全文获取类型
收费全文 | 225533篇 |
免费 | 23343篇 |
国内免费 | 13488篇 |
专业分类
电工技术 | 17960篇 |
技术理论 | 8篇 |
综合类 | 18381篇 |
化学工业 | 32822篇 |
金属工艺 | 13587篇 |
机械仪表 | 15240篇 |
建筑科学 | 18594篇 |
矿业工程 | 6919篇 |
能源动力 | 6694篇 |
轻工业 | 17134篇 |
水利工程 | 5335篇 |
石油天然气 | 10803篇 |
武器工业 | 2468篇 |
无线电 | 27826篇 |
一般工业技术 | 24248篇 |
冶金工业 | 9043篇 |
原子能技术 | 2668篇 |
自动化技术 | 32634篇 |
出版年
2024年 | 1076篇 |
2023年 | 3590篇 |
2022年 | 7135篇 |
2021年 | 9838篇 |
2020年 | 7305篇 |
2019年 | 5862篇 |
2018年 | 6431篇 |
2017年 | 7611篇 |
2016年 | 6808篇 |
2015年 | 9979篇 |
2014年 | 12409篇 |
2013年 | 14793篇 |
2012年 | 16987篇 |
2011年 | 17892篇 |
2010年 | 16507篇 |
2009年 | 15403篇 |
2008年 | 15269篇 |
2007年 | 14389篇 |
2006年 | 13337篇 |
2005年 | 10660篇 |
2004年 | 7561篇 |
2003年 | 6619篇 |
2002年 | 6672篇 |
2001年 | 5795篇 |
2000年 | 4608篇 |
1999年 | 3788篇 |
1998年 | 2611篇 |
1997年 | 2154篇 |
1996年 | 1968篇 |
1995年 | 1700篇 |
1994年 | 1420篇 |
1993年 | 954篇 |
1992年 | 740篇 |
1991年 | 566篇 |
1990年 | 433篇 |
1989年 | 356篇 |
1988年 | 273篇 |
1987年 | 169篇 |
1986年 | 147篇 |
1985年 | 79篇 |
1984年 | 68篇 |
1983年 | 39篇 |
1982年 | 53篇 |
1981年 | 61篇 |
1980年 | 57篇 |
1979年 | 33篇 |
1976年 | 18篇 |
1975年 | 15篇 |
1959年 | 14篇 |
1951年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
41.
To overcome the drawbacks of solid microporous materials for CO2 capture, this proof‐of‐concept study demonstrates a low‐cost and rapid method for producing composites consisting of hypercrosslinked polymers (HCP) with a polyethyleneimine (PEI) binder. The resulting materials capture CO2 through physical and chemical absorption simultaneously. Compared with HCP, the composites exhibit higher CO2 uptake, higher volumetric density, and improved tolerance to water which is attributed to the PEI binder. 相似文献
42.
43.
Malondialdehyde (MDA) was selected to represent a secondary by-product of lipid peroxidation during rice ageing. This study aimed to investigate the effects of MDA modification on the structural characteristics of rice protein. The results showed that as MDA concentration increased, rice protein carbonyl and disulphide groups increased, but sulphydryl content decreased. The blue shift of maximum fluorescence peak, the decrease of rice protein intrinsic fluorescence intensity and the reduction of surface hydrophobicity indicated the formation of protein aggregates caused by MDA oxidative modification. The results of molecular weight distribution and particle size distribution showed that MDA modification resulted in the formation of soluble protein aggregates, and the decrease of rice protein solubility indicated that insoluble protein aggregates were formed. Results of protein electrophoresis showed that MDA modification contributed to rice protein aggregation via non-disulphide covalent bonds. The results showed that rice protein gradually aggregated with increasing MDA concentration. 相似文献
44.
45.
46.
47.
Chenxu Liu Shuguang Zhang Ruonan Ji Peng Wang Jin Zhang Yu Tian Yonggang Meng Yedong He 《Ceramics International》2019,45(4):4747-4755
Semiconductor particles doped Al2O3 coatings were prepared by cathode plasma electrolytic deposition in Al(NO3)3 electrolyte dispersed with SiC micro- and nano-particles (average particle sizes of 0.5–1.7?µm and 40?nm respectively). The effects of the concentrations and particle sizes of the SiC on the microstructures and tribological performances of the composite coatings were studied. In comparison with the case of dispersing with SiC microparticles, the dispersion of SiC nanoparticles in the coatings was more uniform. When the concentration of SiC nanoparticles was 5?g/L, the surface roughness of the composite coating was reduced by 63%, compared with that of the unmodified coating. Friction results demonstrated that the addition of 5?g/L SiC nanoparticles reduced the friction coefficient from 0.60 to 0.38 and decreased the wear volume under dry friction. The current density and bath voltage were measured to analyze the effects of SiC particles on the deposition process. The results showed that the SiC particles could alter the electrical behavior of the coatings during the deposition process, weaken the bombardment of the plasma, and improve the structures of the coatings. 相似文献
48.
文章主要研究用水浸法提取落葵浆果天然染料及研究浸提液对羊毛织物的染色性能。以水为提取剂提取落葵浆果天然染料,探讨提取工艺中料液比、提取温度及时间等因素对落葵浆果天然染料提取效果的影响。研究结果表明,落葵浆果水浸提法优化工艺为:料液比1∶20、提取温度70℃、提取时间30 min。落葵浆果天然染料可以对羊毛织物进行染色,媒染染色与直接染色相比,染色深度深且会呈现不同的颜色。由于媒染剂的络合作用,媒染染色色牢度比直接染色普遍高1~2级。 相似文献
49.
50.