全文获取类型
收费全文 | 410篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 67篇 |
金属工艺 | 2篇 |
机械仪表 | 4篇 |
建筑科学 | 9篇 |
矿业工程 | 2篇 |
能源动力 | 14篇 |
轻工业 | 17篇 |
水利工程 | 1篇 |
石油天然气 | 4篇 |
无线电 | 63篇 |
一般工业技术 | 85篇 |
冶金工业 | 58篇 |
原子能技术 | 5篇 |
自动化技术 | 83篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 12篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 19篇 |
2017年 | 12篇 |
2016年 | 16篇 |
2015年 | 14篇 |
2014年 | 13篇 |
2013年 | 29篇 |
2012年 | 11篇 |
2011年 | 29篇 |
2010年 | 14篇 |
2009年 | 29篇 |
2008年 | 23篇 |
2007年 | 16篇 |
2006年 | 25篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 10篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有422条查询结果,搜索用时 15 毫秒
411.
412.
A method of determination of phase functions required for the generation of sector and cosecant beams using a circular aperture is determined. In the particular case of one-dimensional pattern functions, the two-dimensional form of the relation between pattern functions and aperture functions is reduced to one-dimensional form. The stationary phase method is used to obtain possible solutions for the phase functions. 相似文献
413.
414.
415.
Q. Md. Alfred T. Chakravarty G. Singh S. K. Sanyal 《Journal of Infrared, Millimeter and Terahertz Waves》2007,28(10):881-887
In radar, planar phased array antenna plays vital role in electronic scanning in the azimuth and elevation direction to the horizon. In most operations using planar phased array both the coordinates of azimuth and elevation, are steered electronically. In this paper a conceptual schematic of a phased array antenna with programmable time delay units has been presented. It is shown that by suitably exploiting the time delay matrix one can have electronic beam rotation around the target axis as required in conical scan. Thus both the elevation and azimuth motors in conical scan system are replaced by electronic scanning. Heuristically, we have selected eight consecutive points for beam rotation in a polygon shape and can also be extended almost circular shape by increasing number of array elements and phase shifter (delays) in the delay matrix. The array requires dual control of phase gradient and individual phase values. The whole array is controlled by micro-controller. This presents exciting possibilities in radar operation. 相似文献
416.
Maximum mature larval, cocoon and shell weight were observed during winter season followed by spring and autumn seasons of both white and brick red eri cocoons. Cocoon weight and shell weight were found about 40 and 5%, respectively, as compared to mature larval weight. Degumming loss was estimated at about 10% for white eri and 12% for brick red eri cocoons. Weight of silk fibres varies significantly between layers and decreasing trend was noted from outer to inner layers. Similar trend was observed for single fibre denier and it differs significantly between places (ecoraces), seasons and layers of cocoons. Ascending trend for single fibre tenacity was found from floss to pelade layers of both white and brick red eri silk cocoons and significant influence was observed for places, seasons as well as layers whereas no impact was noted in case of single fibre breaking elongation. Regression equations between weight of degummed cocoon fibres, single fibre denier and single fibre tenacity and to its corresponding values for different places (ecoraces), seasons and cocoon layers were established and estimated R2 and ‘t’ values confirmed the significance of these regression equations. 相似文献
417.
Bismuth ammonium citrate complex (C24H20Bi4O28 x 6NH3 x 10H2O) interacted with sodium sulphide (Na2S) in presence of beta-cyclodextrin (beta-CD) yielding Bi2S3 nanospheres. Solvothermal treatment of the bismuth complex and dimethyl sulphoxide (DMSO) produced Bi2S3 nanorods. Reaction conditions were optimized to investigate the morphology evolution of the product. Electrical properties of the nanorods were monitored in details. 相似文献
418.
V. Nafees Ahmed A.Shriniwas Rao S. Sujeesh H.Z. Fani A. Sanyal S. Mukhopadhyay 《International Journal of Hydrogen Energy》2018,43(17):8190-8197
Bunsen reaction is one of the three reaction steps of iodine-sulfur process. In present study, Bunsen reaction is carried out in co-current reactor to identify effect of different operating conditions on concentrations of Bunsen reaction product mixture. Bunsen reaction studies have been done in tubular reactor, which is made of tantalum tube and stainless steel jacket, in 50–80 °C temperature range, 2–6 bar (g) pressure range. Feed flow rates are varied for HIx (mixture of hydroiodic acid, water and iodine) 1.2 l/h - 3 l/h, SO2 0.02 g/s – 0.24 g/s and O2 0.008 g/s ?0.016 g/s. It has been observed that, increasing SO2 feed flow rate and pressure results in increased mole fraction of HI in HIx phase and H2SO4 in sulfuric acid phase. Increase in temperature increased the mole fraction of HI in HIx phase but decreased the mole fraction of H2SO4 in sulfuric acid phase. Increase in feed I2/H2O ratio and HIx feed flow rate, decreased the mole fraction of HI in HIx phase. Higher pressure improved the conversion of Bunsen reactants to products. 相似文献
419.
420.
Use of clayey soil has been explored in the laboratory scale experiment as a low cost adsorbent for the removal of copper from wastewater. The influence of metal ion concentration, weight of adsorbent, stirring rates, influence of temperature, pH are also evaluated and the results are fitted using adsorption isotherm models. From the experimental results it is observed that almost 90–99% copper can be removed from the solution using clay at optimized pH 5.5. Langmuir adsorption isotherm, Freundlich isotherm and Tempkin isotherm model have been used to describe the distribution of copper between the liquid and solid phases in batch studies and it has been observed that Langmuir isotherm better represents the phenomenon. From the experimental results rate constant, activation energy, Gibbs free energy, enthalpy, and entropy of the reaction are calculated to determine the mechanism of the sorption process. Thomas, Adams-Bohart, and Yoon-Nelson models are applied to the experimental data to determine the characteristic parameters of the column for process design. 相似文献