全文获取类型
收费全文 | 3229篇 |
免费 | 104篇 |
国内免费 | 12篇 |
专业分类
化学 | 2098篇 |
晶体学 | 17篇 |
力学 | 125篇 |
数学 | 451篇 |
物理学 | 654篇 |
出版年
2023年 | 29篇 |
2022年 | 35篇 |
2021年 | 68篇 |
2020年 | 63篇 |
2019年 | 67篇 |
2018年 | 49篇 |
2017年 | 30篇 |
2016年 | 86篇 |
2015年 | 74篇 |
2014年 | 78篇 |
2013年 | 123篇 |
2012年 | 180篇 |
2011年 | 213篇 |
2010年 | 109篇 |
2009年 | 89篇 |
2008年 | 185篇 |
2007年 | 178篇 |
2006年 | 199篇 |
2005年 | 168篇 |
2004年 | 91篇 |
2003年 | 96篇 |
2002年 | 72篇 |
2001年 | 58篇 |
2000年 | 41篇 |
1999年 | 29篇 |
1998年 | 37篇 |
1997年 | 36篇 |
1996年 | 35篇 |
1995年 | 32篇 |
1994年 | 24篇 |
1993年 | 35篇 |
1992年 | 32篇 |
1991年 | 25篇 |
1990年 | 22篇 |
1989年 | 23篇 |
1988年 | 21篇 |
1987年 | 26篇 |
1986年 | 29篇 |
1985年 | 31篇 |
1984年 | 36篇 |
1983年 | 29篇 |
1982年 | 34篇 |
1981年 | 43篇 |
1980年 | 38篇 |
1979年 | 17篇 |
1978年 | 35篇 |
1977年 | 33篇 |
1976年 | 36篇 |
1975年 | 25篇 |
1974年 | 19篇 |
排序方式: 共有3345条查询结果,搜索用时 15 毫秒
1.
Jacob Schach Møller 《Annales Henri Poincare》2005,6(6):1091-1135
In this paper we analyze the bottom of the energy-momentum spectrum of the translation invariant Nelson model, describing
one electron linearly coupled to a second quantized massive scalar field. Our results are valid for all values of the coupling
constant and include an HVZ theorem, non-degeneracy of ground states, existence of isolated groundstates in dimensions 1 and
2, non-existence of ground states embedded in the bottom of the essential spectrum in dimensions 3 and 4, (i.e., at total
momenta where no isolated groundstate eigenvalue exists), and we study regularity and monotonicity properties of the bottom
of the essential spectrum, as a function of total momentum.
Communicated by Joel Feldman
submitted 04/11/04, accepted 17/02/05 相似文献
2.
The periodic precipitation pattern formation in gelatinous media is interpreted as a moving boundary problem. The time law,
spacing law and width law are revisited on the basis of the new scenario. The explicit dependence of the geometric structure
on the initial concentrations of the reactants is derived. Matalon—Packter law, which relates the spacing coefficient with
the initial concentrations is reformulated removing many ambiguities and impractical parameters. Experimental results are
discussed to establish the significance of moving boundary concept in the diffusion controlled pattern forming systems 相似文献
3.
4.
Two bases of states are presented for modules of the graded parafermionic conformal field theory associated to the coset
. The first one is formulated in terms of the two fundamental (i.e., lowest-dimensional) parafermionic modes. In that basis, one can identify the completely reducible representations, i.e., those whose modules contain an infinite number of singular vectors; the explicit form of these vectors is also given. The second basis is a quasiparticle basis, determined in terms of a modified version of the
exclusion principle. A novel feature of this model is that none of its bases are fully ordered and this reflects a hidden structural
exclusion principle. 相似文献
5.
We consider the semilinear Cauchy problem for a class of pseudo-differential operators generating sub-Markovian semigroups.
Solutions of such problems with negative definite nonlinearity play an important role in constructing branching measure-valued
processes. We establish local existence and uniqueness of solutions in the context of the Dirichlet space associated to the
problem. Comparison and global properties of solutions are also studied.
Accepted 29 August 2001. Online publication 17 December 2001. 相似文献
6.
Marilyn M. Olmstead James C. Fettinger Soya Gamsey Jacob W. Clary Bakthan Singaram 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(6):o333-o335
The structures of three chiral vinyldioxazaborocanes are reported, namely (2E)‐ and (2Z)‐6‐benzyl‐2‐buten‐2‐yl‐1,3,6,2‐dioxazaborocane, C27H30BNO2, (II) and (III), respectively, and (2Z)‐2‐buten‐2‐yl‐6‐isobutyl‐1,3,6,2‐dioxazaborocane, C24H32BNO2, (IV). These compounds may be useful in asymmetric reactions. In the structures reported here, the N—B donor–acceptor bond is longer than in any previously reported analogous compounds. 相似文献
7.
Jacob S. Ishay Anna Sverdlov Vitaly Pertsis Yulla Gavrilov David Steinberg 《Photochemistry and photobiology》2004,80(1):115-118
In the cuticle of live social hornets, such as Vespa orientalis (Hymenoptera, Vespinae), endogenous electric effects are encountered, i.e. voltages of 100–200 mV under illumination and currents amounting to several microamperes on its subjection to darkness—clearly a process of charging and discharging. Of the various wavelengths of sunlight, UV was found to be the most contributory to the active cuticular voltage generation. Throughout the warm season of the yearthe–the active period in colonies of social hornets and wasps—colony members exit from the dark nest during the daytime and fly to the field under the hot sun for various foraging purposes, ultimately returning to the nest. Thus, each hornet, be it queen, worker or drone, probably undergoes daily cyclical process of electric charge and discharge in the exterior part of their integument, cuticle, which lasts up to 30–40 min. Such photoelectric phenomenon was detected in both live, ether‐anaesthetized hornets and dead hornets, albeit in the latter the electric values recorded were lower. The present study addresses the possible impact of the phenomenon on vespan daily life and also compares it with a parallel occurrence in electric fish. 相似文献
8.
9.
10.
A Contribution on Ternary Oxides of the AMO4-Type (A = Ti3+, Cr3+; M = Nb5+, Ta5+ ) CrNbO4, CrTaO4, TiNbO4, and TiTaO4 were prepared by CO2-laser technique. X-ray single crystal investigations show a random distribution of the metal ions in Rutil type structure, space group D–P42/mnm. Calculations of the free energy of reaction between Ti2O3 and Nb2O5 show higher stability of TiO2 beside NbO2. In TiNbO4 both metals exhibit the oxidation state +4. 相似文献