全文获取类型
收费全文 | 14941篇 |
免费 | 1578篇 |
国内免费 | 860篇 |
专业分类
电工技术 | 1800篇 |
技术理论 | 2篇 |
综合类 | 1566篇 |
化学工业 | 953篇 |
金属工艺 | 462篇 |
机械仪表 | 1205篇 |
建筑科学 | 282篇 |
矿业工程 | 222篇 |
能源动力 | 332篇 |
轻工业 | 1078篇 |
水利工程 | 74篇 |
石油天然气 | 179篇 |
武器工业 | 231篇 |
无线电 | 4058篇 |
一般工业技术 | 1492篇 |
冶金工业 | 295篇 |
原子能技术 | 75篇 |
自动化技术 | 3073篇 |
出版年
2024年 | 54篇 |
2023年 | 304篇 |
2022年 | 336篇 |
2021年 | 453篇 |
2020年 | 501篇 |
2019年 | 392篇 |
2018年 | 310篇 |
2017年 | 475篇 |
2016年 | 554篇 |
2015年 | 608篇 |
2014年 | 1055篇 |
2013年 | 891篇 |
2012年 | 1265篇 |
2011年 | 1160篇 |
2010年 | 830篇 |
2009年 | 921篇 |
2008年 | 798篇 |
2007年 | 1064篇 |
2006年 | 1035篇 |
2005年 | 902篇 |
2004年 | 662篇 |
2003年 | 551篇 |
2002年 | 473篇 |
2001年 | 448篇 |
2000年 | 350篇 |
1999年 | 214篇 |
1998年 | 152篇 |
1997年 | 112篇 |
1996年 | 77篇 |
1995年 | 81篇 |
1994年 | 80篇 |
1993年 | 50篇 |
1992年 | 42篇 |
1991年 | 37篇 |
1990年 | 28篇 |
1989年 | 31篇 |
1988年 | 20篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1980年 | 4篇 |
1975年 | 2篇 |
1966年 | 2篇 |
1956年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
1.
文章首先对智能化电子信息技术进行了深入的研究,而后分析了该技术在应用过程中出现的问题,最后结合该技术的相关特点给出了相应的问题解决措施,希望能够对智能化电子信息技术的发展提供帮助。 相似文献
2.
Bin Feng Xin Jiang Guisheng Zou Wengan Wang Tianming Sun Heng Yang Guanlei Zhao Mingye Dong Yu Xiao Hongwei Zhu Lei Liu 《Advanced functional materials》2021,31(29):2102359
The realization of liquid metal-based wearable systems will be a milestone toward high-performance, integrated electronic skin. However, despite the revolutionary progress achieved in many other components of electronic skin, liquid metal-based flexible sensors still suffer from poor sensitivity due to the insufficient resistance change of liquid metal to deformation. Herein, a nacre-inspired architecture composed of a biphasic pattern (liquid metal with Cr/Cu underlayer) as “bricks” and strain-sensitive Ag film as “mortar” is developed, which breaks the long-standing sensitivity bottleneck of liquid metal-based electronic skin. With 2 orders of magnitude of sensitivity amplification while maintaining wide (>85%) working range, for the first time, liquid metal-based strain sensors rival the state-of-art counterparts. This liquid metal composite features spatially regulated cracking behavior. On the one hand, hard Cr cells locally modulate the strain distribution, which avoids premature cut-through cracks and prolongs the defect propagation in the adjacent Ag film. On the other hand, the separated liquid metal cells prevent unfavorable continuous liquid-metal paths and create crack-free regions during strain. Demonstrated in diverse scenarios, the proposed design concept may spark more applications of ultrasensitive liquid metal-based electronic skins, and reveals a pathway for sensor development via crack engineering. 相似文献
3.
