全文获取类型
收费全文 | 3637篇 |
免费 | 165篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 41篇 |
综合类 | 2篇 |
化学工业 | 970篇 |
金属工艺 | 72篇 |
机械仪表 | 82篇 |
建筑科学 | 147篇 |
矿业工程 | 4篇 |
能源动力 | 123篇 |
轻工业 | 293篇 |
水利工程 | 26篇 |
石油天然气 | 10篇 |
无线电 | 340篇 |
一般工业技术 | 671篇 |
冶金工业 | 457篇 |
原子能技术 | 14篇 |
自动化技术 | 551篇 |
出版年
2023年 | 27篇 |
2022年 | 63篇 |
2021年 | 104篇 |
2020年 | 68篇 |
2019年 | 78篇 |
2018年 | 86篇 |
2017年 | 74篇 |
2016年 | 106篇 |
2015年 | 77篇 |
2014年 | 92篇 |
2013年 | 200篇 |
2012年 | 194篇 |
2011年 | 234篇 |
2010年 | 195篇 |
2009年 | 166篇 |
2008年 | 203篇 |
2007年 | 183篇 |
2006年 | 138篇 |
2005年 | 132篇 |
2004年 | 121篇 |
2003年 | 91篇 |
2002年 | 98篇 |
2001年 | 68篇 |
2000年 | 61篇 |
1999年 | 55篇 |
1998年 | 90篇 |
1997年 | 61篇 |
1996年 | 59篇 |
1995年 | 59篇 |
1994年 | 44篇 |
1993年 | 47篇 |
1992年 | 36篇 |
1991年 | 26篇 |
1990年 | 32篇 |
1989年 | 28篇 |
1988年 | 24篇 |
1987年 | 31篇 |
1986年 | 23篇 |
1985年 | 21篇 |
1984年 | 26篇 |
1983年 | 27篇 |
1982年 | 19篇 |
1981年 | 22篇 |
1980年 | 15篇 |
1978年 | 25篇 |
1977年 | 24篇 |
1976年 | 24篇 |
1975年 | 18篇 |
1974年 | 18篇 |
1973年 | 15篇 |
排序方式: 共有3803条查询结果,搜索用时 15 毫秒
1.
2.
Many media processing applications create a load that varies significantly over time. Hence, if such an application is assigned a lower processing-time budget than needed in its worst-case load situation, deadline misses are likely to occur. This problem can be dealt with by designing media processing applications in a scalable fashion. A scalable media processing application can run in multiple qualities, leading to correspondingly different resource demands. The problem we consider is to find an accompanying quality control strategy, which minimizes both the number of deadline misses and the number of quality changes, while maximizing the quality of processing. We present an initial approach to the above problem by modeling it as a Markov decision process (MDP). Our model is based on measuring relative progress at milestones. Solving the MDP results in a quality control strategy that can be applied during runtime with only little overhead. We evaluate our approach by means of a practical example, which concerns a scalable MPEG-2 decoder. 相似文献
3.
A micromechanics analysis is performed for the determination of the five independent elastic moduli of unidirectional fiber composites. By considering viscoelastic phases and by using the correspondence principle and the inversion of the Laplace transform, the five time-dependent functions which characterize the effective behavior of viscoelastic composites are established. The predicted time-dependent behavior is applied for the analysis of viscoelastic laminated plates. The resulting viscoelastic effects are shown, and comparison between the results obtained within the classical laminated plate theory and the first-order shear deformation theory is discussed. 相似文献
4.
Jacob Hooker David Hinks Gerardo Montero Christopher Conlee 《Coloration Technology》2002,118(6):273-276
The synthesis of azo dyes via a conventional aqueous-based diazotisation and coupling reaction requires the use of relatively high concentrations of mineral acids, which leads to high electrolyte concentrations in wastewater. Reported in this paper is an environmentally benign one-pot method for the synthesis of a nonionic azo dye, N,N -diethyl- N -{4-[( E )-(4-nitrophenyl)diazenyl]phenyl}amine, in supercritical carbon dioxide without using a mineral acid. The product yield increased significantly with temperature, with 91% theoretical yield afforded at 80 °C. The pressure of the system had little influence on product yield. 相似文献
5.
Gibbs energies of formation of CoF2 and MnF2 have been measured in the temperature range from 700 to 1100 K using Al2O3-dispersed CaF2 solid electrolyte and Ni+NiF2 as the reference electrode. The dispersed solid electrolyte has higher conductivity than pure CaF2 thus permitting accurate measurements at lower temperatures. However, to prevent reaction between Al2O3 in the solid electrolyte and NiF2 (or CoF2) at the electrode, the dispersed solid electrolyte was coated with pure CaF2, thus creating a composite structure. The free energies of formation of CoF2 and MnF2 are (± 1700) J mol−1; {fx37-1} The third law analysis gives the enthalpy of formation of solid CoF2 as ΔH° (298·15 K) = −672·69 (± 0·1) kJ mol−1, which compares with a value of −671·5 (± 4) kJ mol−1 given in Janaf tables. For solid MnF2, ΔH°(298·15 K) = − 854·97 (± 0·13) kJ mol−1, which is significantly different from a value of −803·3 kJ mol−1 given in the compilation by Barinet al. 相似文献
6.
7.
8.
9.
Wouter Bergmann Tiest Marcel Bruijn Henk Hoevers Piet de Korte Jan van der Kuur Wim Mels 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2004,520(1-3):329-332
We have performed numerical calculations of the noise in voltage-biased superconducting transition edge-based X-ray microcalorimeters, using a finite-element model. Details of the model are discussed, as well as results for different absorber geometries. The results are in agreement with an analytical model and show that the amount of internal thermal fluctuation noise can be reduced by using a segmented absorber. The simulation also agrees well with experimental data, which, for our detectors, contain no major unidentified noise sources. Furthermore, the discrepancy between the (small-signal) theoretical and the measured energy resolutions for 5.9 keV X-rays, for our sensors typically a factor of 2, is explained by a more accurate modelling of the sensor responsivity, taking into account the large signal behaviour. 相似文献
10.