全文获取类型
收费全文 | 18817篇 |
免费 | 1280篇 |
国内免费 | 168篇 |
专业分类
电工技术 | 283篇 |
综合类 | 77篇 |
化学工业 | 4551篇 |
金属工艺 | 469篇 |
机械仪表 | 646篇 |
建筑科学 | 631篇 |
矿业工程 | 50篇 |
能源动力 | 1233篇 |
轻工业 | 1745篇 |
水利工程 | 241篇 |
石油天然气 | 264篇 |
武器工业 | 4篇 |
无线电 | 2006篇 |
一般工业技术 | 3735篇 |
冶金工业 | 1037篇 |
原子能技术 | 157篇 |
自动化技术 | 3136篇 |
出版年
2024年 | 82篇 |
2023年 | 373篇 |
2022年 | 778篇 |
2021年 | 1283篇 |
2020年 | 980篇 |
2019年 | 1076篇 |
2018年 | 1206篇 |
2017年 | 1078篇 |
2016年 | 1075篇 |
2015年 | 652篇 |
2014年 | 977篇 |
2013年 | 1788篇 |
2012年 | 1162篇 |
2011年 | 1245篇 |
2010年 | 868篇 |
2009年 | 753篇 |
2008年 | 574篇 |
2007年 | 495篇 |
2006年 | 421篇 |
2005年 | 277篇 |
2004年 | 243篇 |
2003年 | 231篇 |
2002年 | 182篇 |
2001年 | 142篇 |
2000年 | 142篇 |
1999年 | 139篇 |
1998年 | 290篇 |
1997年 | 236篇 |
1996年 | 192篇 |
1995年 | 139篇 |
1994年 | 110篇 |
1993年 | 113篇 |
1992年 | 80篇 |
1991年 | 80篇 |
1990年 | 74篇 |
1989年 | 64篇 |
1988年 | 49篇 |
1987年 | 53篇 |
1986年 | 68篇 |
1985年 | 57篇 |
1984年 | 53篇 |
1983年 | 54篇 |
1982年 | 35篇 |
1981年 | 32篇 |
1980年 | 29篇 |
1979年 | 24篇 |
1978年 | 32篇 |
1977年 | 35篇 |
1976年 | 47篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
21.
22.
AbstractIndustry 4.0 aims at providing a digital representation of a production landscape, but the challenges in building, maintaining, optimizing, and evolving digital models in inter-organizational production chains have not been identified yet in a systematic manner. In this paper, various Industry 4.0 research and technical challenges are addressed, and their present scenario is discussed. Moreover, in this article, the novel concept of developing experience-based virtual models of engineering entities, process, and the factory is presented. These models of production units, processes, and procedures are accomplished by virtual engineering object (VEO), virtual engineering process (VEP), and virtual engineering factory (VEF), using the knowledge representation technique of Decisional DNA. This blend of the virtual and physical domains permits monitoring of systems and analysis of data to foresee problems before they occur, develop new opportunities, prevent downtime, and even plan for the future by using simulations. Furthermore, the proposed virtual model concept not only has the capability of Query Processing and Data Integration for Industrial Data but also real-time visualization of data stream processing. 相似文献
23.
24.
25.
26.
Adaptive robust boundary control of shaft vibrations under perturbations with unknown upper bounds 下载免费PDF全文
This paper presents robust and adaptive boundary control designs to stabilize the two‐dimensional vibration of hybrid shaft model. The hybrid shaft is mathematically represented by a set of partial differential equations, governing the shaft vibrations, coupled to ordinary differential equations, describing rigid body spinning and dynamic boundary conditions. The control objective is to stabilize the transverse vibrations of the perturbed shaft while regulating the spinning rate. To achieve this, the paper first establishes robust boundary control laws that fulfil the control objective in the presence of modeling uncertainties and external disturbances operating over the shaft domain and boundary. Lyapunov‐based analyses show that the proposed robust control exponentially stabilizes the shaft with vanishing distributive perturbations, while assuring ultimately bounded vibrations in the case of nonvanishing perturbations. Then, adaptive control philosophy is utilized to achieve redesigned robust controllers that only use online adaptation of control gains without acquiring the knowledge of bounds on perturbations, as well as dynamic parameters. An advantage of this design is avoiding an overconservative robust control law, which may induce poor stability and chattering in tackling system perturbations with unknown upper bounds. Simulations through finite element method illustrate the results. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
27.
Dr. Raysa Khan Tareque Dr. Storm Hassell-Hart Dr. Tobias Krojer Dr. Anthony Bradley Dr. Srikannathasan Velupillai Dr. Romain Talon Dr. Michael Fairhead Dr. Iain J. Day Kamlesh Bala Dr. Robert Felix Dr. Paul D. Kemmitt Prof. Paul Brennan Prof. Frank von Delft Dr. Laura Díaz Sáez Prof. Kilian Huber Prof. John Spencer 《ChemMedChem》2020,15(24):2513-2520
Combined photochemical arylation, “nuisance effect” (SNAr) reaction sequences have been employed in the design of small arrays for immediate deployment in medium-throughput X-ray protein–ligand structure determination. Reactions were deliberately allowed to run “out of control” in terms of selectivity; for example the ortho-arylation of 2-phenylpyridine gave five products resulting from mono- and bisarylations combined with SNAr processes. As a result, a number of crystallographic hits against NUDT7, a key peroxisomal CoA ester hydrolase, have been identified. 相似文献
28.
Reza Soleimani Amir Hossein Saeedi Dehaghani Ali Rezai-Yazdi Seyed Abolhassan Hosseini Seyedeh Pegah Hosseini Alireza Bahadori 《化学工程与技术》2020,43(3):514-522
Solubility is one of the most indispensable physicochemical properties determining the compatibility of components of a blending system. Research has been focused on the solubility of carbon dioxide in polymers as a significant application of green chemistry. To replace costly and time-consuming experiments, a novel solubility prediction model based on a decision tree, called the stochastic gradient boosting algorithm, was proposed to predict CO2 solubility in 13 different polymers, based on 515 published experimental data lines. The results indicate that the proposed ensemble model is an effective method for predicting the CO2 solubility in various polymers, with highly satisfactory performance and high efficiency. It produces more accurate outputs than other methods such as machine learning schemes and an equation of state approach. 相似文献
29.
30.
Enas Taha Sayed Hussain Alawadhi A.G. Olabi Aisha Jamal Menna Salah Almahdi Juiaria Khalid Mohammad Ali Abdelkareem 《International Journal of Hydrogen Energy》2021,46(8):5975-5983
Microbial fuel cell (MFC) is a promising technology for simultaneous wastewater treatment and energy harvesting. The properties of the anode material play a critical role in the performance of the MFC. In this study, graphene oxide was prepared by a modified hummer's method. A thin layer of graphene oxide was incorporated on the carbon brush using an electrophoretic technique. The deoxygenated graphene oxide formed on the surface of the carbon brush (RGO-CB) was investigated as a bio-anode in MFC operated with real wastewater. The performance of the MFC using the RGO-CB was compared with that using plain carbon brush anode (PCB). Results showed that electrophoretic deposition of graphene oxide on the surface of carbon brush significantly enhanced the performance of the MFC, where the power density increased more than 10 times (from 33 mWm?2 to 381 mWm?2). Although the COD removal was nearly similar for the two MFCs, i.e., with PCB and RGO-CB; the columbic efficiency significantly increased in the case of RGO-CB anode. The improved performance in the case of the modified electrode was related to the role of the graphene in improving the electron transfer from the microorganism to the anode surface, as confirmed from the electrochemical impedance spectroscopy measurements. 相似文献