全文获取类型
收费全文 | 3808篇 |
免费 | 358篇 |
国内免费 | 344篇 |
专业分类
电工技术 | 157篇 |
综合类 | 145篇 |
化学工业 | 85篇 |
金属工艺 | 56篇 |
机械仪表 | 720篇 |
建筑科学 | 37篇 |
矿业工程 | 14篇 |
能源动力 | 54篇 |
轻工业 | 14篇 |
水利工程 | 3篇 |
石油天然气 | 24篇 |
武器工业 | 103篇 |
无线电 | 1548篇 |
一般工业技术 | 486篇 |
冶金工业 | 14篇 |
原子能技术 | 4篇 |
自动化技术 | 1046篇 |
出版年
2024年 | 11篇 |
2023年 | 43篇 |
2022年 | 39篇 |
2021年 | 67篇 |
2020年 | 50篇 |
2019年 | 52篇 |
2018年 | 71篇 |
2017年 | 114篇 |
2016年 | 118篇 |
2015年 | 141篇 |
2014年 | 187篇 |
2013年 | 226篇 |
2012年 | 225篇 |
2011年 | 311篇 |
2010年 | 249篇 |
2009年 | 323篇 |
2008年 | 343篇 |
2007年 | 366篇 |
2006年 | 436篇 |
2005年 | 294篇 |
2004年 | 227篇 |
2003年 | 235篇 |
2002年 | 129篇 |
2001年 | 104篇 |
2000年 | 53篇 |
1999年 | 31篇 |
1998年 | 25篇 |
1997年 | 9篇 |
1996年 | 12篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有4510条查询结果,搜索用时 187 毫秒
21.
Sungho Jin 《Journal of Electronic Materials》2003,32(12):1366-1370
In packaging of microelectromechanical systems (MEMS), optical, and electronic devices, there is a need to directly bond a
wide variety of inorganic materials, such as oxides, nitrides, and semiconductors. Such applications involve hermetic-sealing
components, three-dimensional MEMS assembly components as well as active semiconductor or optical components, dielectric layers,
diffusion barriers, waveguides, and heat sinks. These materials are known to be very difficult to wet and bond with low melting-point
solders. New Sn-Ag- or Au-Sn-based universal solders doped with a small amount of rare-earth (RE) elements have been developed,
which now allow direct and powerful bonding onto the surfaces of various MEMS, optical, or electronic device materials. The
microstructure, interface properties, and mechanical behavior of the bonds as well as the potential packaging applications
of these new solder materials for MEMS and optical fiber devices are described. Various packaging-related structural, thermal,
or electrical issues in MEMS are also discussed. 相似文献
22.
MEMS的系统级设计对保证其整体综合性能和合理开发MEMS产品至关重要。针对MEMS的多能量域耦合、多信号混合的特点以及能量非保守等特殊要求 ,提出了基于多端口组件网络的MEMS系统级建模方法———采用多端口组件表示MEMS的功能结构部件 ,组件与组件通过端口联成网络表示整个系统 ;用统一规范化的微分代数方程表征并用硬件描述语言表述多端口组件。针对梁等具体的MEMS功能结构部件 ,采用宏建模方法确定其行为方程 ,从而得到有特定物理意义的、可供重用的组件模型。最后 ,给出了微加速度计的基于多端口组件网络方法的系统级设计示例 相似文献
23.
24.
WANG Jiqing 《声学技术》2004,23(Z3)
This paper gives an overview of the research at Institute of Acoustics, Tongji University, on functional absorbers and experience acquired in practical applications over the past three decades. Experiments and analysis of the absorption characteristics of three different geometrical forms of functional absorbers, i.e., panels, cubes and tubes, were conducted with different arrangements. The resulting esthetical effects are illustrated with pictures. Several non-fiber materials are used to compose functional absorbers with advantages both in acoustic properties and in architectural features. Cost effectiveness analysis is also given in order to provide design guidelines. 相似文献
25.
26.
Nano-crystal embedded PbO-P2O5 glass has been prepared and characterized by XRD and TEM measurements. The ultrasonic velocity and attenuation measured within
the temperature range 80–300 K show significant structure and interesting feature with the presence of nano-crystalline region.
The glass samples were prepared by melt-quench method and nano-crystals of different sizes were produced by heat treatment
of the glasses for different durations of heating. All the processes were carried out at or above glass transition temperature.
A theoretical model that takes account of the effects of thermally activated relaxation, anharmonicity as well as microscopic
elastic inhomogeneities arising out of fluctuations has been successfully applied to interpret the variation of ultrasonic
velocity and attenuation data. An interesting outcome of this application has been to propose a method for the determination
of the size of nano-crystals from the ultrasonic attenuation data. 相似文献
27.
PCR芯片和生化微分析系统 总被引:1,自引:0,他引:1
介绍了PCR微芯片的最新研究进展,给出了不同结构的PCR芯片设计原理以及特点,介绍由PCR芯片为主要单元的集成微全分析系统的相关研究,同时简要介绍了对PCR的仿真模拟等。 相似文献
28.
29.
Recent experiments have shown that metallic materials display significant size effects when the characteristic length scale of non-uniform plastic deformation is close to a micron. Couple stress plasticity has been developed to explain such phenomena by Fleck and Hutchinson. The mechanical behaviors of ultra-thin nickel beams in different boundary conditions were studied with the hybrid element developed for couple stress plasticity before. Strong scale effects are found when the beam's thickness is close to the material characteristic length scale. Such phenomena will disappear if the beam' s thickness is greatly larger than the material characteristic length scale. The scale effect is the beams inherent property and it does not change with the change of support conditions. 相似文献
30.
文章介绍了超精度的新型地震传感器DSU,它由微机电系统(MEMS)和兼有模拟电路和24位△—∑数字电路的混合器件(ASIC)组成,其失真度可达0.0032%,响应频带0~800Hz。DSU采集链使采集站、大线和检波器合为一体,既消除了电磁干扰和道间串音,又提高了采集数据的精度。DSU及DSU采集链的应用将为地震采集技术向超精度发展提供可靠保证。 相似文献