全文获取类型
收费全文 | 20458篇 |
免费 | 332篇 |
国内免费 | 157篇 |
专业分类
电工技术 | 271篇 |
综合类 | 9篇 |
化学工业 | 2623篇 |
金属工艺 | 675篇 |
机械仪表 | 242篇 |
建筑科学 | 497篇 |
矿业工程 | 54篇 |
能源动力 | 344篇 |
轻工业 | 687篇 |
水利工程 | 124篇 |
石油天然气 | 115篇 |
无线电 | 968篇 |
一般工业技术 | 1925篇 |
冶金工业 | 1902篇 |
原子能技术 | 190篇 |
自动化技术 | 10321篇 |
出版年
2022年 | 130篇 |
2021年 | 163篇 |
2020年 | 130篇 |
2019年 | 139篇 |
2018年 | 176篇 |
2017年 | 165篇 |
2016年 | 204篇 |
2015年 | 181篇 |
2014年 | 469篇 |
2013年 | 904篇 |
2012年 | 1149篇 |
2011年 | 3553篇 |
2010年 | 1499篇 |
2009年 | 1404篇 |
2008年 | 1114篇 |
2007年 | 969篇 |
2006年 | 829篇 |
2005年 | 897篇 |
2004年 | 822篇 |
2003年 | 831篇 |
2002年 | 524篇 |
2001年 | 181篇 |
2000年 | 174篇 |
1999年 | 188篇 |
1998年 | 317篇 |
1997年 | 213篇 |
1996年 | 189篇 |
1995年 | 148篇 |
1994年 | 157篇 |
1993年 | 146篇 |
1992年 | 137篇 |
1991年 | 116篇 |
1990年 | 120篇 |
1989年 | 150篇 |
1988年 | 109篇 |
1987年 | 125篇 |
1986年 | 133篇 |
1985年 | 141篇 |
1984年 | 181篇 |
1983年 | 127篇 |
1982年 | 122篇 |
1981年 | 101篇 |
1980年 | 90篇 |
1979年 | 99篇 |
1978年 | 82篇 |
1977年 | 102篇 |
1976年 | 98篇 |
1975年 | 87篇 |
1974年 | 92篇 |
1973年 | 75篇 |
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
101.
Integrated model-driven dashboard development 总被引:1,自引:0,他引:1
Themis Palpanas Pawan Chowdhary George Mihaila Florian Pinel 《Information Systems Frontiers》2007,9(2-3):195-208
Business performance modeling and model-driven business transformation are two research directions that are attracting much attention lately. In this study, we propose an approach for dashboard development that is model-driven and can be integrated with the business performance models. We adopt the business performance modeling framework, and we extend it in order to capture the reporting aspect of the business operation. We describe models that can effectively represent all the elements necessary for the business performance reporting process, and the interactions among them. We demonstrate how all these models can be combined and automatically generate the final solution. We further extend the proposed framework with mechanisms that can detect changes in the models and incrementally update the deployed solutions. Finally, we discuss our experience from the application of our technique in a real-world scenario. This case study shows that our technique can be efficiently applied to and handle changes in the underlying business models, delivering significant benefits in terms of both development time and flexibility. 相似文献
102.
Data collection, both automatic and manual, lies at the heart of all empirical studies. The quality of data collected from
software informs decisions on maintenance, testing and wider issues such as the need for system re-engineering. While of the
two types stated, automatic data collection is preferable, there are numerous occasions when manual data collection is unavoidable.
Yet, very little evidence exists to assess the error-proneness of the latter. Herein, we investigate the extent to which manual
data collection for Java software compared with its automatic counterpart for the same data. We investigate three hypotheses
relating to the difference between automated and manual data collection. Five Java systems were used to support our investigation.
Results showed that, as expected, manual data collection was error-prone, but nowhere near the extent we had initially envisaged.
Key indicators of mistakes in manual data collection were found to be poor developer coding style, poor adherence to sound
OO coding principles, and the existence of relatively large classes in some systems. Some interesting results were found relating
to the collection of public class features and the types of error made during manual data collection. The study thus offers
an insight into some of the typical problems associated with collecting data manually; more significantly, it highlights the
problems that poorly written systems have on the quality of visually extracted data. 相似文献
103.
104.
海洋钻井液有机物添加剂生物降解性评价 总被引:1,自引:0,他引:1
随着海洋石油的勘探开发,钻井液有机添加剂不可避免地进入海洋.因此在海洋勘探开发过程中应选择环保性能好,即生物降解性能好的有机物添加剂。用累计耗氧量法测定了海洋钻井液有机添加剂的生物降解性,研究评价了有机添加剂的生物降解规律和机理,探讨了有机物生物降解性同其化学结构的内在联系,为海洋勘探开发过程中选择环保性能好的有机物添加剂提供理论依据。总结实验结果发现:淀粉类(如DFD-140和FI-E1等)最容易生物降解;其次是纤维素类(如MV-CMC等)和烯类单体聚合物(如PAM和PHP);而沥青类、两性离子类则难以生物降解,有的甚至对生物降解起抑制作用。 相似文献
105.
Alvaro E. Gil Author Vitae Author Vitae 《Automatica》2006,42(2):245-250
Resource allocation involves deciding how to divide a resource of limited availability among multiple demands in a way that optimizes current objectives. In this brief paper we focus on one type of distributed resource allocation problem where via an imperfect communication network multiple processors can share the load presented by multiple task types. We introduce asynchronous “cooperative” resource allocation strategies, and show that they lead to a bounded cumulative demand. 相似文献
106.
Andrea Bacciotti Author Vitae Author Vitae 《Automatica》2006,42(3):453-458
Differential equations with discontinuous right-hand side and solutions intended in Carathéodory sense are considered. For these equations, sufficient conditions which guarantee both Lyapunov stability and asymptotic stability in terms of nonsmooth Lyapunov functions are given. An invariance principle is also proven. 相似文献
107.
Abstract. This article proposes an extension to scalar component methodology for the identification and estimation of VARMA models. The complete methodology determines the exact positions of all free parameters in any VARMA model with a predetermined embedded scalar component structure. This leads to an exactly identified system of equations that is estimated using full information maximum likelihood. 相似文献
108.
Bullwhip reduction for ARMA demand: The proportional order-up-to policy versus the full-state-feedback policy 总被引:1,自引:0,他引:1
Gerard Gaalman Author Vitae 《Automatica》2006,42(8):1283-1290
A ‘proportional’ order-up-to policy reacting to ARMA demand is analyzed using stochastic optimal control theory. This policy is compared with a full-state-feedback order-up-to policy. Necessary conditions for an optimum of a weighted sum of the inventory and the ordering variances for both policies are formulated. Based on this a relatively simple expression for the ‘full-state’ policy is derived. The comparison between the two policies demonstrates that the ‘intuitively’ designed proportional policy does not fulfill the objective of controlling both the inventory and ordering variance for all parameter values of the demand model as well as the full-state-feedback policy. The full-state-feedback policy outperforms the proportional policy in several aspects. 相似文献
109.
110.
George M. Prince 《Creativity & Innovation Management》2003,12(4):240-246
Independently of the creativity movement, others have demonstrated the benefits of creating positive fields. I have reviewed a number of cases involving field below and added some from my own creativity experiences. I then explore the psychological explanation of why such fields are effective and go on to the findings of recent brain research, which not only reinforce the benefits of positive fields but also throw light on the difficulty of creating them. Finally, I offer some suggestions from my own experience of what can be done to create positive fields. I believe that this should now be the focus of our efforts: to the extent that we are successful, we should get the creativity and innovation we need as a by‐product. 相似文献