全文获取类型
收费全文 | 98536篇 |
免费 | 12699篇 |
国内免费 | 5028篇 |
专业分类
电工技术 | 49512篇 |
技术理论 | 3篇 |
综合类 | 7714篇 |
化学工业 | 3465篇 |
金属工艺 | 1850篇 |
机械仪表 | 4058篇 |
建筑科学 | 3033篇 |
矿业工程 | 2037篇 |
能源动力 | 8552篇 |
轻工业 | 1194篇 |
水利工程 | 2549篇 |
石油天然气 | 930篇 |
武器工业 | 641篇 |
无线电 | 13890篇 |
一般工业技术 | 3555篇 |
冶金工业 | 1819篇 |
原子能技术 | 2210篇 |
自动化技术 | 9251篇 |
出版年
2024年 | 514篇 |
2023年 | 1400篇 |
2022年 | 2588篇 |
2021年 | 3027篇 |
2020年 | 3391篇 |
2019年 | 2741篇 |
2018年 | 2454篇 |
2017年 | 3523篇 |
2016年 | 3760篇 |
2015年 | 4277篇 |
2014年 | 7192篇 |
2013年 | 5827篇 |
2012年 | 8069篇 |
2011年 | 8685篇 |
2010年 | 6352篇 |
2009年 | 6371篇 |
2008年 | 6320篇 |
2007年 | 7377篇 |
2006年 | 6536篇 |
2005年 | 5217篇 |
2004年 | 4233篇 |
2003年 | 3432篇 |
2002年 | 2612篇 |
2001年 | 2272篇 |
2000年 | 1889篇 |
1999年 | 1373篇 |
1998年 | 924篇 |
1997年 | 723篇 |
1996年 | 709篇 |
1995年 | 527篇 |
1994年 | 462篇 |
1993年 | 283篇 |
1992年 | 253篇 |
1991年 | 159篇 |
1990年 | 132篇 |
1989年 | 117篇 |
1988年 | 87篇 |
1987年 | 65篇 |
1986年 | 43篇 |
1985年 | 43篇 |
1984年 | 66篇 |
1983年 | 54篇 |
1982年 | 56篇 |
1981年 | 25篇 |
1980年 | 15篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1976年 | 6篇 |
1959年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
BOOTSTRAP CONTROL CHARTS 总被引:1,自引:0,他引:1
63.
采用Cr_(25)Al_5合金进行煤渣/种子条件下静态腐蚀试验(温度1373-1573k,时间50-150hr),试验后得出三种温度下腐蚀重量变化与腐蚀时间的关系,并借助金相显微镜、扫描电镜和俄歇分析进行有关形貌及成份分析,试验表明,温度是材料腐蚀的主要因素,在1473k条件下材料的抗蚀性最好,Al、Si元素在腐蚀过渡层中富集,Cr元素变化不大,但有从基体向外扩散的趋势。由此,这一材料若能进一步改进,可望在控制壁面温度的半热壁型通道中进行试验研究。 相似文献
64.
This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASVC has a 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results based on the p-q transformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains. 相似文献
65.
Yung Chien Hsu Hung-Ch'i Chang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,64(2):137-148
The behavior of inducted gas from liquid surface and the; power requirements in an agitated tank using a mechanical agitator are studied in order to increase the amount of gas self-induction and the gas retention time for gas absorption. A 45° six-blade downward impeller turbine was utilized in this study. Air and water, air and 40 wt% 60 wt%, and 80 wt% of glycerin water, and air and 106 cP silicon oil were employed as gas and liquid phases. Variables which were studied included geometrical factors (immersed depth of impeller, baffle with and diameter of impeller) and the physical properties of the liquid (viscosity, density, and surface tension). The correlations for the onset speed of impeller and power consumption after gas induction in the agitated tank are established from our experimental results. The amount of gas self-induction from the liquid surface in the agitated tank increases with increasing impeller diameter and speed and decreases with increasing baffle width, depth of impeller and viscosity of liquid. 相似文献
66.
A novel hierarchical intelligent controller configuration is proposed using an artificial neural network as a control-mode classifier in the supervisory level and a set of pre-designed controllers in the lower level. Controller outputs are modified nonlinearly by the classifying signals in a structure resembling one artificial neuron with adaptively changed weights. The lower-level local controllers are implemented using neural networks. An illustrative example of this approach is based on the transient stabilization of a single-machine infinite-bus system studied in Flexible AC Transmission Systems (FACTS) research. 相似文献
67.
数字调幅制式是当前国际上较先进的调制技术,DX系列全固态数字调幅中波发射机的电声指标和工业效率都是很先进的,过去的DX大功率机采用风冷方式,本文介绍了最新水冷DX-600发射机的设备情况和技术特点。 相似文献
68.
Marcus T. Schmitz Bashir M. Al-Hashimi Petru Eles 《Design Automation for Embedded Systems》2002,6(4):401-424
In this paper, we introduce the LOPOCOS (Low Power Co-synthesis) system, a prototype CAD tool for system level co-design. LOPOCOS targets the design of energy-efficient embedded systems implemented as heterogeneous distributed architectures. In particular, it is designed to solve the specific problems involved in architectures that include dynamic voltage scalable (DVS) processors. The aim of this paper is to demonstrate how LOPOCOS can support the system designer in identifying energy-efficient hardware/software implementations for the desired embedded systems. Hence, highlighting the necessary optimization steps during design space exploration for DVS enable architectures. The optimization steps carried out in LOPOCOS involve component allocation and task/communication mapping as well as scheduling and dynamic voltage scaling. LOPOCOS has the following key features, which contribute to this energy efficiency. During the voltage scaling valuable power profile information of task execution is taken into account, hence, the accuracy of the energy estimation is improved. A combined optimization for scheduling and communication mapping based on genetic algorithm, optimizes simultaneously execution order and communication mapping towards the utilization of the DVS processors and timing behaviour. Furthermore, a separation of task and communication mapping allows a more effective implementation of both task and communication mapping optimizationsteps. Extensive experiments are conducted to demonstrate the efficiency of LOPOCOS. We report up to 38% higher energy reductions compared to previous co-synthesis techniques for DVS systems. The investigations include a real-life example of an optical flow detection algorithm. 相似文献
69.
首先对OFDM的发展以及应用做了简要的介绍,然后讨论了当前OFDM研究过程中的两个关键技术问题,最后展望了OFDM的未来发展。 相似文献
70.
S. M. Nikonov I. V. Elkin I. A. Lipatov A. V. Basov A. V. Kapustin A. A. Rovnov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2007,41(6):351-354
Results of experiments conducted on a large-scale integral PSB-VVéR bench and directed toward investigation of the performance
of new passive safety systems for nuclear plants with a water-cooled power reactor, an additional system for passive flooding
of the active zone, and a system for the passive removal of heat from steam generators are presented.
__________
Translated from élektricheskie Stantsii, No. 9, September 2007, pp. 7–10. 相似文献