全文获取类型
收费全文 | 254篇 |
免费 | 7篇 |
专业分类
化学 | 152篇 |
晶体学 | 2篇 |
力学 | 11篇 |
数学 | 10篇 |
物理学 | 86篇 |
出版年
2022年 | 2篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 15篇 |
2012年 | 5篇 |
2011年 | 12篇 |
2010年 | 12篇 |
2009年 | 3篇 |
2008年 | 26篇 |
2007年 | 27篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 18篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1972年 | 1篇 |
1969年 | 2篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1906年 | 2篇 |
排序方式: 共有261条查询结果,搜索用时 15 毫秒
91.
The DNA binding conformation and the photophysical properties of the semiflexible binuclear ruthenium complex [micro-bidppz(phen)4Ru2]4+ (2) were studied with optical spectroscopy and compared to the rigid, planar homologue in syn conformation [micro-dtpf(phen)4Ru2]4+ (3) and the parent "light-switch" complex [Ru(phen)2dppz]2+ (1). Comparison of calculated and observed absorption bands of the bridging ligand, bidppz, confirm earlier suggestions that 2 is significantly nonplanar, both free in solution and when intercalated into poly(dAdT)2, but the conclusion that the intercalated conformation is an anti rotamer is not substantiated by comparison of linear and circular dichroism spectra of 2 and 3. The behavior of the emission quantum yield as a function of temperature is similar for the two binuclear complexes 2 and 3 in different protic solvents, and a quantitative analysis suggests that, in solution, the solvent is more strongly hydrogen bonded to the excited state of 2 than to 1. However, the observation that for 2 the radiative rate constant increases to a value similar to 1 upon intercalation into DNA suggests that the difference between 1 and 2 in accepting hydrogen bonds is less pronounced when intercalated. 相似文献
92.
Miller DH Sanghi B Shipsey IP Xin B Adams GS Anderson M Cummings JP Danko I Ge JY Hu D Moziak B Napolitano J He Q Insler J Muramatsu H Park CS Thorndike EH Yang F Artuso M Blusk S Khalil S Li J Menaa N Mountain R Nisar S Randrianarivony K Sia R Skwarnicki T Stone S Wang JC Bonvicini G Cinabro D Dubrovin M Lincoln A Asner DM Edwards KW Naik P Briere RA Ferguson T Tatishvili G Vogel H Watkins ME Rosner JL Adam NE Alexander JP Cassel DG Duboscq JE Ehrlich R Fields L Gibbons L Gray R Gray SW 《Physical review letters》2007,99(12):122002
We measure the mass of the eta meson using psi(2S) --> etaJ/psi events acquired with the CLEO-c detector operating at the CESR e(+)e(-) collider. Using the four decay modes eta --> gamma gamma, 3pi(0), pi(+)pi(-)pi(0), and pi(+)pi(-)gamma, we find M(eta) = 547.785 +/- 0.017 +/- 0.057 MeV, in which the first uncertainty is statistical and the second systematic. This result has an uncertainty comparable to the two most precise previous measurements and is consistent with that of NA48, but is inconsistent at the level of 6.5 sigma with the much smaller mass obtained by GEM. 相似文献
93.
Tobias Frank Johannes CM Schlachetzki Bettina G?ricke Katrin Meuer Gundula Rohde Gunnar PH Dietz Mathias B?hr Armin Schneider Jochen H Weishaupt 《BMC neuroscience》2009,10(1):49-10
Background
The hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) plays a crucial role in controlling the number of neutrophil progenitor cells. Its function is mediated via the G-CSF receptor, which was recently found to be expressed also in the central nervous system. In addition, G-CSF provided neuroprotection in models of neuronal cell death. Here we used the retinal ganglion cell (RGC) axotomy model to compare effects of local and systemic application of neuroprotective molecules. 相似文献94.
Nanocrystalline particles of Co2+doped lithium aluminate (Co2+:LAO) and Ni2+‐doped lithium aluminate (Ni2+:LAO) were synthesized by sol–gel method. The crystalline nature and particle size of the samples were characterized by X‐ray diffraction analysis (XRD). The morphology and the presence Co2+ and Ni2+ in the synthesized samples were analyzed by scanning electron microscope (SEM) and energy dispersive X‐ray analysis (EDAX). The presences of functional groups in the samples were analyzed using FT‐IR analysis. The optical absorbance of the synthesized samples were observed using UV absorption spectral analysis. The frequency dependent dielectric behaviour of the synthesized nano materials was analyzed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
95.
Topological winding and unwinding in a quasi-one-dimensional metastable Bose-Einstein condensate are shown to be manipulated by changing the strength of interaction or the frequency of rotation. Exact diagonalization analysis reveals that quasidegenerate states emerge spontaneously near the transition point, allowing a smooth crossover between topologically distinct states. On a mean-field level, the transition is accompanied by formation of gray solitons, or density notches, which serve as an experimental signature of this phenomenon. 相似文献
96.
Ecklund KM Love W Savinov V Lopez A Mendez H Ramirez J Ge JY Miller DH Shipsey IP Xin B Adams GS Anderson M Cummings JP Danko I Hu D Moziak B Napolitano J He Q Insler J Muramatsu H Park CS Thorndike EH Yang F Artuso M Blusk S Khalil S Li J Mountain R Nisar S Randrianarivony K Sultana N Skwarnicki T Stone S Wang JC Zhang LM Bonvicini G Cinabro D Dubrovin M Lincoln A Rademacker J Asner DM Edwards KW Naik P Reed J Briere RA Ferguson T Tatishvili G Vogel H Watkins ME Rosner JL Alexander JP 《Physical review letters》2008,100(16):161801
Using a sample of tagged D(s)(+) decays collected near the D(s)(*+/-)D(s)(-/+) peak production energy in e(+)e(-) collisions with the CLEO-c detector, we study the leptonic decay D(s)(+)-->tau(+)nu(tau) via the decay channel tau(+)-->e(+)nu(e)nu(tau). We measure B(D(s)(+)-->tau(+)nu(tau))=(6.17+/-0.71+/-0.34)%, where the first error is statistical and the second systematic. Combining this result with our measurements of D(s)(+)-->mu(+)nu(mu) and D(s)(+)-->tau(+)nu(tau) (via tau(+)-->pi(+)nu(tau)), we determine f(D(s))=(274+/-10+/-5) MeV. 相似文献
97.
Lincoln Chayes Nicholas Crawford Dmitry Ioffe Anna Levit 《Journal of statistical physics》2008,133(1):131-149
This paper studies a generalization of the Curie-Weiss model (the Ising model on a complete graph) to quantum mechanics. Using a natural probabilistic representation of this model, we give a complete picture of the phase diagram of the model in the parameters of inverse temperature and transverse field strength. Further analysis computes the critical exponent for the vanishing of the order parameter in the approach to the critical curve and gives useful stability properties for a variational problem associated with the representation. 相似文献
98.
We report that organic semiconductors such as alpha-sexithiophene (alpha-6T) have magnetoresistance (MR) with unexpected sign changes; depending on applied voltage, temperature, and layer thickness, the resistance may either increase or decrease upon application of a small magnetic field (<100 mT). We propose that MR and the inversion of MR are due to the role of hyperfine interaction in a magnetic field, as illustrated by the recombination-limited regime. 相似文献
99.
100.
Lincoln Wolfenstein 《Nuclear Physics B》1980,175(1):93-96
We develop the consequences of a model for neutrino oscillations due to Zee involving extra Higgs bosons. The model leads naturally to large amplitude oscillations. 相似文献