全文获取类型
| 收费全文 | 65327篇 |
| 免费 | 5442篇 |
| 国内免费 | 1192篇 |
专业分类
| 电工技术 | 4027篇 |
| 技术理论 | 3篇 |
| 综合类 | 5952篇 |
| 化学工业 | 4303篇 |
| 金属工艺 | 2140篇 |
| 机械仪表 | 2485篇 |
| 建筑科学 | 12817篇 |
| 矿业工程 | 1741篇 |
| 能源动力 | 1057篇 |
| 轻工业 | 15917篇 |
| 水利工程 | 3664篇 |
| 石油天然气 | 2001篇 |
| 武器工业 | 238篇 |
| 无线电 | 3421篇 |
| 一般工业技术 | 3459篇 |
| 冶金工业 | 3512篇 |
| 原子能技术 | 207篇 |
| 自动化技术 | 5017篇 |
出版年
| 2025年 | 604篇 |
| 2024年 | 1518篇 |
| 2023年 | 1452篇 |
| 2022年 | 1697篇 |
| 2021年 | 2038篇 |
| 2020年 | 2281篇 |
| 2019年 | 1787篇 |
| 2018年 | 1563篇 |
| 2017年 | 1849篇 |
| 2016年 | 1929篇 |
| 2015年 | 2122篇 |
| 2014年 | 4511篇 |
| 2013年 | 3541篇 |
| 2012年 | 4548篇 |
| 2011年 | 4635篇 |
| 2010年 | 3687篇 |
| 2009年 | 3886篇 |
| 2008年 | 3488篇 |
| 2007年 | 4092篇 |
| 2006年 | 3696篇 |
| 2005年 | 2999篇 |
| 2004年 | 2628篇 |
| 2003年 | 2387篇 |
| 2002年 | 2079篇 |
| 2001年 | 1499篇 |
| 2000年 | 1255篇 |
| 1999年 | 969篇 |
| 1998年 | 637篇 |
| 1997年 | 502篇 |
| 1996年 | 434篇 |
| 1995年 | 363篇 |
| 1994年 | 268篇 |
| 1993年 | 204篇 |
| 1992年 | 184篇 |
| 1991年 | 123篇 |
| 1990年 | 93篇 |
| 1989年 | 85篇 |
| 1988年 | 61篇 |
| 1987年 | 58篇 |
| 1986年 | 33篇 |
| 1985年 | 36篇 |
| 1984年 | 26篇 |
| 1983年 | 17篇 |
| 1982年 | 19篇 |
| 1981年 | 9篇 |
| 1980年 | 21篇 |
| 1979年 | 6篇 |
| 1977年 | 7篇 |
| 1975年 | 4篇 |
| 1959年 | 6篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
971.
972.
Effective planning of water quality management is important for facilitating sustainable socio-economic development in watershed systems. An interval-parameter robust quadratic programming (IRQP) method is developed by incorporating techniques of robust programming and interval quadratic programming within a general optimization framework. The IRQP improves upon existing quadratic programming methods, and can tackle uncertainties presented as interval numbers and fuzzy sets as well as their combinations. Moreover, it can deal with nonlinearities in the objective function such that economies-of-scale effects can be reflected. The developed method is applied to a case study of a water quality management under uncertainty. A number of decision alternatives are generated based on the interval solutions as well as the projected applicable conditions. They represent multiple decision options with various environmental and economic considerations. Willingness to accept a low economic revenue will guarantee satisfying the water quality requirements. A strong desire to acquire a high benefit will run the risk of violating environmental criteria. 相似文献
973.
Andre R. Ferreira 《工程优选》2013,45(9):1073-1093
Optimal operation models for a hydropower system using partial constraint satisfaction (PCS) approaches are proposed and developed in this study. The models use mixed integer nonlinear programming (MINLP) formulations with binary variables. The models also integrate a turbine unit commitment formulation along with water quality constraints used for evaluation of reservoir downstream water quality impairment. New PCS-based models for hydropower optimization formulations are developed using binary and continuous evaluator functions to maximize the constraint satisfaction. The models are applied to a real-life hydropower reservoir system in Brazil. Genetic Algorithms (GAs) are used to solve the optimization formulations. Decision maker's preferences towards power production targets and water quality improvements are incorporated using partial satisfaction constraints to obtain compromise operating rules for a multi-objective reservoir operation problem dominated by conflicting goals of energy production, water quality and consumptive water uses. 相似文献
974.
Control chart techniques for high‐quality process have attracted great attention in modern precision manufacturing. Traditional control charts are no longer applicable because of high false alarm rate. To solve this problem, in this article a new statistical process monitoring method, the counted number between omega‐event statistical process control charts, abbreviated as CBΩ charts, is proposed. The phrase omega event denotes that one observation falls into some certain interval and the CBΩ chart is to monitor the number of consecutive parts between successive r omega events. On the basis of CBΩ charts, a dual‐CBΩ monitoring scheme is developed. This scheme sets up two CBΩ charts with symmetrical omega events, (μ + ?σ, + ∞) and (? ∞, μ ? ?σ), respectively. The performance of CBΩ charts and dual‐CBΩ monitoring is investigated. Dual‐CBΩ monitoring has shown its capability in detecting both mean and variance shift and convenience in implementation compared with other traditional charts. Dual‐CBΩ monitoring can reduce false alarm rate greatly without introducing an unacceptable loss of sensitivity in detecting out‐of‐control signals in high‐quality process control. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
975.
