全文获取类型
收费全文 | 150505篇 |
免费 | 3204篇 |
国内免费 | 629篇 |
专业分类
化学 | 72332篇 |
晶体学 | 1205篇 |
力学 | 8573篇 |
综合类 | 5篇 |
数学 | 43032篇 |
物理学 | 29191篇 |
出版年
2023年 | 547篇 |
2022年 | 475篇 |
2021年 | 1092篇 |
2020年 | 1177篇 |
2019年 | 1241篇 |
2018年 | 11343篇 |
2017年 | 11000篇 |
2016年 | 8237篇 |
2015年 | 2932篇 |
2014年 | 2538篇 |
2013年 | 4815篇 |
2012年 | 8574篇 |
2011年 | 15163篇 |
2010年 | 8632篇 |
2009年 | 8592篇 |
2008年 | 10812篇 |
2007年 | 12814篇 |
2006年 | 4296篇 |
2005年 | 5181篇 |
2004年 | 4793篇 |
2003年 | 4604篇 |
2002年 | 3368篇 |
2001年 | 1708篇 |
2000年 | 1539篇 |
1999年 | 1079篇 |
1998年 | 935篇 |
1997年 | 863篇 |
1996年 | 1045篇 |
1995年 | 715篇 |
1994年 | 722篇 |
1993年 | 742篇 |
1992年 | 694篇 |
1991年 | 613篇 |
1990年 | 569篇 |
1989年 | 530篇 |
1988年 | 456篇 |
1987年 | 471篇 |
1986年 | 441篇 |
1985年 | 648篇 |
1984年 | 613篇 |
1983年 | 434篇 |
1982年 | 535篇 |
1981年 | 496篇 |
1980年 | 469篇 |
1979年 | 435篇 |
1978年 | 403篇 |
1976年 | 368篇 |
1975年 | 342篇 |
1974年 | 335篇 |
1973年 | 344篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
It is wellknown that the technique of character sums together with the tools of algebraic number theory is the adequate method for the study of difference sets in abelian groups, compare for instance Ott [5] or Turyn [6]. In this paper we use this method to prove a new non-existence theorem for certain difference sets in abelian groups of order rpa rp^a , where r 1 2 r \neq 2 and p are distinct primes. 相似文献
992.
993.
We solve a bitangential interpolation problem for contractive multipliers
on the Arveson space with an arbitrary interpolating set in the closed
unit ball . The solvability criterion is established in terms of positive
kernels. The set of all solutions is parametrized by a Redheffer transform.
Submitted: February 2, 2002. 相似文献
994.
995.
Andrei N. Yakunin 《Central European Journal of Physics》2004,2(3):535-555
A cubic structure of polymer colloid complexes is studied. The technique of the research includes i) an analysis of well-known
literature SAXS data; on this basis, ii) constructing a simple model to estimate geometric structure parameters and to obtain
a simulated scattering curve; and iii) comparing the model with the real structure obtained from the SAXS data, using the
reconstruction of electron density distribution. A bicontinuous structure in cubic mesophases is formed.
Dedicated to the memory of Alexander T. Dembo 相似文献
996.
Victor P. Palamodov 《Arkiv f?r Matematik》2004,42(1):119-152
A fundamental solution of the acoustical equation with a variable refraction coefficient is constructed. The solution satisfies
the limiting absorption and radiation conditions. The optimal high frequency estimate is proved for square means of the solution.
The source function for the diffusion equation is a by-product of this construction.
Partially supported by a stipend of the Mathematical Scientific Research Institute at Berkeley, 2001. 相似文献
997.
G. Sreenivasulu Reddy J. Hanumanthachari T. Vasanthi 《Southeast Asian Bulletin of Mathematics》2003,26(2):331-335
This paper is mainly dealt with the structure of totally ordered rings (t.o. rings) whose positive cones are finitely generated as multiplicative right ideals.AMS Subject Classification (1991): 16W80, 13J25 相似文献
998.
We consider a discretized volume V consisting of finite, congruent and attached copies of a tile t. We find a group L
V
the orbit of which, when applied to t, is just V. We show the connection between the structural matrixQ in the formal solution of a boundary value problem formulated for volume V and the so called auxiliary matrix of the graph Γ
v
associated with V. We show boundary value problems to be isomorphic if the graphs associated with the volumes are isomorphic, or, if the covering
groups are Sunada pairs. 相似文献
999.
Sam Efromovich 《Annals of the Institute of Statistical Mathematics》2004,56(2):205-223
A blockwise shrinkage is a popular procedure of adaptation that has allowed the statisticians to establish an impressive bouquet
of asymptotic mathematical results and develop softwares for solving practical problems. Traditionally risks of the estimates
are studied via upper bounds that imply sufficient conditions for a blockwise shrinkage procedure to be minimax. This article
suggests to analyze the estimates via exact (non-asymptotic) lower bounds established for a no-signal setting. The approach
complements the familiar minimax, Bayesian and numerical analysis, it allows to find necessary conditions for a procedure
to attain desired rates, and it sheds a new light on popular choices of blocks and thresholds recommended in the literature.
Mathematical results are complemented by a numerical study.
Supported in part by NSF Grants DMS-9971051 and DMS-0243606. 相似文献
1000.