全文获取类型
收费全文 | 19399篇 |
免费 | 1668篇 |
国内免费 | 949篇 |
专业分类
电工技术 | 1615篇 |
技术理论 | 3篇 |
综合类 | 1671篇 |
化学工业 | 855篇 |
金属工艺 | 502篇 |
机械仪表 | 1235篇 |
建筑科学 | 400篇 |
矿业工程 | 250篇 |
能源动力 | 310篇 |
轻工业 | 1085篇 |
水利工程 | 76篇 |
石油天然气 | 122篇 |
武器工业 | 265篇 |
无线电 | 5198篇 |
一般工业技术 | 1510篇 |
冶金工业 | 302篇 |
原子能技术 | 75篇 |
自动化技术 | 6542篇 |
出版年
2024年 | 22篇 |
2023年 | 295篇 |
2022年 | 354篇 |
2021年 | 492篇 |
2020年 | 557篇 |
2019年 | 382篇 |
2018年 | 367篇 |
2017年 | 566篇 |
2016年 | 673篇 |
2015年 | 729篇 |
2014年 | 1311篇 |
2013年 | 1069篇 |
2012年 | 1491篇 |
2011年 | 1453篇 |
2010年 | 1036篇 |
2009年 | 1189篇 |
2008年 | 1138篇 |
2007年 | 1465篇 |
2006年 | 1431篇 |
2005年 | 1241篇 |
2004年 | 953篇 |
2003年 | 852篇 |
2002年 | 724篇 |
2001年 | 602篇 |
2000年 | 459篇 |
1999年 | 286篇 |
1998年 | 186篇 |
1997年 | 122篇 |
1996年 | 98篇 |
1995年 | 99篇 |
1994年 | 86篇 |
1993年 | 59篇 |
1992年 | 42篇 |
1991年 | 41篇 |
1990年 | 27篇 |
1989年 | 36篇 |
1988年 | 20篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 3篇 |
1980年 | 3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 15 毫秒
1.
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
2.
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
3.
4.
通过对江苏省全省电子渠道用户的总量和地区分布,分析了电子渠道缴费用户的流失及消费情况,找出了目前电子渠道存在的一些问题,并提出相应的策略。 相似文献
5.
Zhao Li Yahong Yuan Tianli Yue Jianghong Meng 《International Journal of Food Science & Technology》2019,54(9):2679-2689
5-HMF (5-hydroxymethyl-furfural) is a product of thermal treatment and is increasingly considered a food contaminant. Here, different concentrations of 5-HMF were measured in apple juice to evaluate the performance of the electronic nose (EN) and electronic tongue (ET) as rapid detection techniques for 5-HMF when coupled with chemometric analysis. Principal component analysis (PCA) and linear discriminant analysis (LDA) evaluated the discrimination capacity of EN and ET for 5-HMF. Loading analysis examined the discrimination contribution of the EN sensors. Partial least square (PLS) regression analysis established a quantitative prediction model for different concentrations of 5-HMF based on EN and ET data set. The optimal models had a coefficient of determination (R2) of 0.926 and a root-mean-square error of prediction (RMSEP) of 0.4168 in EN; there were R2 of 0.914 and RMSEP of 0.5836 in ET. These results demonstrate that EN and ET coupled with chemometric analysis are two promising approaches for the rapid and online detection of 5-HMF in apple juice. 相似文献
6.
7.
《International Journal of Hydrogen Energy》2019,44(20):9873-9882
Oxidative steam reforming of methanol (OSRM), which is a convenient reaction for producing hydrogen, suffers from the hot spot formation problem when conventional particle catalysts are used. Recently, an anodic aluminum oxide (AAO)-supported Cu-Zn catalyst was proposed as an OSRM catalyst for its high thermal conductivity through the aluminum metal body. In this study, OSRM was conducted in a prototype reactor packed with the AAO plate catalyst strips. It was verified that the high thermal conductivity of the catalyst effectively suppresses the hot spot formation and makes the temperature profile smooth along the reactor. The start-up time of the reactor depended on the preheating temperature and was very short (less than 2 min) for preheating over 503 K. The methanol conversion and reactor temperature increased with increasing O2/CH3OH mole ratio, indicating that the mole ratio can be used as a control variable to operate the reactor at desired conditions. Further, a reactor model was developed and verified, and the simulation showed that for a given total reactor volume, an optimal reactor configuration could be achieved by shortening the reactor length while widening the cross-sectional area. 相似文献
8.
Smart cities are built upon information and communication technologies (ICTs) to enable a broad range of advanced services. Through a comprehensive literature review, this study identified four pitfalls brought by the pervasive application of ICT, including information insecurity, privacy leakage, information islands, and digital divide. Therefore, a questionnaire survey together with 27 interviews was conducted in Hong Kong to investigate how the public perceived these pitfalls within the context of mobile apps providing real-time parking information which form a major part of smart mobility. System insecurity and privacy leakage were found to arouse worries among the app-users while their awareness of protecting personal data was found to have room for improvement. Islands of real-time parking information occur as a result of the lack of collaboration among private carpark operators. Digital divide existed widely among the disadvantaged groups and the problem cannot be solved by mere provision of ICT facilities. Overall, technologies alone cannot make a city smart or smarter. It is the suitable way in which ICTs are used to serve all citizens that matters. 相似文献
9.
Few literature studies have investigated the relationships between different uses and gratifications (U&Gs) of mobile instant messaging (MIM) apps, continuation, and purchase intentions. To address this gap, the researchers aimed to examine the influence of the content, social, process, and technology U&Gs of MIM on continuation intentions toward MIMs, and purchase intentions toward virtual goods available on MIMs. A comprehensive research model was developed based on the U&G theory, which was tested using cross-sectional data from 309 Japanese MIM users. The study considered six different U&Gs of MIM as independent variables and purchase intentions towards stickers and continuation intentions towards MIM as dependent variables. The study results suggest that exposure U&G has a significant positive association with MIM sticker purchase intentions. The entertainment and affection U&G are positively associated with continuation intentions towards MIM use. The study contributes to the literature by investigating U&Gs that motivate MIM users to have both positive purchase intentions toward virtual goods, such as stickers, and continuation intentions toward MIMs. The study has significant theoretical and practical implications for both researchers and practitioners who are interested in virtual goods, the virtual economy, MIM apps, social media, new media, and the service economy. 相似文献
10.
烧结生产,是钢铁工业的重要环节。烧结矿生产的各种矿料、燃料、辅料配比和烧结矿成品需要称重计量。烧结料配料与烧结矿成品基本是采用皮带机输送,烧结矿生产物料适宜采用电子皮带秤计量。为简化电子皮带秤的结构,降低安装和维护工作量,可将皮带机的上托辊,采用模块式计量托辊代替,可组合组装成多段计量的电子皮带秤。模块式计量托辊,可安装到原皮带机或原皮带电子秤,替代原托辊或原计量托辊。简化电子皮带秤的结构和安装,减少安装与维护工程量。嵌入式计量托辊模块,为发明专利产品。 相似文献