全文获取类型
收费全文 | 71613篇 |
免费 | 8505篇 |
国内免费 | 4471篇 |
专业分类
电工技术 | 5747篇 |
技术理论 | 6篇 |
综合类 | 5874篇 |
化学工业 | 10843篇 |
金属工艺 | 4116篇 |
机械仪表 | 4963篇 |
建筑科学 | 5323篇 |
矿业工程 | 2704篇 |
能源动力 | 2157篇 |
轻工业 | 5779篇 |
水利工程 | 1782篇 |
石油天然气 | 3043篇 |
武器工业 | 777篇 |
无线电 | 8581篇 |
一般工业技术 | 8162篇 |
冶金工业 | 3258篇 |
原子能技术 | 931篇 |
自动化技术 | 10543篇 |
出版年
2024年 | 274篇 |
2023年 | 1334篇 |
2022年 | 2648篇 |
2021年 | 3737篇 |
2020年 | 2817篇 |
2019年 | 2270篇 |
2018年 | 2490篇 |
2017年 | 2857篇 |
2016年 | 2506篇 |
2015年 | 3606篇 |
2014年 | 4405篇 |
2013年 | 5147篇 |
2012年 | 5627篇 |
2011年 | 5629篇 |
2010年 | 4949篇 |
2009年 | 4351篇 |
2008年 | 4259篇 |
2007年 | 3775篇 |
2006年 | 3340篇 |
2005年 | 2793篇 |
2004年 | 2058篇 |
2003年 | 2124篇 |
2002年 | 2603篇 |
2001年 | 2256篇 |
2000年 | 1446篇 |
1999年 | 1107篇 |
1998年 | 768篇 |
1997年 | 644篇 |
1996年 | 526篇 |
1995年 | 478篇 |
1994年 | 387篇 |
1993年 | 262篇 |
1992年 | 234篇 |
1991年 | 183篇 |
1990年 | 127篇 |
1989年 | 122篇 |
1988年 | 86篇 |
1987年 | 52篇 |
1986年 | 51篇 |
1985年 | 36篇 |
1984年 | 19篇 |
1983年 | 18篇 |
1982年 | 26篇 |
1981年 | 21篇 |
1980年 | 35篇 |
1979年 | 19篇 |
1978年 | 12篇 |
1977年 | 12篇 |
1959年 | 10篇 |
1951年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
31.
32.
Qi Yang Qilong Wu Yang Liu Shuiping Luo Xiaotong Wu Xixia Zhao Haiyuan Zou Baihua Long Wen Chen Yujia Liao Lanxi Li Pei Kang Shen Lele Duan Zewei Quan 《Advanced materials (Deerfield Beach, Fla.)》2020,32(36):2002822
Engineering novel Sn-based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1−xBix alloy nanoparticles (x up to 0.20) with native Bi-doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi-SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state-of-the-art Bi-SnOx nanoshells derived from Sn0.80Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm−2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO. 相似文献
33.
Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii 下载免费PDF全文
Wen Li Xiaobei Li Yan Yang Feng Zhou Yanfang Liu Shuai Zhou Hailong Yu 《International Journal of Food Science & Technology》2015,50(11):2360-2366
Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels. 相似文献
34.
35.
36.
37.
38.
采用ETAG 004:2013《外墙外保温薄抹灰系统欧洲技术认证指南》中规定的静态泡沫块法,测试在单位面积上使用不同数量锚栓的岩棉板外保温系统的抗风压性能。通过试验可以得出:在混凝土墙体上单纯采用敲击式锚栓锚固岩棉板外保温系统时,拉伸强度可达12.9 k Pa;单位面积增加锚栓的使用量可以提高系统的抗拉承载力,但在不同条件下增加相同数量锚栓对系统抗风载能力提高的程度不同;在普通混凝土墙中,单纯锚固岩棉板保温系统破坏时,单个锚栓承载力平均值的最大值约为其拉拔承载力的50.3%。 相似文献
39.
40.
Bo Wang Edison Huixiang Ang Yang Yang Yufei Zhang Hongbo Geng Minghui Ye Cheng Chao Li 《Advanced functional materials》2020,30(28)
Orthorhombic molybdenum trioxide (MoO3) is one of the most promising anode materials for sodium‐ion batteries because of its rich chemistry associated with multiple valence states and intriguing layered structure. However, MoO3 still suffers from the low rate capability and poor cycle induced by pulverization during de/sodiation. An ingenious two‐step synthesis strategy to fine tune the layer structure of MoO3 targeting stable and fast sodium ionic diffusion channels is reported here. By integrating partially reduction and organic molecule intercalation methodologies, the interlayer spacing of MoO3 is remarkably enlarged to 10.40 Å and the layer structural integration are reinforced by dimercapto groups of bismuththiol molecules. Comprehensive characterizations and density functional theory calculations prove that the intercalated bismuththiol (DMcT) molecules substantially enhanced electronic conductivity and effectively shield the electrostatic interaction between Na+ and the MoO3 host by conjugated double bond, resulting in improved Na+ insertion/extraction kinetics. Benefiting from these features, the newly devised layered MoO3 electrode achieves excellent long‐term cycling stability and outstanding rate performance. These achievements are of vital significance for the preparation of sodium‐ion battery anode materials with high‐rate capability and long cycling life using intercalation chemistry. 相似文献