全文获取类型
收费全文 | 961篇 |
免费 | 83篇 |
国内免费 | 75篇 |
专业分类
电工技术 | 65篇 |
综合类 | 51篇 |
化学工业 | 153篇 |
金属工艺 | 111篇 |
机械仪表 | 36篇 |
建筑科学 | 75篇 |
矿业工程 | 33篇 |
能源动力 | 21篇 |
轻工业 | 74篇 |
水利工程 | 18篇 |
石油天然气 | 69篇 |
武器工业 | 18篇 |
无线电 | 173篇 |
一般工业技术 | 80篇 |
冶金工业 | 44篇 |
原子能技术 | 17篇 |
自动化技术 | 81篇 |
出版年
2024年 | 2篇 |
2023年 | 24篇 |
2022年 | 26篇 |
2021年 | 36篇 |
2020年 | 39篇 |
2019年 | 18篇 |
2018年 | 27篇 |
2017年 | 30篇 |
2016年 | 18篇 |
2015年 | 52篇 |
2014年 | 49篇 |
2013年 | 61篇 |
2012年 | 75篇 |
2011年 | 74篇 |
2010年 | 53篇 |
2009年 | 62篇 |
2008年 | 52篇 |
2007年 | 55篇 |
2006年 | 40篇 |
2005年 | 51篇 |
2004年 | 33篇 |
2003年 | 26篇 |
2002年 | 37篇 |
2001年 | 23篇 |
2000年 | 25篇 |
1999年 | 23篇 |
1998年 | 22篇 |
1997年 | 10篇 |
1996年 | 19篇 |
1995年 | 18篇 |
1994年 | 14篇 |
1993年 | 5篇 |
1992年 | 10篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1985年 | 1篇 |
排序方式: 共有1119条查询结果,搜索用时 0 毫秒
61.
如何通过金属监督质量管理的优化创新来更好地服务当前电力设备材料等级越来越高的需求,已经成为目前电力行业内金属监督质量管理工作面临的一项挑战性课题。文章主要分析了现阶段电力行业金属监督质量管理工作中普遍存在的问题、不足和难点,并明确金属监督质量管理工作的基本要求,最后提出了金属监督质量管理工作优化的相关措施,对电力行业金属监督质量管理工作提供有助益的参考。 相似文献
62.
磁控溅射氧化钒薄膜的研究进展 总被引:1,自引:0,他引:1
氧化钒因其优秀的相变特性和电阻开关特性而广受关注,在氧化钒薄膜多种制备工艺中,磁控溅射法优势明显。本文总结了近年来国内外研究者对磁控溅射法制备氧化钒薄膜的基础工艺研究成果,概述了不同溅射工艺对二氧化钒薄膜结晶特性及光学、电学性能的影响,并对相关机理进行了简要分析。相关结论对氧化钒薄膜的性能提高和应用扩展有一定的指导意义。 相似文献
63.
Hailan Yi Xiaojian Mao Guohong Zhou Shi Chen Xiaoqing Zou Shiwei Wang Shunzo Shimai 《Ceramics International》2012,38(7):5557-5561
Transparent alumina ceramics with oriented grains were successfully prepared by slip casting under an assisted magnetic field and sintering at 1850 °C for 5 h in vacuum. In-line transmittance of the alumina ceramic shaped under 12 T reaches as high as 70.3% at 600 nm. Detailed crystal plane evolution of grain oriented alumina ceramics with the assistance of different magnitude magnetic field was studied by XRD characterization. The results indicate that complete textured structure could only be realized with a magnetic field strength above 12 T. Furthermore, the grain microstructure was observed by optical microscope in different directions. 相似文献
64.
65.
A NiO(x) buffer layer is introduced in GaN-based light-emitting diodes to form low resistance ohmic contacts between p-type GaN and graphene conductive electrodes, leading to improved performance with lower operating voltage and higher light output power. 相似文献
66.
