全文获取类型
收费全文 | 349篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
化学 | 260篇 |
晶体学 | 1篇 |
力学 | 22篇 |
数学 | 25篇 |
物理学 | 65篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 10篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 28篇 |
2015年 | 25篇 |
2014年 | 25篇 |
2013年 | 54篇 |
2012年 | 26篇 |
2011年 | 33篇 |
2010年 | 20篇 |
2009年 | 19篇 |
2008年 | 16篇 |
2007年 | 16篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 7篇 |
2002年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
排序方式: 共有373条查询结果,搜索用时 0 毫秒
371.
Kodis G Terazono Y Liddell PA Andréasson J Garg V Hambourger M Moore TA Moore AL Gust D 《Journal of the American Chemical Society》2006,128(6):1818-1827
Functional mimics of a photosynthetic antenna-reaction center complex comprising five bis(phenylethynyl)anthracene antenna moieties and a porphyrin-fullerene dyad organized by a central hexaphenylbenzene core have been prepared and studied spectroscopically. The molecules successfully integrate singlet-singlet energy transfer and photoinduced electron transfer. Energy transfer from the five antennas to the porphyrin occurs on the picosecond time scale with a quantum yield of 1.0. Comparisons with model compounds and theory suggest that the F?rster mechanism plays a major role in the extremely rapid energy transfer, which occurs at rates comparable to those seen in some photosynthetic antenna systems. A through-bond, electron exchange mechanism also contributes. The porphyrin first excited singlet state donates an electron to the attached fullerene to yield a P(*+)-C(60)(*-) charge-separated state, which has a lifetime of several nanoseconds. The quantum yield of charge separation based on light absorbed by the antenna chromophores is 80% for the free base molecule and 96% for the zinc analogue. 相似文献
372.
Piper betle Linn. is a traditional plant associated with the Asian and southeast Asian cultures. Its use is also recorded in folk medicines in these regions. Several of its medicinal properties have recently been proven. Phytochemical analysis showed the presence of mainly terpenes and phenols in betel leaves. These constituents vary in the different cultivars of Piper betle. In this paper we have attempted to profile eight locally available betel cultivars using the recently developed mass spectral ionization technique of direct analysis in real time (DART). Principal component analysis has also been employed to analyze the DART MS data of these betel cultivars. The results show that the cultivars of Piper betle could be differentiated using DART MS data. 相似文献
373.
Lihua Lin Pongpen Kaewdee Vikas Nandal Ryota Shoji Hiroyuki Matsuzaki Kazuhiko Seki Mamiko Nakabayashi Naoya Shibata Xiaoping Tao Xizhuang Liang Yiwen Ma Takashi Hisatomi Tsuyoshi Takata Prof. Kazunari Domen 《Angewandte Chemie (International ed. in English)》2023,62(42):e202310607
Photocatalytic water splitting is an ideal means of producing hydrogen in a sustainable manner, and developing highly efficient photocatalysts is a vital aspect of realizing this process. The photocatalyst Y2Ti2O5S2 (YTOS) is capable of absorbing at wavelengths up to 650 nm and exhibits outstanding thermal and chemical durability compared with other oxysulfides. However, the photocatalytic performance of YTOS synthesized using the conventional solid-state reaction (SSR) process is limited owing to the large particle sizes and structural defects associated with this synthetic method. Herein, we report the synthesis of YTOS particles by a flux-assisted technique. The enhanced mass transfer efficiency in the flux significantly reduced the preparation time compared with the SSR method. In addition, the resulting YTOS showed improved photocatalytic H2 and O2 evolution activity when loaded with Rh and Co3O4 co-catalysts, respectively. These improvements are attributed to the reduced particle size and enhanced crystallinity of the material as well as the slower decay of photogenerated carriers on a nanosecond to sub-microsecond time range. Further optimization of this flux-assisted method together with suitable surface modification is expected to produce high-quality YTOS crystals with superior photocatalytic activity. 相似文献