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   25261篇
  免费   3891篇
  国内免费   2109篇
电工技术   3371篇
综合类   3269篇
化学工业   987篇
金属工艺   610篇
机械仪表   1822篇
建筑科学   3498篇
矿业工程   1836篇
能源动力   395篇
轻工业   687篇
水利工程   917篇
石油天然气   752篇
武器工业   293篇
无线电   3888篇
一般工业技术   1861篇
冶金工业   531篇
原子能技术   102篇
自动化技术   6442篇
  2024年   31篇
  2023年   275篇
  2022年   426篇
  2021年   599篇
  2020年   705篇
  2019年   526篇
  2018年   548篇
  2017年   700篇
  2016年   859篇
  2015年   1021篇
  2014年   1514篇
  2013年   1344篇
  2012年   2046篇
  2011年   2175篇
  2010年   1910篇
  2009年   1979篇
  2008年   2060篇
  2007年   2525篇
  2006年   2121篇
  2005年   1822篇
  2004年   1380篇
  2003年   1178篇
  2002年   837篇
  2001年   689篇
  2000年   590篇
  1999年   412篇
  1998年   295篇
  1997年   225篇
  1996年   140篇
  1995年   86篇
  1994年   64篇
  1993年   58篇
  1992年   29篇
  1991年   22篇
  1990年   17篇
  1989年   11篇
  1988年   8篇
  1987年   7篇
  1986年   4篇
  1985年   4篇
  1984年   3篇
  1983年   2篇
  1982年   1篇
  1981年   4篇
  1980年   1篇
  1979年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
针对MG170/410-WD滚筒式采煤机在大倾角、仰角、“三软”煤层使用中遗漏在机道中的浮煤多、装煤效率低等问题,通过添加螺旋板数量对采煤机滚筒进行改造。改造后,在滚筒转速不变的情况下,提高抛煤效率,缩短了工作面割煤和工作面空顶时间,提高了装煤效率,从源头上降低了顶板管理的安全风险。  相似文献   
42.
The paper presents an algebraic construction of the basic notions of soft set theory. Here we introduce the definition of bijective soft groups, dependent and independent soft groups. Some of their properties are investigated. Also we investigate the relationships between bijective soft groups and classical groups. In addition, we express some applications of bijective soft groups on coding theory.  相似文献   
43.
Fault detection, isolation and optimal control have long been applied to industry. These techniques have proven various successful theoretical results and industrial applications. Fault diagnosis is considered as the merge of fault detection (that indicates if there is a fault) and fault isolation (that determines where the fault is), and it has important effects on the operation of complex dynamical systems specific to modern industry applications such as industrial electronics, business management systems, energy, and public sectors. Since the resources are always limited in real-world industrial applications, the solutions to optimally use them under various constraints are of high actuality. In this context, the optimal tuning of linear and nonlinear controllers is a systematic way to meet the performance specifications expressed as optimization problems that target the minimization of integral- or sum-type objective functions, where the tuning parameters of the controllers are the vector variables of the objective functions. The nature-inspired optimization algorithms give efficient solutions to such optimization problems. This paper presents an overview on recent developments in machine learning, data mining and evolving soft computing techniques for fault diagnosis and on nature-inspired optimal control. The generic theory is discussed along with illustrative industrial process applications that include a real liquid level control application, wind turbines and a nonlinear servo system. New research challenges with strong industrial impact are highlighted.  相似文献   
44.
45.
针对深部软岩巷道围岩变形量大,传统支护结构失效的问题,以煤峪口矿回采巷道为研究背景,综合应用数值模拟和工程实践对原支护方案下巷道破坏特征进行分析,提出采用中空注浆锚索进行补强支护,并采用FLAC3D分析了两种支护方案下巷道围岩的收敛量以及应力分布情况,得出了优化支护方案能够有效控制巷道围岩破碎程度,并通过工程实践得到验证。  相似文献   
46.
47.
The convergence of materials science, electronics, and biology, namely bioelectronic interfaces, leads novel and precise communication with biological tissue, particularly with the nervous system. However, the translation of lab-based innovation toward clinical use calls for further advances in materials, manufacturing and characterization paradigms, and design rules. Herein, a translational framework engineered to accelerate the deployment of microfabricated interfaces for translational research is proposed and applied to the soft neurotechnology called electronic dura mater, e-dura. Anatomy, implant function, and surgical procedure guide the system design. A high-yield, silicone-on-silicon wafer process is developed to ensure reproducible characteristics of the electrodes. A biomimetic multimodal platform that replicates surgical insertion in an anatomy-based model applies physiological movement, emulates therapeutic use of the electrodes, and enables advanced validation and rapid optimization in vitro of the implants. Functionality of scaled e-dura is confirmed in nonhuman primates, where epidural neuromodulation of the spinal cord activates selective groups of muscles in the upper limbs with unmet precision. Performance stability is controlled over 6 weeks in vivo. The synergistic steps of design, fabrication, and biomimetic in vitro validation and in vivo evaluation in translational animal models are of general applicability and answer needs in multiple bioelectronic designs and medical technologies.  相似文献   
48.
Although structural coloring and photoluminescence (PL) have been investigated for radiation-responsive color change, electroluminescence (EL) has not been used for the radiation-responsive system. An electro-photoluminescence (EPL) color change is presented here. The phosphors in the alternating current electroluminescence (ACEL) act simultaneously as electro-luminophores and photo-luminophores. The EPL chromaticity is systematically investigated depending on the ACEL frequency and UV intensity. It is found that the PL variation depending on UV intensity is the mechanism of the EPL color change. It is revealed that EL and PL can be controlled independently in the low electric field so that the EPL chromaticity can be adjusted by a linear combination of the EL color and the PL color. The EPL color-changing device is used as a deformable visual encryption system and a soft skin for a soft robotic rover, imitating the concealment and signaling functions in nature.  相似文献   
49.
50.
高压断路器操动机构振动信号为非平稳性信号,蕴含着丰富的操动机构工作状态的信息,对操动机构工作状态的检验辨识具有重大意义。提出一种基于小波时频图和卷积神经网络的断路器故障诊断方法。对操动机构振动信号进行连续小波变换生成时频图(CWT),并对时频图进行统一压缩预处理;将预处理后的时频图作为特征图输入卷积神经网络AlexNet模型;通过对网络参数的调整,逐步改进网络模型,有监督地实现对操动机构故障状态的辨识诊断。结果表明,该方法能够有效地运用于断路器操动机构故障辨识诊断,与小波频带能量-RBF、小波频带能量-SVM的故障识别相比,故障识别准确率最高。  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