全文获取类型
收费全文 | 156665篇 |
免费 | 6828篇 |
国内免费 | 3477篇 |
专业分类
电工技术 | 4452篇 |
技术理论 | 10篇 |
综合类 | 6562篇 |
化学工业 | 24154篇 |
金属工艺 | 8846篇 |
机械仪表 | 7663篇 |
建筑科学 | 8523篇 |
矿业工程 | 2734篇 |
能源动力 | 3290篇 |
轻工业 | 7971篇 |
水利工程 | 2481篇 |
石油天然气 | 4986篇 |
武器工业 | 561篇 |
无线电 | 17782篇 |
一般工业技术 | 25483篇 |
冶金工业 | 6453篇 |
原子能技术 | 1077篇 |
自动化技术 | 33942篇 |
出版年
2024年 | 263篇 |
2023年 | 1205篇 |
2022年 | 2021篇 |
2021年 | 2736篇 |
2020年 | 2174篇 |
2019年 | 1888篇 |
2018年 | 16154篇 |
2017年 | 15391篇 |
2016年 | 11833篇 |
2015年 | 3383篇 |
2014年 | 3733篇 |
2013年 | 4383篇 |
2012年 | 7655篇 |
2011年 | 14072篇 |
2010年 | 12348篇 |
2009年 | 9430篇 |
2008年 | 10589篇 |
2007年 | 11593篇 |
2006年 | 4234篇 |
2005年 | 4781篇 |
2004年 | 3560篇 |
2003年 | 3331篇 |
2002年 | 2664篇 |
2001年 | 2045篇 |
2000年 | 2081篇 |
1999年 | 2242篇 |
1998年 | 1959篇 |
1997年 | 1609篇 |
1996年 | 1534篇 |
1995年 | 1167篇 |
1994年 | 1080篇 |
1993年 | 759篇 |
1992年 | 590篇 |
1991年 | 482篇 |
1990年 | 342篇 |
1989年 | 283篇 |
1988年 | 259篇 |
1987年 | 157篇 |
1986年 | 114篇 |
1985年 | 82篇 |
1984年 | 39篇 |
1983年 | 38篇 |
1982年 | 44篇 |
1968年 | 43篇 |
1966年 | 42篇 |
1965年 | 44篇 |
1959年 | 37篇 |
1958年 | 37篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
针对现有技术中输送系统控制不稳定、控制能力低下等问题,本文提出基于工业CAN总线的输送系统集成化控制.在控制系统CAN通信节点利用代码进行数据的转化,通过emit关键字将数据绘制成显示曲线,由输入的代码不断对系统数据进行刷新,实现了输送系统的实时监控,提高了系统运行的安全性.通过时间同步技术将SAEAS6802时钟同步协议与时钟修正算法相结合,有效地对数据处理时间和接收时间进行校正,减少了数据接收误差,提高了时间同步精度.实验结果表明,本文研究方法提高了输送控制系统的运行安全性和可靠性. 相似文献
32.
33.
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front... 相似文献
34.
The capture of particles by charged droplets was simulated by considering the electrostatic interactions of droplet-droplet and droplet-particle. The results indicate that the electrostatic repulsion between droplets leads to a dynamic accumulation mode of particles. However, the droplet spacing has an insignificant effect on the capture efficiency when the electrostatic deposition predominates. The increase of droplet charge remarkably improves the capture efficiency, in which the capture of fine particles accounts for the largest proportion. Compared to the droplet charge, the droplet size shows a limited improvement in the capture efficiency. Reducing the droplet velocity prolongs the capture time instead of enhancing the capture capacity per unit time, thereby improving capture efficiency. 相似文献
35.
Wei-Li Xie Xiao-Dong Zhang Wen-Hui Liu Qi Xie Guang-Wu Wen Xiao-Xiao Huang Jian-Dong Zhu Fei-Xiang Ma 《稀有金属(英文版)》2019,(3)
SiC nano wires were fabricated on the silicon substrate dipped with a layer of Ni catalyst at 900 ℃ by gas pressure annealing processing. The morphologies and crystal structures were determined by scanning electron microscopy(SEM), transmission electron microscopy(TEM)and X-ray diffraction(XRD). The results show that the assynthesized nanowires are β-SiC single crystalline with diameter range of 50-100 nm, and length of tens of micron by directly annealing at 900 ℃. The SiC nano wires grow along the [111] direction with highly uniform morphology. And the possible growth mechanism of SiC nano wires is proposed.The present work provides an efficient strategy for the production of high-quality SiC nano wires. 相似文献
36.
Qiang Liu Xinyu Mao Xiaoying Li Penghui Chen Xin Liu Ziyu Liu Danyang Zhu Haohong Chen Tengfei Xie Jiang Li 《Journal of the American Ceramic Society》2021,104(10):4927-4931
0.5 at.% Cr:ZnGa2O4 precursor was synthesized by the co-precipitation method with nitrates as raw materials, using ammonium carbonate as the precipitant. Low-agglomerated Cr:ZnGa2O4 powders with an average particle size of 43 nm were obtained by calcining the precursor at 900℃ for 4 h. Using the powders as starting materials, 0.5 at.% Cr:ZnGa2O4 ceramics with an average grain size of about 515 nm were prepared by presintering at 1150℃ for 5 h in air and HIP post-treatment at 1100℃ for 3 h under 200 MPa Ar. The in-line transmittance of 0.5 at.% Cr:ZnGa2O4 ceramics with a thickness of 1.3 mm reaches 59.5% at the wavelength of 700 nm. The Cr:ZnGa2O4 ceramics can be effectively excited by visible light and produce persistent luminescence at 700 nm. For Cr:ZnGa2O4 transparent ceramics, the brightness of afterglow was larger than 0.32 mcd/m2 after 30 min, which is far superior to that of Cr:ZnGa2O4 persistent luminescence powders. 相似文献
37.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms. 相似文献
38.
39.
Deep Integration of Innovation and Entrepreneurship (InE) Education in Chinese University Classrooms
Recently, InE has been regarded as a popular education strategy in Chinese universities. However, problems have been exposed in the adoption of InE, for example, in InE courses and competitions. The purpose of this paper is to provide a possible solution to the problems, which is to organize effective InE courses by integrating InE with Inter-Course-level Problem-Based Learning (ICPBL). A detailed case is demonstrated by an ICPBL elective course design with deep integration of InE in the teaching, learning, and assessments. This paper contributes to a new curriculum design for promoting InE education in practically for Chinese universities. 相似文献
40.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献