全文获取类型
收费全文 | 5224篇 |
免费 | 192篇 |
国内免费 | 26篇 |
专业分类
电工技术 | 77篇 |
综合类 | 11篇 |
化学工业 | 1019篇 |
金属工艺 | 157篇 |
机械仪表 | 122篇 |
建筑科学 | 51篇 |
矿业工程 | 17篇 |
能源动力 | 311篇 |
轻工业 | 319篇 |
水利工程 | 38篇 |
石油天然气 | 20篇 |
无线电 | 662篇 |
一般工业技术 | 1186篇 |
冶金工业 | 742篇 |
原子能技术 | 34篇 |
自动化技术 | 676篇 |
出版年
2023年 | 78篇 |
2022年 | 130篇 |
2021年 | 192篇 |
2020年 | 153篇 |
2019年 | 138篇 |
2018年 | 184篇 |
2017年 | 176篇 |
2016年 | 189篇 |
2015年 | 118篇 |
2014年 | 198篇 |
2013年 | 421篇 |
2012年 | 225篇 |
2011年 | 248篇 |
2010年 | 208篇 |
2009年 | 276篇 |
2008年 | 185篇 |
2007年 | 138篇 |
2006年 | 138篇 |
2005年 | 117篇 |
2004年 | 111篇 |
2003年 | 107篇 |
2002年 | 91篇 |
2001年 | 70篇 |
2000年 | 70篇 |
1999年 | 73篇 |
1998年 | 148篇 |
1997年 | 110篇 |
1996年 | 122篇 |
1995年 | 83篇 |
1994年 | 84篇 |
1993年 | 80篇 |
1992年 | 60篇 |
1991年 | 70篇 |
1990年 | 68篇 |
1989年 | 47篇 |
1988年 | 46篇 |
1987年 | 45篇 |
1986年 | 42篇 |
1985年 | 47篇 |
1984年 | 32篇 |
1983年 | 25篇 |
1982年 | 27篇 |
1981年 | 35篇 |
1980年 | 23篇 |
1979年 | 30篇 |
1978年 | 33篇 |
1977年 | 27篇 |
1976年 | 33篇 |
1975年 | 15篇 |
1973年 | 13篇 |
排序方式: 共有5442条查询结果,搜索用时 0 毫秒
51.
52.
McFee J.E. Ellingson R.O. Elliott J. Das Y. 《IEEE transactions on instrumentation and measurement》1996,45(1):153-158
An experimental instrument is described which explicitly estimates location of ferrous rods parallel to a plane of measurement by analyzing simultaneous magnetic field and position data. The instrument consists of a unit containing a fluxgate magnetometer, position sensor and signal-conditioning circuits, connected to a unit containing a microprocessor, displays and associated electronics. An operator scans the sensor unit over the measurement surface, and the microprocessor estimates location, rod length and diameter. Experiments to estimate the parameters of horizontal typical reinforcing rods under a horizontal plane showed that the axis position could be estimated with an error of less than 0.5 cm, the length with a precision of <5 cm (<3.5%) and the depth with a precision of <0.4 cm at depths of 8 to 18 cm. Estimation of rod diameter was unreliable due to the presence of substantial remanent magnetization 相似文献
53.
54.
A typical or conventional workstation for a repetitive drill press operation was evaluated and subsequently redesigned by incorporating the concepts and principles of work design and ergonomics. The production task comprised of drilling four holes on a prepared steel plate. A methods–time measurement (MTM) analysis was conducted to eliminate unnecessary motions and improve the necessary (work) motions involved in task performance. The specific features of the redesigned workstation were specially designed equipment (jig, fixture, etc.), a suitable adjustable chair, proper work height, a placement of tools/equipment within reach envelope, and a comprehensive operator training method. An experimental investigation was conducted to evaluate and test the redesigned workstation in terms of operator productivity (production quantity and quality output) and satisfaction. The increases in quantity (number of holes drilled) and quality (number of good holes drilled) output were 22 and 50%, respectively, for the redesigned workstation compared to the typical or conventional workstation. The high improvement in quality output (50%) could be attributed to the improved design of the jig and fixture and the comprehensive operator training method, which emphasizes the quality aspect of production output. The improvement in operator satisfaction (scores) were highly significant. This investigation has demonstrated the beneficial effect of a combined work design and ergonomics approach, especially for the redesign of a workstation for a repetitive drill press operation. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 395–410, 2007. 相似文献
55.
Long-period fibre gratings in specially designed birefringent few-mode fibres are used to demonstrate spectrally flat polarisers with bandwidths of 10 nm and polarisation extinction levels of 20 dB. This is enabled by the special dispersive properties of few-mode fibres, yielding fibre polarisers with performance approaching that of bulk-optic devices. 相似文献
56.
The classical stochastic analog of the deterministic linear system in engineering is the linear system driven by white noise. As the promise of artificial neural networks in modeling nonlinear systems continues to grow, the need for a stochastic analog with quantitative foundations for analysis and synthesis will increase. This paper presents recent work in this direction, examining recurrent neural nets (RNN driven by white noise. We examine the effect of noise on the typical continuous-time RNN model. First, we perform qualitative analysis establishing uniform boundedness of moments of the neuron states over time. To enable practical application, however, it is necessary to relate these properties to useful measures that can be estimated. We thus subsequently derive bias and variance measures for the noisy RNN with respect to the corresponding deterministic RNN. This has significant practical implications, since net design is nonminimal in the sense that several nets can solve the same problem. The results allow the user to evaluate given RNN for noise performance. The designer can use these results to constrain the design space so that the design satisfies performance specifications whenever possible. An example is provided using the measures derived in this paper to predetermine the best among several RNN designs for a given problem. 相似文献
57.
Although the basal ganglia have been shown to be critical for the expression of emotion in prosody and facial expressions, it is unclear whether they are also critical for recognition of emotions. Selective pathology of parts of the basal ganglia is a hallmark of individuals with Parkinson's disease, and such patients have been examined in several studies of emotion. We examined 18 patients with Parkinson's disease (11 men, 7 women) and 13 age-, education-, gender ratio-, and IQ-matched normal controls on their ability to recognize emotions signaled by facial expressions. Parkinson's patients performed entirely normally on a quantitative task of recognizing emotional facial expressions. The findings do not support the notion that the sectors of basal ganglia that are dysfunctional in Parkinson's disease are essential for recognizing emotion in facial expressions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
58.
Kundu Abhijit Adhikari Saikat Das Arnima Kanjilal Maitreyi Ray Mukherjee Moumita 《Microsystem Technologies》2021,27(2):569-584
Microsystem Technologies - Photo-sensors are integral part of different bio-medical diagnostic equipment. Each type of bio-molecules possess unique spectral fingerprint in visible wavelength region... 相似文献
59.
Sinha Swati Shaw Siddharth Biswas Kunal De Debashis Das Samir Chandra Sarkar Angsuman Bandyopadhyay Jaya 《Microsystem Technologies》2021,27(11):4087-4100
Microsystem Technologies - Single-Walled Carbon Nanotubes (SWCNTs) are widely used as potential carriers in drug delivery systems. The objective of this work was to observe the effects of pristine,... 相似文献
60.
Biswas Uttara Rakshit Jayanta Kumar Das Joyashree Bharti Gaurav Kumar Suthar Bhuvneshwer Amphawan Angela Najjar Monia 《SILICON》2021,13(3):885-892
Silicon - In the present report, a photonic crystal based micro-ring resonator (MRR) structure is proposed which is very compact in size and has very fast response and is employed for temperature... 相似文献