glass samples takes place in sequences. After a short heat treatment, 5 min at 550 °C, a layered structure with a preferred orientation of crystallites on the surface is observed. After a long heat treatment, 8 h at the same temperature, normal polycrystalline bulk samples are obtained. 相似文献
9.
In this paper we show that by the analysis of 2D images collected with a laboratory X-ray microdiffractometer it is possible to non-destructively evaluate the structure, the microstructure, and the preferred orientation of films. In particular, the structural analysis of Co/Au multilayers on Si(1 0 0) deposited at different Ar pressures are reported and discussed. 相似文献
10.
恰当选择原材料、确保铆接工序质量、重视工作电解液的配比、严控各工序成品率是提高超小型铝电解电容器投入产出一次合格率的关键。以10V-47μF(4mm×7mm)产品为例,投入产出一次合格率达94%以上。 相似文献