首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   19073篇
  免费   1087篇
  国内免费   542篇
电工技术   562篇
技术理论   2篇
综合类   1167篇
化学工业   2715篇
金属工艺   1773篇
机械仪表   4003篇
建筑科学   553篇
矿业工程   363篇
能源动力   357篇
轻工业   1063篇
水利工程   71篇
石油天然气   1433篇
武器工业   183篇
无线电   726篇
一般工业技术   3017篇
冶金工业   589篇
原子能技术   34篇
自动化技术   2091篇
  2025年   163篇
  2024年   591篇
  2023年   573篇
  2022年   549篇
  2021年   834篇
  2020年   784篇
  2019年   654篇
  2018年   498篇
  2017年   596篇
  2016年   543篇
  2015年   470篇
  2014年   726篇
  2013年   1348篇
  2012年   928篇
  2011年   817篇
  2010年   627篇
  2009年   714篇
  2008年   672篇
  2007年   1006篇
  2006年   1059篇
  2005年   1048篇
  2004年   917篇
  2003年   787篇
  2002年   743篇
  2001年   643篇
  2000年   529篇
  1999年   426篇
  1998年   324篇
  1997年   234篇
  1996年   234篇
  1995年   178篇
  1994年   112篇
  1993年   107篇
  1992年   66篇
  1991年   49篇
  1990年   30篇
  1989年   31篇
  1988年   13篇
  1987年   16篇
  1986年   19篇
  1985年   6篇
  1984年   10篇
  1983年   5篇
  1982年   3篇
  1981年   2篇
  1980年   3篇
  1979年   4篇
  1977年   2篇
  1955年   1篇
  1951年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Flexible manufacturing systems (FMSs) are a class of automated systems that can be used to improve productivity in batch manufacturing. Four stages of decision making have been defined for an FMS—the design, planning, scheduling, and control stages. This research focuses on the planning stage, and specifically in the area of scheduling batches of parts through the system.The literature to date on the FMS planning stage has mostly focused on the machine grouping, tool loading, and parttype selection problems. Our research carries the literature a step further by addressing the problem of scheduling batches of parts. Due to the use of serial-access material-handling systems in many FMSs, the batch-scheduling problem is modeled for a flexible flow system (FFS). This model explicitly accounts for setup times between batches that are dependent on their processing sequence.A heuristic procedure is developed for this batch-scheduling problem—the Maximum Savings (MS) heuristic. The MS heuristic is based upon the savings in time associated with a particular sequence and selecting the one with the maximum savings. It uses a two-phase method, with the savings being calculated in phase I, while a branch-and-bound procedure is employed to seek the best heuristic solution in phase II. Extensive computational results are provided for a wide variety of problems. The results show that the MS heuristic provides good-quality solutions.  相似文献   
2.
Evaluating the design of flexible manufacturing systems is complex. Developing a measure of performance useful for evaluating alternate designs continues to be interesting. Here, total productivity of the system is proposed as an appropriate measure. Specification of parameters based upon strategic considerations for this measure are discussed. Finally, the usefulness of the measure is demonstrated through an example.  相似文献   
3.
This paper introduces a generic decision-making framework for assigning resources of a manufacturing system to production tasks. Resources are broadly defined production units, such as machines, human operators, or material handling vehicles; and tasks are activities performed by resources. In the specific context of FMS, resources correspond to individual machines; tasks correspond to operations to be performed on parts. The framework assumes a hierarchical structure of the system and calls for the execution of four consecutive steps to make a decision for the assignment of a resource to a task. These steps are 1) establishment of decision-making criteria, 2) formation of alternative assignments, 3) estimation of the consequences of the assignments, and 4) selection of the best alternative assignment. This framework has been applied to an existing FMS as an operational policy that decides what task will be executed on which resource of this FMS. Simulation runs provide some initial results of the application of this policy. It is shown that the policy provides flexibility in terms of system performance and computational effort.  相似文献   
4.
