全文获取类型
收费全文 | 39315篇 |
免费 | 2937篇 |
国内免费 | 674篇 |
专业分类
电工技术 | 1108篇 |
技术理论 | 1篇 |
综合类 | 951篇 |
化学工业 | 8108篇 |
金属工艺 | 1678篇 |
机械仪表 | 2683篇 |
建筑科学 | 1439篇 |
矿业工程 | 393篇 |
能源动力 | 1471篇 |
轻工业 | 3015篇 |
水利工程 | 368篇 |
石油天然气 | 727篇 |
武器工业 | 89篇 |
无线电 | 6312篇 |
一般工业技术 | 7512篇 |
冶金工业 | 2140篇 |
原子能技术 | 569篇 |
自动化技术 | 4362篇 |
出版年
2024年 | 62篇 |
2023年 | 529篇 |
2022年 | 601篇 |
2021年 | 1318篇 |
2020年 | 1023篇 |
2019年 | 975篇 |
2018年 | 1151篇 |
2017年 | 1309篇 |
2016年 | 1324篇 |
2015年 | 1349篇 |
2014年 | 1793篇 |
2013年 | 2568篇 |
2012年 | 2543篇 |
2011年 | 2967篇 |
2010年 | 2258篇 |
2009年 | 2262篇 |
2008年 | 2120篇 |
2007年 | 1836篇 |
2006年 | 1710篇 |
2005年 | 1510篇 |
2004年 | 1246篇 |
2003年 | 1214篇 |
2002年 | 1300篇 |
2001年 | 1027篇 |
2000年 | 901篇 |
1999年 | 908篇 |
1998年 | 1085篇 |
1997年 | 749篇 |
1996年 | 628篇 |
1995年 | 452篇 |
1994年 | 419篇 |
1993年 | 313篇 |
1992年 | 238篇 |
1991年 | 214篇 |
1990年 | 168篇 |
1989年 | 159篇 |
1988年 | 119篇 |
1987年 | 108篇 |
1986年 | 87篇 |
1985年 | 67篇 |
1984年 | 58篇 |
1983年 | 38篇 |
1982年 | 26篇 |
1981年 | 43篇 |
1980年 | 30篇 |
1979年 | 18篇 |
1978年 | 10篇 |
1977年 | 21篇 |
1976年 | 30篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Feng Wenran Li Zhen Chen Yingying Chen Jinyang Lang Haoze Wan Jianghong Gao Yan Dong Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in... 相似文献
2.
Ji Hye Yang Sae Kwang Ku IL Je Cho Je Hyeon Lee Chang-Su Na Sung Hwan Ki 《International journal of molecular sciences》2021,22(4)
Hepatic fibrosis occurs when liver tissue becomes scarred from repetitive liver injury and inflammatory responses; it can progress to cirrhosis and eventually to hepatocellular carcinoma. Previously, we reported that neoagarooligosaccharides (NAOs), produced by the hydrolysis of agar by β-agarases, have hepatoprotective effects against acetaminophen overdose-induced acute liver injury. However, the effect of NAOs on chronic liver injury, including hepatic fibrosis, has not yet been elucidated. Therefore, we examined whether NAOs protect against fibrogenesis in vitro and in vivo. NAOs ameliorated PAI-1, α-SMA, CTGF and fibronectin protein expression and decreased mRNA levels of fibrogenic genes in TGF-β-treated LX-2 cells. Furthermore, downstream of TGF-β, the Smad signaling pathway was inhibited by NAOs in LX-2 cells. Treatment with NAOs diminished the severity of hepatic injury, as evidenced by reduction in serum alanine aminotransferase and aspartate aminotransferase levels, in carbon tetrachloride (CCl4)-induced liver fibrosis mouse models. Moreover, NAOs markedly blocked histopathological changes and collagen accumulation, as shown by H&E and Sirius red staining, respectively. Finally, NAOs antagonized the CCl4-induced upregulation of the protein and mRNA levels of fibrogenic genes in the liver. In conclusion, our findings suggest that NAOs may be a promising candidate for the prevention and treatment of chronic liver injury via inhibition of the TGF-β/Smad signaling pathway. 相似文献
3.
4.
Multimedia Tools and Applications - The study presents a new approach to automate segmentation of clinically significant brain tumor and, to a certain extent, addresses two major issues associated... 相似文献
5.
Hong Sae Jin Park Nam Il Hwang Dae Keun Yi Tae Gyu Eum Hyang Lan 《Food science and biotechnology》2022,31(6):669-679
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex... 相似文献
6.
7.
8.
Jiajia Suo Bowen Yang Edoardo Mosconi Hyeon-Seo Choi YeonJu Kim Shaik M. Zakeeruddin Filippo De Angelis Michael Grätzel Hui-Seon Kim Anders Hagfeldt 《Advanced functional materials》2021,31(34):2102902
Surface passivation treatment is a widely used strategy to resolve trap-mediated nonradiative recombination toward high-efficiency metal-halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in-depth understanding of its passivation mechanism. Here, a systematic study on a mixed-salt passivation strategy of formamidinium bromide (FABr) coupled with different F-substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F-substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed-salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI2. Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high-quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed-salt treatment. In addition, the introduction of the moisture resisted F-substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long-term stability under a high humid atmosphere as well as operational conditions. 相似文献
9.
10.
Dr. Yibin Zhang Dr. Shuai Xia Shulin Wan Tessa E. Steenwinkel Tara Vohs Prof. Rudy L. Luck Prof. Thomas Werner Prof. Haiying Liu 《Chembiochem : a European journal of chemical biology》2021,22(13):2282-2291
Abnormal levels of glutathione, a cellular antioxidant, can lead to a variety of diseases. We have constructed a near-infrared ratiometric fluorescent probe to detect glutathione concentrations in biological samples. The probe consists of a coumarin donor, which is connected through a disulfide-tethered linker to a rhodamine acceptor. Under the excitation of the coumarin donor at 405 nm, the probe shows weak visible fluorescence of the coumarin donor at 470 nm and strong near-infrared fluorescence of the rhodamine acceptor at 652 nm due to efficient Forster resonance energy transfer (FRET) from the donor to the acceptor. Glutathione breaks the disulfide bond through reduction, which results in a dramatic increase in coumarin fluorescence and a corresponding decrease in rhodamine fluorescence. The probe possesses excellent cell permeability, biocompatibility, and good ratiometric fluorescence responses to glutathione and cysteine with a self-calibration capability. The probe was utilized to ratiometrically visualize glutathione concentration alterations in HeLa cells and Drosophila melanogaster larvae. 相似文献