全文获取类型
收费全文 | 583篇 |
免费 | 39篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 143篇 |
金属工艺 | 31篇 |
机械仪表 | 28篇 |
建筑科学 | 18篇 |
矿业工程 | 3篇 |
能源动力 | 19篇 |
轻工业 | 120篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 20篇 |
一般工业技术 | 131篇 |
冶金工业 | 6篇 |
原子能技术 | 5篇 |
自动化技术 | 89篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 16篇 |
2020年 | 14篇 |
2019年 | 15篇 |
2018年 | 26篇 |
2017年 | 13篇 |
2016年 | 24篇 |
2015年 | 25篇 |
2014年 | 43篇 |
2013年 | 98篇 |
2012年 | 35篇 |
2011年 | 28篇 |
2010年 | 51篇 |
2009年 | 43篇 |
2008年 | 33篇 |
2007年 | 16篇 |
2006年 | 8篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 5篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 2篇 |
1962年 | 2篇 |
1961年 | 3篇 |
1957年 | 2篇 |
排序方式: 共有625条查询结果,搜索用时 15 毫秒
621.
Photo-electro-catalytic oxidation reactions of 1,6-hexanediol were carried out in a coil-type continuous-flow microreactor with an immobilized TiO2 catalyst material. Bio-based adipic acid was formed as the only intermediate product before the total mineralization process. The production was stable, enabling green, selective and continuous resource conversion, but with low, non-optimized yields. In addition, the catalyzed chemical kinetics was modeled, based on mechanisms as well as approximated rate-determining steps. The Butler-Volmer relation was used for activation. The electro-catalytic oxidative pathway was demonstrated to dominate over photo-catalysis, also on account of the band gap characteristics of the titania nanotube electrode. 相似文献
622.
Christopher James Heard Lukáš Grajciar Filip Uhlík Mariya Shamzhy Maksym Opanasenko Jiří Čejka Petr Nachtigall 《Advanced materials (Deerfield Beach, Fla.)》2020,32(44):2003264
Zeolites are among the most environmentally friendly materials produced industrially at the Megaton scale. They find numerous commercial applications, particularly in catalysis, adsorption, and separation. Under ambient conditions aluminosilicate zeolites are stable when exposed to water or water vapor. However, at extreme conditions as high temperature, high water vapor pressure or increased acidity/basicity, their crystalline framework can be destroyed. The stability of the zeolite framework under aqueous conditions also depends on the concentration and character of heteroatoms (other than Al) and the topology of the zeolite. The factors critical for zeolite (in)stability in the presence of water under various conditions are reviewed from the experimental as well as computational sides. Nonreactive and reactive interactions of water with zeolites are addressed. The goal of this review is to provide a comparative overview of all-silica zeolites, aluminosilicates and zeolites with other heteroatoms (Ti, Sn, and Ge) when contacted with water. Due attention is also devoted to the situation when partial zeolite hydrolysis is used beneficially, such as the formation of hierarchical zeolites, synthesis of new zeolites or fine-tuning catalytic or adsorption characteristics of zeolites. 相似文献
623.
Peter Gajdoš Jaroslav Hambalko Jean-Marc Nicaud Milan Čertík 《Yeast (Chichester, England)》2020,37(1):141-147
The 3-acetyl-1,2-diacylglycerols (acTAGs) are the molecules that are structurally similar to triacylglycerols (TAGs). They are naturally produced by plants of the family Celastraceae and animals such as Cervus nippon and Eurosta solidaginis. The presence of acetate in the sn–3 position of the glycerol backbone confers advantages to these compounds, for example, lower viscosity and calorific value compared to classical TAGs. In this work, the gene EeDAcT, which encodes diacylglycerol acetyltransferase in a species of bush (Euonymus europaeus), was overexpressed in strains Po1d (capable of accumulating storage lipids) and JMY1877 (incapable of accumulating storage lipids) of Yarrowia lipolytica, to test the activity of the gene EeDAcT and the production of acTAGs in oleaginous and nonoleaginous genetic backgrounds. It was observed that both the strains containing the gene EeDAcT (YL33 and YL35 for Po1d and JMY1877 strains, respectively) produced acTAGs. The strain YL33 accumulated up to 20% intracellular lipids, 20% of which was acTAGs, and 40% was TAGs. On the other hand, the strain YL35, which showed interrupted TAGs accumulation, produced up to 10% acTAGs as the only storage lipid. Unfortunately, the quantity of acTAGs produced in YL35 was insignificant, as the overall lipid accumulated in the strain was not more than 4% of the biomass. The fatty acid profile of acTAGs produced by the YL33 strain was remarkably similar to TAGs, and both of these structures were rich in oleic (45%) and palmitic (25%) acids. 相似文献
624.
Slaviša Stajić Boris Pisinov Igor Tomasevic Ilija Djekic Dušica Čolović Snežana Ivanović Dušan Živković 《International Journal of Food Science & Technology》2020,55(3):1032-1045
Four different levels (25–100%) of culled goat meat were used in frankfurter formulation (frankfurters G25, G50, G75 and G100) instead of beef (CON). Technological properties, fatty acid profile and sensory properties were examined during the 6-week cold storage. The formulation had significant impact of fatty acids profile – n-6/n-3 ratios progressively decrease from 14.63 in CON to 6.63 in G100. Higher goat meat content led to progressively higher lightness and lower redness in frankfurters. This was also observed by consumers but not negatively perceived. Check-all-that-apply (CATA) analysis shows that more than 80% of consumers marked pleasant colour as present in goat frankfurters and CON. The similar was observed for pleasant appearance, pleasant odour, tasty, soft and juicy. Moreover, atypical taste and odour were mostly not marked as present (73.8% and 62.5%, respectively). The panellists pointed at G50 as the most preferred, while consumers most frequently marked G75. 相似文献
625.
Vijay Bijalwan Pavel Tofel Zdeněk Spotz Klára Částková Dinara Sobola Jiří Erhart Karel Maca 《Journal of the American Ceramic Society》2020,103(8):4611-4624
We report a large piezoelectric constant (d33), 720 pC/N and converse piezoelectric constant (d33*), 2215 pm/V for 0.55(Ba0.9Ca0.1)TiO3-0.45Ba(Sn0.2Ti0.8)O3 ceramics; the biggest value achieved for lead-free piezoceramics so far. The ceramic powders were calcined between 1050°C-1350°C and sintered at 1480°C. The best properties were obtained at a calcination temperature (CT) of 1350°C. The fitting combination of processing and microstructural parameters for example, initial powder particle size >2 µm, ceramics density ~95%, and grain size ~40 µm led to a formation of orthorhombic-tetragonal-pseudo-cubic (O-T-PC) mixed phase boundary near room temperature, supported by Raman spectra, pointed to the extremely high piezoelectric activity. These conditions significantly increase piezoelectric constants, together with high relative permittivity (εr) >5000 and a low loss tangent (tan δ) of 0.029. In addition, the d33 value stabilizes in the range of 400-500 pC/N for all samples calcined between 1050°C and 1250°C. The results entail that the (Ba,Ca)(Sn,Ti)O3 ceramics are strong contenders to be a substitute for lead-based materials for room temperature applications. 相似文献