全文获取类型
收费全文 | 22447篇 |
免费 | 1060篇 |
国内免费 | 1256篇 |
专业分类
化学 | 8793篇 |
晶体学 | 158篇 |
力学 | 127篇 |
综合类 | 38篇 |
数学 | 13900篇 |
物理学 | 1747篇 |
出版年
2023年 | 123篇 |
2022年 | 136篇 |
2021年 | 162篇 |
2020年 | 261篇 |
2019年 | 559篇 |
2018年 | 497篇 |
2017年 | 381篇 |
2016年 | 354篇 |
2015年 | 513篇 |
2014年 | 747篇 |
2013年 | 1956篇 |
2012年 | 952篇 |
2011年 | 1456篇 |
2010年 | 1275篇 |
2009年 | 1331篇 |
2008年 | 1641篇 |
2007年 | 1618篇 |
2006年 | 1276篇 |
2005年 | 944篇 |
2004年 | 837篇 |
2003年 | 737篇 |
2002年 | 840篇 |
2001年 | 566篇 |
2000年 | 553篇 |
1999年 | 545篇 |
1998年 | 466篇 |
1997年 | 398篇 |
1996年 | 378篇 |
1995年 | 416篇 |
1994年 | 402篇 |
1993年 | 286篇 |
1992年 | 253篇 |
1991年 | 169篇 |
1990年 | 167篇 |
1989年 | 156篇 |
1988年 | 118篇 |
1987年 | 106篇 |
1986年 | 110篇 |
1985年 | 146篇 |
1984年 | 137篇 |
1983年 | 75篇 |
1982年 | 111篇 |
1981年 | 108篇 |
1980年 | 100篇 |
1979年 | 76篇 |
1978年 | 88篇 |
1977年 | 55篇 |
1976年 | 48篇 |
1974年 | 31篇 |
1973年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
82.
83.
Valery Agoshkov Paola Gervasio Alfio Quarteroni 《Mediterranean Journal of Mathematics》2006,3(2):147-176
New domain decomposition methods (DDM) based on optimal control approach are introduced for the coupling of first and second
order equations on overlapping subdomains. Several cost functionals and control functions are proposed. Uniqueness and existence
results are proved for the coupled problem, and the convergence of iterative processes is analyzed.
The work was supported by the Russian Foundation for Basic Research (04-01-00615) and it was partly carried out while the
first author was visiting the IACS at EPFL. 相似文献
84.
85.
Martin Loebl 《Advances in Mathematics》2007,211(2):546-565
We define a q-chromatic function and q-dichromate on graphs and compare it with existing graph functions. Then we study in more detail the class of general chordal graphs. This is partly motivated by the graph isomorphism problem. Finally we relate the q-chromatic function to the colored Jones function of knots. This leads to a curious expression of the colored Jones function of a knot diagram K as a chromatic operator applied to a power series whose coefficients are linear combinations of long chord diagrams. Chromatic operators are directly related to weight systems by the work of Chmutov, Duzhin, Lando and Noble, Welsh. 相似文献
86.
Piotr Borodulin-Nadzieja 《Topology and its Applications》2007,154(18):3107-3124
We investigate properties of minimally generated Boolean algebras. It is shown that all measures defined on such algebras are separable but not necessarily weakly uniformly regular. On the other hand, there exist Boolean algebras small in terms of measures which are not minimally generated. We prove that under CH a measure on a retractive Boolean algebra can be nonseparable. Some relevant examples are indicated. Also, we give two examples of spaces satisfying some kind of Efimov property. 相似文献
87.
Summary The paper addresses the problem of the implementation of nonhomogeneous essential Dirichlet type boundary conditions in thep-version of the finite element method.Partially supported by the Office of Naval Research under Grant N-00014-85-K-0169Research partially supported by the Air Force Office of Scientific Research, Air Force Systems Command, USAF, under Grant Number AFOSR 85-0322 相似文献
88.
The object of the present investigation is to introduce a new trigonometric method of summation which is both regular and
Fourier effective and determine its status with reference to other methods of summation (see §2-§4) and also give an application
of this method to determine the degree of approximation in a new Banach space of functions conceived as a generalized Holder
metric (see §5). 相似文献
89.
Robert Hochberg 《Combinatorica》2006,26(1):47-64
We prove that the class of homogeneous quasi-arithmetic progressions has unbounded discrepancy. That is, we show that given any 2-coloring of the natural numbers and any positive integer D, one can find a real number α≥1 and a set of natural numbers of the form {0, [α], [2α], [3α], . . . , [kα]} so that one color appears at least D times more than the other color. This was already proved by Beck in 1983, but the proof given here is somewhat simpler and
gives a better bound on the discrepancy. 相似文献
90.
A magic labelling of a set system is a labelling of its points by distinct positive integers so that every set of the system has the same sum,
the magic sum. Examples are magic squares (the sets are the rows, columns, and diagonals) and semimagic squares (the same, but without
the diagonals). A magilatin labelling is like a magic labelling but the values need be distinct only within each set. We show that the number of n × n magic or magilatin labellings is a quasipolynomial function of the magic sum, and also of an upper bound on the entries in
the square. Our results differ from previous ones because we require that the entries in the square all be different from
each other, and because we derive our results not by ad hoc reasoning but from a general theory of counting lattice points in rational inside-out polytopes. We also generalize from
set systems to rational linear forms.
Dedicated to the memory of Claudia Zaslavsky, 1917–2006
Received August 10, 2005 相似文献