全文获取类型
收费全文 | 869篇 |
免费 | 11篇 |
国内免费 | 3篇 |
专业分类
化学 | 582篇 |
晶体学 | 9篇 |
力学 | 17篇 |
数学 | 167篇 |
物理学 | 108篇 |
出版年
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2018年 | 9篇 |
2016年 | 15篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 54篇 |
2012年 | 29篇 |
2011年 | 29篇 |
2010年 | 11篇 |
2009年 | 8篇 |
2008年 | 20篇 |
2007年 | 29篇 |
2006年 | 28篇 |
2005年 | 29篇 |
2004年 | 24篇 |
2003年 | 38篇 |
2002年 | 26篇 |
2000年 | 6篇 |
1998年 | 6篇 |
1997年 | 19篇 |
1996年 | 6篇 |
1995年 | 10篇 |
1993年 | 10篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1985年 | 18篇 |
1984年 | 30篇 |
1983年 | 16篇 |
1982年 | 18篇 |
1981年 | 24篇 |
1980年 | 22篇 |
1979年 | 13篇 |
1978年 | 22篇 |
1977年 | 22篇 |
1976年 | 14篇 |
1975年 | 13篇 |
1974年 | 13篇 |
1973年 | 40篇 |
1972年 | 7篇 |
1971年 | 5篇 |
1970年 | 8篇 |
1969年 | 7篇 |
1968年 | 8篇 |
1934年 | 9篇 |
排序方式: 共有883条查询结果,搜索用时 15 毫秒
61.
C-Glycosyl amino acids represent stable mimics of monomeric units within natural O-linked glycoproteins. Olefin cross-metathesis has been used to provide alkene precursors for a mercury(II)-mediated cyclization, yielding alpha-C-glucosyl serine and alanine. 相似文献
62.
63.
We give an elementary proof of a critical lemma of Arjeh Cohen used in his fundamental paper giving an axiomatic characterization
of Grassmann spaces of finite singular rank. 相似文献
64.
Bogdan Constantinescu Angela Vasilescu Martin Radtke Uwe Reinholz Claire Pacheco Laurent Pichon Ernest Oberländer-Târnoveanu 《Applied Physics A: Materials Science & Processing》2012,109(2):395-402
A thorough microscopic investigation by SR XRF and micro-PIXE brings insight into the probable techniques used in the manufacture of thirteen Dacian gold bracelets, one of the most spectacular archaeological finds ever on the territory of Romania. 相似文献
65.
66.
Formation of two unknown, tricyclic trimers of diketene, 3 and 4 , was observed in diketene solutions containing (CH3)3SiCl/NaI or TsOH. 相似文献
67.
It is known that the exact density functional must give ground-state energies that are piecewise linear as a function of electron number. In this work we prove that this is also true for the lowest-energy excited states of different spin or spatial symmetry. This has three important consequences for chemical applications: the ground state of a molecule must correspond to the state with the maximum highest-occupied-molecular-orbital energy, minimum lowest-unoccupied-molecular-orbital energy, and maximum chemical hardness. The beryllium, carbon, and vanadium atoms, as well as the CH(2) and C(3)H(3) molecules are considered as illustrative examples. Our result also directly and rigorously connects the ionization potential and electron affinity to the stability of spin states. 相似文献
68.
More often than not, models of flavor symmetry rely on the use of nonrenormalizable operators (in the guise of flavons) to accomplish the phenomenologically successful tribimaximal mixing of neutrinos. We show instead how a simple renormalizable two-parameter neutrino mass model of tribimaximal mixing can be constructed with the non-Abelian discrete symmetry T(7) and the gauging of B-L. This is also achieved without the addition of auxiliary symmetries and particles present in almost all other proposals. Most importantly, it is verifiable at the Large Hadron Collider. 相似文献
69.
We present theorems which provide the existence of invariant whiskered tori in finite-dimensional exact symplectic maps and flows. The method is based on the study of a functional equation expressing that there is an invariant torus.We show that, given an approximate solution of the invariance equation which satisfies some non-degeneracy conditions, there is a true solution nearby. We call this an a posteriori approach.The proof of the main theorems is based on an iterative method to solve the functional equation.The theorems do not assume that the system is close to integrable nor that it is written in action-angle variables (hence we can deal in a unified way with primary and secondary tori). It also does not assume that the hyperbolic bundles are trivial and much less that the hyperbolic motion can be reduced to constant linear map.The a posteriori formulation allows us to justify approximate solutions produced by many non-rigorous methods (e.g. formal series expansions, numerical methods). The iterative method is not based on transformation theory, but rather on successive corrections. This makes it possible to adapt the method almost verbatim to several infinite-dimensional situations, which we will discuss in a forthcoming paper. We also note that the method leads to fast and efficient algorithms. We plan to develop these improvements in forthcoming papers. 相似文献
70.
Debajyoti Choudhury Saurabh D. Rindani B. Ananthanarayan K. R. S. Balaji Debajyoti Choudhury Manuel Drees Shashikant Dugad Gautam Dutta Sukanta Dutta Naveen Gaur Ambar Ghosal Walter Grimus Ernest Ma Shubhendra Mohanty P. N. Pandita M. K. Parida Subhendu Rakshit Saurabh D. Rindani D. P. Roy Probir Roy Sarira Sahu N. N. Singh Sudhir K. Vempati Francesco Vissani 《Pramana》1998,51(1-2):305-311
This report summarises the activities of the working group on ‘Physics beyond the Standard Model’. The results of investigations
in incorporatingR-parity in grand unification, the possibility of a light charged Higgs boson in extension of MSSM and radiative generation
of neutral vector boson self-couplings within the MSSM are described. Also given is an account of activities in neutrino physics,
namely a proposal for a study of the atmospheric muon anomaly in deep underground mines, a field theoretic study of neutrino
oscillations and a mechanism to generate appropriate masses of three active plus one sterile neutrino species. 相似文献