全文获取类型
收费全文 | 710篇 |
免费 | 39篇 |
专业分类
电工技术 | 8篇 |
综合类 | 3篇 |
化学工业 | 149篇 |
金属工艺 | 18篇 |
机械仪表 | 9篇 |
建筑科学 | 58篇 |
矿业工程 | 4篇 |
能源动力 | 26篇 |
轻工业 | 152篇 |
水利工程 | 2篇 |
无线电 | 39篇 |
一般工业技术 | 91篇 |
冶金工业 | 117篇 |
原子能技术 | 1篇 |
自动化技术 | 72篇 |
出版年
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 23篇 |
2020年 | 19篇 |
2019年 | 22篇 |
2018年 | 29篇 |
2017年 | 23篇 |
2016年 | 18篇 |
2015年 | 27篇 |
2014年 | 27篇 |
2013年 | 53篇 |
2012年 | 43篇 |
2011年 | 48篇 |
2010年 | 35篇 |
2009年 | 27篇 |
2008年 | 33篇 |
2007年 | 30篇 |
2006年 | 28篇 |
2005年 | 17篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 13篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 3篇 |
1983年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1975年 | 5篇 |
1973年 | 2篇 |
1964年 | 2篇 |
1962年 | 2篇 |
1959年 | 3篇 |
1956年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有749条查询结果,搜索用时 15 毫秒
131.
132.
133.
Michał Świeca Urszula Gawlik-Dziki Dariusz Dziki Barbara Baraniak Jarosław Czyż 《Food chemistry》2013
Different types of breads enriched with onion skin were studied. The objectives were twofold: to show and examine protein–phenolic interactions and to discuss results concerning phenolic content, antioxidant activity and protein digestibility in the light of in vitro bioaccessibility. Phenolic contents and antiradical abilities were linked with the level of onion skin supplement however, the amounts determined were significantly lower than expected. Fortification influenced protein digestibility (a reduction from 78.4% for control breads to 55% for breads with a 4% supplement). Electrophoretic and chromatographic studies showed the presence of indigestible protein–flavonoid complexes – with molecular weights about 25 kDa and 14.5 kDa; however, the reduction of free amino group levels and the increase in chromatogram areas suggest that flavonoids also bind to other bread proteins. The interaction of phenolics with proteins affects antioxidant efficacy and protein digestibility; thus, they have multiple effects on food quality and pro-health properties. 相似文献
134.
135.
136.
A technique of analysis is described using a silver ion-loaded HPLC (Ag+/HPLC) column, gradient elution, and a laser light scattering detector followed by capillary gas chromatography (GC) for the determination of the fatty acid methyl ester (FAME) composition of rapeseed oil, the respective hydrogenated fat, some dietary fats, and human milk fat. With the use of Ag+/HPLC, FAMEs were separated into the following classes: saturated, trans-monounsaturated, cis-monounsaturated, trans–trans-di-unsaturated, trans–cis-di-unsaturated, cis–cis-di-unsaturated, and higher unsaturated FAMEs. Within each class, partial separation of positional isomers was also possible. Fractions of the eluate containing trans and cis C18:1 were separately collected and re-analyzed by GC in order to quantitate the positional isomers eight trans and nine cis in rapeseed oil and in human milk fat. The profiles of eight trans positional isomers in human milk fat and in hydrogenated rapeseed oil were alike but entirely different from that of six C18:1 trans isomers in bovine milk fat. Out of nine C18:1 cis isomers found in hydrogenated fat, only C18:1-9c and C18:1-11c were found in both human and bovine milk fat which may indicate some discrimination which occurs for certain isomers in fatty acid metabolism. 相似文献
137.
Co, Co–Mn (67:33 at.%) and Co–Cu (67:33 at.%) coatings were fabricated using magnetron sputtering on two kinds of ferritic stainless steels (Crofer22APU and F17TNb) in order to form spinel protective coatings on metallic interconnects for solid oxide fuel cells. Despite the thickness unevenness at different regions, dense metallic coatings were successfully applied onto all necessary surfaces of the channelled interconnect substrates. Upon oxidation, spinel oxide coatings with very low Cr content were formed, reducing effectively the Cr release. Among the three protective coatings, Co–Cu coating showed the lowest area specific resistance (<15 mΩ cm2 at 800 °C). 相似文献
138.
A sequence S is nonrepetitive if no two adjacent blocks of S are the same. In 1906 Thue proved that there exist arbitrarily long nonrepetitive sequences over 3 symbols. We consider the online variant of this result in which a nonrepetitive sequence is constructed during a play between two players: Bob is choosing a position in a sequence and Alice is inserting a symbol on that position taken from a fixed set A. The goal of Bob is to force Alice to create a repetition, and if he succeeds, then the game stops. The goal of Alice is naturally to avoid that and thereby to construct a nonrepetitive sequence of any given length.We prove that Alice has a strategy to play arbitrarily long provided the size of the set A is at least 12. This is the online version of the theorem of Thue. The proof is based on nonrepetitive colorings of outerplanar graphs. On the other hand, one can prove that even over 4 symbols Alice has no chance to play for too long. The minimum size of the set of symbols needed for the online version of Thue?s theorem remains unknown. 相似文献
139.
140.
A problem of a modelling of vibrations of thin plates with a functionally graded macrostructure and a tolerance-periodic microstructure in planes parallel to the plate midplane is analysed. The proposed model, based on the Kirchhoff plate theory assumptions and additional hypothesis of the tolerance averaging technique [Wo?niak et al., editors. Thermomechanics of heterogeneous solids and structures. Tolerance averaging approach. ?ód?, University Press, Technical University of ?ód?; 2008], describes the effect of the microstructure size on dynamic behaviour of the plate. In this paper, as an example there are analysed free vibration frequencies of a functionally graded plate band. These frequencies are obtained in the framework of two proposed models—the tolerance model and the asymptotic model, using the known Ritz method. 相似文献