全文获取类型
收费全文 | 17554篇 |
免费 | 420篇 |
国内免费 | 123篇 |
专业分类
化学 | 12001篇 |
晶体学 | 98篇 |
力学 | 330篇 |
数学 | 2921篇 |
物理学 | 2085篇 |
综合类 | 662篇 |
出版年
2022年 | 86篇 |
2021年 | 145篇 |
2020年 | 167篇 |
2019年 | 169篇 |
2018年 | 136篇 |
2017年 | 130篇 |
2016年 | 281篇 |
2015年 | 304篇 |
2014年 | 314篇 |
2013年 | 718篇 |
2012年 | 794篇 |
2011年 | 1027篇 |
2010年 | 505篇 |
2009年 | 422篇 |
2008年 | 924篇 |
2007年 | 963篇 |
2006年 | 982篇 |
2005年 | 1050篇 |
2004年 | 931篇 |
2003年 | 772篇 |
2002年 | 685篇 |
2001年 | 210篇 |
2000年 | 203篇 |
1999年 | 174篇 |
1998年 | 168篇 |
1997年 | 216篇 |
1996年 | 271篇 |
1995年 | 180篇 |
1994年 | 176篇 |
1993年 | 166篇 |
1992年 | 167篇 |
1991年 | 154篇 |
1990年 | 150篇 |
1989年 | 134篇 |
1988年 | 146篇 |
1987年 | 155篇 |
1986年 | 121篇 |
1985年 | 268篇 |
1984年 | 241篇 |
1983年 | 184篇 |
1982年 | 254篇 |
1981年 | 208篇 |
1980年 | 264篇 |
1979年 | 231篇 |
1978年 | 235篇 |
1977年 | 244篇 |
1976年 | 206篇 |
1975年 | 167篇 |
1974年 | 160篇 |
1973年 | 154篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Richard P. Stanley 《Israel Journal of Mathematics》2004,143(1):317-339
We survey three recent developments in algebraic combinatorics. The first is the theory of cluster algebras and the Laurent
phenomenon of Sergey Fomin and Andrei Zelevinsky. The second is the construction of toric Schur functions and their application
to computing three-point Gromov-Witten invariants, by Alexander Postnikov. The third development is the construction of intersection
cohomology for nonrational fans by Paul Bressler and Valery Lunts and its application by Kalle Karu to the torich-vector of a nonrational polytope. We also briefly discuss the “half hard Lefschetz theorem” of Ed Swartz and its application
to matroid complexes.
Partially supported by NSF grant #DMS-9988459. 相似文献
73.
We present a linear rational pseudospectral (collocation) method with preassigned poles for solving boundary value problems. It consists in attaching poles to the trial polynomial so as to make it a rational interpolant. Its convergence is proved by transforming the problem into an associated boundary value problem. Numerical examples demonstrate that the rational pseudospectral method is often more efficient than the polynomial method. 相似文献
74.
Richard Arratia Bla Bollobs Gregory B. Sorkin 《Journal of Combinatorial Theory, Series B》2004,92(2):199-233
Motivated by circle graphs, and the enumeration of Euler circuits, we define a one-variable “interlace polynomial” for any graph. The polynomial satisfies a beautiful and unexpected reduction relation, quite different from the cut and fuse reduction characterizing the Tutte polynomial.It emerges that the interlace graph polynomial may be viewed as a special case of the Martin polynomial of an isotropic system, which underlies its connections with the circuit partition polynomial and the Kauffman brackets of a link diagram. The graph polynomial, in addition to being perhaps more broadly accessible than the Martin polynomial for isotropic systems, also has a two-variable generalization that is unknown for the Martin polynomial. We consider extremal properties of the interlace polynomial, its values for various special graphs, and evaluations which relate to basic graph properties such as the component and independence numbers. 相似文献
75.
The use of reagent concentration has resulted in increased rates for all stages of the REM resin synthesis of tertiary amines. These increases in rate translate into faster reaction times, higher yields and lower reagent consumption. Of the methods examined, the most successful was the use of perfluorous solvents, either alone or with a small amount of organic co-solvent. 相似文献
76.
Richard P. Kent IV 《Geometriae Dedicata》2004,106(1):145-159
We answer a question of J. Anderson's by producing infinitely many commensurability classes of fibered hyperbolic 3-manifolds whose fundamental groups contain subgroups that are locally free and not free. These manifolds are obtained by performing 0–surgery on a collection of knots with the same properties. 相似文献
77.
We study the stability and the properties of the ground state of neutral systems containing up to four positively charged
bosons and their antiparticles. Examples are the di-pionium molecule (π
+
π
−)2, which is almost identical to the positronium molecule (e
+
e
−)2, the tri-pionium (π
+
π
−)3, and the quadri-pionium (π
+
π
−)4 molecules. We briefly compare our results on the energy to those on the large-N limit of (π
+
π
−)
N
. We also show that the annihilation probability can be calculated accurately with simple wave functions when one uses the
generalized Schwinger rule.
Received September 5, 1994; accepted for publication October 15, 1994 相似文献
78.
79.
Richard Valenta 《Czechoslovak Journal of Physics》1998,48(9):1035-1048
The purpose of this paper is to solve the coupled non-homogeneous equations derived from the basic classical theory of the
acoustic propagation in visco-thermal fluid. The 1D radial distribution of pressure and temperature inside a spherical object
was found. It is supposed that both acoustic and thermal conditions on a surface of the object are known. The starting equations
are considered in the time domain and their solution was found without initial conditions for steady harmonic motion. 相似文献
80.