全文获取类型
收费全文 | 3695篇 |
免费 | 481篇 |
国内免费 | 265篇 |
专业分类
电工技术 | 136篇 |
综合类 | 303篇 |
化学工业 | 488篇 |
金属工艺 | 215篇 |
机械仪表 | 647篇 |
建筑科学 | 134篇 |
矿业工程 | 72篇 |
能源动力 | 71篇 |
轻工业 | 143篇 |
水利工程 | 65篇 |
石油天然气 | 248篇 |
武器工业 | 31篇 |
无线电 | 420篇 |
一般工业技术 | 659篇 |
冶金工业 | 90篇 |
原子能技术 | 208篇 |
自动化技术 | 511篇 |
出版年
2024年 | 14篇 |
2023年 | 90篇 |
2022年 | 125篇 |
2021年 | 165篇 |
2020年 | 171篇 |
2019年 | 142篇 |
2018年 | 133篇 |
2017年 | 186篇 |
2016年 | 179篇 |
2015年 | 163篇 |
2014年 | 223篇 |
2013年 | 243篇 |
2012年 | 250篇 |
2011年 | 301篇 |
2010年 | 209篇 |
2009年 | 199篇 |
2008年 | 178篇 |
2007年 | 214篇 |
2006年 | 187篇 |
2005年 | 150篇 |
2004年 | 139篇 |
2003年 | 116篇 |
2002年 | 110篇 |
2001年 | 93篇 |
2000年 | 75篇 |
1999年 | 66篇 |
1998年 | 56篇 |
1997年 | 47篇 |
1996年 | 41篇 |
1995年 | 30篇 |
1994年 | 25篇 |
1993年 | 28篇 |
1992年 | 21篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 9篇 |
1984年 | 1篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1968年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有4441条查询结果,搜索用时 15 毫秒
31.
探讨了采用ICT技术对弹药进行无损检测的可行性,介绍了ICT系统的组成,重点讨论了提高ICT成像质量所采取的措施,给出了弹药中缺陷的CT扫描图像。结果表明ICT技术具有其它常规检测方法无法比拟的优越性,对弹药有很好的检测效果。 相似文献
32.
Infrared thermography for inspecting the adhesion integrity of plastic welded joints 总被引:1,自引:0,他引:1
This work aim at developing a non-destructive tool for the evaluation of bonded plastic joints. The paper examines infrared thermographic transmission and reflection mode imaging and validates the feasibility of the thermal NDT approach for this application. Results demonstrate good estimation performance for adhesion integrity, uniformity and bond strength using a transmission mode application of infrared thermography. In addition, results from a pulsed infrared thermographic application using a modified dynamic infrared tomography scheme show good performance for estimating adhesion layer thickness mapping and detecting delaminations. 相似文献
33.
SHAO Jun Shanghai University of Science Technology Shanghai ChinaXU Hua CHEN Nianyi Shanghai Institute of Metallurgy Academia Sinica Shanghai China SHAO Jun Associate Professor Dept.of Chemistry Shanghai University of Science Technology Shanghai China 《金属学报(英文版)》1990,3(10):221-225
The structure and properties of molten salt solution o J Li,K|F,Cl system have been investigedby computerized simulation of molecular dynamic method.The partial RDF,the partial molarenergy of mixing and the diffusion coeffients of Li~+,K~+,F~- and Cl~- have been calculated.The results are in agreement with the experimental values.The regularities of the distributionof ions and mieroscopic holes are discussed based on the results of computerized simulation. 相似文献
34.
网络层析成像能够在网络内部节点不提供测量协作的情况下,根据端到端的测量结果,间接地估计网络内部链路性能参数,是一种重要的网络测量手段,能直接指导网络管理和网络优化,目前受到国内外学术界和工业界广泛的关注.在广泛收集国内外资料的基础上,首先总结了目前网络层析成像使用的主要端到端测量方法和技术;再根据不同参数对链路性能刻画程度的不同,将链路性能参数的网络层析成像方法分为两类:定量参数推断方法和定性参数推断方法;然后,针对不同类型参数的估计问题,概括分析了现有算法的特点;最后指出该类方法未来的研究方向与潜在的应用前景. 相似文献
35.