67.
Chao Xia Mengmeng Cao Jinfeng Xia Danyu Jiang Guohong Zhou Caiyan Yu Huili Li 《Journal of the American Ceramic Society》2020,103(8):4507-4516
In this work, we synthesized a series of novel carbon dots (CDs) by using phenylenediamines (three isomers: o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine) as starting materials via facile solvothermal approach. As-prepared CDs could emit bright blue, green, yellow, orange, and red light with relatively high PLQY, individually. Optical properties could be controlled by simply varying reaction parameters. The luminescent mechanism was investigated and analyzed in detail. Finally, the blue-emitting CDs and green-emitting CDs showed many appealing properties, such as high sensitivity (limit of detection = 4.52 and 3.50 nmol/L), quick response (<2 minutes), broad response window (0-70 nmol/L), and excellent selectivity for detecting Cr6+ and Al3+ cations, respectively. Thus, they have potential to be developed as the corresponding optical probes. While as-prepared orange-emitting CDs could be applied as a bio-imaging reagent due to its long-wavelength emission, relatively high PLQY, low toxicity, excellent water solubility, and good biocompatibility. 相似文献
68.
引入影响汽车行驶转向性能的轮胎侧偏、悬架侧倾和,前轮定位等主要因素,建立了汽车整体式转向梯形机构的优化数学模型,从四个方面对梯形机构进行优化设计。通过对这些结果的分析对比,得出了具有实用价值的结论。 相似文献
69.
Yan Liu Lin Gan Xianpeng Qin Guohong Zhou Juan Jiang Tianjin Zhang Song Hu Zhengjuan Wang 《Journal of the American Ceramic Society》2023,106(6):3557-3567
Highly transparent yttria ceramics were fabricated by pressureless sintering with Nb2O5 or Ta2O5 as a novel sintering additive. The optical transmittance, microstructural evolution, and thermo-mechanical properties of the samples were investigated. The optimal doping concentrations of Nb2O5 and Ta2O5 are 0.3 and 0.2 at.%, respectively, which are much lower compared to those of previously reported counterparts. The transmittance of the sample with 0.3 at.% Nb2O5 reaches 81.6% at 1100 nm and 72.4% at 400 nm (2 mm in thickness), similar transmittance was obtained in the sample with 0.2 at.% Ta2O5. The microhardness (∼7 GPa), fracture toughness (∼0.85 MPa·m1/2), and biaxial strength (∼200 MPa) of the present samples were confirmed to be comparable or even better compared to those of previously reported transparent yttria ceramics fabricated by pressureless sintering. Furthermore, the present samples, by virtue of the low doping concentrations, possessed relatively high thermal conductivity values (>10 W/m·K), which substantially guaranteed high thermal shock resistance. 相似文献
70.
Fabrication of Transparent Dysprosium Aluminum Garnet (Dy3Al5O12) Ceramics via a Solid‐State Reaction Method 下载免费PDF全文
Song Hu Xianpeng Qin Chunhua Lu Guohong Zhou Zhongzi Xu Shiwei Wang 《Journal of the American Ceramic Society》2015,98(6):1714-1716
Polycrystalline, transparent Dy3Al5O12 ceramics were firstly fabricated by a solid‐state reaction method using high‐purity Dy2O3 and Al2O3 powders. The fully dense Dy3Al5O12 ceramic with an average grain size of less than 10 μm was obtained by vacuum sintering at 1820°C for 6 h. The in‐line transmittance of the optimized sample reaches 80% in the visible region. Scanning electron microscopy reveals that no secondary phases and almost no pores are observed at grain boundaries or triple junctions, and the fracture mode of the ceramic is mainly transgranular. The Dy3Al5O12 ceramic is promising for magneto‐optical applications. Verdet constant of the Dy3Al5O12 transparent ceramic is as high as ?0.41 min·(Oe·cm)?1. 相似文献