全文获取类型
收费全文 | 3267篇 |
免费 | 95篇 |
国内免费 | 17篇 |
专业分类
化学 | 2054篇 |
晶体学 | 20篇 |
力学 | 128篇 |
数学 | 457篇 |
物理学 | 720篇 |
出版年
2023年 | 29篇 |
2022年 | 34篇 |
2021年 | 58篇 |
2020年 | 70篇 |
2019年 | 67篇 |
2018年 | 48篇 |
2017年 | 36篇 |
2016年 | 81篇 |
2015年 | 68篇 |
2014年 | 69篇 |
2013年 | 145篇 |
2012年 | 185篇 |
2011年 | 200篇 |
2010年 | 105篇 |
2009年 | 89篇 |
2008年 | 171篇 |
2007年 | 173篇 |
2006年 | 168篇 |
2005年 | 144篇 |
2004年 | 88篇 |
2003年 | 87篇 |
2002年 | 67篇 |
2001年 | 52篇 |
2000年 | 43篇 |
1999年 | 35篇 |
1998年 | 41篇 |
1997年 | 36篇 |
1996年 | 37篇 |
1995年 | 32篇 |
1994年 | 38篇 |
1993年 | 44篇 |
1992年 | 44篇 |
1991年 | 32篇 |
1990年 | 33篇 |
1989年 | 30篇 |
1988年 | 26篇 |
1986年 | 32篇 |
1985年 | 24篇 |
1984年 | 39篇 |
1983年 | 29篇 |
1982年 | 38篇 |
1981年 | 43篇 |
1980年 | 48篇 |
1979年 | 29篇 |
1978年 | 33篇 |
1977年 | 42篇 |
1976年 | 35篇 |
1975年 | 32篇 |
1974年 | 25篇 |
1973年 | 28篇 |
排序方式: 共有3379条查询结果,搜索用时 0 毫秒
1.
A set of exact conditions is compiled for the purpose of developing and testing approximations for the exchange-correlation energy as a functional of the electron density. Special emphasis is placed upon recently developed density-scaling relationships. Commonly used generalized gradient approximations are compared against several of these conditions. A direct tabular comparison of these functionals (not of calculated properties) with one another is also made. © 1994 John Wiley & Sons, Inc. 相似文献
2.
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
3.
Let G be a finite group. A complete Sylow product of G is a product of Sylow subgroups of G, one for each prime divisor of |G|. We shall call G a Sylow factorizable group if it is equal to at least one of its complete Sylow products. We prove that if G is a Sylow factorizable group then the
intersection of all complete Sylow products of G is equal to the solvable radical of G. We generalize the concepts and the result to Sylow products which involve an arbitrary subset of the prime divisors of |G|.
Received: 26 January 2005 相似文献
4.
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
5.
6.
7.
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
8.
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
9.
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
10.
Alick KT Law Deepak Gupta Shawn Levy Douglas C Wallace Robert J McKeon Charles R Buck 《BMC neuroscience》2004,5(1):1