全文获取类型
收费全文 | 295篇 |
免费 | 18篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 81篇 |
金属工艺 | 2篇 |
机械仪表 | 18篇 |
建筑科学 | 6篇 |
能源动力 | 8篇 |
轻工业 | 13篇 |
无线电 | 46篇 |
一般工业技术 | 70篇 |
冶金工业 | 21篇 |
自动化技术 | 43篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 8篇 |
2014年 | 12篇 |
2013年 | 20篇 |
2012年 | 19篇 |
2011年 | 18篇 |
2010年 | 17篇 |
2009年 | 13篇 |
2008年 | 10篇 |
2007年 | 11篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有313条查询结果,搜索用时 15 毫秒
131.
Giancarlo Bartolucci Dan Neculoiu Mircea Dragoman Flavio Giacomozzi Romolo Marcelli Alexandru Müller 《International Journal of Circuit Theory and Applications》2003,31(5):529-539
This paper describes the design, the realization and the experimental characterization of a micromachined band‐pass filter with a working frequency of 38GHz. The synthesis of the structure has been carried out by means of the image parameter representation of two‐port networks. A coupled line coplanar configuration has been adopted for the filtering network. The good agreement between theoretical and experimental results demonstrates the validity of the proposed design approach. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
132.
α,ω-Diglycidyl-oligoethylenoxides were prepared by reacting α,ω-dihydroxy-oligoethylenoxides with epichlorohydrin. They were then crosslinked with triethylenetetramine to form catalyst beads which were tested for their liquid-solid phase-transfer catalyst activity in the reaction of 1-bromobutane with potassium phenoxide. Regardless of the oxyethylene chain length, the catalyst beads showed significant activity, which was relatively high for oligomers with a great number of oxyethylene repeating units. 相似文献
133.
Mircea Grigoriu 《Canadian Metallurgical Quarterly》2003,129(1):43-49
A new algorithm is developed for generating samples of stationary Gaussian random fields. The algorithm is based on a model derived from the spectral representation theorem for weakly stationary random fields. The model consists of a superposition of a random number of waves with random amplitude and frequency, can match the second moment properties of any target random field, and becomes Gaussian as the intensity of two independent Poisson processes, defining the number of waves and their frequencies, increases indefinitely. In contrast to the current Monte Carlo simulation algorithms, the proposed algorithm: (1) does not produce periodic samples; and (2) does not require the discretization of the frequency domain. The proposed Monte Carlo algorithm is applied to generate samples of a stationary Gaussian field defined on 2. 相似文献
134.
135.
136.
Enhanced Collective Magnetic Properties Induced by the Controlled Assembly of Iron Oxide Nanoparticles in Chains 下载免费PDF全文
Delphine Toulemon Mircea V. Rastei David Schmool José Sáiz Garitaonandia Luis Lezama Xavier Cattoën Sylvie Bégin‐Colin Benoit P. Pichon 《Advanced functional materials》2016,26(15):2454-2462
1D assemblies of magnetic nanoparticles are of great potential for designing novel nanostructured materials with enhanced collective magnetic properties. In that challenging context, a new assembly strategy is presented to prepare chains of magnetic nanoparticles that are well‐defined in structure and in spatial arrangement. The 1D assembly of iron oxide nanoparticles onto a substrate is controlled using “click” chemistry under an external magnetic field. Co‐aligned single nanoparticle chains separated by regular distances can be obtained by this strategy. The intrinsic high uniaxial anisotropy results in a strong enhancement of magnetic collective properties in comparison to 2D monolayers or isolated nanoparticles. In contrast to the intensively studied bundle chains of nanoparticles, the finely tuned chain structure reported here allows evidencing a first order intrachain dipolar interaction and a second order interchain magnetic coupling. This study offers new insights into the collective magnetic properties of highly anisotropic particulate assemblies which have been investigated by combining superconducting quantum interference device magnetometry, magnetic force microscopy, and ferromagnetic resonance. 相似文献
137.
138.
The aim of this study is to investigate the migration of heavy metals in meat can under different parameters (varnish, storage time, storage temperature, storage humidity and varnish width and porosity). The physicochemical and organoleptic properties of the meat can have been analyzed. The metal content (Cd, Pb, Cu, Fe, Zn and Sn) were determined by flame and graphite furnace atomic absorption spectrometry after microwave digestion. The organoleptic and physicochemical properties of the samples have not modified significantly during the experiments. The metals migration is not influenced significantly by the varnish type. The highest level of metals in food products was observed at 4 and 50 °C. The porosity influenced significantly (p < 0.05) the migration of metals while the varnish width influence is not a significant one. The migration modeling using 3rd grade polynomial model achieved models with high coefficients of regression (greater than 0.9858). 相似文献
139.
Jordi Sancho-Parramon Davor Gracin Mircea Modreanu Andreja Gajovi 《Solar Energy Materials & Solar Cells》2009,93(10):1768-1772
In the present study we analyzed nanocrystalline silicon (nc-Si)-based p–i–n thin film structures (SiC/nc-Si/n-doped amorphous Si) on glass produced by radio-frequency plasma-enhanced chemical vapor deposition. The crystallinity of the nc-Si layer was modified by varying the deposition conditions ([SiH4]/[H2] ratio in the plasma and radio-frequency power). Structural properties of the samples (crystalline fraction and crystal size distribution) were inferred by Raman spectroscopy. Different optical spectroscopy methods were combined for the determination of the optical constants in different spectral ranges: spectrophotometry, ellipsometry and photothermal deflection spectroscopy. Characterization results evidence that the optical properties of the nc-Si layers are strongly connected with the layer structural properties. Thus, the correlation between density of defects, Urbach energy, band-gap and line-shape of dielectric function critical points with the crystalline properties of the films is established. 相似文献
140.
Mircea Teodorescu Paul O. Stanescu Horia Iovu Constantin Draghici 《Reactive and Functional Polymers》2010,70(7):419-425
The free radical polymerization of vinyl acetate in the presence of a liquid polysulfide H(SCH2CH2OCH2OCH2CH2S)nH (thiocol) was investigated from the point of view of reaction mechanism and characterization of the resulting copolymers. It was shown that, besides the thiol end groups that were consumed very rapidly, the disulfide groups within the thiocol chain were also involved in chain transfer processes. The chain transfer constant of the thiocol S–S groups in the polymerization reaction was estimated from their rate of consumption versus the rate of monomer consumption (CT = 0.89). The resulting copolymers, made up of randomly distributed thiocol sequences and PVAc blocks, were characterized by 1H NMR, GPC, DSC and TGA measurements. The copolymers displayed only one glass transition each, which decreased as the PVAc block length decreased, while their thermal stability was lower than that of both thiocol and PVAc. The molecular weight of the copolymers increased with VAc conversion as a consequence of the insertion of PVAc blocks within the thiocol chain. 相似文献