全文获取类型
收费全文 | 324篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
化学 | 94篇 |
晶体学 | 3篇 |
力学 | 1篇 |
数学 | 17篇 |
物理学 | 216篇 |
出版年
2020年 | 5篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 11篇 |
2012年 | 8篇 |
2011年 | 16篇 |
2010年 | 5篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 11篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1996年 | 12篇 |
1995年 | 19篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 20篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1971年 | 5篇 |
1970年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有331条查询结果,搜索用时 15 毫秒
101.
Vicic DA Anderson TJ Cowan JA Schultz AJ 《Journal of the American Chemical Society》2004,126(26):8132-8133
Reaction of two equiv of 1-adamantylzinc bromide with (dippm)NiBr2 (dippm = bis(di-isopropylphosphino)methane) led to a dinuclear metal complex containing a unique linear bridging hydride ligand. The hydride was characterized by neutron diffraction methods, which confirmed a linear bonding mode. Preliminary reactivity studies of this unusual dimer are reported. 相似文献
102.
Abe K Abe K Abe T Adam I Akimoto H Aston D Baird KG Baltay C Band HR Barklow TL Bauer JM Bellodi G Berger R Blaylock G Bogart JR Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Calcaterra A Cassell R Chou A Cohn HO Coller JA Convery MR Cook V Cowan RF Crawford G Damerell CJ Daoudi M de Groot N de Sangro R Dong DN Doser M Dubois R Erofeeva I Eschenburg V Fahey S Falciai D Fernandez JP Flood K Frey R Hart EL Hasuko K Hertzbach SS Huffer ME Huynh X Iwasaki M Jackson DJ 《Physical review letters》2002,88(15):151801
The parity violation parameters A(b) and A(c) of the Zb(b) and Zc(c) couplings have been measured directly, using the polar angle dependence of the polarized cross sections at the Z(0) pole. Bottom and charmed hadrons were tagged via their semileptonic decays. Both the electron and muon analyses take advantage of new multivariate techniques to increase the analyzing power. Based on the 1993-1998 SLD sample of 550,000 Z(0) decays produced with highly polarized electron beams, we measure A(b) = 0.919+/-0.030(stat)+/-0.024(syst), and A(c) = 0.583+/-0.055(stat)+/-0.055(syst). 相似文献
103.
Ahmad QR Allen RC Andersen TC Anglin JD Barton JC Beier EW Bercovitch M Bigu J Biller SD Black RA Blevis I Boardman RJ Boger J Bonvin E Boulay MG Bowler MG Bowles TJ Brice SJ Browne MC Bullard TV Bühler G Cameron J Chan YD Chen HH Chen M Chen X Cleveland BT Clifford ET Cowan JH Cowen DF Cox GA Dai X Dalnoki-Veress F Davidson WF Doe PJ Doucas G Dragowsky MR Duba CA Duncan FA Dunford M Dunmore JA Earle ED Elliott SR Evans HC Ewan GT Farine J Fergani H Ferraris AP Ford RJ Formaggio JA Fowler MM 《Physical review letters》2002,89(1):011302
The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted 8B spectrum, the night minus day rate is 14.0%+/-6.3%(+1.5%)(-1.4%) of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the nu(e) asymmetry is found to be 7.0%+/-4.9%(+1.3%)(-1.2%). A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the large mixing angle solution. 相似文献
104.
Ahmad QR Allen RC Andersen TC D Anglin J Barton JC Beier EW Bercovitch M Bigu J Biller SD Black RA Blevis I Boardman RJ Boger J Bonvin E Boulay MG Bowler MG Bowles TJ Brice SJ Browne MC Bullard TV Bühler G Cameron J Chan YD Chen HH Chen M Chen X Cleveland BT Clifford ET Cowan JH Cowen DF Cox GA Dai X Dalnoki-Veress F Davidson WF Doe PJ Doucas G Dragowsky MR Duba CA Duncan FA Dunford M Dunmore JA Earle ED Elliott SR Evans HC Ewan GT Farine J Fergani H Ferraris AP Ford RJ Formaggio JA Fowler MM 《Physical review letters》2002,89(1):011301
Observations of neutral-current nu interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current (NC), elastic scattering, and charged current reactions and assuming the standard 8B shape, the nu(e) component of the 8B solar flux is phis(e) = 1.76(+0.05)(-0.05)(stat)(+0.09)(-0.09)(syst) x 10(6) cm(-2) s(-1) for a kinetic energy threshold of 5 MeV. The non-nu(e) component is phi(mu)(tau) = 3.41(+0.45)(-0.45)(stat)(+0.48)(-0.45)(syst) x 10(6) cm(-2) s(-1), 5.3sigma greater than zero, providing strong evidence for solar nu(e) flavor transformation. The total flux measured with the NC reaction is phi(NC) = 5.09(+0.44)(-0.43)(stat)(+0.46)(-0.43)(syst) x 10(6) cm(-2) s(-1), consistent with solar models. 相似文献
105.
106.
107.
108.
A precise knowledge of the temperature and number of hot electrons generated in the interaction of short-pulse high-intensity lasers with solids is crucial for harnessing the energy of a laser pulse in applications such as laser-driven ion acceleration or fast ignition. Nevertheless, present scaling laws tend to overestimate the hot electron temperature when compared to experiment and simulations. We present a novel approach that is based on a weighted average of the kinetic energy of an ensemble of electrons. We find that the scaling of electron energy with laser intensity can be derived from a general Lorentz invariant electron distribution ansatz that does not rely on a specific model of energy absorption. The scaling derived is in perfect agreement with simulation results and clearly follows the trend seen in recent experiments, especially at high laser intensities where other scalings fail to describe the simulations accurately. 相似文献
109.
Abdullah?M?Asiri Harry?G?Heller David?S?Hughes Michael?B?HursthouseEmail author John?Kendrick Frank?JJ?Leusen Riccardo?Montis 《Chemistry Central journal》2014,8(1):70
Background
Derivatives of fulgides have been shown to have interesting photochromic properties. We have synthesised a number of such derivatives and have found, in some cases, that crystals can be made to change colour on crushing, a phenomenon we have termed “tribochromism”. We have studied a number of derivatives by X-ray crystallography, to see if the colour is linked to molecular structure or crystal packing, or both, and our structural results have been supported by calculation of molecular and lattice energies.Results
A number of 5-dicyanomethylene-4-diphenylmethylene-3-disubstitutedmethylene-tetrahydrofuran-2-one compounds have been prepared and structurally characterised. The compounds are obtained as yellow or dark red crystals, or, in one case, both. In two cases where yellow crystals were obtained, we found that crushing the crystals gave a deep red powder. Structure determinations, including those of the one compound which gave both coloured forms, depending on crystallisation conditions, showed that the yellow crystals contained molecules in which the structure comprised a folded conformation at the diphenylmethylene site, whilst the red crystals contained molecules in a twisted conformation at this site. Lattice energy and molecular conformation energies were calculated for all molecules, and showed that the conformational energy of the molecule in structure IIIa (yellow) is marginally higher, and the conformation thus less stable, than that of the molecule in structure IIIb (red). However, the van der Waals energy for crystal structure IIIa, is slightly stronger than that of structure IIIb – which may be viewed as a hint of a metastable packing preference for IIIa, overcome by the contribution of a more stabilising Coulomb energy to the overall more favourable lattice energy of structure IIIb.Conclusions
Our studies have shown that the crystal colour is correlated with one of two molecular conformations which are different in energy, but that the less stable conformation can be stabilised by its host crystal lattice.110.