首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   416篇
  免费   8篇
  国内免费   44篇
化学   20篇
综合类   1篇
数学   401篇
物理学   46篇
  2024年   3篇
  2023年   11篇
  2022年   19篇
  2021年   10篇
  2020年   12篇
  2019年   11篇
  2018年   14篇
  2017年   10篇
  2016年   6篇
  2015年   10篇
  2014年   10篇
  2013年   45篇
  2012年   6篇
  2011年   17篇
  2010年   12篇
  2009年   24篇
  2008年   23篇
  2007年   19篇
  2006年   21篇
  2005年   15篇
  2004年   25篇
  2003年   26篇
  2002年   27篇
  2001年   24篇
  2000年   16篇
  1999年   14篇
  1998年   14篇
  1997年   13篇
  1996年   2篇
  1995年   3篇
  1994年   1篇
  1992年   1篇
  1989年   2篇
  1987年   1篇
  1982年   1篇
排序方式: 共有468条查询结果,搜索用时 15 毫秒
31.
We propose a conceptual framework that leads to an abstract characterization for the exact solvability of Calabi–Yau varieties in terms of abelian varieties with complex multiplication. The abelian manifolds are derived from the cohomology of the Calabi–Yau manifold, and the conformal field theoretic quantities of the underlying string emerge from the number theoretic structure induced on the varieties by the complex multiplication symmetry. The geometric structure that provides a conceptual interpretation of the relation between geometry and conformal field theory is discrete, and turns out to be given by the torsion points on the abelian varieties.  相似文献   
32.
We show that the Chern character of a variation of polarized Hodge structures of weight one with nilpotent residues at dies up to torsion in the Chow ring, except in codimension 0.  相似文献   
33.
Composition of tocochromanols in kernels recovered from 16 different apricot varieties (Prunus armeniaca L.) was studied. Three tocopherol (T) homologues, namely α, γ and δ, were quantified in all tested samples by an RP-HPLC/FLD method. The γ-T was the main tocopherol homologue identified in apricot kernels and constituted approximately 93% of total detected tocopherols. The RP-UPLC-ESI/MSn method detected trace amounts of two tocotrienol homologues α and γ in the apricot kernels. The concentration of individual tocopherol homologues in kernels of different apricots varieties, expressed in mg/100 g dwb, was in the following range: 1.38–4.41 (α-T), 42.48–73.27 (γ-T) and 0.77–2.09 (δ-T). Moreover, the ratio between individual tocopherol homologues α:γ:δ was nearly constant in all varieties and amounted to approximately 2:39:1.  相似文献   
34.
    
  相似文献   
35.
    
In PG(4,q2), q odd, let Q(4,q2) be a non‐singular quadric commuting with a non‐singular Hermitian variety H(4,q2). Then these varieties intersect in the set of points covered by the extended generators of a non‐singular quadric Q0 in a Baer subgeometry Σ0 of PG(4,q2). It is proved that any maximal partial ovoid of H(4,q2) intersecting Q0 in an ovoid has size at least 2(q2+1). Further, given an ovoid O of Q0, we construct maximal partial ovoids of H(4,q2) of size q3+1 whose set of points lies on the hyperbolic lines 〈P,X〉 where P is a fixed point of O and X varies in O{P}. © 2009 Wiley Periodicals, Inc. J Combin Designs 17: 307–313, 2009  相似文献   
36.
    
Toric manifolds, a topological generalization of smooth projective toric varieties, are determined by an -dimensional simple convex polytope and a function from the set of codimension-one faces into the primitive vectors of an integer lattice. Their cohomology was determined by Davis and Januszkiewicz in 1991 and corresponds with the theorem of Danilov-Jurkiewicz in the toric variety case. Recently it has been shown by Buchstaber and Ray that they generate the complex cobordism ring. We use the Adams spectral sequence to compute the -theory of all toric manifolds and certain singular toric varieties.

  相似文献   

37.
    
Let X be a smooth complex projective variety and let Z ? X be a smooth surface, which is the zero locus of a section of an ample vector bundle ? of rank dimX – 2 ≥ 2 on X. Let H be an ample line bundle on X, whose restriction H Z to Z is a very ample line bundle and assume that (Z, H Z ) is a Bordiga surface, i.e., a rational surface having (?2, ?? (4)) as its minimal adjunction theoretic reduction. Triplets (X, ?, H) as above are discussed and classified. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
38.
    
We will examine the arithmetic of some of the members of a pencil of symmetric quintics in projective 4‐space. We will give evidence for the modularity of some of the exceptional members (even the non‐rigid ones) and give a proof in one rigid case. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
39.
    
  相似文献   
40.
Norman R. Reilly 《代数通讯》2013,41(11):3624-3659
We study the lattice ?(RSn) of subvarieties of the variety of semigroups generated by completely 0-simple semigroups over groups with exponent dividing n, with a particular focus on the lattice ??(RSn) consisting of those varieties that are generated by completely 0-simple semigroups. The sublattice of ??(RSn) consisting of the aperiodic varieties is described and several endomorphisms of ?(RSn) considered. The complete congruence on ??(RSn) that relates varieties containing the same aperiodic completely 0-simple semigroups is considered in some detail.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号