全文获取类型
收费全文 | 3472篇 |
免费 | 217篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 40篇 |
综合类 | 5篇 |
化学工业 | 880篇 |
金属工艺 | 42篇 |
机械仪表 | 89篇 |
建筑科学 | 171篇 |
矿业工程 | 6篇 |
能源动力 | 124篇 |
轻工业 | 599篇 |
水利工程 | 32篇 |
石油天然气 | 19篇 |
无线电 | 213篇 |
一般工业技术 | 514篇 |
冶金工业 | 146篇 |
原子能技术 | 14篇 |
自动化技术 | 803篇 |
出版年
2024年 | 10篇 |
2023年 | 47篇 |
2022年 | 132篇 |
2021年 | 145篇 |
2020年 | 118篇 |
2019年 | 137篇 |
2018年 | 127篇 |
2017年 | 114篇 |
2016年 | 151篇 |
2015年 | 118篇 |
2014年 | 152篇 |
2013年 | 295篇 |
2012年 | 240篇 |
2011年 | 279篇 |
2010年 | 221篇 |
2009年 | 204篇 |
2008年 | 201篇 |
2007年 | 172篇 |
2006年 | 132篇 |
2005年 | 110篇 |
2004年 | 88篇 |
2003年 | 71篇 |
2002年 | 79篇 |
2001年 | 37篇 |
2000年 | 35篇 |
1999年 | 31篇 |
1998年 | 45篇 |
1997年 | 32篇 |
1996年 | 25篇 |
1995年 | 22篇 |
1994年 | 13篇 |
1993年 | 22篇 |
1992年 | 11篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 5篇 |
排序方式: 共有3697条查询结果,搜索用时 31 毫秒
111.
In this paper we introduce a framework to represent robot task plans based on Petri nets. Our approach enables modelling a robot task, analysing its qualitative and quantitative properties and using the Petri net representation for actual plan execution. The overall model is obtained from the composition of simple models, leading to a modular approach. Analysis is applied to a closed loop between the robot controller and the environment Petri net models. We focus here on the quantitative properties, captured by stochastic Petri net models. Furthermore, we introduce a method to identify the environment and action layer parameters of the stochastic Petri net models from real data, improving the significance of the model. The framework building blocks and a single-robot task model are detailed. Results of a case study with simulated soccer robots show the ability of the framework to provide a systematic modelling tool, and of determining, through well-known analysis methods for stochastic Petri nets, relevant properties of the task plan applied to a particular environment. 相似文献
112.
Pedro Gómez-Gasquet Carlos Andrés Francisco-Cruz Lario 《Expert systems with applications》2012,39(9):8095-8107
This paper deals with a variant of flowshop scheduling, namely, the hybrid or flexible flowshop with sequence dependent setup times. This type of flowshop is frequently used in the batch production industry and helps reduce the gap between research and operational use. This scheduling problem is NP-hard and solutions for large problems are based on non-exact methods. An improved genetic algorithm (GA) based on software agent design to minimise the makespan is presented. The paper proposes using an inherent characteristic of software agents to create a new perspective in GA design. To verify the developed metaheuristic, computational experiments are conducted on a well-known benchmark problem dataset. The experimental results show that the proposed metaheuristic outperforms some of the well-known methods and the state-of-art algorithms on the same benchmark problem dataset. 相似文献
113.
Robert Baggen José Pedro Correia Katrin Schill Joost Visser 《Software Quality Journal》2012,20(2):287-307
We provide an overview of the approach developed by the Software Improvement Group for code analysis and quality consulting
focused on software maintainability. The approach uses a standardized measurement model based on the ISO/IEC 9126 definition
of maintainability and source code metrics. Procedural standardization in evaluation projects further enhances the comparability
of results. Individual assessments are stored in a repository that allows any system at hand to be compared to the industry-wide
state of the art in code quality and maintainability. When a minimum level of software maintainability is reached, the certification
body of TüV Informationstechnik GmbH issues a Trusted Product Maintainability certificate for the software product. 相似文献
114.
