全文获取类型
收费全文 | 260392篇 |
免费 | 3080篇 |
国内免费 | 894篇 |
专业分类
化学 | 144597篇 |
晶体学 | 4186篇 |
力学 | 10605篇 |
综合类 | 18篇 |
数学 | 25450篇 |
物理学 | 79510篇 |
出版年
2019年 | 1868篇 |
2018年 | 2264篇 |
2017年 | 2248篇 |
2016年 | 3751篇 |
2015年 | 2539篇 |
2014年 | 3677篇 |
2013年 | 10550篇 |
2012年 | 8035篇 |
2011年 | 9983篇 |
2010年 | 6702篇 |
2009年 | 6538篇 |
2008年 | 9322篇 |
2007年 | 9112篇 |
2006年 | 9021篇 |
2005年 | 8448篇 |
2004年 | 7493篇 |
2003年 | 6857篇 |
2002年 | 6747篇 |
2001年 | 8542篇 |
2000年 | 6287篇 |
1999年 | 4961篇 |
1998年 | 3790篇 |
1997年 | 3840篇 |
1996年 | 3671篇 |
1995年 | 3493篇 |
1994年 | 3308篇 |
1993年 | 3102篇 |
1992年 | 3776篇 |
1991年 | 3819篇 |
1990年 | 3624篇 |
1989年 | 3631篇 |
1988年 | 3571篇 |
1987年 | 3595篇 |
1986年 | 3317篇 |
1985年 | 4314篇 |
1984年 | 4464篇 |
1983年 | 3646篇 |
1982年 | 3896篇 |
1981年 | 3612篇 |
1980年 | 3658篇 |
1979年 | 3937篇 |
1978年 | 4114篇 |
1977年 | 3972篇 |
1976年 | 3928篇 |
1975年 | 3733篇 |
1974年 | 3587篇 |
1973年 | 3812篇 |
1972年 | 2428篇 |
1971年 | 1890篇 |
1968年 | 1887篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
31.
Panpan Li Quanbin Liang Eugene Yau-Hin Hong Chin-Yiu Chan Yat-Hin Cheng Ming-Yi Leung Mei-Yee Chan Kam-Hung Low Hongbin Wu Vivian Wing-Wah Yam 《Chemical science》2020,11(42):11601
A class of acceptor–donor–acceptor chromophoric small-molecule non-fullerene acceptors, 1–4, with difluoroboron(iii) β-diketonate (BF2bdk) as the electron-accepting moiety has been developed. Through the variation of the central donor unit and the modification on the peripheral substituents of the terminal BF2bdk acceptor unit, their photophysical and electrochemical properties have been systematically studied. Taking advantage of their low-lying lowest unoccupied molecular orbital energy levels (from −3.65 to −3.72 eV) and relatively high electron mobility (7.49 × 10−4 cm2 V−1 s−1), these BF2bdk-based compounds have been employed as non-fullerene acceptors in organic solar cells with maximum power conversion efficiencies of up to 4.31%. Moreover, bistable resistive memory characteristics with charge-trapping mechanisms have been demonstrated in these BF2bdk-based compounds. This work not only demonstrates for the first time the use of a boron(iii) β-diketonate unit in constructing non-fullerene acceptors, but also provides more insights into designing organic materials with multi-functional properties.Boron(iii) β-diketonates have been demonstrated to serve as multi-functional materials in NFA-based OPVs and organic resistive memories. 相似文献
32.
33.
34.
35.
Applied Magnetic Resonance - The suggested approach allowed us to derive analytical expressions for modeling the shape of solid-echo signal and its time evolution for a system of three-spin groups... 相似文献
36.
37.
38.
39.
Mechanistic Aspects of a Highly Active Dinuclear Zinc Catalyst for the Co‐polymerization of Epoxides and CO2
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Stefan Kissling Peter T. Altenbuchner Dr. Maximilian W. Lehenmeier Dr. Eberhardt Herdtweck Dr. Peter Deglmann Dr. Uwe B. Seemann Prof. Dr. Bernhard Rieger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8148-8157
The dinuclear zinc complex reported by us is to date the most active zinc catalyst for the co‐polymerization of cyclohexene oxide (CHO) and carbon dioxide. However, co‐polymerization experiments with propylene oxide (PO) and CO2 revealed surprisingly low conversions. Within this work, we focused on clarification of this behavior through experimental results and quantum chemical studies. The combination of both results indicated the formation of an energetically highly stable intermediate in the presence of propylene oxide and carbon dioxide. A similar species in the case of cyclohexene oxide/CO2 co‐polymerization was not stable enough to deactivate the catalyst due to steric repulsion. 相似文献
40.