全文获取类型
收费全文 | 613篇 |
免费 | 79篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 73篇 |
综合类 | 21篇 |
化学工业 | 59篇 |
金属工艺 | 44篇 |
机械仪表 | 51篇 |
建筑科学 | 31篇 |
矿业工程 | 9篇 |
能源动力 | 10篇 |
轻工业 | 70篇 |
水利工程 | 20篇 |
石油天然气 | 47篇 |
武器工业 | 13篇 |
无线电 | 60篇 |
一般工业技术 | 73篇 |
冶金工业 | 20篇 |
原子能技术 | 26篇 |
自动化技术 | 91篇 |
出版年
2024年 | 5篇 |
2023年 | 10篇 |
2022年 | 41篇 |
2021年 | 46篇 |
2020年 | 33篇 |
2019年 | 28篇 |
2018年 | 23篇 |
2017年 | 37篇 |
2016年 | 18篇 |
2015年 | 38篇 |
2014年 | 38篇 |
2013年 | 31篇 |
2012年 | 46篇 |
2011年 | 41篇 |
2010年 | 28篇 |
2009年 | 39篇 |
2008年 | 26篇 |
2007年 | 23篇 |
2006年 | 13篇 |
2005年 | 17篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 17篇 |
2001年 | 18篇 |
2000年 | 12篇 |
1999年 | 16篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 3篇 |
排序方式: 共有718条查询结果,搜索用时 812 毫秒
51.
A Short-Term Forecasting Algorithm for Network Traffic Based on Chaos Theory and SVM 总被引:1,自引:0,他引:1
Xingwei Liu Xuming Fang Zhenhua Qin Chun Ye Miao Xie 《Journal of Network and Systems Management》2011,19(4):427-447
Recently, the forecasting technologies for network traffic have played a significant role in network management, congestion
control and network security. Forecasting algorithms have also been investigated for decades along with the development of
Time Series Analysis (TSA). Chaotic Time Series Analysis (CTSA) may be used to model and forecast the time series by Chaos
Theory. As one of the prevailing intelligent forecasting algorithms, it is worthwhile to integrate CTSA and Support Vector
Machine (SVM). In this paper, after the vulnerabilities of Local Support Vector Machine (LSVM) in forecasting modeling are
analyzed, the Dynamic Time Wrapping (DTW) and the “Dynamic K” strategy are introduced, as well as a short-term network traffic
forecasting algorithm LSVM-DTW-K based on Chaos Theory and SVM is presented. Finally, two sets of network traffic datasets
collected from wired and wireless campus networks, respectively, are studied for our experiments. 相似文献
52.
针对目前我国低压船舶岸电电源系统存在的变压变频问题,提出一种基于可降压多脉冲自耦变压整流器的新型低压岸电供电电源系统,实现380V/50Hz~450V/60Hz三相电源的转换,为靠港船舶可靠供电.系统采用降压式12脉冲自耦变压整流技术降低谐波对系统及电网的影响,其中降压式自耦变压器可以实现对输入电压的降压调节,无需后续降压电路,减少系统的体积和质量,降低成本.文中详细分析了降压式12脉自耦变压整流器的工作原理,理论推导了输入电流、输出电压及变压器等效容量表达式.最后通过MATLAB建模进行仿真分析,验证了系统的正确性和可行性. 相似文献
53.
针对焊接式金属波纹管在工作中出现的随机振动问题,运用虚拟激励法理论,采用MATLAB编程得到波纹管在随机激励下轴向和径向时域下的信号;将时域信号利用快速傅里叶变换得到频域信号,并导入Workbench软件中进行随机振动分析;同时对波纹管的危险结构尺寸(波片厚度、焊箍半径和最小弯曲半径)进行响应面优化分析。结果表明:波纹管在受外界随机激励下的频率介于固有频率一阶和三阶之间;波纹管轴向最大响应变形发生在镶嵌静环的一端即自由端,径向最大响应变形发生在靠近波纹管的固定端的波片弧度较大处,随机激励时等效应力集中在靠近焊箍侧,这些位置在工作过程中最容易损坏,与实际工作中的破坏位置相吻合。通过响应面优化分析和自适应多目标优化,得到一组优化关键材料参数,使得波纹管的振动性能得到较大改善,降低了波纹管的损坏率,为焊接金属波纹管的结构参数设计提供理论参考。 相似文献
54.
