全文获取类型
收费全文 | 10517篇 |
免费 | 294篇 |
国内免费 | 258篇 |
专业分类
化学 | 985篇 |
晶体学 | 23篇 |
力学 | 141篇 |
综合类 | 24篇 |
数学 | 9062篇 |
物理学 | 834篇 |
出版年
2023年 | 17篇 |
2022年 | 22篇 |
2021年 | 48篇 |
2020年 | 63篇 |
2019年 | 269篇 |
2018年 | 279篇 |
2017年 | 149篇 |
2016年 | 116篇 |
2015年 | 135篇 |
2014年 | 307篇 |
2013年 | 646篇 |
2012年 | 407篇 |
2011年 | 630篇 |
2010年 | 556篇 |
2009年 | 769篇 |
2008年 | 822篇 |
2007年 | 748篇 |
2006年 | 612篇 |
2005年 | 435篇 |
2004年 | 358篇 |
2003年 | 296篇 |
2002年 | 273篇 |
2001年 | 243篇 |
2000年 | 228篇 |
1999年 | 305篇 |
1998年 | 239篇 |
1997年 | 176篇 |
1996年 | 262篇 |
1995年 | 225篇 |
1994年 | 226篇 |
1993年 | 161篇 |
1992年 | 130篇 |
1991年 | 86篇 |
1990年 | 74篇 |
1989年 | 77篇 |
1988年 | 48篇 |
1987年 | 57篇 |
1986年 | 46篇 |
1985年 | 82篇 |
1984年 | 62篇 |
1983年 | 31篇 |
1982年 | 64篇 |
1981年 | 69篇 |
1980年 | 44篇 |
1979年 | 38篇 |
1978年 | 34篇 |
1977年 | 28篇 |
1976年 | 33篇 |
1975年 | 10篇 |
1974年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 531 毫秒
1.
2.
The growth-fragmentation equation describes a system of growing and dividing particles, and arises in models of cell division, protein polymerisation and even telecommunications protocols. Several important questions about the equation concern the asymptotic behaviour of solutions at large times: at what rate do they converge to zero or infinity, and what does the asymptotic profile of the solutions look like? Does the rescaled solution converge to its asymptotic profile at an exponential speed? These questions have traditionally been studied using analytic techniques such as entropy methods or splitting of operators. In this work, we present a probabilistic approach: we use a Feynman–Kac formula to relate the solution of the growth-fragmentation equation to the semigroup of a Markov process, and characterise the rate of decay or growth in terms of this process. We then identify the Malthus exponent and the asymptotic profile in terms of a related Markov process, and give a spectral interpretation in terms of the growth-fragmentation operator and its dual. 相似文献
3.
4.
This paper deals with the Cauchy–Dirichlet problem for the fractional Cahn–Hilliard equation. The main results consist of global (in time) existence of weak solutions, characterization of parabolic smoothing effects (implying under proper condition eventual boundedness of trajectories), and convergence of each solution to a (single) equilibrium. In particular, to prove the convergence result, a variant of the so-called ?ojasiewicz–Simon inequality is provided for the fractional Dirichlet Laplacian and (possibly) non-analytic (but ) nonlinearities. 相似文献
5.
G. Panina 《Central European Journal of Mathematics》2003,1(2):157-168
All 3-dimensional convex polytopes are known to be rigid. Still their Minkowski differences (virtual polytopes) can be flexible
with any finite freedom degree. We derive some sufficient rigidity conditions for virtual polytopes and present some examples
of flexible ones. For example, Bricard's first and second flexible octahedra can be supplied by the structure of a virtual
polytope. 相似文献
6.
7.
We investigate congruence classes and direct congruence classes of m-tuples in the complex projective space ℂP
n
. For direct congruence one allows only isometries which are induced by linear (instead of semilinear) mappings. We establish
a canonical bijection between the set of direct congruence classes of m-tuples of points in ℂP
n
and the set of equivalence classes of positive semidefinite Hermitean m×m-matrices of rank at most n+1 with 1's on the diagonal. As a corollary we get that the direct congruence class of an m-tuple is uniquely determined by the direct congruence classes of all of its triangles, provided that no pair of points of
the m-tuple has distance π/2. Examples show that the situation changes drastically if one replaces direct congruence classes by
congruence classes or if distances π/2 are allowed. Finally we do the same
kind of investigation also for the complex hyperbolic space ℂH
n
. Most of the results are completely analogous, however, there are also some interesting differences.
Received: 15 January 1996 相似文献
8.
9.
The Al2O3−CdSe interface of a thin-film transistor is investigated in the frequency range 30 Hz-30 kHz under weak depletion and accumulation.
The surface states are, most likely, located in the insulator Al2O3 with a concentration varying from 4·1018 to 1019 cm−3 eV−1. The surface states have a negligible influence on the thin-film transistor operation. 相似文献
10.
Summary We present an approximation method of a space-homogeneous transport equation which we prove is convergent. The method is very promising for numerical computation. Comparison of a numerical computation with an exact solution is given for the Master equation. 相似文献