A new optimization model is discussed for the design of cellular manufacturing systems. It is based on an integer programming formulation that updates some other models by eliminating redundant machine assignment and cost coefficients dependent on cell configuration. To reduce computational burdens, a simplified integer programming model and a decomposition algorithm are proposed. Several computer solutions were performed to evaluate the performance of the new model. The computational results are discussed.  相似文献   
5.
田立  于忠波 《炭素技术》2007,26(1):22-27
研制了高粘结强度、低电阻率、高渗透性能接头栓,并说明了改进的目标和方向。研究了电极接头栓的使用性能、主要作用和选用接头栓补救电极和接头连接质量的优点;研究了电极接头栓的原料选择、原料配比、添加剂和发泡剂的选取;确定了电极接头栓的生产技术要求和生产工艺流程。试验证明,研制的高性能接头栓具有高粘结、强固结、有效补强的作用。  相似文献   
6.
本研究目的在于探究战略网络生成中制造模式的推动作用。文章首先分析了制造模式在技术经济范式变迁中扮演的角色,总结出制造模式与技术经济范式之间的关系,接着运用数学抽象和哲学思辨的方法,提炼出人类历史上三次制造模式对技术经济范式的价值实现函数。基于该函数研究发现:精益生产中目的在于充分调动人的主观能动性,以实现人的解放的复合机制——现场管理、劳工关系管理和知识管理等体系是制造模式未来的发展方向;战略网络的演进服务于制造模式的价值实现功能,它的生成是为了弥补制造模式柔性不足的缺陷。  相似文献   
7.
采用烧结方法制备得到纳米α-Fe_2O_3,利用X射线衍射仪(XRD)和透射电镜(TEM)对样品进行了表征,研究了纳米α-Fe_2O_3作为液体石蜡添加剂的摩擦磨损性能。结果表明,添加纳米添加剂后,润滑油摩擦系数改变不明显,但磨损率显著降低。磨损率与纳米α-Fe_2O_3添加剂的表面积和添加量密切相关,当纳米材料的表面积为47m~2/g时磨损率最低,磨损率值降低为3.78×10~(-15) m~2/g;添加量为1.0wt%,润滑油磨损率最低。  相似文献   
8.
在我国,计算机技术在机械制造企业的应用刚刚开始起步,虽然取得了一定的效果,但在应用规模、范围上与发达国家相比还存在较大的距离。为了加快我国机械企业信息化的步伐,本文具体探讨了计算机技术在我国机械制造与管理中应用特点与现状,列举了一些实例,探讨了计算机技术在机械制造与管理中的应用发展。  相似文献   
9.
Networked Manufacturing is the trend evolution for manufacture enterprise to gain core competence in the networked economy environment. In this paper, the definition of the strategic alliance is introduced and its life cycle is described. As the selection of suitable partners is of vital importance to the success for strategic alliance in Networked Manufacturing environment, also in this paper, the definition, criteria and process for partner selection are introduced. Then the fuzzy-AHP (Analytic Hierarchy Process) method, as a fuzzy extension of analytic hierarchical approach for partner selection, is given. In the end, a case study is provided.  相似文献   
10.
W. Cavestro 《Automatica》1986,22(6):739-743
This paper deals with small and medium sized firms. Since the late seventies small and medium sized mechanical engineering firms in France have resorted increasingly to new technologies, and in particular to numerical control. Numerical control has introduced major changes in work organization. On the one hand it tends to reinforce the role of methods of production engineering whatever the type of numerical control may be. Programming is seldom left to the machine operators, except in the case of straightforward machining operations or in machining shops with a strong tradition of highly skilled or artisan labour. Numerical control, on the other hand, does provide more opportunity for collaboration between the workshop and the production engineers. On a workshop level it introduces a more mobile division of labour between programmers, machine setters and operators, which covers everything from the start-up of programs to the supervision of maching operations. The operator may therefore acquire new skills, but this is only possible if there are open-ended training systems available to facilitate the transmission of know-how from the programmers to the machine setters and from the machine setters to the operators, and vice versa. Small and medium sized firms would appear to have a special role to play in developing skills.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号