全文获取类型
收费全文 | 1485篇 |
免费 | 164篇 |
国内免费 | 139篇 |
专业分类
电工技术 | 23篇 |
综合类 | 39篇 |
化学工业 | 195篇 |
金属工艺 | 124篇 |
机械仪表 | 215篇 |
建筑科学 | 19篇 |
矿业工程 | 14篇 |
能源动力 | 40篇 |
轻工业 | 485篇 |
水利工程 | 19篇 |
石油天然气 | 27篇 |
武器工业 | 23篇 |
无线电 | 124篇 |
一般工业技术 | 112篇 |
冶金工业 | 227篇 |
原子能技术 | 26篇 |
自动化技术 | 76篇 |
出版年
2024年 | 9篇 |
2023年 | 35篇 |
2022年 | 57篇 |
2021年 | 116篇 |
2020年 | 96篇 |
2019年 | 78篇 |
2018年 | 74篇 |
2017年 | 69篇 |
2016年 | 97篇 |
2015年 | 71篇 |
2014年 | 133篇 |
2013年 | 133篇 |
2012年 | 86篇 |
2011年 | 122篇 |
2010年 | 68篇 |
2009年 | 62篇 |
2008年 | 45篇 |
2007年 | 62篇 |
2006年 | 77篇 |
2005年 | 47篇 |
2004年 | 49篇 |
2003年 | 41篇 |
2002年 | 33篇 |
2001年 | 18篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 13篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 20篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 5篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1979年 | 1篇 |
排序方式: 共有1788条查询结果,搜索用时 21 毫秒
1.
对鞍钢股份无缝钢管厂连轧机前毛管坯横移装置存在的设计缺陷进行了分析,并提出改进方案,将原横移装置由高架轨道横移机构及上下升降链传动装置,改进为地面轨道横移系统及同步旋转臂实现取管、放管过程。实施后消除了生产故障,缩短了轧制周期,降低生产成本。 相似文献
2.
分片汇接的网状网结构是江苏省本地电话网的基本框架,而汇接局和连接汇接局的传输系统则是网路规划与通信建设的重点。 相似文献
3.
This paper describes an agent-based framework with a tandem integration architecture for cooperating distributed, heterogeneous, and autonomous concurrent engineering systems. The approach has been experimented with using the prototype AGENTS system. It is demonstrated that design tools can be dynamically connected and configured to construct highly complex systems on an incremental basis, designing and proving one system at a time without bothering the rest. A major advantage of the approach is the balance between the interoperability and the autonomy of individual systems. 相似文献
4.
单螺杆挤出机—熔体泵串联挤出系统的性能与应用 总被引:3,自引:0,他引:3
从原理与应用方面,分析、探讨了单螺杆挤出机-熔体泵串联挤出系统的优异性能以及在塑料挤出成型领域的高效应用。 相似文献
5.
We study tandem queues with finite intermediate buffers and develop a general blocking scheme that unifies and generalizes various blocking schemes previously studied in the literature, such as manufacturing blocking, communication blocking, kanban blocking and its variations. In the general blocking scheme, job movement and service at each stage are controlled by three parameters, which represent, respectively, the upper limits (at that stage) on work-in-process inventory, finished goods inventory, and buffer space. We derive a set of recursive equations that characterize the dynamics of the system, in terms of the job completion and departure processes, and establish comparison results for these processes in the settings of stochastic ordering, variability ordering and stochastic convexity. Free of distributional assumptions, the results provide characterization of system behavior with respect to the control parameters as well as to the arrival and service processes. We also compare system performance under two different modes of operation: make-to-order versus make-to-stock, and demonstrate the trade-off between improving service and reducing inventory. Numerical studies are also presented to illustrate the diversity of performance trade-off, including composition of inventory, offered by the general model.Supported in part by NSF under grant ECS-89-96201. 相似文献
6.
7.
8.
The tokamak and tandem mirror concepts are compared with alternate confinement concepts using the criteria established in DOE/ET-0047, An Evaluation of Alternate Magnetic Fusion Concepts 1977. The concepts are evaluated and rated in each of three broad categories: confidence in physics and technology, and reactor desirability. The STARFIRE and MARS reactors are used as a basis for comparing the mainline tokamak and tandem mirror concepts with the alternate concepts evaluated in DOE/ET-0047. Two recent alternate concepts, theohmically heated toroidal experiment (OHTE) and thecompact reversed field pinch reactor (CRFPR), are also evaluated. Results indicate that the physics of the mainline tokamaks and tandem mirrors is better understood than that of most alternate concepts. Both mainline concepts rank near the middle for technology requirements, and both rank near or at the bottom when compared with the reactor desirability of alternate concepts. 相似文献
9.
简要介绍了自主设计制造、具有完全自主知识产权的1 250 mm五机架六辊冷连轧产线工艺及设备特点。重点阐述了冷连轧工艺控制系统的硬件配置、软件架构及核心技术。采用基于简易有限元的轧制力模型及基于成本函数的多目标负荷分配模型,实现了高精度的轧制规程计算。开发了原料板快速启车技术与板形多变量综合最优控制技术,实现了冷轧产品的尺寸精准控制。现场实际应用效果表明,机组稳定运行率达到99.8%以上,不同规格的产品厚度控制精度均达到±0.8%以内,板形控制精度均达到5I以内。 相似文献
10.
Manuel Baena-García José M. Carmona-Cejudo Rafael Morales-Bueno 《Journal of Computer and System Sciences》2014
Discovering frequent factors from long strings is an important problem in many applications, such as biosequence mining. In classical approaches, the algorithms process a vast database of small strings. However, in this paper we analyze a small database of long strings. The main difference resides in the high number of patterns to analyze. To tackle the problem, we have developed a new algorithm for discovering frequent factors in long strings. We present an Apriori-like solution which exploits the fact that any super-pattern of a non-frequent pattern cannot be frequent. The SANSPOS algorithm does a multiple-pass, candidate generation and test approach. Multiple length patterns can be generated in a pass. This algorithm uses a new data structure to arrange nodes in a trie. A Positioning Matrix is defined as a new positioning strategy. By using Positioning Matrices, we can apply advanced prune heuristics in a trie with a minimal computational cost. The Positioning Matrices let us process strings including Short Tandem Repeats and calculate different interestingness measures efficiently. Furthermore, in our algorithm we apply parallelism to transverse different sections of the input strings concurrently, speeding up the resulting running time. The algorithm has been successfully used in natural language and biological sequence contexts. 相似文献