全文获取类型
收费全文 | 650篇 |
免费 | 18篇 |
国内免费 | 65篇 |
专业分类
化学 | 24篇 |
晶体学 | 1篇 |
力学 | 3篇 |
综合类 | 9篇 |
数学 | 671篇 |
物理学 | 25篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 12篇 |
2021年 | 15篇 |
2020年 | 11篇 |
2019年 | 20篇 |
2018年 | 19篇 |
2017年 | 13篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 17篇 |
2013年 | 67篇 |
2012年 | 10篇 |
2011年 | 10篇 |
2010年 | 15篇 |
2009年 | 34篇 |
2008年 | 38篇 |
2007年 | 41篇 |
2006年 | 33篇 |
2005年 | 42篇 |
2004年 | 33篇 |
2003年 | 36篇 |
2002年 | 48篇 |
2001年 | 33篇 |
2000年 | 33篇 |
1999年 | 30篇 |
1998年 | 23篇 |
1997年 | 20篇 |
1996年 | 13篇 |
1995年 | 12篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 5篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有733条查询结果,搜索用时 0 毫秒
41.
Antonio Lanteri Roberto Muñ oz 《Transactions of the American Mathematical Society》2006,358(12):5565-5585
Let be a smooth complex projective variety, let be an ample and spanned line bundle on , defining a morphism and let be its discriminant locus, the variety parameterizing the singular elements of . We present two bounds on the dimension of and its main component relying on the geometry of . Classification results for triplets reaching the bounds as well as significant examples are provided.
42.
Z. Szylicka 《Algebra Universalis》1998,39(1-2):1-29
In the paper we present bases and hyperbases of hyperidentities of some generalizations of the variety L of all lattices and the variety D of distributive lattices. We describe the form of hyperidentities of some varieties with two binary operations.
Received January 22, 1997; accepted in final form January 7, 1998. 相似文献
43.
This is a continuation of the determination begun in K-Theory 10 (1996), 517–596, of explicit index reduction formulas for function fields of twisted flag varieties of adjoint semisimple algebraic groups. We give index reduction formulas for the varieties associated to the classical simple groups of outer type A
n-1 and D
n, and the exceptional simple groups of type E
6 and E
7. We also give formulas for the varieties associated to transfers and direct products of algebraic groups. This allows one to compute recursively the index reduction formulas for the twisted flag varieties of any semi-simple algebraic group. 相似文献
44.
In this paper, we determine the structures of the transfer ideal and its radical ideal for the ring of polynomials F p[x, y] under the action of dihedral group D2 p in the modular case. We mainly use Transfer variety, p order elements, and Hilbert’s Nullstellensatz Theorem. 相似文献
45.
The piecewise algebraic variety is the set of all common zeros of multivariate splines. We show that solving a parametric
piecewise algebraic variety amounts to solve a finite number of parametric polynomial systems containing strict inequalities.
With the regular decomposition of semi-algebraic systems and the partial cylindrical algebraic decomposition method, we give
a method to compute the supremum of the number of torsion-free real zeros of a given zero-dimensional parametric piecewise
algebraic variety, and to get distributions of the number of real zeros in every n-dimensional cell when the number reaches the supremum. This method also produces corresponding necessary and sufficient conditions
for reaching the supremum and its distributions. We also present an algorithm to produce a necessary and sufficient condition
for a given zero-dimensional parametric piecewise algebraic variety to have a given number of distinct torsion-free real zeros
in every n-cell in the n-complex.
This work was supported by National Natural Science Foundation of China (Grant Nos. 10271022, 60373093, 60533060), the Natural
Science Foundation of Zhejiang Province (Grant No. Y7080068) and the Foundation of Department of Education of Zhejiang Province
(Grant Nos. 20070628 and Y200802999) 相似文献
46.
Jørgen Bang‐Jensen Tilde My Christiansen Alessandro Maddaloni 《Journal of Graph Theory》2017,85(2):545-567
The k‐linkage problem is as follows: given a digraph and a collection of k terminal pairs such that all these vertices are distinct; decide whether D has a collection of vertex disjoint paths such that is from to for . A digraph is k‐linked if it has a k‐linkage for every choice of 2k distinct vertices and every choice of k pairs as above. The k‐linkage problem is NP‐complete already for [11] and there exists no function such that every ‐strong digraph has a k‐linkage for every choice of 2k distinct vertices of D [17]. Recently, Chudnovsky et al. [9] gave a polynomial algorithm for the k‐linkage problem for any fixed k in (a generalization of) semicomplete multipartite digraphs. In this article, we use their result as well as the classical polynomial algorithm for the case of acyclic digraphs by Fortune et al. [11] to develop polynomial algorithms for the k‐linkage problem in locally semicomplete digraphs and several classes of decomposable digraphs, including quasi‐transitive digraphs and directed cographs. We also prove that the necessary condition of being ‐strong is also sufficient for round‐decomposable digraphs to be k‐linked, obtaining thus a best possible bound that improves a previous one of . Finally we settle a conjecture from [3] by proving that every 5‐strong locally semicomplete digraph is 2‐linked. This bound is also best possible (already for tournaments) [1]. 相似文献
47.
We compute the Euler characteristics of the individual connectedcomponents of the intersection of two opposed big cells in thereal flag variety of type G2, verifying a conjecture of Rietsch[6]. 2000 Mathematical Subject Classification: primary 14M15; secondary20G20. 相似文献
48.
Shalom Eliahou Rafael H. Villarreal 《Proceedings of the American Mathematical Society》2002,130(2):345-351
Let be a toric set in the affine space . Given a set of binomials in the toric ideal of , we give a criterion for deciding the equality rad( ) = . This criterion extends to arbitrary dimension, and to arbitrary fields, an earlier result which concerned only monomial curves over an algebraically closed field of characteristic zero.
49.
Indranil Biswas 《Transactions of the American Mathematical Society》2002,354(10):3883-3891
Let be an ample line bundle over a complex abelian variety . We show that the space of all global sections over of and are both of dimension one. Using this it is shown that the moduli space of rank one holomorphic connections on a compact Riemann surface does not admit any nonconstant algebraic function. On the other hand, is biholomorphic to the moduli space of characters of , which is an affine variety. So is algebraically distinct from the character variety if is of genus at least one.
50.