全文获取类型
收费全文 | 76213篇 |
免费 | 6623篇 |
国内免费 | 7210篇 |
专业分类
化学 | 30831篇 |
晶体学 | 395篇 |
力学 | 6467篇 |
综合类 | 1315篇 |
数学 | 25437篇 |
物理学 | 25601篇 |
出版年
2023年 | 605篇 |
2022年 | 991篇 |
2021年 | 1464篇 |
2020年 | 1674篇 |
2019年 | 1804篇 |
2018年 | 1501篇 |
2017年 | 1831篇 |
2016年 | 2070篇 |
2015年 | 1870篇 |
2014年 | 2714篇 |
2013年 | 4958篇 |
2012年 | 3152篇 |
2011年 | 3550篇 |
2010年 | 3080篇 |
2009年 | 4227篇 |
2008年 | 4649篇 |
2007年 | 4929篇 |
2006年 | 4626篇 |
2005年 | 3893篇 |
2004年 | 3589篇 |
2003年 | 3586篇 |
2002年 | 3278篇 |
2001年 | 2743篇 |
2000年 | 2725篇 |
1999年 | 2368篇 |
1998年 | 2249篇 |
1997年 | 1865篇 |
1996年 | 1627篇 |
1995年 | 1481篇 |
1994年 | 1364篇 |
1993年 | 1190篇 |
1992年 | 1151篇 |
1991年 | 897篇 |
1990年 | 735篇 |
1989年 | 650篇 |
1988年 | 586篇 |
1987年 | 433篇 |
1986年 | 381篇 |
1985年 | 452篇 |
1984年 | 440篇 |
1983年 | 213篇 |
1982年 | 345篇 |
1981年 | 409篇 |
1980年 | 308篇 |
1979年 | 299篇 |
1978年 | 221篇 |
1977年 | 208篇 |
1976年 | 158篇 |
1974年 | 112篇 |
1973年 | 106篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Determination of contact stresses in problems on bending of a package of transversely isotropic bars
V. I. Zubko 《Mechanics of Composite Materials》2004,40(6):495-508
A mechanomathematical model for bending of packages of transversely isotropic bars of rectangular cross section is proposed. Adhesion, slippage, and separation zones between the bars are considered. The resolving equations for deflections and tangential displacements are supplemented with a system of linear differential equations for determining the normal and tangential contact stresses, and boundary conditions are formulated. A scheme for analytical solution of two contact problems—a package under the action of a distributed load and a round stamp—is considered. For these packages, a transition is performed from the initial system of differential equations for determining the contact stresses, where the unknown functions are interrelated by recurrent relationships, to one linear differential equation of fourth order and then to a system of linear algebraic equations. This transition allows us to integrate the initial system and get expressions for the contact stresses.Translated from Mekhanika Kompozitnykh Materialov, Vol. 40, No. 6, pp. 761–778, November–December, 2004. 相似文献
992.
Denisov V. I. Denisova I. P. Svertilov S. I. 《Theoretical and Mathematical Physics》2004,138(1):142-149
We consider the effect that the gravitational field of a neutrino pulse radiated in the collapse of presupernova nuclei has on the observable optical radiation spectra of atoms at the supernova surface. We show that at the modern level of development of experimental methods, neutrino monitoring supplemented by optical monitoring of supernova candidates provides a unique possibility to check whether the Einstein equivalence principle is satisfied for neutrinos of each of the three types (electron, muon, and tau-lepton) and their antiparticles, to estimate the change of the gravitational potential at the surface of the star at the instant of the neutrino radiation pulse, and to obtain upper limits on the mass values of these neutrinos in a new way. 相似文献
993.
Bobik V. V. Bobonich F. M. Belokopytov Yu. V. 《Theoretical and Experimental Chemistry》2003,39(6):364-368
We have used potentiometric titration with tetrabutylammonium hydroxide to determine the acid center content on the outer surface of dealuminated natural and synthetic mordenites. We have established a symbatic relationship between the 2,2-dimethylbutane content in the hydroisomerization products of n-hexane on dealuminated palladium-containing mordenites and the number of their external acid centers. We have studied the possibility of partial deactivation of such centers during ion-exchange deposition of palladium on the catalysts, using a tetraammine palladium solution. 相似文献
994.
995.
996.
Ioan Tomescu 《Journal of Graph Theory》2003,43(3):210-222
In the set of graphs of order n and chromatic number k the following partial order relation is defined. One says that a graph G is less than a graph H if ci(G) ≤ ci(H) holds for every i, k ≤ i ≤ n and at least one inequality is strict, where ci(G) denotes the number of i‐color partitions of G. In this paper the first ? n/2 ? levels of the diagram of the partially ordered set of connected 3‐chromatic graphs of order n are described. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 210–222, 2003 相似文献
997.
Mathematical Notes - 相似文献
998.
Shi Rong LI 《数学学报(英文版)》2005,21(4):797-802
For a finite group G, let T(G) denote a set of primes such that a prime p belongs to T(G) if and only if p is a divisor of the index of some maximal subgroup of G. It is proved that if G satisfies any one of the following conditions: (1) G has a p-complement for each p∈T(G); (2)│T(G)│= 2: (3) the normalizer of a Sylow p-subgroup of G has prime power index for each odd prime p∈T(G); then G either is solvable or G/Sol(G)≌PSL(2, 7) where Sol(G) is the largest solvable normal subgroup of G. 相似文献
999.
Frank N. Proske Madan L. Puri 《Proceedings of the American Mathematical Society》2003,131(9):2937-2944
In this article we prove a strong law of large numbers for Borel measurable nonseparably valued random elements in the case of generalized random sets.
1000.
利用Ditzian-Totik光滑模对于[0,1]上定义的非角连续函数f(x),且f(x)≠0,文中证明存在正系数多项式Pn(x)及常数C,使得|f9x)-1/Pn(x)|≤Cωψ^λ(f,n^-1/2(ψ(x) 1/√n)^1-λ)。当λ=1时,上述结果导出已有的整体估计,而当0≤λ<1时,得到倒数逼近一个新的点态局部估计。 相似文献