36.
本文分析了电脑横机的结构与功能,提出了基于嵌入式的电脑横机控制系统,采用了S3C2410为主处理芯片,通过FPGA扩展端口,系统读取织物花型数据,控制横机各个动作子系统来完成编制动作,该电脑横机控制系统与传统电脑横机系统相比较,工作效率高,可移植性强。 相似文献
37.
在电磁波 CT 测试中,发射、接收探头间的电磁波射线发射点、接收点位置决定反演后成果数据记录点的位置。为了确定电磁波仪发射、接收探头记录点位置,对探头分别进行钢管屏蔽实验,实验表明电磁波仪工作时电磁波能量主要集中在两探头的馈电点及天线末端间近似于平行四边形的区域内,不宜直接地简化为一条直线,将平行四边形区域简化为4条线段进行电磁波层析成像反演计算更符合实际情况。在此基础上,提出对电磁波 CT 数据采取4条射线路径单独反演后,再将4个结果按综合平均的方法进行处理。将此种处理方法应用于武汉地铁岩溶勘察数据处理中,并与目前基于1条射线的反演处理方法进行对比、验证。对比剖面反演数据结果表明,在采用同一反演软件条件下4条射线路径综合反演法精度优于1条射线反演法。 相似文献
38.
The next generations of advanced energy systems will require materials that can withstand high doses of irradiation at elevated temperatures. Therefore, a methodology has been developed for the fabrication of high-dose ion-irradiated atom probe tomography specimens at a specific dose with the use of a focused ion beam milling system. The method also enables the precise ion dose of the atom probe tomography specimen to be estimated from the local concentration of the implanted ions. The method has been successfully applied to the characterization of the distribution of nanoclusters in a radiation-tolerant 14YWT nanostructured ferritic steel under ion irradiation to doses up to 400 displacements per atom. 相似文献
39.
With the continuous shrinking of transistors and advent of new transistor architectures to keep in pace with Moore's law and ITRS goals, there is a rising interest in multigate 3D-devices like FinFETs where the channel is surrounded by gates on multiple surfaces. The performance of these devices depends on the dimensions and the spatial distribution of dopants in source/drain regions of the device. As a result there is a need for new metrology approach/technique to characterize quantitatively the dopant distribution in these devices with nanometer precision in 3D.In recent years, atom probe tomography (APT) has shown its ability to analyze semiconductor and thin insulator materials effectively with sub-nm resolution in 3D. In this paper we will discuss the methodology used to study FinFET-based structures using APT. Whereas challenges and solutions for sample preparation linked to the limited fin dimensions already have been reported before, we report here an approach to prepare fin structures for APT, which based on their processing history (trenches filled with Si) are in principle invisible in FIB and SEM. Hence alternative solutions in locating and positioning them on the APT-tip are presented. We also report on the use of the atom probe results on FinFETs to understand the role of different dopant implantation angles (10° and 45°) when attempting conformal doping of FinFETs and provide a quantitative comparison with alternative approaches such as 1D secondary ion mass spectrometry (SIMS) and theoretical model values. 相似文献
40.
Electron tomography (ET) combines electron microscopy and the principles of tomographic imaging in order to reconstruct the three-dimensional structure of complex biological specimens at molecular resolution. Weighted back-projection (WBP) has long been the method of choice since the reconstructions are very fast. It is well known that iterative methods produce better images, but at a very costly time penalty. In this work, it is shown that efficient parallel implementations of iterative methods, based primarily on data decomposition, can speed up such methods to an extent that they become viable alternatives to WBP. Precomputation of the coefficient matrix has also turned out to be important to substantially improve the performance regardless of the number of processors used. Matrix precomputation has made it possible to speed up the block-iterative component averaging (BICAV) algorithm, which has been studied before in the context of computerized tomography (CT) and ET, by a factor of more than 3.7. Component-averaged row projections (CARP) is a recently introduced block-parallel algorithm, which was shown to be a robust method for solving sparse systems arising from partial differential equations. It is shown that this algorithm is also suitable for single-axis ET, and is advantageous over BICAV both in terms of runtime and image quality. The experiments were carried out on several datasets of ET of various sizes, using the blob model for representing the reconstructed object. 相似文献