全文获取类型
收费全文 | 645篇 |
免费 | 28篇 |
国内免费 | 64篇 |
专业分类
化学 | 27篇 |
晶体学 | 2篇 |
力学 | 1篇 |
综合类 | 26篇 |
数学 | 673篇 |
物理学 | 8篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 13篇 |
2019年 | 14篇 |
2018年 | 20篇 |
2017年 | 26篇 |
2016年 | 6篇 |
2015年 | 9篇 |
2014年 | 14篇 |
2013年 | 108篇 |
2012年 | 15篇 |
2011年 | 24篇 |
2010年 | 18篇 |
2009年 | 34篇 |
2008年 | 43篇 |
2007年 | 46篇 |
2006年 | 36篇 |
2005年 | 35篇 |
2004年 | 38篇 |
2003年 | 29篇 |
2002年 | 31篇 |
2001年 | 28篇 |
2000年 | 31篇 |
1999年 | 16篇 |
1998年 | 24篇 |
1997年 | 8篇 |
1996年 | 22篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有737条查询结果,搜索用时 31 毫秒
111.
ZHANG JunQiang & LI XianHua School of Mathematical Sciences Soochow University Suzhou China 《中国科学 数学(英文版)》2010,(5)
Let G be a finite p-group.If the order of the derived subgroup of each proper subgroup of G divides pi,G is called a Di-group.In this paper,we give a characterization of all D1-groups.This is an answer to a question introduced by Berkovich. 相似文献
112.
We study two properties of subgroups of a topological group (relative minimality and co-minimality), that generalize minimality. Many applications, mostly related to semidirect products and generalized Heisenberg groups are given. 相似文献
113.
The goal of this article is to study finite groups admitting a pseudocomplemented subgroup lattice (PK-groups) or a pseudocomplemented normal subgroup lattice (PKN-groups). In particular, we obtain a complete classification of finite PK-groups and of finite nilpotent PKN-groups. We also study groups with a Stone normal subgroup lattice, and we classify finite groups for which every subgroup has a Stone normal subgroup lattice. Finally, we obtain a complete classification of finite groups for which every subgroup is monolithic. 相似文献
114.
In this note, we classify the finite groups admitting a nonsolvable normal subgroup with three induced irreducible character degrees. 相似文献
115.
We provide a method to find free groups of rank two in the group of infinite unitriangular matrices. Our groups are generated by two block-diagonal matrices, namely of the form A = diag(C, C, C…), B = diag(I t , C, C…), where C is a matrix of finite dimension. We give a necessary and sufficient condition for A and B defined above to generate a free group when C is a transvection. We formulate a sufficient condition to generate a free group, when C is a product of any number of commuting transvections. We provide a classification of groups defined above, when C is of degree 3 or 4. 相似文献
116.
In this paper, finite groups having exactly two conjugate classes of non-subnormal subgroups of G are completely classified. 相似文献
117.
In this paper, we show that certain generalized free products of nilpotent-by-finite groups are subgroup separable when the amalgamated subgroup is h× D where D is in the center of both factors. 相似文献
118.
We say that a subgroup H of a finite group G is solitary (respectively, normal solitary) when it is a subgroup (respectively, normal subgroup) of G such that no other subgroup (respectively, normal subgroup) of G is isomorphic to H. A normal subgroup N of a group G is said to be quotient solitary when no other normal subgroup K of G gives a quotient isomorphic to G/N. We show some new results about lattice properties of these subgroups and their relation with classes of groups and present examples showing a negative answer to some questions about these subgroups. 相似文献
119.
The (one-way) shape memory effect is a phenomenon that when a martensitic alloy is deformed in a martensitic state it recovers its original shape upon heating to the parent phase. This is a universal effect for certain martensitic alloys. We will assess the mechanism of the effect critically and select the essential factors which govern the effect. We try to understand it from a unified view, invoking the group–subgroup symmetry relation between the parent and martensite phase, along with analysis of reversible twinning modes in martensite. By such an assessment, we will show why typical shape memory alloys, such as Ti–Ni, Cu–Al–Ni etc., exhibit good shape memory characteristics, while others, such as ferrous alloys, do not. Thus, we will show that most of the shape memory characteristics of various martensitic alloys can be understood consistently from such an approach. 相似文献
120.
Given a field F and integer n≥3, we introduce an invariant sn (F) which is defined by examining the vanishing of subspaces of alternating bilinear forms on 2-dimensional subspaces of vector spaces. This invariant arises when we calculate the largest dimension of a subspace of n?×?n skew-symmetric matrices over F which contains no elements of rank 2. We show how to calculate sn (F) for various families of field F, including finite fields. We also prove the existence of large subgroups of the commutator subgroup of certain p-groups of class 2 which contain no non-identity commutators. 相似文献