《Quality Engineering》2012,24(4):450-460
ABSTRACTOngoing changes in the world of quality engineering have not been adequately captured in traditional textbooks or training materials. This article discusses the “megatrends” that are emerging and advocates that serious efforts be made to address, among other things, the new meaning of “customer satisfaction” as well as the performance of an organization. Thoughts and arguments are presented in terms of the concerns of three categories of stakeholders: business leaders, quality professionals, and end customers. Accordingly, a “New 5S” perspective is advocated for effectiveness as well as “future proofing” of the quality profession. 相似文献
976.
Eva Hopma Ashwin Ittoo Yuan Lu Ilse Luyk Laura Maruster Joël Ribeiro Ton Weijters Hans Wortmann 《Quality and Reliability Engineering International》2012,28(8):873-886
Advance technology development and wide use of the World Wide Web have made it possible for new product development organizations to access multi‐sources of data‐related customer complaints. However, the number of customer plaints of highly innovative consumer electronic products is still increasing; that is, product quality and reliability is at risk. This article aims to understand why existing solutions from literature as well as from industry to deal with these increasingly complex multiple data sources are not able to manage product quality and reliability. Three case studies in industry are discussed. On the basis of the case study results, this article also identifies a new research agenda that is needed to improve product quality and reliability under this circumstance. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
977.
Marcus B. Perry Joseph J. Pignatiello Jr James R. Simpson 《Quality and Reliability Engineering International》2007,23(3):327-339
Knowing when a process has changed would simplify the search for and identification of the special cause. In this paper, we propose a maximum‐likelihood estimator for the change point of the process fraction non‐conforming without requiring knowledge of the exact change type a priori. Instead, we assume the type of change present belongs to a family of monotonic changes. We compare the proposed change‐point estimator to the maximum‐likelihood estimator for the process change point derived under a simple step change assumption. We do this for a number of monotonic change types and following a signal from a binomial cumulative sum (CUSUM) control chart. We conclude that it is better to use the proposed change point estimator when the type of change present is only known to be monotonic. The results show that the proposed estimator provides process engineers with an accurate and useful estimate of the time of the process change regardless of the type of monotonic change that may be present. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
978.
Lie‐Fern Hsu 《Quality and Reliability Engineering International》2007,23(2):269-272
He and Grigoryan (Quality and Reliability Engineering International 2002; 18 :343–355) formulated the design of a double‐sampling (DS) s control chart as an optimization problem and solved it with a genetic algorithm. They concluded that the DS s control charts can be a more economically preferable alternative in detecting small shifts than traditional s control charts. We explain that, since they only considered the average sample size when the process is in control, their conclusion is questionable. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
979.
结合流体中微悬臂梁振动频率响应的理论模型,通过实验、理论计算和基于流固耦合的有限元仿真3种方法,分析了在空气和去离子水中不同结构、尺寸的微悬臂梁的谐振频率、品质因子以及幅频响应曲线,并对3种方法得到的结果进行了对比.结果显示,空气中各种方法得到的谐振频率较为吻合,相对于实验值的偏差在1%以内.去离子水中,梁谐振频率的理论值和仿真值基本一致,而实验值则较大,前两者相对于实验值的偏差在13.9%～27.3%之间;对于品质因子,理论值和仿真值依然较一致,但相对于实验值出现较大偏差,最大达70.5%.分析表明,对于液体环境下压电陶瓷激励的微悬臂梁,频率响应曲线中干扰峰的存在会严重影响微悬臂梁品质因子的准确测量.微悬臂梁动态特性的研究对基于微悬臂梁的传感器的设计优化和液相原子力显微术的应用具有一定意义. 相似文献
980.
Zhang Wu Yafen Liu Zhen He Michael B. C. Khoo 《Quality and Reliability Engineering International》2010,26(6):541-554
This article proposes a Cumulative Sum (CUSUM) scheme, called the TC‐CUSUM scheme, for monitoring a negative or hazardous event. This scheme is developed using a two‐dimensional Markov model. It is able to check both the time interval (T) between occurrences of the event and the size (C) of each occurrence. For example, a traffic accident may be defined as an event, and the number of injured victims in each case is the event size. Our studies show that the TC‐CUSUM scheme is several times more effective than many existing charts for event monitoring, so that cost or loss incurred by an event can be reduced by using this scheme. Moreover, the TC‐CUSUM scheme performs more uniformly than other charts for detecting both T shift and C shift, as well as the joint shift in T and C. The improvement in the performance is achieved because of the use of the CUSUM feature and the simultaneous monitoring of T and C. The TC‐CUSUM scheme can be applied in manufacturing systems, and especially in non‐manufacturing sectors (e.g. supply chain management, health‐care industry, disaster management, and security control). Copyright © 2009 John Wiley & Sons, Ltd. 相似文献