全文获取类型
收费全文 | 5913篇 |
免费 | 210篇 |
国内免费 | 188篇 |
专业分类
电工技术 | 221篇 |
技术理论 | 1篇 |
综合类 | 286篇 |
化学工业 | 1236篇 |
金属工艺 | 456篇 |
机械仪表 | 593篇 |
建筑科学 | 470篇 |
矿业工程 | 110篇 |
能源动力 | 247篇 |
轻工业 | 483篇 |
水利工程 | 32篇 |
石油天然气 | 204篇 |
武器工业 | 35篇 |
无线电 | 279篇 |
一般工业技术 | 751篇 |
冶金工业 | 358篇 |
原子能技术 | 91篇 |
自动化技术 | 458篇 |
出版年
2024年 | 17篇 |
2023年 | 76篇 |
2022年 | 118篇 |
2021年 | 139篇 |
2020年 | 136篇 |
2019年 | 111篇 |
2018年 | 122篇 |
2017年 | 129篇 |
2016年 | 148篇 |
2015年 | 181篇 |
2014年 | 281篇 |
2013年 | 311篇 |
2012年 | 303篇 |
2011年 | 445篇 |
2010年 | 314篇 |
2009年 | 324篇 |
2008年 | 285篇 |
2007年 | 331篇 |
2006年 | 353篇 |
2005年 | 278篇 |
2004年 | 283篇 |
2003年 | 237篇 |
2002年 | 214篇 |
2001年 | 162篇 |
2000年 | 145篇 |
1999年 | 177篇 |
1998年 | 136篇 |
1997年 | 117篇 |
1996年 | 83篇 |
1995年 | 85篇 |
1994年 | 52篇 |
1993年 | 42篇 |
1992年 | 35篇 |
1991年 | 33篇 |
1990年 | 29篇 |
1989年 | 17篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1972年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有6311条查询结果,搜索用时 31 毫秒
991.
基于WinCC6.0及S7-200PLC的材料分拣监控系统设计 总被引:1,自引:0,他引:1
本文采用西门子s7-200系列PLC和winCC监控软件相结合的控制模式,实现了材料、分拣的全自动监视与控制。S7-200PLC和以WinCC为OPC客户端的监控软件之间的通讯采用s7—200PCACCESS作为OPC服务器实现。经过对材料分拣装置的实时监控,证明系统稳定性和准确度较好,能满足监控系统的需要。 相似文献
992.
993.
复合材料构件数字化制造的关键技术 总被引:1,自引:0,他引:1
针对复合材料构件数字化制造技术的关键技术,即数控下料技术、激光定位技术和自动铺放技术进行了阐述,指出了复合材料构件数字化制造技术是通过计算机软、硬件及其网络环境实现复合材料产品设计/制造的一种多学科的先进制造技术. 相似文献
994.
介绍了多纤维增强重型汽车制动器摩擦材料组分的选取和制备方法.通过对正交试验和方差进行分析,得出了配方中各成分的最佳质量百分比.同时对摩擦磨损试验结果进行了分析和探讨,试验结果表明,所研制的摩擦材料具有足够的机械性能和优越的摩擦磨损性能,较好的抗热衰退和恢复性能. 相似文献
995.
Jean-Michel Thomassin Christine Jérôme Thomas Pardoen Christian Bailly Isabelle Huynen Christophe Detrembleur 《Materials Science and Engineering: R: Reports》2013,74(7):211-232
The extensive development of electronic systems and telecommunications has lead to major concerns regarding electromagnetic pollution. Motivated by environmental questions and by a wide variety of applications, the quest for materials with high efficiency to mitigate electromagnetic interferences (EMI) pollution has become a mainstream field of research. This paper reviews the state-of-the-art research in the design and characterization of polymer/carbon based composites as EMI shielding materials. After a brief introduction, in Section 1, the electromagnetic theory will be briefly discussed in Section 2 setting the foundations of the strategies to be employed to design efficient EMI shielding materials. These materials will be classified in the next section by the type of carbon fillers, involving carbon black, carbon fiber, carbon nanotubes and graphene. The importance of the dispersion method into the polymer matrix (melt-blending, solution processing, etc.) on the final material properties will be discussed. The combination of carbon fillers with other constituents such as metallic nanoparticles or conductive polymers will be the topic of Section 4. The final section will address advanced complex architectures that are currently studied to improve the performances of EMI materials and, in some cases, to impart additional properties such as thermal management and mechanical resistance. In all these studies, we will discuss the efficiency of the composites/devices to absorb and/or reflect the EMI radiation. 相似文献
996.
