全文获取类型
收费全文 | 1584篇 |
免费 | 72篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 25篇 |
综合类 | 6篇 |
化学工业 | 343篇 |
金属工艺 | 69篇 |
机械仪表 | 20篇 |
建筑科学 | 60篇 |
矿业工程 | 12篇 |
能源动力 | 53篇 |
轻工业 | 129篇 |
水利工程 | 14篇 |
石油天然气 | 5篇 |
无线电 | 199篇 |
一般工业技术 | 292篇 |
冶金工业 | 228篇 |
原子能技术 | 5篇 |
自动化技术 | 197篇 |
出版年
2022年 | 30篇 |
2021年 | 25篇 |
2020年 | 25篇 |
2019年 | 24篇 |
2018年 | 34篇 |
2017年 | 37篇 |
2016年 | 34篇 |
2015年 | 20篇 |
2014年 | 55篇 |
2013年 | 110篇 |
2012年 | 78篇 |
2011年 | 84篇 |
2010年 | 48篇 |
2009年 | 46篇 |
2008年 | 81篇 |
2007年 | 68篇 |
2006年 | 62篇 |
2005年 | 59篇 |
2004年 | 40篇 |
2003年 | 47篇 |
2002年 | 41篇 |
2001年 | 27篇 |
2000年 | 29篇 |
1999年 | 20篇 |
1998年 | 39篇 |
1997年 | 26篇 |
1996年 | 31篇 |
1995年 | 16篇 |
1994年 | 20篇 |
1993年 | 23篇 |
1992年 | 15篇 |
1991年 | 21篇 |
1990年 | 22篇 |
1989年 | 20篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1982年 | 12篇 |
1980年 | 18篇 |
1979年 | 9篇 |
1976年 | 13篇 |
1975年 | 10篇 |
1973年 | 19篇 |
1972年 | 17篇 |
1971年 | 11篇 |
1969年 | 9篇 |
1961年 | 10篇 |
1959年 | 9篇 |
排序方式: 共有1657条查询结果,搜索用时 15 毫秒
1.
We propose a standardization procedure that provides a convenient, quantitative and reproducible laboratory-based method for measuring the state of polarization (SOP) fluctuations produced by polarization varying devices. This method is based on the SOP distributions generated by commercial polarization scramblers. We show that these devices generate distributions of the maximum change of the SOP (in a given sample time) that follow Rayleigh statistics, which scale linearly with scrambling frequency and the sample time. We use this procedure to measure the SOP fluctuations in a short length of coiled fiber subject to mechanical perturbations. 相似文献
2.
3.
Leo Egghe 《Scientometrics》2005,63(2):277-296
Summary We study new and existing data sets which show that growth rates of sources usually are different from growth rates of items. Examples: references in publications grow with a rate that is different (usually higher) from the growth rate of the publications themselves; article growth rates are different from journal growth rates and so on. In this paper we interpret this phenomenon of “disproportionate growth' in terms of Naranan's growth model and in terms of the self-similar fractal dimension of such an information system, which follows from Naranan's growth model. The main part of the paper is devoted to explain disproportionate growth. We show that the “simple' 2-dimensional informetrics models of source-item relations are not able to explain this but we also show that linear 3-dimensional informetrics (i.e. adding a new source set) is capable to model disproportionate growth. Formulae of such different growth rates are presented using Lotkaian informetrics and new and existing data sets are presented and interpreted in terms of the used linear 3-dimensional model. 相似文献
4.
Equal Strain Consolidation by Vertical Drains 总被引:1,自引:0,他引:1
Chin Jian Leo 《Canadian Metallurgical Quarterly》2004,130(3):316-327
This paper shows the development of a series of closed-form solutions of equal strain consolidation in the presence of a vertical drain with smear and well resistance. Using an approach that considers the effects of both the radial and vertical drainage in a fully coupled fashion, solutions are obtained for the excess pore pressure and the degree of consolidation in the compressible soil subjected to a step- or ramp-loading situation. The closed-form solutions in the present paper may be evaluated in an electronic spreadsheet on a standard personal computer. 相似文献
5.
6.
Kevin R. Boyle Martijn Udink Anton de Graauw Leo P. Ligthart 《Antennas and Propagation, IEEE Transactions on》2007,55(2):373-382
A dual-fed, self-diplexing planar inverted F antenna and an associated RF front-end are described. It is shown that co-design of the antenna and front-end can be used to double the operational bandwidth, without significant size or performance penalties. Indeed, the use of two feeds allows the antenna to be self-diplexing, which results in improved overall efficiency 相似文献
7.
Anil Kumar William R. Leo Lawrence Green Gene L. Woodruff 《Journal of Fusion Energy》1989,8(1-2):107-126
The neutron spectra transmitted across a fission-suppressed hybrid blanket and its components, driven by a low intensity 14 MeV Haefely neutron generator, were measured with a 2×2 NE213 detector at LOTUS facility. These experiments have been analyzed with 2D and 3D codes DOT3.5 and MCNP, respectively. The spectral integrals between 15 to 1 MeV show good agreement among the 2D, the 3D, and the NE213 for 15 cm lead, 18 cm beryllium, and 25 cm graphite slabs. However, there are large discrepancies for 6.2 cm stainless steel and 15 cm lithium carbonate slabs. The assemblies involving two or more of these slabs reflect these tendencies. We observe also considerable disagreement over pointwise spectra for a number of assemblies.Work done while on visiting assignment to Institut de Génie Atomique, E.P.F.L. 相似文献
8.
Solay Leo Raj Singh Sarabdeep Kumar Naveen Amin S. Intekhab Anand Sunny 《SILICON》2021,13(12):4633-4640
Silicon - In this treatise, we have proposed a Single Material Gate–Dual Gate Impact Ionization Metal Oxide Semiconductor (SMG DG-IMOS) based Pressure Sensor. The pressure sensor has the most... 相似文献
9.
Influence of heat treatment on tribological behaviors of novel wrought aluminum bronze 总被引:4,自引:1,他引:4
1 INTRODUCTIONAluminumbronzepossessesexcellentphysical,mechanicalandtribologicalproperties .Itisavailableformakingwear resistingan 相似文献
10.
A predictive model was developed for the fully developed zone of a circulating fluidized bed (CFB) riser reactor operating in the fast fluidization regime that overcomes limitations of existing models. The model accounts for the upward flow of gas and solids in the core and downward flow of the two phases in the annulus. Additionally, a numerical solution methodology for the simulation of a riser reactor employing the hydrodynamic model was devised. A simulation was performed using the fast, main Claus reaction to demonstrate the effects of backmixing in the fast fluidization regime. It was found that the molar flow rates of the reactants leaving a fast fluidized CFB riser reactor were significantly higher than those leaving an identical reactor operating in the pneumatic transport regime. 相似文献