全文获取类型
收费全文 | 154篇 |
免费 | 7篇 |
专业分类
化学 | 77篇 |
数学 | 25篇 |
物理学 | 59篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 4篇 |
2013年 | 21篇 |
2012年 | 6篇 |
2011年 | 12篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 11篇 |
2007年 | 7篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1976年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有161条查询结果,搜索用时 218 毫秒
51.
C. R. Das S. Dhara H. C. Hsu L. C. Chen Y. R. Jeng A. K. Bhaduri Baldev Raj K. H. Chen S. K. Albert 《Journal of Raman spectroscopy : JRS》2009,40(12):1881-1884
The mechanism of the recrystallization in epitaxial (0001) GaN film, introduced by the indentation technique, is probed by lattice dynamic studies using Raman spectroscopy. The recrystallized region is identified by micro‐Raman area mapping. ‘Pop‐in’ bursts in loading lines indicate nucleation of dislocations and climb of dislocations. These processes set in plastic motion of lattice atoms under stress field at the center of indentation for the initiation of the recrystallization process. A planar defect migration mechanism is evolved. A pivotal role of vacancy migration is noted, for the first time, as the rate‐limiting factor for the dislocation dynamics initiating the recrystallization process in GaN. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
52.
Binayak S. Choudhury Arpan Dhara Soumen Samanta 《Physics of Particles and Nuclei Letters》2017,14(4):644-646
We present a protocol for perfectly teleporting a five-qubit state of specific type. We utilize a sixqubit entangled quantum channel for this purpose. In this protocol only four out of 26 possible measurement outcomes appear. This leads to a substantial convenience in the implementation of the protocol. 相似文献
53.
Bishler L. Dhara Saswati Grigoryev T. Mironov A. Morozov A. Morozov An. Ramadevi P. Singh Vivek Kumar Sleptsov A. 《JETP Letters》2020,111(9):494-499
JETP Letters - We evaluate the differences of HOMFLY-PT invariants for pairs of mutant knots colored with representations of SL(N), which are large enough to distinguish between them. These mutant... 相似文献
54.
Debabrata Dhara Arumugam Jayaraman Marcel Hrterich Rian D. Dewhurst Holger Braunschweig 《Chemical science》2022,13(19):5631
While a stable base-free arylalumylene bearing a sterically encumbered terphenyl substituent has been reported previously, we herein report that our attempts to form a base-stabilised arylalumylene bearing a relatively small terphenyl substituent and an N-heterocyclic carbene base led instead to a “masked” dialumene (LRAl AlRL), self-stabilised by one peripheral aromatic group. Intriguingly, examining the behavior of this species or its transient dialumene formed from reducing the diiodoarylalane in aromatic solvents under different conditions reveals that they both decouple into the desired base-stabilised arylalumylene. This transient acyclic, dicoordinate alumylene is highly reactive, deconstructing benzene and toluene to furnish dialuminium derivatives of pentalene, providing the first example of a neutral AlI compound able to deconstruct these less reactive arenes. Computational insights were also gained on the dialumene dissociation and on the mechanism of arene deconstruction by alumylene.Attempts to form a base-stabilised arylalumylene by reducing an NHC-coordinated diiodoterphenylalane led to a masked dialumene. Reactivity studies showed it decouples to initially aimed arylalumylene, which easily deconstructs less reactive arenes. 相似文献
55.
56.
57.
58.
Reduction of the indole-1-carboxaldehydes (-) with borane /THF gives the 1-methylindoles () in 42-91-% yields together with the di(indolylmethyl)ethers (), the indolyl-methyl indolines (), the unsymmetric ether() and the indolenine () as the minor products, except . This appears to be the first report on the formation of symmetric ethers in the borane/THF reduction of an oxygen function. The formation of and from and implies that electrophilic substitution takes place primarily at position 3 of 3-substituted indoles, did not form the corresponding probably because of steric hindrance. These results are discussed in relation to the mechanisms of borane/THF reduction, origin of the different products and electrophilic substitution in 3-substituted indoles. 相似文献
59.
Dhara S Chandra S Magudapathy P Kalavathi S Panigrahi BK Nair KG Sastry VS Hsu CW Wu CT Chen KH Chen LC 《The Journal of chemical physics》2004,121(24):12595-12599
Photoluminescence study using the 325 nm He-Cd excitation is reported for the Au nanoclusters embedded in SiO(2) matrix. Au clusters are grown by ion beam mixing with 100 KeV Ar(+) irradiation on Au [40 nm]/SiO(2) at various fluences and subsequent annealing at high temperature. The blue bands above approximately 3 eV match closely with reported values for colloidal Au nanoclusters and supported Au nanoislands. Radiative recombination of sp electrons above Fermi level to occupied d-band holes are assigned for observed luminescence peaks. Peaks at 3.1 and 3.4 eV are correlated to energy gaps at the X- and L-symmetry points, respectively, with possible involvement of relaxation mechanism. The blueshift of peak positions at 3.4 eV with decreasing cluster size is reported to be due to the compressive strain in small clusters. A first principle calculation based on density functional theory using the full potential linear augmented plane wave plus local orbitals formalism with generalized gradient approximation for the exchange correlation energy is used to estimate the band gaps at the X- and L-symmetry points by calculating the band structures and joint density of states for different strain values in order to explain the blueshift of approximately 0.1 eV with decreasing cluster size around L-symmetry point. 相似文献
60.