The Mg-3.0Nd-0.2Zn-0.4Zr (NZ30K) alloys were prepared by direct-chill casting (DCC) and sand mould casting (SMC) processes,respectively and their microstructures and mechanical properties were investigated.The results indicate that casting method plays a remarkable influence on the microstructure and mechanical properties of as-cast NZ30K alloy.The grain size increases from 35-40μm in the billets made by the DCC to about 100-120μm in the billets by the SMC.The aggregation of Mg12Nd usually found at the trip... 相似文献
55.
Heng Zhang Yunyan Peng Youhua Xiao Shuai Kong Xingwei He Lina Liu Gaobo Lou Yi Kuang Shenyuan Fu Qingqing Rao 《应用聚合物科学杂志》2024,141(6):e54929
Epoxy resin (EP) has attracted considerable attention in packaging, electronic devices, aerospace, and coatings fields owing to its remarkable chemical and physical performance. However, the inherent flammable performance and unfavorable brittle nature seriously restricted its application in sophisticated industry. Herein, an efficient reactive 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardant (DB-DAD) was prepared by a facile “one-pot” method. Due to their synergistic gas-phase and solid-phase flame-retardant effects, DB-DAD modified EP composites (EP/DB-DAD composite) easily achieved UL-94 V-0 ratings, and an EP/DB-DAD composite with a 0.32 wt% phosphorus content had an excellent (30.2%) limiting oxygen index. In addition, the amounts of heat and smoke decreased by 28.1% and 24.8%, respectively. Due to the introduction of long and flexible aliphatic chains, the EP/DB-DAD composites exhibited satisfactory mechanical properties, the flexural and tensile toughness of EP/6% DB-DAD were 82.5% and 62.2% higher than those of neat EP, respectively. Furthermore, EP/DB-DAD composite showed good transparency (>85%) and favorable UV shielding performance. The EP/DB-DAD composite with good comprehensive performance is extremely promising to accelerate EP application in high-tech industries. 相似文献
56.
介绍了美国AB公司可编程控制器(PLC)控制网络在水厂中的应用。着重介绍了系统硬件组成,软件实现及监控软件的汉化方法。该系统操作简单,功能强,可靠性高,实现了自来水生产过程的自动化。 相似文献
57.
多媒体通信:需求与对策 总被引:1,自引:0,他引:1
本文首先对网络环境下的多媒体应用程序进行了分类,介绍了多媒体通信所涉及的一些比较重要的基本概念,包括静态媒体和连续媒体概念、等时通信和异步通信概念等,讨论了连续媒体数据的基本特征。在此基础上,我们讨论了多媒体通信、特别是连续媒体通信对网络技术提出的要求和基本对策,最后得出结论 相似文献
58.
Juncheng Xu Xingwei Wang K.L. Cooper G.R. Pickrell Anbo Wang 《Photonics Technology Letters, IEEE》2006,18(10):1134-1136
We present a miniature fiber-optic pressure sensor with a diameter of only 125 /spl mu/m. The sensor works as an extrinsic Fabry-Pe/spl acute/rot interferometer and the cavity length can be controlled with a resolution of about several nanometers. Also the sensor sensitivity can be easily adjusted by controlling the sensor gauge length. A passive temperature compensation scheme was used to reduce most of the sensor's temperature dependence. Since the sensor is composed entirely of fused silica, it is reliable, biocompatible, corrosion resistant, and immune to electromagnetic interference and has high-temperature capability. 相似文献
59.
60.