全文获取类型
收费全文 | 443195篇 |
免费 | 6323篇 |
国内免费 | 1808篇 |
专业分类
化学 | 236733篇 |
晶体学 | 5944篇 |
力学 | 19128篇 |
综合类 | 20篇 |
数学 | 59006篇 |
物理学 | 130495篇 |
出版年
2021年 | 2789篇 |
2020年 | 3253篇 |
2019年 | 3549篇 |
2018年 | 5987篇 |
2017年 | 6026篇 |
2016年 | 7784篇 |
2015年 | 5898篇 |
2014年 | 7494篇 |
2013年 | 20406篇 |
2012年 | 18716篇 |
2011年 | 21203篇 |
2010年 | 13537篇 |
2009年 | 13204篇 |
2008年 | 17598篇 |
2007年 | 17748篇 |
2006年 | 16444篇 |
2005年 | 20053篇 |
2004年 | 17993篇 |
2003年 | 14308篇 |
2002年 | 11660篇 |
2001年 | 12334篇 |
2000年 | 9426篇 |
1999年 | 7361篇 |
1998年 | 5987篇 |
1997年 | 5880篇 |
1996年 | 5697篇 |
1995年 | 5172篇 |
1994年 | 4936篇 |
1993年 | 4910篇 |
1992年 | 5458篇 |
1991年 | 5424篇 |
1990年 | 5023篇 |
1989年 | 4969篇 |
1988年 | 4956篇 |
1987年 | 4761篇 |
1986年 | 4505篇 |
1985年 | 6452篇 |
1984年 | 6530篇 |
1983年 | 5318篇 |
1982年 | 5817篇 |
1981年 | 5593篇 |
1980年 | 5416篇 |
1979年 | 5448篇 |
1978年 | 5679篇 |
1977年 | 5439篇 |
1976年 | 5696篇 |
1975年 | 5215篇 |
1974年 | 5272篇 |
1973年 | 5517篇 |
1972年 | 3328篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
941.
The Laplacian and Dirac operators on critical planar graphs 总被引:6,自引:0,他引:6
R. Kenyon 《Inventiones Mathematicae》2002,150(2):409-439
On a periodic planar graph whose edge weights satisfy a certain simple geometric condition, the discrete Laplacian and Dirac
operators have the property that their determinants and inverses only depend on the local geometry of the graph. We obtain
explicit expressions for the logarithms of the (normalized) determinants, as well as the inverses of these operators. We relate
the logarithm of the determinants to the volume plus mean curvature of an associated hyperbolic ideal polyhedron. In the associated
dimer and spanning tree models, for which the determinants of the Dirac operator and the Laplacian respectively play the role
of the partition function, this allows us to compute the entropy and correlations in terms of the local geometry. In addition,
we define a continuous family of special discrete holomorphic functions which, via convolutions, gives a general process for
constructing discrete holomorphic functions and discrete harmonic functions on critical planar graphs.
Oblatum 6-III-2002 & 12-VI-2002?Published online: 6 August 2002 相似文献
942.
A datalogger was developed to identify vocalizing dolphins within socially interacting captive groups. Every 50 ms the logger stores data on the level and frequency of detected sound. Dataloggers are temporarily attached to dolphins by suction cups for data collection sessions lasting up to 45 min. Later, computer analysis of data from the dataloggers reveals which dolphin produced each vocalization recorded during the session. Results from use of dataloggers with two captive bottlenose dolphins (Tursiops truncatus) at the New England Aquarium in Boston, MA are presented. The possible use of dataloggers with wild dolphins is discussed. 相似文献
943.
The classical (first integral) methods of studying restrictions on the possible motion of gravitationally interacting bodies are reviewed. The simple and flexible inequality method is extended to a similar approach to the relationship between possible forbidden motion and (asymptotic) symmetries in the relativistic few-body problem. This extended method is used to reproduce the standard results of bounded motion for a test particle in a Schwarzschild geometry. The existence of bounded motion is shown for the general relativistic few-body problem and the difficulties in determining such bounded motion is analysed. The use of this approach to obtaining a relativistic alternative to the classical Roche lobe analysis in contact binaries is discussed. 相似文献
944.
Pál Sohár Gábor Bernáth Géza Stájer Angela E. Szabo 《Magnetic resonance in chemistry : MRC》1989,27(9):872-876
Pentacyclic isoxazolines were obtained by the cycloaddition of benzonitrile oxide to norbornene-azetidinone-fused 3,1-oxazines. The constitutions of two of the isomers obtained, and the configurations and conformations of all products, were determined by means of 1H and 13C NMR spectroscopy and DNOE experiments. 相似文献
945.
946.
Myron B. Allen Mark C. Curran 《Numerical Methods for Partial Differential Equations》1989,5(2):121-132
An adaptive grid refinement procedure allows accurate solutions to advection-dominated, time-dependent flows using finite-element collocation. The technique relies on a data structure that is readily amenable to parallel computing. The paper discusses computational aspects of the method. 相似文献
947.
Using the symbolic computation program MAPLE, we compute several terms of an asymptotic expansion for the distribution function of the logistic midrange. 相似文献
948.
949.
950.