全文获取类型
收费全文 | 4316篇 |
免费 | 103篇 |
国内免费 | 90篇 |
专业分类
电工技术 | 57篇 |
技术理论 | 2篇 |
综合类 | 226篇 |
化学工业 | 281篇 |
金属工艺 | 351篇 |
机械仪表 | 1063篇 |
建筑科学 | 286篇 |
矿业工程 | 98篇 |
能源动力 | 143篇 |
轻工业 | 227篇 |
水利工程 | 13篇 |
石油天然气 | 58篇 |
武器工业 | 24篇 |
无线电 | 181篇 |
一般工业技术 | 407篇 |
冶金工业 | 91篇 |
原子能技术 | 20篇 |
自动化技术 | 981篇 |
出版年
2024年 | 2篇 |
2023年 | 43篇 |
2022年 | 57篇 |
2021年 | 103篇 |
2020年 | 128篇 |
2019年 | 56篇 |
2018年 | 55篇 |
2017年 | 72篇 |
2016年 | 72篇 |
2015年 | 92篇 |
2014年 | 193篇 |
2013年 | 279篇 |
2012年 | 215篇 |
2011年 | 246篇 |
2010年 | 205篇 |
2009年 | 197篇 |
2008年 | 178篇 |
2007年 | 268篇 |
2006年 | 268篇 |
2005年 | 235篇 |
2004年 | 226篇 |
2003年 | 239篇 |
2002年 | 171篇 |
2001年 | 146篇 |
2000年 | 120篇 |
1999年 | 144篇 |
1998年 | 109篇 |
1997年 | 90篇 |
1996年 | 56篇 |
1995年 | 41篇 |
1994年 | 50篇 |
1993年 | 41篇 |
1992年 | 22篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 15篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 10篇 |
1981年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有4509条查询结果,搜索用时 281 毫秒
1.
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
2.
3.
Although hybrid Petri net (HPN) is a popular formalism in modelling hybrid production systems, the HPN model of large scale systems gets substantially complicated for analysis and control due to large dimensionality of such systems. To overcome this problem, a typical approach is to decompose the net into subnets and then control the plant through hierarchical or decentralized structures. Although this concept has been widely discussed in the literature for discrete PNs, there is a lack of research for HPNs. In this paper, a new method of decomposition of first-order hybrid Petri nets (FOHPNs) is proposed first and then the hierarchical control of the subnets through a coordinator is introduced. The advantage of using the proposed approach is validated by an existing example. A sugar milling case study is analysed by using a decomposed FOHPN model and the optimization results are compared against the results of the approaches presented in other papers. Simulation results show not only an improvement in production rate, but also show the ability to control the plant online. In addition, by using the hierarchical control structure for an FOHPN model, it is possible to reduce the cost of communication links, improve the reliability of the system, maintain the plant locally, and partially redesign the system. 相似文献
4.
The workforce ageing phenomenon is recently affecting most of the Organisation for Economic Co-operation and Development (OECD) member countries, due to a general ageing of their populations and a higher average retirement age of the workforce. In this paper, the topic of ageing workforce management is addressed from a production research standpoint, with the aim of understanding how older workers can be supported and involved in a manufacturing system. First, the current state of the art related to the ageing workforce in production systems is presented. This is structured according to four main topics: (1) analysis and evaluation of ageing workers’ functional capacities, (2) consideration of ageing workers’ capacities in industrial system modelling and management, (3) analysis and exploitation of ageing workers’ expertise, (4) acknowledgement, analysis, design and integration of supporting technologies. Next, the discussion on the impact of the ageing workforce on manufacturing systems’ performances leads to the comparison of some technological advances that are related to the Industry 4.0 paradigms. Finally, a future research agenda on this topic is proposed, based on the same topics classification proposed for the literature analysis. Five different research areas are derived, suggesting future directions for appropriate research concerning the employ of older workers in production environments. 相似文献
5.
