全文获取类型
收费全文 | 260436篇 |
免费 | 21542篇 |
国内免费 | 11485篇 |
专业分类
电工技术 | 15878篇 |
技术理论 | 17篇 |
综合类 | 16966篇 |
化学工业 | 43238篇 |
金属工艺 | 14766篇 |
机械仪表 | 16269篇 |
建筑科学 | 21010篇 |
矿业工程 | 7815篇 |
能源动力 | 7430篇 |
轻工业 | 17273篇 |
水利工程 | 4734篇 |
石油天然气 | 15434篇 |
武器工业 | 2041篇 |
无线电 | 29882篇 |
一般工业技术 | 30728篇 |
冶金工业 | 12897篇 |
原子能技术 | 2885篇 |
自动化技术 | 34200篇 |
出版年
2024年 | 1191篇 |
2023年 | 4614篇 |
2022年 | 8359篇 |
2021年 | 11265篇 |
2020年 | 8616篇 |
2019年 | 6880篇 |
2018年 | 7868篇 |
2017年 | 8873篇 |
2016年 | 7810篇 |
2015年 | 10449篇 |
2014年 | 13080篇 |
2013年 | 15831篇 |
2012年 | 17180篇 |
2011年 | 18245篇 |
2010年 | 15574篇 |
2009年 | 14900篇 |
2008年 | 14304篇 |
2007年 | 13376篇 |
2006年 | 13838篇 |
2005年 | 12007篇 |
2004年 | 8006篇 |
2003年 | 6818篇 |
2002年 | 6152篇 |
2001年 | 5506篇 |
2000年 | 5713篇 |
1999年 | 6680篇 |
1998年 | 5483篇 |
1997年 | 4585篇 |
1996年 | 4450篇 |
1995年 | 3620篇 |
1994年 | 2942篇 |
1993年 | 2109篇 |
1992年 | 1712篇 |
1991年 | 1320篇 |
1990年 | 950篇 |
1989年 | 785篇 |
1988年 | 627篇 |
1987年 | 431篇 |
1986年 | 326篇 |
1985年 | 216篇 |
1984年 | 172篇 |
1983年 | 122篇 |
1982年 | 123篇 |
1981年 | 102篇 |
1980年 | 84篇 |
1979年 | 33篇 |
1978年 | 27篇 |
1977年 | 24篇 |
1976年 | 26篇 |
1975年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
A technique for SiO2 formation by liquid-phase deposition (LPD) at nearly room temperature for low-temperature processed (LTP) polysilicon thin-film transistor (poly-Si TFT) was developed. LPD SiO2 film with a lower P-etch rate shows a dense structure. LPD SiO2 also exhibits good electrical characteristics. LTP poly-Si thin-film transistors (TFTs) with LPD SiO 2 as the gate insulator have been fabricated and investigated. Their characteristics indicate performance adequate for their use as pixel transistors in liquid crystal displays (LCDs) 相似文献
22.
23.
The use of the analytically decoupled near-tip displacement solutions as an alternative approach, is presented in this paper for the efficient finite element evaluation of the decoupled weight functions for an orthotropic 2-D crack. This alternative approach has been validated by directly comparing the prior weight function results with a symmetric mesh approach in the crack-tip neighborhood, and indirectly by comparing the calculated stress intensity factors (KI(II)) values using the computed weight functions with available KI(II) solutions of the 2-D mixed mode orthotropic cracks. In addition, this approach with analytically decoupled near-tip displacement solutions for calculating weight functions at all locations, can facilitate further extension of weight function evaluations to a more general 2-D anisotropic crack. 相似文献
24.
25.
Motoharu Fujigaki In Hong Yang Yoshiharu Morimoto Eung Kyo Han 《NDT & E International》1996,29(4):197-203
There is no good method to measure the shape and the strain distributions of a structure changing with time. We have previously proposed the Fourier transform grid method (FTGM) to measure the three-dimensional shape and surface strain distributions of stationary objects by analysing the two-dimensional grating images recorded with two cameras. In the stereoscopic method, it is very important to determine the accurate geometric parameters of the camera system. In this paper, the positions and the directions of cameras are accurately determined using the FTGM applied to images of a reference object on which a two-dimensional grating is drawn. Applications for analysing shape and strain distributions of vibrating rubber plates and a moving human skin are shown. 相似文献
26.
WCDMA与GSM在空中接口上存在较大差异,WCDMA基于码分多址技术,GSM基于时分多址技术。GSM主要处理语音和低速数据,而WCDMA引入了多种速率的数据业务,根据业务的QoS进行资源控制和分配,因此在无线网络规划方法上,WCDMA与GSM存在较大差异。文章从容量规划、覆盖规划、蜂窝布局、规划流程、网络评估等方面对WCDMA与GSM的无线网络规划进行了比较和分析。 相似文献
27.
Gang Chen Zhonghua Yang Chor Ping Low 《Industrial Informatics, IEEE Transactions on》2006,2(4):269-280
In this paper, we address agent coordination from a dynamic systems perspective and propose a dynamic coordination model, which is inspired by biological metabolic systems. A new coordination mechanism through dynamic local adjustment (CDLA) is presented, and coordination is achieved when every agent utilizes explicitly the global system dynamics and performs iteratively a dynamic local adjustment procedure. The CDLA mechanism is investigated in an example multiagent shop floor system. The results show that the example manufacturing process is well-coordinated and the coordination approach is practically applicable and effective 相似文献
28.
29.
Resistance microwelding of fine crossed nickel wires is of increasing industrial importance for electrical connections in
downsized electronic and medical devices, but the understanding of the process is very limited. A study has, therefore, been
performed to clarify the basic joining mechanisms, in which the effects of main process parameters (welding current and force
and weld time) were investigated by detailed mechanical testing and metallurgical examinations. A bonding mechanism with main
process stages (wire cold collapse, surface melting, molten-phase squeeze-out and, solid-state bonding) was proposed. A new
technique has also been developed to optimize the process by initiating the welding current well before the electrode force
has reached its full nominal value. 相似文献
30.
Polyester‐based polyurethane/nano‐silica composites were obtained via in situ polymerization and investigated by Fourier‐transform infrared spectroscopy (FTIR), or FTIR coupled with attenuated total reflectance (FTIR‐ATR), Transmission electron microscopy (TEM), atomic force microscopy (AFM), an Instron testing machine, dynamic mechanical analysis (DMA) and ultraviolet‐visible spectrophotometry (UV‐vis). FTIR analysis showed that in situ polymerization provoked some chemical reactions between polyester molecules and nano‐silica particles. FTIR‐ATR, TEM and AFM analyses showed that both surface and interface contained nano‐silica particles. Instron testing and DMA data showed that introducing nano‐silica particles into polyurethane enhanced the hardness, glass temperature and adhesion strength of polyurethane to the substrate, but also increased the resin viscosity. UV‐vis spectrophotometry showed that nano‐silica obtained by the fumed method did not shield UV radiation in polyurethane films. Copyright © 2003 Society of Chemical Industry 相似文献