全文获取类型
收费全文 | 2372篇 |
免费 | 165篇 |
国内免费 | 4篇 |
学科分类
工业技术 | 2541篇 |
出版年
2024年 | 9篇 |
2023年 | 25篇 |
2022年 | 53篇 |
2021年 | 102篇 |
2020年 | 92篇 |
2019年 | 102篇 |
2018年 | 111篇 |
2017年 | 103篇 |
2016年 | 129篇 |
2015年 | 76篇 |
2014年 | 103篇 |
2013年 | 218篇 |
2012年 | 144篇 |
2011年 | 191篇 |
2010年 | 130篇 |
2009年 | 168篇 |
2008年 | 144篇 |
2007年 | 118篇 |
2006年 | 87篇 |
2005年 | 73篇 |
2004年 | 60篇 |
2003年 | 42篇 |
2002年 | 44篇 |
2001年 | 23篇 |
2000年 | 16篇 |
1999年 | 25篇 |
1998年 | 33篇 |
1997年 | 18篇 |
1996年 | 21篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有2541条查询结果,搜索用时 437 毫秒
91.
We investigate channel equalization problem for time-varying flat fading channels under bounded channel uncertainties. We analyze three robust methods to estimate an unknown signal transmitted through a time-varying flat fading channel. These methods are based on minimizing certain mean-square error criteria that incorporate the channel uncertainties into their problem formulations instead of directly using the inaccurate channel information that is available. We present closed-form solutions to the channel equalization problems for each method and for both zero mean and nonzero mean signals. We illustrate the performances of the equalization methods through simulations. 相似文献
92.
Aydogan Sakir Kocyigit Adem Cirak Burcu Bozkurt Erdogan Erman Yilmaz Mehmet 《Journal of Materials Science: Materials in Electronics》2022,33(9):6059-6069
Journal of Materials Science: Materials in Electronics - Zinc oxide (ZnO) rods film was fabricated by homemade and simple spray pyrolysis technique on a p-type silicon (Si) substrate, and the film... 相似文献
93.
Bilge N. Altay Veronika Husovska Alexandra Pekarovicova Paul D. Fleming 《Color research and application》2019,44(6):910-916
Unused base inks that are not going to be used for printing production are considered to be hazardous materials. Their disposal is expensive, and strict environmental regulations should be followed for their disposal. As an alternative, this article describes how spectral data of unused base inks can be gathered and mixed to generate new colors to incorporate them back to print production for small‐volume jobs. In this study, 30 different Pantone colors were selected as target colors. The CIE L*a*b* spectral data of Pantone colors and unused base inks were gathered via a spectrophotometer. A commercial formulation software, based on multiflux theory and CIE L*a*b* color space, was used to formulate ink recipes that contained the base inks. To quantify the performance of ink recipes, they were mixed and printed using an offset printability tester. The CIELAB ΔE*ab metric, developed by CIE, was used to detect the visual differences between the target Pantone Color and printed colors. 相似文献
94.
Carbon black (CB) obtained from used car tire rubbers were treated with concentrated sulfuric and nitric acids. The oxidized CB (CB‐COO‐Na+) is subsequently modified with epichlorohydrin (ECH) and amines including polyethylene imine (PEI). These modified CBs such as CB‐PEI are used as metal‐free catalysts in methanolysis of sodium borohydride (NaBH4) to produce hydrogen. The hydrogen generation rate (HGR) of 3089 ± 44.69 mL.min‐1.g‐1 is accomplished at room temperature with CB‐PEI‐hydrochloric acid (HCl) catalyst. The resulting activation energy of 34.7 kJ/mol for the temperature range of ?20°C to +30°C compares favorably to most of alternative catalysts reported in literature while reaction catalyzing capabilities of CB‐PEI‐HCl particles extend to the subzero temperature range (?20°C‐0°C). The reuse and regeneration studies conducted for the CB‐PEI‐HCl catalyst showed that these catalysts do provide complete conversion at every use up to five consecutive runs and retain 50 ± 2.5% of the original hydrogen generation rate at the fifth consecutive reuse. The CBs‐based catalysts are fully regenerated with HCl treatment. 相似文献
95.
96.
97.
98.
99.
Scientometrics - A novel hashing algorithm is applied to match two prominent and important bibliographic databases at the paper level. In the literature, such tasks have been studied and conducted... 相似文献
100.