全文获取类型
收费全文 | 1645篇 |
免费 | 55篇 |
国内免费 | 1篇 |
专业分类
化学 | 895篇 |
晶体学 | 8篇 |
力学 | 42篇 |
数学 | 149篇 |
物理学 | 400篇 |
无线电 | 207篇 |
出版年
2021年 | 13篇 |
2020年 | 16篇 |
2019年 | 22篇 |
2017年 | 12篇 |
2016年 | 34篇 |
2015年 | 27篇 |
2014年 | 40篇 |
2013年 | 63篇 |
2012年 | 60篇 |
2011年 | 80篇 |
2010年 | 33篇 |
2009年 | 35篇 |
2008年 | 72篇 |
2007年 | 69篇 |
2006年 | 70篇 |
2005年 | 70篇 |
2004年 | 64篇 |
2003年 | 54篇 |
2002年 | 61篇 |
2001年 | 47篇 |
2000年 | 50篇 |
1999年 | 30篇 |
1998年 | 17篇 |
1997年 | 14篇 |
1996年 | 29篇 |
1995年 | 28篇 |
1994年 | 34篇 |
1993年 | 33篇 |
1992年 | 25篇 |
1991年 | 13篇 |
1990年 | 27篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 18篇 |
1986年 | 24篇 |
1985年 | 27篇 |
1984年 | 22篇 |
1983年 | 15篇 |
1982年 | 15篇 |
1981年 | 27篇 |
1980年 | 11篇 |
1979年 | 18篇 |
1978年 | 13篇 |
1977年 | 20篇 |
1976年 | 17篇 |
1975年 | 23篇 |
1974年 | 25篇 |
1973年 | 17篇 |
1972年 | 22篇 |
1967年 | 13篇 |
排序方式: 共有1701条查询结果,搜索用时 15 毫秒
991.
Donnelly J.P. Huang R.K. Walpole J.N. Missaggia L.J. Harris C.T. Plant J.J. Bailey R.J. Mull D.E. Goodhue W.D. Turner G.W. 《Quantum Electronics, IEEE Journal of》2003,39(2):289-298
The slab-coupled optical waveguide laser (SCOWL) concept, recently proposed and demonstrated, is extended to the AlGaAs-InGaAs-GaAs material system. Both 980- and 915-nm SCOWL devices feature a nearly circular large-diameter single-spatial mode that can be butt coupled with high efficiency to a single-mode fiber. Single-ended continuous-wave output powers of greater than 1 W have been obtained at 980 nm. 相似文献
992.
Katelyn M. Duncan Donald L. Kellis Jonathan S. Huff Matthew S. Barclay Jeunghoon Lee Daniel B. Turner Paul H. Davis Bernard Yurke William B. Knowlton Ryan D. Pensack 《Molecules (Basel, Switzerland)》2022,27(19)
Molecular aggregates are of interest to a broad range of fields including light harvesting, organic optoelectronics, and nanoscale computing. In molecular aggregates, nonradiative decay pathways may emerge that were not present in the constituent molecules. Such nonradiative decay pathways may include singlet fission, excimer relaxation, and symmetry-breaking charge transfer. Singlet fission, sometimes referred to as excitation multiplication, is of great interest to the fields of energy conversion and quantum information. For example, endothermic singlet fission, which avoids energy loss, has been observed in covalently bound, linear perylene trimers and tetramers. In this work, the electronic structure and excited-state dynamics of dimers of a perylene derivative templated using DNA were investigated. Specifically, DNA Holliday junctions were used to template the aggregation of two perylene molecules covalently linked to a modified uracil nucleobase through an ethynyl group. The perylenes were templated in the form of monomer, transverse dimer, and adjacent dimer configurations. The electronic structure of the perylene monomers and dimers were characterized via steady-state absorption and fluorescence spectroscopy. Initial insights into their excited-state dynamics were gleaned from relative fluorescence intensity measurements, which indicated that a new nonradiative decay pathway emerges in the dimers. Femtosecond visible transient absorption spectroscopy was subsequently used to elucidate the excited-state dynamics. A new excited-state absorption feature grows in on the tens of picosecond timescale in the dimers, which is attributed to the formation of perylene anions and cations resulting from symmetry-breaking charge transfer. Given the close proximity required for symmetry-breaking charge transfer, the results shed promising light on the prospect of singlet fission in DNA-templated molecular aggregates. 相似文献
993.
Parallel confocal detection of single molecules in real time 总被引:2,自引:0,他引:2
Lundquist PM Zhong CF Zhao P Tomaney AB Peluso PS Dixon J Bettman B Lacroix Y Kwo DP McCullough E Maxham M Hester K McNitt P Grey DM Henriquez C Foquet M Turner SW Zaccarin D 《Optics letters》2008,33(9):1026-1028
The confocal detection principle is extended to a highly parallel optical system that continuously analyzes thousands of concurrent sample locations. This is achieved through the use of a holographic laser illumination multiplexer combined with a confocal pinhole array before a prism dispersive element used to provide spectroscopic information from each confocal volume. The system is demonstrated to detect and identify single fluorescent molecules from each of several thousand independent confocal volumes in real time. 相似文献
994.
Victor L. Meaurio C. R. Mc. Cabe G. Fenner W. A. Turner P. Slavik H. König O. Wilms L. Fischbach K. Schröder G. Chesneau H. Ditz F. Bardach M. Gröger H. Manz G. Edgar F. Rutter F. A. Gooch W. Scott G. L. Kelley J. A. Wiley R. T. Bohn W. C. Wright P. Jannasch H. Harwood E. Jaboulay 《Analytical and bioanalytical chemistry》1922,61(6):240-256
995.
G. E. F. Lundell H. W. Knowles J. Hanu A. Soukup O. Baudisch King Ferrari Holladay K. Schr?der J. Bellucci L. Grassi Brown Rodeja Turner Archibald und Fulton 《Fresenius' Journal of Analytical Chemistry》1922,61(1-2):60-66
Ohne Zusammenfassung
Die Zitate zu diesem Referat folgen ausnahmsweise am Schlusse des ganzen Artikels S. 66. 相似文献
996.
997.
998.
999.
1000.
Gemma F. Turner Dr. Fallyn Campbell Dr. Stephen A. Moggach Prof. Simon Parsons Dr. Andrés E. Goeta Prof. M. Carmen Muñoz Prof. José A. Real 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(8):3130-3135
High-pressure single-crystal X-ray diffraction has been used to trap both the low-spin (LS) and high-spin (HS) states of the iron(II) Hofmann spin crossover framework, [FeII(pdm)(H2O)[Ag(CN)2]2⋅H2O, under identical experimental conditions, allowing the structural changes arising from the spin-transition to be deconvoluted from previously reported thermal effects. 相似文献