997.
Rami As’ad 《国际生产研究杂志》2013,51(12):3731-3749
In this paper, we address an instance of the dynamic capacitated multi-item lot-sizing problem (CMILSP) typically encountered in steel rolling mills. Production planning is carried out at the master production schedule level, where the various end items lot sizes are determined such that the total cost is minimised. Through incorporating the various technological constraints associated with the manufacturing process, the integrated production–inventory problem is formulated as a mixed integer bilinear program (MIBLP). Typically, such class of mathematical models is solved via linearisation techniques which transform the model to an equivalent MILP (mixed integer linear program) at the expense of increased model dimensionality. This paper presents an alternative branch-and-bound based algorithm that exploits the special structure of the mathematical model to minimise the number of branches and obtain the bound at each node. The performance of our algorithm is benchmarked against that of a classical linearisation technique for several problem instances and the obtained results are reported. 相似文献
998.
P. Suwanruji 《国际生产研究杂志》2013,51(21):4607-4629
This research considers inventory replenishment in a stochastic, multi-echelon supply chain involving both production and distribution functions. Simulation is used to compare distribution/material requirements planning (DRP/MRP), re-order point (ROP) and Kanban (KBN) replenishment strategies. Additional experimental factors include the demand pattern and the existence of manufacturing capacity constraints. Trade-off curves between inventory and delivery performance are generated. Statistical techniques, including analysis of variance (ANOVA), are then used to compare the areas under the trade-off curves and determine the relative dominance among the replenishment strategies. The methodology is used to identify both main and interaction effects. With seasonal demand, DRP/MRP performance is found to be best, followed by ROP and KBN, respectively. Without seasonal demand, the relative performance ranking depends on the presence of capacity constraints. Without capacity constraints, ROP performs best, followed by DRP/MRP and KBN. With capacity constraints, the ranking is reversed. This difference in behaviour can be explained using queuing analysis. 相似文献
999.
Chrwan-Jyh Ho 《国际生产研究杂志》2013,51(18):5097-5120
There are two important operational procedures, dampening procedures and lot-sizing rules, considered in the design of material requirement planning (MRP) systems. Lot-sizing rules have been extensively studied, and dampening procedures are relatively unfamiliar to MRP users. Dampening procedures are heuristic rules that serve as information filters to screen out excessive rescheduling messages generated by MRP in response to uncertain events occurring within or outside of production systems. There are distinctive characteristics of various lot-sizing rules, such as the just-in-time feature of lot-for-lot rules in which no inventories are carried. Similarly, dampening procedures contain certain operational characteristics that are compatible with that of lot-sizing rules. Due to this compatibility, the system performance of MRP is expected to improve if compatible dampening procedure and lot-sizing rule are used in an MRP system. The purpose of this paper is to explore this interesting compatibility by a simulation experiment to see whether it leads to better system performance under such deviations in operating environments as lead time uncertainty or scrap variations. Research results show that the performance of an MRP system is significantly affected by the dampening procedure and lot-sizing rule selected. We provide a general guideline to help MRP users determine how to select a dampening procedure and lot-sizing rule in tandem in order to generate better system performance in MRP systems. 相似文献
1000.
In this paper, we consider the material flow network design problem in which locations of input and output points of departments and flow paths are determined concurrently on a given block layout. The objective of the problem is to minimize the sum of transportation cost, flow paths construction cost and penalty cost for non-smooth material flows, i.e., flows with turns. A mixed integer programming model is given for the problem and a three-phase heuristic algorithm is developed to solve the problem. In the suggested algorithm, we generate an initial flow network by determining locations of input/output points and flow paths sequentially in the first and second phases, respectively, and then improve it by changing locations of input/output points and flow paths iteratively in the third phase. To evaluate the performance of the suggested algorithms, a series of computational experiments are performed on well-known problem instances as well as randomly generated test problems. Results of computational experiments show that the suggested algorithm gives good solutions in a short computation time. 相似文献