全文获取类型
收费全文 | 2593篇 |
免费 | 87篇 |
国内免费 | 22篇 |
专业分类
化学 | 1662篇 |
晶体学 | 9篇 |
力学 | 84篇 |
数学 | 485篇 |
物理学 | 462篇 |
出版年
2024年 | 2篇 |
2023年 | 18篇 |
2022年 | 74篇 |
2021年 | 110篇 |
2020年 | 72篇 |
2019年 | 118篇 |
2018年 | 110篇 |
2017年 | 81篇 |
2016年 | 95篇 |
2015年 | 106篇 |
2014年 | 89篇 |
2013年 | 155篇 |
2012年 | 155篇 |
2011年 | 190篇 |
2010年 | 138篇 |
2009年 | 119篇 |
2008年 | 154篇 |
2007年 | 161篇 |
2006年 | 130篇 |
2005年 | 126篇 |
2004年 | 111篇 |
2003年 | 61篇 |
2002年 | 63篇 |
2001年 | 35篇 |
2000年 | 26篇 |
1999年 | 15篇 |
1998年 | 22篇 |
1997年 | 17篇 |
1996年 | 19篇 |
1995年 | 19篇 |
1994年 | 14篇 |
1993年 | 16篇 |
1992年 | 13篇 |
1991年 | 9篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1973年 | 1篇 |
1969年 | 1篇 |
1961年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有2702条查询结果,搜索用时 140 毫秒
101.
102.
Dr. Zhijia Wang Mikhail Ivanov Dr. Yuting Gao Laura Bussotti Prof. Paolo Foggi Huimin Zhang Prof. Nino Russo Prof. Bernhard Dick Prof. Jianzhang Zhao Prof. Mariangela Di Donato Dr. Gloria Mazzone Prof. Liang Luo Prof. Matvey Fedin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(5):1091-1102
Spin–orbit charge-transfer intersystem crossing (SOCT-ISC) is useful for the preparation of heavy atom-free triplet photosensitisers (PSs). Herein, a series of perylene-Bodipy compact electron donor/acceptor dyads showing efficient SOCT-ISC is prepared. The photophysical properties of the dyads were studied with steady-state and time-resolved spectroscopies. Efficient triplet state formation (quantum yield ΦT=60 %) was observed, with a triplet state lifetime (τT=436 μs) much longer than that accessed with the conventional heavy atom effect (τT=62 μs). The SOCT-ISC mechanism was unambiguously confirmed by direct excitation of the charge transfer (CT) absorption band by using nanosecond transient absorption spectroscopy and time-resolved electron paramagnetic resonance (TREPR) spectroscopy. The factors affecting the SOCT-ISC efficiency include the geometry, the potential energy surface of the torsion, the spin density for the atoms of the linker, solvent polarity, and the energy matching of the 1CT/3LE states. Remarkably, these heavy atom-free triplet PSs were demonstrated as a new type of efficient photodynamic therapy (PDT) reagents (phototoxicity, EC50=75 nm ), with a negligible dark toxicity (EC50=78.1 μm ) compared with the conventional heavy atom PSs (dark toxicity, EC50=6.0 μm, light toxicity, EC50=4.0 nm ). This study provides in-depth understanding of the SOCT-ISC, unveils the design principles of triplet PSs based on SOCT-ISC, and underlines their application as a new generation of potent PDT reagents. 相似文献
103.
104.
105.
106.
The one-pot, three-step, four-component Ugi-IMDAF reaction with 5-hydroxymethylfurfural provides simple access to hydroxymethyl-substituted epoxyisoindolones in a diastereoselective and stereospecific manner. The protocol avoids the transfer or isolation of isocyanides, and the broad scope was illustrated by the synthesis of 22 different compounds bearing various substituents on the heterocyclic core. 相似文献
107.
108.
Ronald C. Crouch Jeffrey G. Raab Marius Pelmuş Evgeny Tischenko Michael Frey Alexei V. Buevich Mikhail Reibarkh R. Thomas Williamson Gary E. Martin 《Magnetic resonance in chemistry : MRC》2022,60(2):210-220
Modification of the recently reported 19F-detected 1,1-ADEQUATE experiment that incorporates dual-optimization to selectively invert a wide range of 1JCC correlations in a 1,n-ADEQUATE experiment is reported. Parameters for the dual-optimization segment of the pulse sequence were modified to accommodate the increased size of 1JCC homonuclear coupling constants of poly- and perfluorinated molecules relative to protonated molecules to allow broadband inversion of the 1JCC correlations. The observation and utility of isotope shifts are reported for the first time for 1,1- and 1,n-ADEQUATE correlations. 相似文献
109.
110.