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   286篇
  免费   23篇
  国内免费   23篇
化学   79篇
晶体学   5篇
力学   45篇
综合类   5篇
数学   144篇
物理学   54篇
  2024年   1篇
  2023年   3篇
  2022年   11篇
  2021年   5篇
  2020年   14篇
  2019年   10篇
  2018年   5篇
  2017年   8篇
  2016年   10篇
  2015年   9篇
  2014年   15篇
  2013年   27篇
  2012年   14篇
  2011年   18篇
  2010年   10篇
  2009年   15篇
  2008年   20篇
  2007年   14篇
  2006年   16篇
  2005年   14篇
  2004年   14篇
  2003年   15篇
  2002年   8篇
  2001年   4篇
  2000年   9篇
  1999年   8篇
  1998年   5篇
  1997年   4篇
  1996年   2篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   5篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1985年   2篇
  1982年   2篇
  1967年   1篇
排序方式: 共有332条查询结果,搜索用时 15 毫秒
41.
Crossing by lines all edges of a line arrangement   总被引:1,自引:0,他引:1  
  相似文献   
42.
The conjecture of Bahri, Bendersky, Cohen and Gitler (2010)  [3] on wedge decompositions of polyhedral products of shifted complexes is settled affirmatively. As a corollary, it is proved that the homotopy type of the complement of a coordinate subspace arrangement associated with a shifted complex, tensored with RrRr for any r≥1r1, has the homotopy type of a wedge of spheres.  相似文献   
43.
特定性能的类周期电磁金属阵列已成功应用于多种类型的电磁器件中,以实现其电磁辐射或散射性能的提升设计.类周期电磁金属阵列可描述为由多个相似形状的电磁金属单元按照特定的布局形式组合形成.布局形式由阵列的布局参数确定,通常包括每个单元的尺寸、转角以及位置参数.布局参数往往规模较大且相互独立,需要经过设计优化以满足阵列的性能要...  相似文献   
44.
45.
46.
《Discrete Mathematics》2019,342(1):233-249
A Weyl arrangement is the hyperplane arrangement defined by a root system. Saito proved that every Weyl arrangement is free. The Weyl subarrangements of type A are represented by simple graphs. Stanley gave a characterization of freeness for this type of arrangements in terms of their graph. In addition, the Weyl subarrangements of type B can be represented by signed graphs. A characterization of freeness for them is not known. However, characterizations of freeness for a few restricted classes are known. For instance, Edelman and Reiner characterized the freeness of the arrangements between type A1 and type B. In this paper, we give a characterization of the freeness and supersolvability of the Weyl subarrangements of type B under certain assumption.  相似文献   
47.
The Blueline Rasbora (Rasbora sarawakensis) is a small ray-finned fish categorized under the genus Rasbora in the Cyprinidae family. In this study, the complete mitogenome sequence of R. sarawakensis was sequenced using four primers targeting overlapping regions. The mitogenome is 16,709 bp in size, accommodating 22 transfer RNA genes, 13 protein-coding genes, two ribosomal RNA genes and a putative control region. Identical gene organisation was detected between this species and other genus counterparts. The heavy strand houses 28 genes while the light strand stores the other nine genes. Most protein-coding genes employ ATG as start codon, excluding COI gene, which utilizes GTG instead. The central conserved sequence blocks (CSB-F, CSB-E and CSB-D), variable sequence blocks (CSB-3, CSB-2 and CSB-1) as well as the terminal associated sequence (TAS) are conserved in the control region. The maximum likelihood phylogenetic tree revealed the divergence of R. sarawakensis from the basal region of the Rasbora clade, where its evolutionary relationships with R. maculatus and R. pauciperforata are poorly resolved as indicated by the low bootstrap values. This work acts as steppingstone towards further molecular evolution and population genetics studies of Rasbora genus in future.  相似文献   
48.
We report, for the first time, a detailed crystallographic study of the supramolecular arrangement for a set of zinc(II) Schiff base complexes containing the ligand 2,6-bis((E)-((2-(dimethylamino)ethyl)imino)methyl)-4-R-phenol], where R=methyl/tert-butyl/chloro. The supramolecular study acts as a pre-screening tool for selecting the compartmental ligand R of the Schiff base for effective binding with a targeted protein, bovine serum albumin (BSA). The most stable hexagonal arrangement of the complex [Zn − Me] (R=Me) stabilises the ligand with the highest FMO energy gap (ΔE=4.22 eV) and lowest number of conformations during binding with BSA. In contrast, formation of unstable 3D columnar vertebra for [Zn − Cl] (R=Cl) tend to activate the system with lowest FMO gap (3.75 eV) with highest spontaneity factor in molecular docking. Molecular docking analyses reported in terms of 2D LigPlot+ identified site A, a cleft of domains IB, IIIA and IIIB, as the most probable protein binding site of BSA. Arg144, Glu424, Ser428, Ile455 and Lys114 form the most probable interactions irrespective of the type of compartmental ligands R of the Schiff base whereas Arg185, Glu519, His145, Ile522 act as the differentiating residues with ΔG=−7.3 kcal mol−1.  相似文献   
49.
50.
Hanlon  Phil  Zaslavsky  Thomas 《Order》1997,14(3):229-257
We study new posets Q obtained by removing from a geometric lattice L ofa biased graph certain flats indexed by a simplicial complex . (One example of L is the lattice of flats of thevector matroid of a root system B n .) We study the structureand compute the characteristic polynomial of Q. With certainchoices of L and , including ones for which Q is alattice interpolating between those of B n and D n , we observe curious relationships among the roots of thecharacteristic polynomials of Q, L, and .  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