全文获取类型
收费全文 | 30598篇 |
免费 | 3142篇 |
国内免费 | 2388篇 |
专业分类
电工技术 | 6475篇 |
技术理论 | 2篇 |
综合类 | 2501篇 |
化学工业 | 2150篇 |
金属工艺 | 342篇 |
机械仪表 | 1787篇 |
建筑科学 | 1676篇 |
矿业工程 | 697篇 |
能源动力 | 1428篇 |
轻工业 | 389篇 |
水利工程 | 1981篇 |
石油天然气 | 1016篇 |
武器工业 | 237篇 |
无线电 | 2935篇 |
一般工业技术 | 1909篇 |
冶金工业 | 1275篇 |
原子能技术 | 191篇 |
自动化技术 | 9137篇 |
出版年
2024年 | 154篇 |
2023年 | 407篇 |
2022年 | 750篇 |
2021年 | 919篇 |
2020年 | 1041篇 |
2019年 | 792篇 |
2018年 | 769篇 |
2017年 | 923篇 |
2016年 | 1149篇 |
2015年 | 1218篇 |
2014年 | 2132篇 |
2013年 | 2290篇 |
2012年 | 2509篇 |
2011年 | 2405篇 |
2010年 | 1887篇 |
2009年 | 1984篇 |
2008年 | 1882篇 |
2007年 | 2115篇 |
2006年 | 1927篇 |
2005年 | 1658篇 |
2004年 | 1335篇 |
2003年 | 1117篇 |
2002年 | 959篇 |
2001年 | 766篇 |
2000年 | 643篇 |
1999年 | 510篇 |
1998年 | 372篇 |
1997年 | 288篇 |
1996年 | 260篇 |
1995年 | 229篇 |
1994年 | 175篇 |
1993年 | 98篇 |
1992年 | 96篇 |
1991年 | 87篇 |
1990年 | 61篇 |
1989年 | 53篇 |
1988年 | 32篇 |
1987年 | 19篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 5篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1959年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Recently, efficient scheduling algorithms based on Lagrangian relaxation have been proposed for scheduling parallel machine
systems and job shops. In this article, we develop real-world extensions to these scheduling methods. In the first part of
the paper, we consider the problem of scheduling single operation jobs on parallel identical machines and extend the methodology
to handle multiple classes of jobs, taking into account setup times and setup costs. The proposed methodology uses Lagrangian
relaxation and simulated annealing in a hybrid framework. In the second part of the paper, we consider a Lagrangian relaxation
based method for scheduling job shops and extend it to obtain a scheduling methodology for a real-world flexible manufacturing
system with centralized material handling.
This research was supported in part by the Office of Naval Research and the Department of Science and Technology grant N00014-93-1017. 相似文献
32.
韩选江 《南京建筑工程学院学报》2002,(4):67-74
为有效保护地面上的生态环境,开发利用地下空间资源并营建新世纪的地下水城,在新的21世纪里将会建造更多的地下工程以满足人们生产生活的各种需要。文中介绍了地下工程施工中采用的逆作法、盾构法、新奥法、沉管隧道、顶管工程和大型沉井施工新技术,供同行们参考应用。 相似文献
33.
34.
35.
In this paper, we study a manufacturing system consisting of two machines separated by two intermediate buffers, and capable of producing two different products. Each product requires a constant processing time on each of the machines. Each machine requires a constant non-negligible setup change time from one product to the other. The demand rate for each product is considered to be piecewise constant. Each machine undergoes failure and repair. The time-to-failure and time-to-repair are exponentially distributed random variables. The setup change and processing operations are resumable. We model our system as a continuous time, continuous flow process. An optimal control problem is formulated for the system to minimize the total expected discounted cost over an infinite horizon. To determine the optimal control policy structure, a discrete version of the problem is solved numerically using a dynamic programming formulation with a piecewise linear penalty function. A real-time control algorithm is then developed with the objective of maintaining low work-in-process inventory and keeping the production close to the demand. The algorithm uses a hierarchical control structure to generate the loading times for each product on each machine in real time and to respond to random disruptions in the system. The system is simulated using this algorithm to study its performance. The performance of the algorithm is also compared to alternative policies. 相似文献
36.
对溢洪闸门自动监控系统中几个问题的探讨 总被引:1,自引:1,他引:0
结合某水电站介绍了溢洪闸门自动监控系统的结构、功能,讨论了该研制过程中的几个问题的解决办法. 相似文献
37.
服务作业系统设计技术路线及方法体系的研究 总被引:2,自引:0,他引:2
服务项目实施需要特定的设施和作业系统。阐述了服务作业系统的特征,以工业工程和市场营销等多学科为指导,探讨了该类系统的设计目标和原理,提出了完整服务作业系统设计技术路线和方法体系。 相似文献
38.
39.
40.
Scheduling emergency medicine residents (EMRs) is a complex task, which considers a large number of rules (often conflicting) related to various aspects such as limits on the number of consecutive work hours, number of day and night shifts that should be worked by each resident, resident staffing requirements according to seniority levels for the day and night shifts, restrictions on the number of consecutive day and night shifts assigned, vacation periods, weekend off requests, and fair distribution of responsibilities among the residents. Emergency rooms (ERs) are stressful workplaces, and in addition shift work is well-known to be more demanding than regular daytime work. For this reason, preparing schedules that suit the working rules for EMRs is especially important for reducing the negative impact on shift workers physiologically, psychologically, and socially. In this paper, we present a goal programming (GP) model that accommodates both hard and soft constraints for a monthly planning horizon. The hard constraints should be adhered to strictly, whereas the soft constraints can be violated when necessary. The relative importance values of the soft constraints have been computed by the analytical hierarchy process (AHP), which are used as coefficients of the deviations from the soft constraints in the objective function. The model has been tested in the ER of a major local university hospital. The main conclusions of the study are that problems of realistic size can be solved quickly and the generated schedules have very high qualities compared to the manually prepared schedules, which require a lot of effort and time from the chief resident who is responsible for this duty. 相似文献