BackgroundConsidering the growing participation of woman in the labor market and the high prevalence of the musculoskeletal disorders (MSD) in the footwear industry workers, the aim of this study was to evaluate and compare female and male footwear industry workers in relation to their demographics, occupational characteristics, stress levels, MSD symptoms prevalence, physical activity levels, alcohol and tobacco use.MethodsThe study included 175 female and 182 male footwear industry workers. Data was collected using the Perceived Stress Scale – 10, the Standardized Nordic Questionnaire, the International Physical Activity Questionnaire, the Alcohol Use Disorders Identification Test, and the Fagerstrom test for Nicotine Dependence.ResultsThe female workers were younger, had less time in the company and in the current job. They reported more stress (p = 0.001), had less time for physical activity (p = 0.004), higher prevalence of MSD symptoms in the last 12 months (p = 0.003), and consumed less alcohol (p = 0.006) than the male workers.ConclusionsFemale and male footwear industry workers presented significant differences in their demographics, occupational characteristics, stress levels, MSD prevalence, physical activity levels, alcohol and tobacco use. These differences should be taken into consideration in the implementation of intervention programs for optimum outcomes.Relevance to industryFemale footwear industry workers were more stressed, presented higher prevalence of MSD symptoms, and reported less time for physical activity than male footwear industry workers. The differences between male and female workers should be taken into consideration in the implementation of MSD prevention programs. 相似文献
6.
Assembly line balancing is important for the efficiency of the assembly process, however, a wide range of disruptions can break the current workload balance. Some researchers explored the task assignment plan for the assembly line balancing problem with the assumption that the assembly process is smooth with no disruption. Other researchers considered the impacts of disruptions, but they only explored the task re-assignment solutions for the assembly line re-balancing problem with the assumption that the re-balancing decision has been made already. There is limited literature exploring on-line adjustment solutions (layout adjustment and production rate adjustment) for an assembly line in a dynamic environment. This is because real-time monitoring of an assembly process was impossible in the past, and it is difficult to incorporate uncertainty factors into the balancing process because of the randomness and non-linearity of these factors. However, Industry 4.0 breaks the information barriers between different parts of an assembly line, since smart, connected products, which are enabled by advanced information and communication technology, can intelligently interact and communicate with each other and collect, process and produce information. Smart control of an assembly line becomes possible with the large amounts of real-time production data in the era of Industry 4.0, but there is little literature considering this new context. In this study, a fuzzy control system is developed to analyze the real-time information of an assembly line, with two types of fuzzy controllers in the fuzzy system. Type 1 fuzzy controller is used to determine whether the assembly line should be re-balanced to satisfy the demand, and type 2 fuzzy controller is used to adjust the production rate of each workstation in time to eliminate blockage and starvation, and increase the utilization of machines. Compared with three assembly lines without the proposed fuzzy control system, the assembly line with the fuzzy control system performs better, in terms of blockage ratio, starvation ratio and buffer level. Additionally, with the improvement of information transparency, the performance of an assembly line will be better. The research findings shed light on the smart control of the assembly process, and provide insights into the impacts of Industry 4.0 on assembly line balancing. 相似文献
7.
In recent years, the Industry 4.0 concept brings new demands and trends in different areas; one of them is distributing computational power to the cloud. This concept also introduced the Reference Architectural Model for Industry 4.0 (RAMI 4.0). The efficiency of data communications within the RAMI 4.0 model is a critical issue. Aiming to evaluate the efficiency of data communication in the Cloud Based Cyber-Physical Systems (CB-CPS), this study analyzes the periods and data amount required to communicate with individual hierarchy levels of the RAMI 4.0 model. The evaluation of the network properties of the communication protocols eligible for CB-CPS is presented. The network properties to different cloud providers and data centers’ locations have been measured and interpreted. To test the findings, an architecture for cloud control of laboratory model was proposed. It was found that the time of the day; the day of the week; and data center utilization have a negligible impact on latency. The most significant impact lies in the data center distance and the speed of the communication channel. Moreover, the communication protocol also has impact on the latency. The feasibility of controlling each level of RAMI 4.0 through cloud services was investigated. Experimental results showed that control is possible in many solutions, but these solutions mostly cannot depend just on cloud services. The intelligence on the edge of the network will play a significant role. The main contribution is a thorough evaluation of different cloud providers, locations, and communication protocols to provide recommendations sufficient for different levels of the RAMI 4.0 architecture. 相似文献
8.
加氢反应器制造技术的新进展 总被引:2,自引:1,他引:1
王玉台 《石油化工设备技术》2006,27(5):8-9,13
随着加氢装置的大型化,对加氢反应器的设计、主体材质的选用及制造均提出了新的、更高的要求。文章较全面地介绍了国内外加氢反应器的设计准则、主体材质(抗氢钢)和制造技术等方面的新进展。 相似文献
9.
介绍了书籍装订热熔胶生产工艺及产品的技术指标,对1000t/a生产装置的投资与产品成本进行了核算。分析结果表明,总投资110万元,年利润达266万元。 相似文献
10.