全文获取类型
收费全文 | 22526篇 |
免费 | 2355篇 |
国内免费 | 1477篇 |
专业分类
电工技术 | 3986篇 |
综合类 | 2872篇 |
化学工业 | 1082篇 |
金属工艺 | 717篇 |
机械仪表 | 2297篇 |
建筑科学 | 654篇 |
矿业工程 | 548篇 |
能源动力 | 518篇 |
轻工业 | 448篇 |
水利工程 | 248篇 |
石油天然气 | 350篇 |
武器工业 | 287篇 |
无线电 | 2802篇 |
一般工业技术 | 1901篇 |
冶金工业 | 534篇 |
原子能技术 | 166篇 |
自动化技术 | 6948篇 |
出版年
2024年 | 66篇 |
2023年 | 257篇 |
2022年 | 314篇 |
2021年 | 483篇 |
2020年 | 648篇 |
2019年 | 615篇 |
2018年 | 605篇 |
2017年 | 782篇 |
2016年 | 849篇 |
2015年 | 853篇 |
2014年 | 1222篇 |
2013年 | 1344篇 |
2012年 | 1604篇 |
2011年 | 1737篇 |
2010年 | 1255篇 |
2009年 | 1285篇 |
2008年 | 1375篇 |
2007年 | 1646篇 |
2006年 | 1478篇 |
2005年 | 1314篇 |
2004年 | 1076篇 |
2003年 | 981篇 |
2002年 | 821篇 |
2001年 | 669篇 |
2000年 | 612篇 |
1999年 | 468篇 |
1998年 | 372篇 |
1997年 | 324篇 |
1996年 | 248篇 |
1995年 | 201篇 |
1994年 | 187篇 |
1993年 | 116篇 |
1992年 | 132篇 |
1991年 | 80篇 |
1990年 | 73篇 |
1989年 | 49篇 |
1988年 | 43篇 |
1987年 | 20篇 |
1986年 | 25篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1982年 | 16篇 |
1981年 | 16篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1966年 | 6篇 |
1964年 | 13篇 |
1963年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
对智能电动机控制器的情况作了介绍,结合工作实践提出了维护要点和建议,并对该控制器的参数设置进行了说明,这对使用该设备的工业企业有一定的指导意义。 相似文献
42.
IR2520是自适应镇流器控制器与600V半桥驱动器单片IC ,可用来驱动半桥配置中的荧光灯。文中介绍了IR2520的主要特点和基本原理 ,给出了它的典型应用电路。 相似文献
43.
通过分析PHS网络中各寻呼区的统计指标,剖析指标劣化的根本原因,采取修改相应的参数配置、移站、调整天线等措施进行网络优化,优化实施后再次收集统计指标做对比分析,总结经验。 相似文献
44.
本文研究了具有典型分解特征的Al-Zn-Ce非晶合金的形成和晶化过程,探讨了各种相的生成顺序。XRD和DSC测试结果表明强烈的化合物短程序有利于Al-Zn-Ce非晶合金的形成。在Al-Zn-Ce非晶合金的晶化过程中存在复杂的相选择行为,多种相的竞争形核和有限生长使其具有复杂的结构特点。同时,结果也表明冷速对该体系非晶的形成有很大影响。 相似文献
45.
SIMADYN D控制器应用于动态无功补偿,标志武钢动态无功补偿控制实现数字化突破。提高了系统的可靠性、调节精度和动态指标。 相似文献
46.
Delevoye-Turrell Yvonne; Giersch Anne; Wing Alan M.; Danion Jean-Marie 《Canadian Metallurgical Quarterly》2007,116(1):56
Many everyday activities depend on the capacity to organize and smoothly execute motor sequences. The authors tested the hypothesis that a sequencing deficit is associated with schizophrenia. They used a new method to distinguish between lower and higher order mechanisms for the impairment. The 1st task involved triggered sequences in which sensory information from 1 movement was the cue for initiation of the following movement. Results showed that the motor sequences were performed as fluently in patients as in controls. The 2nd and 3rd tasks involved sequences in which the entire movement sequence could be preplanned. Patients executed the sequences less fluently than controls but only under the condition where action sequences were required. Furthermore, the patients' fluency deficit increased with sequence complexity. The high discrimination power of Task 3 gave the authors a means to control for a potential psychometric confound involving differential discriminating power and to argue in favor of a specific higher order motor fluency deficit in patients with schizophrenia. It is suggested that basic lower order mechanisms that integrate sensory information with outgoing motor commands are preserved in schizophrenia, whereas higher order integrative mechanisms that are required for the smooth coordination of motor sequences are impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
47.
已往库存论中的决策模型,它是把现实过程用数学的方法进行分析,得到决策值,但不能看到决策的过程,不能反映出现实生活中的不确定性、动态性。运用Delphi 7.0和SQL server 2000对销售过程进行了动态仿真,利用Newsboy模型的推广(S,s)订购策略来监控库存并做出决策,这样就体现出此过程的不确定性、动态性;且举出了一个仿真商品销售的实例,对其中的一些关键技术,如何仿真、算法的实现等进行了阐述。 相似文献
48.
In this report, we describe the nature of intermediate order in silicon as determined by recent measurements on thin films using transmission electron microscopy (TEM) and Raman scattering. The TEM images show in addition to the expected continuous random network (CRN), the presence of highly ordered quasi-one-dimensional “chain-like objects” (CLO's) that are 1–2 nm wide and tens of nm long that meander and show some evidence of cross-linking with each other. The presence of these objects correlate to a Raman feature centered at 490 cm−1 whose width is 35–40 cm−1, and is used to quantify the heterogeneity in terms of the CLO and CRN (=475 cm−1 scattering) concentrations. The 490 and 35 cm−1 values are consistent with bond angle deviations approaching 0°, and thus reinforces an association with the CLOs. We find that in reference quality a-Si:H (made using pure SiH4), the CLO concentration is about 5 vol%, while in state-of-the-art material using high H2 levels of dilution during processing, it increases to about 15%. Increased stability of such material to light-soaking is thus not mediated by a direct volumetric replacement of poor with high-quality components. Rather, an important characteristic of intermediate order in silicon is the low-dimensional aspect of its order, which allows it to influence more total volume than which it is itself composed. Consistent with these and other recent findings, we propose a tensegrity model of amorphous silicon. 相似文献
49.
50.
A neural network model for fault detection in conjunction with a programmable logic controller 总被引:2,自引:0,他引:2
This paper discusses the feasibility of using neural networks as a tool in the fault detection process. A neural network is integrated with a state language programmable logic controller, an important device in an automatic control system. Time series data related to time spent in a state is gathered and used as input into a neural network, for the purpose of identifying when a fault has occurred. A feedforward neural network is used to identify which (if any) of three types of faults may have occurred. Experimental results related to sensitivity and accuracy measures are presented. A brief review of related applications and research is also presented. 相似文献