《Journal of the European Ceramic Society》2020,40(10):3577-3584
In this work, the grain boundaries composition of the polycrystalline CaCu3Ti4O12 (CCTO) was investigated. A Focused Ion Beam (FIB)/lift-out technique was used to prepare site-specific thin samples of the grain boundaries interface of CCTO ceramics. Scanning transmission electron microscopy (STEM) coupled with energy dispersive X-ray spectrometry (EDXS) and Electron Energy Loss Spectroscopy (EELS) systems were used to characterize the composition and nanostructure of the grain and grain boundaries region. It is known that during conventional sintering, discontinuous grain growth occurs and a Cu-rich phase appears at grain boundaries. This Cu-rich phase may affect the final dielectric properties of CCTO but its structure and chemical composition remained unknown. For the first time, this high-resolution FIB-TEM-STEM study of CCTO interfacial region highlights the composition of the phases segregated at grain boundaries namely CuO, Cu2O and the metastable phase Cu3TiO4. 相似文献
4.
《International Journal of Hydrogen Energy》2020,45(16):9546-9554
Hierarchical composites represent a class of efficient electrocatalysts for renewable energy storage and conversion technologies owing to the porous structure and additional exposure of metal sites. Herein, a Ni-based metal organic frameworks (MOFs) (marked as Ni-BDC, BDC stands for 1,4-benzenedicarboxylic acid) nanosheet is successfully fabricated on hydroxyl iron oxide (FeOOH) array with carbon fiber cloth (CFC) as substrate. Benefit from the coordination tuning synergistic effect of the distinct chemical composition and the hierarchical structure for fast mass transportation, the as-obtained FeOOH@Ni-BDC illustrates excellent catalytic ability for electrochemical water oxidation with low overpotential of 270 mV to reach 10 mA/cm2 current and good durability in alkaline electrolyte. The novelty of this work lies in the modulation of electronic structure of the FeOOH with Ni-BDC through coordination effect to enhance the activity of the hierarchical composite electrocatalyst. This work is expected to guide the preparation of efficient electrocatalyst for new type alternative energy sources exploitation in near future. 相似文献
5.
介绍了皮带秤秤架响应特性曲线分析方法,对四种结构形式的秤架进行了响应特性曲线分析和比较,得出的结论是:悬浮式秤架的计量特性最好。 相似文献
6.
基于调谐频率与分频处理的高分辨率反演技术 总被引:12,自引:2,他引:10
讨论了基于调谐频率与分频处理的高分辨率反演技术,给出了方法的基本原理,即利用地震数据的调谐频率和分频处理分析,半定量地确定储层厚度,并将其作为地震反演的约束条件。方法的实现过程是:通过层状地质模型的地震正演模拟,建立不同主频子波时地层厚度与调谐频率的关系;利用地震资料时-频分析技术,实现地震资料分频处理;利用合成地震记录标定地震子波主频;利用分频处理结果,借助于调谐频率分析与调谐振幅分析,给出地震反演约束条件;利用反演算法消除地震子波影响,提高和拓展地震资料的频带范围,实现储层的高分辨率成像。普光地区的应用实例表明,调谐频率与分频处理的高分辨率反演方法无需对储层空间变化规律进行假设,适用于强非均质碳酸盐岩储层的高分辨率成像。 相似文献
7.
The performance of the energy consumption of an electronic valve and a classical thermostatic valve has been compared when these expansion valves are adopted in a vapour compression plant subjected to a cold store. The main aim is to verify experimentally which type of expansion valve would be preferable from energy point of view when a classical thermostat or a fuzzy logic algorithm are used as the control system for the refrigeration capacity. The fuzzy logic‐based control is able to modulate continuously the compressor speed through an inverter. The results show that with a fuzzy algorithm, the thermostatic expansion valve allows an energy saving of about 8% in comparison with the electronic valve. When on–off control is used, the electric energy consumption obtained both with the electronic valve and with the thermostatic valve is comparable. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
9.
10.
介绍如何利用AutoCAD开发适合电气专业使用的CAD系统,通过编制电气CAD的功能菜单,构造电气元件库,增强CAD的专业性能。编制电气CAD可以有效地统一本单位电气制图标准,方便电气工程师使用CAD进行专业设计。 相似文献