全文获取类型
收费全文 | 309735篇 |
免费 | 25187篇 |
国内免费 | 16543篇 |
专业分类
电工技术 | 38691篇 |
技术理论 | 30篇 |
综合类 | 32798篇 |
化学工业 | 26680篇 |
金属工艺 | 10036篇 |
机械仪表 | 20854篇 |
建筑科学 | 31162篇 |
矿业工程 | 14209篇 |
能源动力 | 13266篇 |
轻工业 | 11822篇 |
水利工程 | 23644篇 |
石油天然气 | 14814篇 |
武器工业 | 4061篇 |
无线电 | 23353篇 |
一般工业技术 | 16598篇 |
冶金工业 | 10533篇 |
原子能技术 | 3434篇 |
自动化技术 | 55480篇 |
出版年
2024年 | 1055篇 |
2023年 | 2999篇 |
2022年 | 5938篇 |
2021年 | 7407篇 |
2020年 | 8116篇 |
2019年 | 6111篇 |
2018年 | 5761篇 |
2017年 | 7769篇 |
2016年 | 9013篇 |
2015年 | 10029篇 |
2014年 | 19069篇 |
2013年 | 17110篇 |
2012年 | 22856篇 |
2011年 | 23825篇 |
2010年 | 17959篇 |
2009年 | 18196篇 |
2008年 | 17962篇 |
2007年 | 23184篇 |
2006年 | 21055篇 |
2005年 | 18984篇 |
2004年 | 15456篇 |
2003年 | 13994篇 |
2002年 | 10984篇 |
2001年 | 9181篇 |
2000年 | 7625篇 |
1999年 | 6119篇 |
1998年 | 4550篇 |
1997年 | 3740篇 |
1996年 | 3154篇 |
1995年 | 2729篇 |
1994年 | 2210篇 |
1993年 | 1536篇 |
1992年 | 1273篇 |
1991年 | 944篇 |
1990年 | 749篇 |
1989年 | 655篇 |
1988年 | 450篇 |
1987年 | 328篇 |
1986年 | 223篇 |
1985年 | 235篇 |
1984年 | 212篇 |
1983年 | 157篇 |
1982年 | 118篇 |
1981年 | 73篇 |
1980年 | 69篇 |
1979年 | 63篇 |
1978年 | 37篇 |
1977年 | 35篇 |
1976年 | 29篇 |
1959年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Scheduling semiconductor wafer manufacturing systems has been viewed as one of the most challenging optimization problems owing to the complicated constraints, and dynamic system environment. This paper proposes a fuzzy hierarchical reinforcement learning (FHRL) approach to schedule a SWFS, which controls the cycle time (CT) of each wafer lot to improve on-time delivery by adjusting the priority of each wafer lot. To cope with the layer correlation and wafer correlation of CT due to the re-entrant process constraint, a hierarchical model is presented with a recurrent reinforcement learning (RL) unit in each layer to control the corresponding sub-CT of each integrated circuit layer. In each RL unit, a fuzzy reward calculator is designed to reduce the impact of uncertainty of expected finishing time caused by the rematching of a lot to a delivery batch. The results demonstrate that the mean deviation (MD) between the actual and expected completion time of wafer lots under the scheduling of the FHRL approach is only about 30 % of the compared methods in the whole SWFS. 相似文献
992.
With the development of the globalization of economy and manufacturing industry, distributed manufacturing mode has become a hot topic in current production research. In the context of distributed manufacturing, one job has different process routes in different workshops because of heterogeneous manufacturing resources and manufacturing environments in each factory. Considering the heterogeneous process planning problems and shop scheduling problems simultaneously can take advantage of the characteristics of distributed factories to finish the processing task well. Thus, a novel network-based mixed-integer linear programming (MILP) model is established for distributed integrated process planning and scheduling problem (DIPPS). The paper designs a new encoding method based on the process network and its OR-nodes, and then proposes a discrete artificial bee colony algorithm (DABC) to solve the DIPPS problem. The proposed DABC can guarantee the feasibility of individuals via specially-designed mapping and switching operations, so that the process precedence constraints contained by the network graph can be satisfied in the entire procedure of the DABC algorithm. Finally, the proposed MILP model is verified and the proposed DABC is tested through some open benchmarks. By comparing with other powerful reported algorithms and obtaining new better solutions, the experiment results prove the effectiveness of the proposed model and DABC algorithm successfully. 相似文献
993.
In recent years, the concept of digital twin (DT) is attracting more and more attention from researchers and engineers. But there is still no consensus on what a right DT is. On one hand, some common models are renamed as DTs. On the other hand, some DTs extremely pursue ‘the same’ as physical objects, which bring unnecessary complexities to them. In this paper, we try to answer two questions from the point of view of model engineering: how to define a right digital twin, and how to build a right digital twin. The concept and related technologies of model engineering are introduced. Some basic principles and a set of metrics for a right DT are given. An evolutionary concurrent modeling method for DT (ECoM4DT) is proposed not only inheriting the theory from classic M&S methods but also highlighting the characteristics of DT compared with traditional models to systemically guide the DT modeling process. 相似文献
994.
《Calphad》2021
Accurate Young's modulus is the necessity for the design of biomedical Ti alloys. A combinatorial method of the diffusion couple, nanoindentation, electron probe microanalysis (EPMA), and CALculation of PHAse Diagrams (CALPHAD) techniques has been utilized to construct the Young's modulus database of Ti alloys with various compositions in the present work. Two groups of body-centered cubic (bcc) Ti–Nb–Zr–Mo quaternary diffusion couples annealed at 1273 K for 25 h were experimentally prepared. Subsequently, the composition-dependent mechanical properties in the wide compositional range of Ti-based alloys were obtained by using EPMA and nanoindentation probes. Finally, on the basis of the measured Young's moduli in the present and previous work and the modeling parameters of Young's modulus of Ti–Nb–Zr system, the Young's modulus database of bcc Ti–Nb–Zr–Mo system was established through the CALPHAD approach. The CALPHAD-type database of bcc Ti–Nb–Zr–Mo system can provide the accurate Young's moduli of Ti alloys with wide compositions. 相似文献
995.
Automating stages for deformable objects in the production line, in which assembling a wire harness into a predefined position is a complex task owing to the specialized characteristics of the objects. Besides a few automatized systems proposed in the other studies to implement this task under simplified setup conditions, a significant portion of this process remains to be completed manually in industrial environments. To construct an automatic wire harness assembly system, the development of a method that can automatically detect the wire harness profile in a 3D environment and, consequently, guide robot arms to implement assembly tasks is indispensable. Therefore, this study presents an approach that satisfies this requirement, which not only proposes a deep learning-based system to detect the wire profile, but also improves the accuracy of the detected results through a correction method according to the depth values of contiguous areas. The verification of the approach in a robot system that highlights its usefulness and practicality demonstrates the potential of the proposed method to replace people and consequently, reduce labour costs in factory environments. 相似文献
996.
网络信息分级是保障网络信息内容安全的重要手段。主要构建了网络信息资源分级体系框架六元组模型,分析了相关组成元素的内容,以适应不同行业应用。 相似文献
997.
998.
999.
1000.
从选型、设计、调试3个方面比较了中小型控制系统中采用的触摸屏加PLC方案和图形控制器方案的优缺点;以某工厂供粉控制系统为例,给出了一种采用图形控制器来代替触摸屏加PLC的控制方案。实际应用说明了该控制方案的可行性及优势。 相似文献