全文获取类型
收费全文 | 50816篇 |
免费 | 8996篇 |
国内免费 | 7061篇 |
专业分类
化学 | 36718篇 |
晶体学 | 733篇 |
力学 | 3024篇 |
综合类 | 483篇 |
数学 | 5867篇 |
物理学 | 20048篇 |
出版年
2024年 | 53篇 |
2023年 | 1007篇 |
2022年 | 1217篇 |
2021年 | 1574篇 |
2020年 | 2046篇 |
2019年 | 1991篇 |
2018年 | 1758篇 |
2017年 | 1728篇 |
2016年 | 2482篇 |
2015年 | 2498篇 |
2014年 | 3068篇 |
2013年 | 3855篇 |
2012年 | 4711篇 |
2011年 | 4963篇 |
2010年 | 3496篇 |
2009年 | 3355篇 |
2008年 | 3630篇 |
2007年 | 3271篇 |
2006年 | 3077篇 |
2005年 | 2353篇 |
2004年 | 1824篇 |
2003年 | 1471篇 |
2002年 | 1392篇 |
2001年 | 1196篇 |
2000年 | 1093篇 |
1999年 | 1048篇 |
1998年 | 853篇 |
1997年 | 787篇 |
1996年 | 767篇 |
1995年 | 704篇 |
1994年 | 595篇 |
1993年 | 500篇 |
1992年 | 473篇 |
1991年 | 361篇 |
1990年 | 326篇 |
1989年 | 272篇 |
1988年 | 221篇 |
1987年 | 195篇 |
1986年 | 171篇 |
1985年 | 164篇 |
1984年 | 107篇 |
1983年 | 74篇 |
1982年 | 63篇 |
1981年 | 39篇 |
1980年 | 18篇 |
1979年 | 10篇 |
1977年 | 2篇 |
1971年 | 2篇 |
1959年 | 3篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Crystal engineering, as a burgeoning technology, has been widely used to construct metalloporphyrins biomimetic catalysts. Herein, a bimetallic metal-organic framework (MOF) was constructed by 4-(4-carboxyphenyl)-1,2,4-triazole ligand, Co2+ and Zr4+ metal ions by solvothermal reaction(named PFC-88). A N,N-chelation site was found between the two adjacent ligands in PFC-88, consequently a porphyrin-like structure was obtained through chelating Fe3+ in this site by post-modification, named PFC-88-Fe. The result of a single crystal X-ray technology verified that Fe ions were successfully metalated in the N,N-chelation site of PFC-88, which is assisted by the X-ray absorption near-edge structure(XANES) spectra. An o-phenylenediamine oxidation reaction was applied to assessing the catalytic activity of PFC-88-Fe, in which the absorbance increases of phenazine-2,3-diamine at λ=418 nm were recorded by absorption spectroscopy in kinetic mode, exhibiting the application potential as a biomimetic catalyst. 相似文献
2.
Yin Qingqing Xu Fen Sun Lixian Li Yaying Liao Lumin Wang Tao Guan Yanxun Xia Yongpeng Zhang Chenchen Wei Sheng Zhang Huanzhi Li Bin 《Journal of Thermal Analysis and Calorimetry》2022,147(12):6583-6592
Journal of Thermal Analysis and Calorimetry - Polyethylene glycol (PEG) is widely used as phase change materials (PCMs). However, the leakage and low thermal conductivity issues restrict its... 相似文献
3.
4.
Journal of Algebraic Combinatorics - Highly nonlinear functions (bent functions, perfect nonlinear functions, etc.) on finite fields and finite (abelian or nonabelian) groups have been studied in... 相似文献
5.
Acta Mathematicae Applicatae Sinica, English Series - In this paper, we investigate a delayed HIV infection model that considers the homeostatic proliferation of CD4+ T cells. The existence and... 相似文献
6.
Hao Lu Xiaodong Wang Hang Wang Andong Zhang Xinming Zheng Na Yu Zheng Tang Xinjun Xu Yahui Liu Ya-Nan Chen Zhishan Bo 《中国科学:化学(英文版)》2022,65(3):594-601
Three nonfused ring electron acceptors (NFREAs) TTC6,TT-C8T and TT-TC8 were purposefully designed and synthesized.The molecular geometry can be adjusted by the steric hindrance of lateral substituents.According to the DFT calculations,from TTC6 to TT-C8T and TT-TC8,planarity of the molecular backbone is gradually improved,accompanying with the enhancing of intramolecular charge transfer effect.As for TT-TC8,the two phenyl substituents are almost perpendicular to the molecular backbone,which endues the acceptor with good solubility and suppresses it to form over-aggregation.Multidirectional regular molecular orientation and closer molecular stacking are formed in TT-TC8 film.As a result,TT-TC8 based devices afford the highest PCE of 13.13%,which is much higher than that of TTC6 (4.41%) and TT-C8T (10.42%) and among the highest PCE values based on NFREAs. 相似文献
7.
Xu Yifan Zhang Hehe Ding Tangjing Tian Ruiqi Sun Dongmei Wang Ming-Sheng Zhou Xiaosi 《中国科学:化学(英文版)》2022,65(9):1807-1816
Science China Chemistry - Due to their enormous potential for large-scale energy storage, rechargeable potassium-ion batteries have been widely researched and developed. However, the drastic volume... 相似文献
8.
9.
10.
Zhao Tianqi Luo Tianzi Fang Bo Shi Lijiang Jin Yongxing Zhou Pengwei Yao Dong Li Chenxia Jing Xufeng Hong Zhi 《Journal of Russian Laser Research》2021,42(5):586-597
Journal of Russian Laser Research - The zero-refractive-index metamaterials have excellent electromagnetic properties, which provide new ideas and methods to realize the control of electromagnetic... 相似文献