全文获取类型
收费全文 | 17200篇 |
免费 | 1583篇 |
国内免费 | 1183篇 |
专业分类
化学 | 9994篇 |
晶体学 | 113篇 |
力学 | 58篇 |
综合类 | 54篇 |
数学 | 7948篇 |
物理学 | 1799篇 |
出版年
2024年 | 19篇 |
2023年 | 304篇 |
2022年 | 186篇 |
2021年 | 254篇 |
2020年 | 491篇 |
2019年 | 553篇 |
2018年 | 535篇 |
2017年 | 364篇 |
2016年 | 535篇 |
2015年 | 642篇 |
2014年 | 936篇 |
2013年 | 1478篇 |
2012年 | 873篇 |
2011年 | 1146篇 |
2010年 | 963篇 |
2009年 | 1112篇 |
2008年 | 1223篇 |
2007年 | 1154篇 |
2006年 | 937篇 |
2005年 | 688篇 |
2004年 | 649篇 |
2003年 | 607篇 |
2002年 | 507篇 |
2001年 | 348篇 |
2000年 | 360篇 |
1999年 | 372篇 |
1998年 | 341篇 |
1997年 | 225篇 |
1996年 | 276篇 |
1995年 | 308篇 |
1994年 | 273篇 |
1993年 | 189篇 |
1992年 | 185篇 |
1991年 | 78篇 |
1990年 | 90篇 |
1989年 | 74篇 |
1988年 | 65篇 |
1987年 | 54篇 |
1986年 | 42篇 |
1985年 | 67篇 |
1984年 | 57篇 |
1983年 | 22篇 |
1982年 | 72篇 |
1981年 | 51篇 |
1980年 | 45篇 |
1979年 | 41篇 |
1978年 | 42篇 |
1977年 | 40篇 |
1976年 | 44篇 |
1975年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
81.
本文用COSY,CHCOR等二维核磁共振技术对TRANILAST,2[]3-(3.4-二甲基苯基)1-氧代-2-丙烯基]氨基]苯甲到进行了~1H、~(13)C NMR谱数据分析及归属,并结合~(13)C弛豫时间T_1 及变温实验对合成产品进行了结构鉴定. 相似文献
82.
Jurie Conradie 《Positivity》2006,10(3):591-606
The possibility of characterizing the Mackey topology of a dual pair of vector spaces as a generalized inductive limit (or
mixed) topology is investigated. Positive answers are given for a wide range of dual pairs of Riesz spaces (vector lattices)
and non-commutative Banach function spaces (or symmetric operator spaces). 相似文献
83.
Oliver Lorscheid 《Archiv der Mathematik》2007,88(4):344-348
This paper shows that for a local field K, a subfield k ⊂ K and a variety X over k, X is complete if and only if for every finite field extension Kʹ | K, the set X(Kʹ) is compact in its strong topology.
The author likes to thank Florian Pop, Jakob Stix, Stefan Wewers, Gunther Cornelissen and his own parents for their support.
Received: 13 April 2006 相似文献
84.
Abdo Y. Alfakih 《Discrete Applied Mathematics》2007,155(10):1244-1253
Let V={1,2,…,n}. A mapping p:V→Rr, where p1,…,pn are not contained in a proper hyper-plane is called an r-configuration. Let G=(V,E) be a simple connected graph on n vertices. Then an r-configuration p together with graph G, where adjacent vertices of G are constrained to stay the same distance apart, is called a bar-and-joint framework (or a framework) in Rr, and is denoted by G(p). In this paper we introduce the notion of dimensional rigidity of frameworks, and we study the problem of determining whether or not a given G(p) is dimensionally rigid. A given framework G(p) in Rr is said to be dimensionally rigid iff there does not exist a framework G(q) in Rs for s?r+1, such that ∥qi-qj∥2=∥pi-pj∥2 for all (i,j)∈E. We present necessary and sufficient conditions for G(p) to be dimensionally rigid, and we formulate the problem of checking the validity of these conditions as a semidefinite programming (SDP) problem. The case where the points p1,…,pn of the given r-configuration are in general position, is also investigated. 相似文献
85.
Teruhisa Tsuda 《Letters in Mathematical Physics》2006,77(1):21-30
Starting from certain point sets in the projective plane, we construct a tropical (or subtraction-free birational) representation of Weyl groups over the field of τ-functions. In particular, our construction includes E
8
(1)
, E
7
(1)
, E
6
(1)
and D
5
(1)
as affine cases; each of them gives rise to the q-difference Painlevé equation. 相似文献
86.
We prove a conjecture by F. Ferrari. Let X be the total space of a nonlinear deformation of a rank two holomorphic vector bundle on a smooth rational curve, such that X has trivial canonical bundle and has sections. Then the normal bundle to such sections is computed in terms of the rank of the Hessian of a suitably defined superpotential at its critical points. 相似文献
87.
Jan P. Boroński 《Topology and its Applications》2007,154(18):3156-3166
A set (or a collection of sets) contained in the Euclidean space Rm is symmetric if it is invariant under the antipodal map. Given a symmetric unicoherent polyhedron X (like an n-dimensional cube or a sphere) and an odd real function f defined on vertices of a certain symmetric triangulation of X, we algorithmically construct a connected symmetric separator of X by choosing a subcollection of the triangulation. Each element of the subcollection contains the vertices v and u such that f(v)f(u)?0. 相似文献
88.
New criteria are provided for determining whether an integral representation of a stable process is minimal. These criteria are based on various nonminimal sets and their projections, and have several advantages over and shed light on already available criteria. In particular, they naturally lead from a nonminimal representation to the one which is minimal. Several known examples are considered to illustrate the main results. The general approach is also adapted to show that the so-called mixed moving averages have a minimal integral representation of the mixed moving average type. 相似文献
89.
90.
构造了第孙中禹种强度不等的非对称三态叠加多模叠加态光场|ψ1(ABC)〉q.利用多模压缩态理论研究了态|ψ1(ABC)〉q第一正交分量高次和压缩.结果发现:①当构成态|ψ1(ABC)〉q的三个多模相干态光场的强度不相等时,在一定条件下,态|ψ1(ABC)〉q的第一正交分量可出现任意幂次的高次和压缩.②当上述的三个多模相干态光场强度相等时,态|ψ1(ABC)〉q的第一正交分量的高次和压缩现象消失.在这种情况下,态|ψ1(ABC)〉q的第一正交分量恒处于NH最小测不准态. 相似文献