全文获取类型
收费全文 | 14635篇 |
免费 | 2739篇 |
国内免费 | 1193篇 |
专业分类
电工技术 | 3007篇 |
技术理论 | 2篇 |
综合类 | 1355篇 |
化学工业 | 1993篇 |
金属工艺 | 621篇 |
机械仪表 | 1092篇 |
建筑科学 | 793篇 |
矿业工程 | 115篇 |
能源动力 | 931篇 |
轻工业 | 342篇 |
水利工程 | 178篇 |
石油天然气 | 204篇 |
武器工业 | 143篇 |
无线电 | 1927篇 |
一般工业技术 | 2558篇 |
冶金工业 | 134篇 |
原子能技术 | 133篇 |
自动化技术 | 3039篇 |
出版年
2024年 | 139篇 |
2023年 | 471篇 |
2022年 | 641篇 |
2021年 | 786篇 |
2020年 | 905篇 |
2019年 | 775篇 |
2018年 | 688篇 |
2017年 | 803篇 |
2016年 | 765篇 |
2015年 | 786篇 |
2014年 | 999篇 |
2013年 | 1084篇 |
2012年 | 1080篇 |
2011年 | 1186篇 |
2010年 | 871篇 |
2009年 | 819篇 |
2008年 | 866篇 |
2007年 | 955篇 |
2006年 | 799篇 |
2005年 | 659篇 |
2004年 | 495篇 |
2003年 | 395篇 |
2002年 | 324篇 |
2001年 | 247篇 |
2000年 | 199篇 |
1999年 | 175篇 |
1998年 | 110篇 |
1997年 | 125篇 |
1996年 | 86篇 |
1995年 | 69篇 |
1994年 | 60篇 |
1993年 | 54篇 |
1992年 | 31篇 |
1991年 | 31篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1959年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Jean-Claude Malela-Majika Sandile Charles Shongwe Olatunde Adebayo Adeoti 《Quality and Reliability Engineering International》2021,37(8):3314-3322
The sensitivity of a monitoring scheme depends on many factors including the variance of the charting statistic which is very important in the computation of the control limits. This paper discusses the computation of the variance of the recently proposed hybrid homogeneously weighted moving average (HHWMA) scheme which was based on an incorrect assumption. The correct variance is used to evaluate the run-length characteristics of the HHWMA scheme. It is observed that the incorrect variance has a significant impact on the sensitivity (or performance) of the HHWMA scheme. 相似文献
2.
3.
《低温学》2015
The development of a high cooling power and high efficiency 4.2 K two stage G-M cryocooler is critically important given its broad applications in low temperature superconductors, MRI, infrared detector and cryogenic electronics. A high efficiency 1.5 W/4.2 K pneumatic-drive G-M cryocooler has recently been designed and developed by ARS. The effect of expansion volume rate and operation conditions on the cooling performance has been experimentally investigated. A typical cooling performance of 1.5 W/4.2 K has been achieved, and the minimum temperature of the second stage is 2.46 K. The steady input power of the compressor at 60 Hz is 6.8 kW, while the operation speed of the rotary valve is 30 rpm. A maximum cooling power of 1.75 W/4.2 K has been obtained in test runs. 相似文献
4.
The supervision of a hybrid power plant, including solar panels, a gas microturbine and a storage unit operating under varying solar power profiles is considered. The Economic Supervisory Predictive controller assigns the power references to the controlled subsystems of the hybrid cell using a financial criterion. A prediction of the renewable sources power is embedded into the supervisor. Results deteriorate when the solar power is unsteady, owing to the inaccuracy of the predictions for a long-range horizon of 10 s. The receding horizon is switched between an upper and a lower value according to the amplitude of the solar power trend. Theoretical results show the relevance of horizon switching, according to a tradeoff between performance and prediction accuracy. Experimental results, obtained in a Hardware In the Loop (HIL) framework, show the relevance of the variable horizon approach. Power amplifiers allow us to simulate virtual components, such as a gas microturbine, and to blend their powers with that of real devices (storage unit, real solar panels). In this case, fuel savings, reaching 15%, obtained under unsteady operating conditions lead to a better overall performance of the hybrid cell. The overall savings obtained in the experiments amount to 12%. 相似文献
5.
《低温学》2015
He-3 is generally recognized for its ability to provide more excellent thermophysical performance than He-4, especially in the 4 K temperature range. However, this was not always the case in our preliminary experiments on a three-stage Stirling-type pulse tube cryocooler (SPTC). Our ongoing studies, as reported in this paper, demonstrate that the different working fluids also affect the performance through their phase shifting capability. This feature has been passed over in large part by researchers considering refrigerant substitution. Unlike previous theoretical analyses that focus primarily on regenerator losses, this report investigates the effects of the working fluid on the phase angle at the cold end in order to quantitatively reveal the relationship between the lowest attainable temperature and the cooling capacity. The analysis agrees well with our experimental results on a three-stage SPTC. While running with the operating parameters optimized for He-3, the lowest temperature of the SPTC decreased from 5.4 K down to 4.03 K. This is the lowest refrigeration temperature ever achieved with a three-stage SPTC. 相似文献
6.
7.
微制造平台微振动的最优控制 总被引:6,自引:0,他引:6
采用混合隔振技术建立了微制造平台隔振系统。该系统以空气弹簧和橡胶层作为被动隔振元件、超磁致伸缩致动器作为主动隔振元件,并采用最优控制理论设计其主动控制器。研究了在不同的性能指标加权阵的情况下,该主动振动控制系统对基础干扰和由微制造设备产生的直接干扰所引起的微制造平台振动的控制效果。研究表明性能指标加权阵对振动控制效果影响非常大。通过大量的仿真实验确定了一组性能指标加权阵,使所设计的主动控制系统能在较宽的频率范围对基础干扰和直接干扰所引起的微制造平台振动进行有效的控制。 相似文献
8.
概述回热式气体制冷技术的现状和前景,对PT,G-M,St和Boreas等各种制冷机的重大技术革新进行了扼要介绍,指出发展趋势。 相似文献
9.
10.