全文获取类型
收费全文 | 341篇 |
免费 | 17篇 |
国内免费 | 49篇 |
专业分类
化学 | 155篇 |
力学 | 2篇 |
综合类 | 1篇 |
数学 | 6篇 |
物理学 | 243篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 7篇 |
2015年 | 7篇 |
2014年 | 9篇 |
2013年 | 20篇 |
2012年 | 16篇 |
2011年 | 25篇 |
2010年 | 37篇 |
2009年 | 18篇 |
2008年 | 25篇 |
2007年 | 17篇 |
2006年 | 21篇 |
2005年 | 9篇 |
2004年 | 24篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 20篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 12篇 |
1996年 | 6篇 |
1995年 | 8篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1988年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有407条查询结果,搜索用时 15 毫秒
381.
Hiroyuki Komatsu Bungo Ochiai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2008,46(11):3673-3681
This article describes the synthesis of and catalysis with a polymeric catalyst (Zn/ 1NHCOO ) carrying salen‐zinc complex structure in the main chain prepared from polyaddition of zinc/bis(4‐hydroxy)salicylidene‐1,2‐diiminoethane and 4,4′‐diphenylmethane diisocyanate. Poly(Zn/ 1NHCOO ) promoted the reaction of glycidyl phenyl ether (2) with 1‐propoxyethyl‐2‐ethylhexanoate (3) only at moderately elevated temperatures. Poly(Zn/ 1NHCOO ) can be recycled by simple filtration from the reaction mixtures, and the recycled polymer is as active as the freshly prepared one. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3673–3681, 2008 相似文献
382.
The democracy of quark flavors is a well-motivated flavor symmetry,but it must be properly broken in order to explain the observed quark mass spectrum and flavor mixing pattern.We reconstruct the texture of flavor democracy breaking and evaluate its strength in a novel way,by assuming a parallelism between the Q = +2/3 and Q =-1/3 quark sectors and using a nontrivial parametrization of the flavor mixing matrix.Some phenomenological implications of such democratic quark mass matrices,including their variations in the hierarchy basis and their evolution from the electroweak scale to a super-high energy scale,are also discussed. 相似文献
383.
All the possible CP-conserving non-linear operators up to the p4-order in the Lagrangian expansion are analysed here for the left-right symmetric model in the non-linear electroweak chiral context coupled to a light dynamical Higgs. The low energy effects will be triggered by an emerging new physics field content in the nature, more specifically, from spin-1 resonances sourced by the straightforward extension of the SM local gauge symmetry to the larger local group SU(2)L×SU(2)R×U(1)B-L. Low energy phenomenology will be altered by integrating out the resonances from the physical spectrum, being manifested through induced corrections onto the left handed operators. Such modifications are weighted by powers of the scales ratio implied by the symmetries of the model and will determine the size of the effective operator basis to be used. The recently observed diboson excess around the invariant mass 1.8 TeV-2 TeV entails a scale suppression that suggests to encode the low energy effects via a much smaller set of effective operators. 相似文献
384.
G.C. Branco D. Emmanuel-Costa R. Gonzlez Felipe H. Serdio 《Physics letters. [Part B]》2009,670(4-5):340-349
We investigate the physical meaning of some of the texture zeros which appear in most of the ansatzes on leptonic masses and their mixing. It is shown that starting from arbitrary lepton mass matrices and making suitable weak basis transformations one can obtain some of these sets of zeros, which therefore have no physical content. We then analyse four-zero texture ansatzes where the charged lepton and neutrino mass matrices have the same structure. The four texture zeros cannot be obtained simultaneously through weak basis transformations, so these ansatzes do have physical content. We show that they can be separated into four classes and study the physical implications of each class. 相似文献
385.
Motivated by the possibility of the formation of CP-odd domains in heavy ion collisions, we investigate the effects of CP violation on the chiral transition within the linear sigma model with two flavors of quarks. We also study how the CP-odd system is affected by the presence of a strong magnetic field, that is presumably generated in a non-central heavy ion collision. We find that both ingredients play an important role, influencing drastically the nature of the phase transition and the critical temperature. 相似文献
386.
A left-right symmetric model with two Higgs bi-doublet is shown to be a consistent model for both spontaneous P and CP violation.
The flavor changing neutral currents can be suppressed by the mechanism of approximate global U(1) family symmetry. The constraints from neural K meson mass difference Δm
K
are calculated and it is demonstrated that a right-handed gauge boson W
2 contribution in box-diagrams with mass well below 1 TeV is allowed due to a cancelation caused by a light-charged Higgs boson
with a mass range of 150–300 GeV. The W
2 contribution to ε
K
can be suppressed from an appropriate choice of additional CP phases appearing in the right-handed Cabbibo-Kobayashi-Maskawa
matrix. The model is also found to be fully consistent with B
0 mass difference Δm
B
and the mixing induced CP violation sin2β
J/ Ψ, which is usually difficult for the model with only one Higgs bi-doublet. The new physics beyond the standard model can be
directly searched at the colliders LHC and ILC.
Supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 10475105 and 10491306) and the Key Project
of Chinese Academy of Sciences (CAS) 相似文献
387.
388.
算符a^K本征态热迭加光场的光子数统计分布 总被引:1,自引:0,他引:1
利用密度矩阵方法,导出了光子湮没算符高次幂a^K(k≥2)本征态热迭加光场光子数统计分布的一般表达式,讨论了热噪声对非经典光场态光数统计分布振荡行为的影响。 相似文献
390.
Changqing XU 《Frontiers of Mathematics in China》2021,16(4):1099
The Fourier matrix is fundamental in discrete Fourier transforms and fast Fourier transforms. We generalize the Fourier matrix, extend the concept of Fourier matrix to higher order Fourier tensor, present the spectrum of the Fourier tensors, and use the Fourier tensor to simplify the high order Fourier analysis. 相似文献