全文获取类型
收费全文 | 56730篇 |
免费 | 15281篇 |
国内免费 | 76篇 |
专业分类
电工技术 | 1005篇 |
综合类 | 28篇 |
化学工业 | 21090篇 |
金属工艺 | 1020篇 |
机械仪表 | 2011篇 |
建筑科学 | 2082篇 |
矿业工程 | 7篇 |
能源动力 | 1640篇 |
轻工业 | 8537篇 |
水利工程 | 394篇 |
石油天然气 | 60篇 |
无线电 | 10048篇 |
一般工业技术 | 15123篇 |
冶金工业 | 2058篇 |
原子能技术 | 314篇 |
自动化技术 | 6670篇 |
出版年
2024年 | 13篇 |
2023年 | 253篇 |
2022年 | 314篇 |
2021年 | 869篇 |
2020年 | 1788篇 |
2019年 | 3489篇 |
2018年 | 3534篇 |
2017年 | 3821篇 |
2016年 | 4421篇 |
2015年 | 4350篇 |
2014年 | 4579篇 |
2013年 | 6201篇 |
2012年 | 3864篇 |
2011年 | 3855篇 |
2010年 | 3707篇 |
2009年 | 3652篇 |
2008年 | 3176篇 |
2007年 | 2765篇 |
2006年 | 2434篇 |
2005年 | 2071篇 |
2004年 | 1968篇 |
2003年 | 1876篇 |
2002年 | 1808篇 |
2001年 | 1556篇 |
2000年 | 1464篇 |
1999年 | 864篇 |
1998年 | 726篇 |
1997年 | 512篇 |
1996年 | 376篇 |
1995年 | 270篇 |
1994年 | 239篇 |
1993年 | 189篇 |
1992年 | 131篇 |
1991年 | 132篇 |
1990年 | 116篇 |
1989年 | 121篇 |
1988年 | 70篇 |
1987年 | 88篇 |
1986年 | 74篇 |
1985年 | 66篇 |
1984年 | 45篇 |
1983年 | 38篇 |
1982年 | 17篇 |
1981年 | 31篇 |
1980年 | 24篇 |
1979年 | 13篇 |
1978年 | 18篇 |
1977年 | 22篇 |
1976年 | 30篇 |
1975年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
1.
2.
3.
4.
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
5.
Bijan Nasri‐Nasrabadi Akif Kaynak Shayan Seyedin Zahra Komeily‐Nia Abbas Z Kouzani 《Polymer International》2019,68(5):922-928
Recent advances in three‐dimensional (3D) printing have enabled the fabrication of interesting structures which are not achievable using traditional fabrication approaches. The 3D printing of carbon microtube composite inks allows fabrication of conductive structures for practical applications in soft robotics and tissue engineering. However, it is challenging to achieve 3D printed structures from solution‐based composite inks, which requires an additional process to solidify the ink. Here, we introduce a wet 3D printing technique which uses a coagulation bath to fabricate carbon microtube composite structures. We show that through a facile nanogrooving approach which introduces cavitation and channels on carbon microtubes, enhanced interfacial interactions with a chitosan polymer matrix are achieved. Consequently, the mechanical properties of the 3D printed composites improve when nanogrooved carbon microtubes are used, compared to untreated microtubes. We show that by carefully controlling the coagulation bath, extrusion pressure, printing distance and printed line distance, we can 3D print composite lattices which are composed of well‐defined and separated printed lines. The conductive composite 3D structures with highly customised design presented in this work provide a suitable platform for applications ranging from soft robotics to smart tissue engineering scaffolds. © 2019 Society of Chemical Industry 相似文献
6.
Silicon - Quadruple gate FinFET is a promising candidate among other multi-gate MOS devices due to it’s better scalability and higher short channel effect suppression capability in advanced... 相似文献
7.
Bokyung Kim Young Ho Ko Massimiliano Runfola Simona Rapposelli Gabriella Ortore Grazia Chiellini Jin Hae Kim 《International journal of molecular sciences》2021,22(7)
Thyromimetics, whose physicochemical characteristics are analog to thyroid hormones (THs) and their derivatives, are promising candidates as novel therapeutics for neurodegenerative and metabolic pathologies. In particular, sobetirome (GC-1), one of the initial halogen-free thyromimetics, and newly synthesized IS25 and TG68, with optimized ADME-Tox profile, have recently attracted attention owing to their superior therapeutic benefits, selectivity, and enhanced permeability. Here, we further explored the functional capabilities of these thyromimetics to inhibit transthyretin (TTR) amyloidosis. TTR is a homotetrameric transporter protein for THs, yet it is also responsible for severe amyloid fibril formation, which is facilitated by tetramer dissociation into non-native monomers. By combining nuclear magnetic resonance (NMR) spectroscopy, computational simulation, and biochemical assays, we found that GC-1 and newly designed diphenyl-methane-based thyromimetics, namely IS25 and TG68, are TTR stabilizers and efficient suppressors of TTR aggregation. Based on these observations, we propose the novel potential of thyromimetics as a multi-functional therapeutic molecule for TTR-related pathologies, including neurodegenerative diseases. 相似文献
8.
9.
10.
Karolina Storesund Francine Amon Anne Steen‐Hansen Shayesteh Haghighatpanah Ida Larsson 《火与材料》2021,45(1):181-190
The aim of this exploratory study has been to investigate the fire properties and environmental aspects of different upholstery material combinations, mainly for domestic applications. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three‐dimensional web structure has been examined as an alternative padding material, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production. 相似文献