全文获取类型
收费全文 | 175篇 |
免费 | 2篇 |
国内免费 | 4篇 |
专业分类
化学 | 58篇 |
力学 | 4篇 |
数学 | 69篇 |
物理学 | 50篇 |
出版年
2021年 | 3篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 6篇 |
2014年 | 4篇 |
2013年 | 32篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 8篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 7篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1972年 | 1篇 |
1967年 | 1篇 |
1964年 | 1篇 |
1958年 | 1篇 |
1955年 | 2篇 |
1926年 | 1篇 |
排序方式: 共有181条查询结果,搜索用时 15 毫秒
41.
42.
We consider the CP-violating asymmetry betweenB
0f and
f in the case thatf is a CP-eigenstate containing no charmed quarks. The asymmetry is assumed to arise as a result of mixing with other channelsf having the same quantum numbers but containing ac
pair. Inelastic unitarity is implemented by means of the K-Matrix formalism, in which the constraints of CPT are manifestly satisfied. The formalism is applied to a hypothetical two-channel problemB
0M
,M
, and then to a realistic four-channel situationB
0
+
–,
0
0,D
+
D
–,D
0
0. Asymmetries and branching ratios are estimated for the decaysB
0
+
–,
0
0. 相似文献
43.
44.
Bimetallic Ag‐Pt Sub‐nanometer Supported Clusters as Highly Efficient and Robust Oxidation Catalysts 下载免费PDF全文
Dr. Fabio R. Negreiros Dr. Avik Halder Dr. Chunrong Yin Dr. Akansha Singh Dr. Giovanni Barcaro Dr. Luca Sementa Dr. Eric C. Tyo Dr. Michael J. Pellin Dr. Stephan Bartling Dr. Karl‐Heinz Meiwes‐Broer Dr. Sönke Seifert Dr. Prasenjit Sen Dr. Sandeep Nigam Dr. Chiranjib Majumder Dr. Nobuyuki Fukui Dr. Hisato Yasumatsu Dr. Stefan Vajda Dr. Alessandro Fortunelli 《Angewandte Chemie (International ed. in English)》2018,57(5):1209-1213
A combined experimental and theoretical investigation of Ag‐Pt sub‐nanometer clusters as heterogeneous catalysts in the CO→CO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size‐selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first‐principles simulations at realistic coverage. In situ GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano‐aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species. 相似文献
45.
46.
It is shown that in the sequential decay $H \to ZZ \to (f_1 \bar f_1 ) + (f_2 \bar f_2 )$ , the energy distribution of the final state particles provides a simple and powerful test of theHZZ vertex. For a standard Higgs boson, the energy spectrum of any final fermion, in the rest frame ofH, is predicted to be dΓ/dx~1+β4?2(x?1)2, with $\beta = \sqrt {1 - 4m_Z^2 /m_H^2 } $ and 1?β≤x=4E/m H ≤1+β. By contrast, the spectrum for a pseudoscalar Higgs is dΓ/dx~β2+(x?1)2. There are characteristic energy correlations betweenf 1 andf 2 and betweenf 1 andf 2. These considerations are applied to the “gold-plated” reactionH→ZZ→μ+μ?μ+μ?, including possible effects ofCP-violation in theHZZ coupling. Our formalism also yields the energy spectra and correlations of leptons in the decay $H \to W^ + W^ - \to l^ + v_l l^ - \bar v_l $ . 相似文献
47.
Antonio Giambruno Sudarshan Sehgal Angela Valenti 《Proceedings of the American Mathematical Society》1997,125(3):629-634
Let be the group algebra of a torsion group over an infinite field . Let be the group of units of . We prove that if satisfies a group identity, then satisfies a polynomial identity. This confirms a conjecture of Brian Hartley.
48.
Zbigniew S. Marciniak Sudarshan K. Sehgal 《Proceedings of the American Mathematical Society》1997,125(4):1005-1009
Let be an arbitrary group. It is proved that if contains a bicyclic unit , then is a nonabelian free subgroup of invertible elements.
49.
50.
Precipitation-redispersion of cerium oxide nanoparticles with poly(acrylic acid): toward stable dispersions 总被引:2,自引:0,他引:2
Sehgal A Lalatonne Y Berret JF Morvan M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(20):9359-9364
We exploit a precipitation-redispersion mechanism for complexation of short chain polyelectrolytes with cerium oxide nanoparticles to extend their stability ranges. As synthesized, cerium oxide sols at pH 1.4 consist of monodisperse cationic nanocrystalline particles having a hydrodynamic diameter of 10 nm and a molecular weight of 400 000 g mol(-1). We show that short chain uncharged poly(acrylic acid) at low pH when added to a cerium oxide sols leads to macroscopic precipitation. As the pH is increased, the solution spontaneously redisperses into a clear solution of single particles with an anionic poly(acrylic acid) corona. The structure and dynamics of cerium oxide nanosols and their hybrid polymer-inorganic complexes in solution are investigated by static and dynamic light scattering, X-ray scattering, and chemical analysis. Quantitative analysis of the redispersed sol gives rise to an estimate of 40-50 polymer chains per particle for stable suspension. This amount represents 20% of the mass of the polymer-nanoparticle complexes. This complexation adds utility to the otherwise unstable cerium oxide dispersions by extending the range of stability of the sols in terms of pH, ionic strength, and concentration. 相似文献