全文获取类型
收费全文 | 11430篇 |
免费 | 350篇 |
国内免费 | 7篇 |
专业分类
化学 | 6113篇 |
晶体学 | 106篇 |
力学 | 210篇 |
数学 | 2236篇 |
物理学 | 3122篇 |
出版年
2021年 | 174篇 |
2020年 | 167篇 |
2019年 | 147篇 |
2018年 | 223篇 |
2017年 | 236篇 |
2016年 | 498篇 |
2015年 | 331篇 |
2014年 | 402篇 |
2013年 | 887篇 |
2012年 | 554篇 |
2011年 | 699篇 |
2010年 | 443篇 |
2009年 | 399篇 |
2008年 | 385篇 |
2007年 | 323篇 |
2006年 | 260篇 |
2005年 | 219篇 |
2004年 | 197篇 |
2003年 | 192篇 |
2002年 | 196篇 |
2001年 | 151篇 |
2000年 | 141篇 |
1999年 | 154篇 |
1998年 | 139篇 |
1997年 | 135篇 |
1996年 | 149篇 |
1995年 | 125篇 |
1994年 | 126篇 |
1993年 | 126篇 |
1992年 | 118篇 |
1991年 | 107篇 |
1990年 | 109篇 |
1989年 | 110篇 |
1988年 | 100篇 |
1987年 | 126篇 |
1986年 | 94篇 |
1985年 | 129篇 |
1984年 | 131篇 |
1983年 | 119篇 |
1982年 | 111篇 |
1981年 | 115篇 |
1980年 | 116篇 |
1979年 | 123篇 |
1978年 | 120篇 |
1977年 | 116篇 |
1976年 | 115篇 |
1975年 | 95篇 |
1974年 | 103篇 |
1973年 | 105篇 |
1969年 | 83篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
81.
82.
Marston Conder Aleksander Malnič Dragan Marušič Primž Potočnik 《Journal of Algebraic Combinatorics》2006,23(3):255-294
A list is given of all semisymmetric (edge- but not vertex-transitive) connected finite cubic graphs of order up to 768. This
list was determined by the authors using Goldschmidt's classification of finite primitive amalgams of index (3,3), and a computer
algorithm for finding all normal subgroups of up to a given index in a finitely-presented group. The list includes several
previously undiscovered graphs. For each graph in the list, a significant amount of information is provided, including its
girth and diameter, the order of its automorphism group, the order and structure of a minimal edge-transitive group of automorphisms,
its Goldschmidt type, stabiliser partitions, and other details about its quotients and covers. A summary of all known infinite
families of semisymmetric cubic graphs is also given, together with explicit rules for their construction, and members of
the list are identified with these. The special case of those graphs having K1,3 as a normal quotient is investigated in detail.
Supported in part by N.Z. Marsden Fund (grant no. UOA 124) and N.Z. Centres of Research Excellence Fund (grant no. UOA 201)
Supported in part by “Ministrstvo za šolstvo, znanost in šport Slovenije”, research program no. 101-506.
Supported in part by research projects no. Z1-4186-0101 and no. Z1-3124-0101. The fourth author would like to thank the University
of Auckland for hospitality during his visit there in 2003. 相似文献
83.
Radu Ioan Boţ Ioan Bogdan Hodrea Gert Wanka 《Nonlinear Analysis: Theory, Methods & Applications》2007
Considering a constrained fractional programming problem, within the present paper we present some necessary and sufficient conditions, which ensure that the optimal objective value of the considered problem is greater than or equal to a given real constant. The desired results are obtained using the Fenchel–Lagrange duality approach applied to an optimization problem with convex or difference of convex (DC) objective functions and finitely many convex constraints. These are obtained from the initial fractional programming problem using an idea due to Dinkelbach. We also show that our general results encompass as special cases some recently obtained Farkas-type results. 相似文献
84.
Lubomír Kubáček 《Mathematica Slovaca》2007,57(1):59-82
In some situations estimates of unknown parameters must be corrected by additional measurements. It is in principle no problem
to calculate the corrected estimates, however, it is of more interest to find formulae for correction itself. The formulae
enable us to design an additional experiment and to judge its usefulness.
The aim of the paper is to find such formulae for several situations.
Supported by the grant of the Council of Czech Government MSM 6 198 959 214. 相似文献
85.
Gašper Jaklič Jernej Kozak Marjeta Krajnc Vito Vitrih Emil Žagar 《Numerical Algorithms》2007,45(1-4):49-60
In this paper, three-pencil lattices on triangulations are studied. The explicit representation of a lattice, based upon barycentric
coordinates, enables us to construct lattice points in a simple and numerically stable way. Further, this representation carries
over to triangulations in a natural way. The construction is based upon group action of S
3 on triangle vertices, and it is shown that the number of degrees of freedom is equal to the number of vertices of the triangulation.
相似文献
86.
The stoichiometric reactions of trimethylaluminum with 2,6‐(MeOCH2)2C6H3OH (LH) revealed compounds L3Al ( 1 ) and L2AlMe ( 2 ). On the other hand reaction of 1 equiv. of LH with trimethylaluminum did not lead to the formation of complex LAlMe2 ( 3 ), rather 2 together with Me3Al were observed as a result of a disproportionation of 3 . Compounds 1 and 2 were characterized by elemental analysis, 1H and 13C NMR spectroscopy and in the case of 1 by X‐ray diffraction. Derivative 2 underwent transmetalation with Ph3SnOH, giving LSnPh3 ( 4 ) as the result of a migration of ligand L from the aluminum to the tin atom. The identity of 4 was established by elemental analysis, 1H, 13C and 119Sn NMR spectroscopy and 1H, 119Sn HMBC experiments. The system 2 and B(C6F5)3 in a 1:1 molar ratio was shown to be active in the polymerization of propylene oxide and ε‐caprolactone. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
87.
Abull is the (self-complementary) graph with verticesa, b, c, d, e and edgesab, ac, bc, bd, ce; a graphG is calledBerge if neitherG not its complement contains a chordless cycle whose length is odd and at least five. We prove that bull-free Berge graphs are perfect; a part of our argument relies on a new property of minimal imperfect graphs.This work was done while both authors were at the School of Computer Science, McGill University; support by NSERC is gratefully acknowledged. 相似文献
88.
89.
The composting of organic solid waste, the mixture of fruit and vegetable leftovers enriched with night soil, was investigated
in a closed thermally insulated reactor. It was found that 80.9 % of the original substrate biodegraded after 14 days. A mathematical
model of the column reactor was proposed where the biodegradation rate of the organic solid waste was described using simple
n-thorder kinetics. A good prediction of process performance was obtained using the proposed kinetics and experimentally obtained
reaction heat.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
90.
We study Fourier multipliers which result from modulating jumps of Lévy processes. Using the theory of martingale transforms we prove that these operators are bounded in Lp(Rd) for 1<p<∞ and we obtain the same explicit bound for their norm as the one known for the second order Riesz transforms. 相似文献