Pedro M. A. Areias Ted Belytschko 《International journal for numerical methods in engineering》2005,62(3):384-415
A new formulation and numerical procedures are developed for the analysis of arbitrary crack propagation in shells using the extended finite element method. The method is valid for completely non‐linear problems. Through‐the‐thickness cracks in sandwich shells are considered. An exact shell kinematics is presented, and a new enrichment of the rotation field is proposed which satisfies the director inextensibility condition. To avoid locking, an enhanced strain formulation is proposed for the 4‐node cracked shell element. A finite strain plane stress constitutive model based on the logarithmic corotational rate is employed. A cohesive zone model is introduced which embodies the special characteristics of the shell kinematics. Stress intensity factors are calculated for selected problems and crack propagation problems are solved. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
115.
Some sufficient conditions concerning stability of solutions of stochastic differential evolution equations with general decay rate are first proved. Then, these results are interpreted as suitable stabilization ones for deterministic and stochastic systems. Also, they permit us to construct appropriate linear stabilizers in some particular situations. 相似文献
116.
Spatial statistics methods have been used to analyse the nuclear pore pattern in rat ventral prostate nuclei isolated from adult animals. The observed results show that: (1) pores on prostate nuclear membranes are not randomly distributed; (2) the data sets obtained from different micrographs are consistent with the same statistical model thus suggesting the existence of a typical pore distribution. 相似文献
117.
118.
Process scale-up remains a considerable challenge for environmental applications of non-thermal plasmas.Undersanding the impact of reactor hydrodynamics in the performance of the process is a key step to overcome this challenge.In this work,we apply chemical engineering concepts to analyse the impact that different non-thermal plasma reactor configurations and regimes,such as laminar or plug flow,may have on the reactor performance.We do this in the particular context of the removal of pollutants by non-thermal plasmas,for which a simplified model is available.We generalise this model to different reactor configurations and,under certain hypotheses,we show that a reactor in the laminar regime may have a behaviour significantly different from one in the plug flow regime,often assumed in the non-thermal plasma literature.On the other hand,we show that a packed-bed reactor behaves very similarly to one in the plug flow regime.Beyond those results,the reader will find in this work a quick introduction to chemical reaction engineering concepts. 相似文献
119.
Pedro Delgado António ArêdeNelson Vila Pouca Patrício RochaAníbal Costa Raimundo Delgado 《Composite Structures》2012,94(4):1280-1287
Hollow bridge piers, particularly those built before the seventies, often have insufficient shear capacity due to inadequate transverse reinforcement details. Therefore, special attention must be given to this very important aspect when reinforced concrete (RC) piers with hollow sections are analysed and retrofitted. This paper covers the experimental analysis of retrofit solutions using CFRP sheets along the piers’ entire height to prevent shear failure. Experimental cyclic tests were carried out to evaluate the shear retrofit strategy efficiency on a set of RC piers with square hollow sections. This work also covers the study of design procedures for CFRP shear retrofitting and the evaluation of the associated ductility capacity improvement. The various transverse reinforcement detailing scenarios were assessed to determine their shear-failure prevention efficiency. The corresponding cyclic response behavior was also evaluated. The most relevant experimental information is presented in the paper, such as the evolution of the outer damage pattern. Finally, shear retrofit solutions, with a 40% increase over the maximum flexural force, show that this strategy is adequate to allow satisfactory ductility behavior. 相似文献
120.
This paper describes an application framework supporting collaborative handheld decision-making (CHDM). The main characteristics of the framework are: (1) extensive usage of visual elements and gestures; and (2) independence from specific decision-making methods, processes and tasks. The research departed from the analysis and systematisation of several CHDM scenarios, highlighting repeatable behaviour across multiple decision-making contexts. From these scenarios, we distilled a coherent set of common functional requirements organised in three main categories: process, macro- and micro-functionality. The proposed framework has been validated at length through the development of several CHDM tools. Six different tools are described in the paper. The main contribution of this work is a common foundation for developing CHDM tools. 相似文献