全文获取类型
收费全文 | 36188篇 |
免费 | 8232篇 |
国内免费 | 1392篇 |
专业分类
化学 | 40720篇 |
晶体学 | 324篇 |
力学 | 465篇 |
数学 | 1963篇 |
物理学 | 2340篇 |
出版年
2023年 | 19篇 |
2022年 | 100篇 |
2021年 | 199篇 |
2020年 | 1246篇 |
2019年 | 2598篇 |
2018年 | 1043篇 |
2017年 | 655篇 |
2016年 | 3397篇 |
2015年 | 3520篇 |
2014年 | 3424篇 |
2013年 | 4078篇 |
2012年 | 2891篇 |
2011年 | 2092篇 |
2010年 | 2818篇 |
2009年 | 2799篇 |
2008年 | 2318篇 |
2007年 | 1709篇 |
2006年 | 1398篇 |
2005年 | 1570篇 |
2004年 | 1386篇 |
2003年 | 1271篇 |
2002年 | 1954篇 |
2001年 | 1357篇 |
2000年 | 1264篇 |
1999年 | 356篇 |
1998年 | 38篇 |
1997年 | 33篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 6篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 20篇 |
1983年 | 12篇 |
1981年 | 13篇 |
1980年 | 18篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1973年 | 6篇 |
1971年 | 6篇 |
1862年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
The main result of the paper is a theorem, using which a new proof of Roth’s theorem is obtained, a new solvability criterion
for the matrix equation AX-YB = C is proved, a formula for a particular solution of the latter is derived, and the least of
the orders of square nonsingular matrices containing a given rectangular matrix as a submatrix is determined. Bibliography:
5 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 323, 2005, pp. 15–23. 相似文献
4.
5‐Amino‐4‐methyl‐2‐phenyl‐6‐substitutedfuro[2,3‐d]pyrimidines ( 2a‐c ) were reacted with 2,5‐dimethoxytetrahydrfuran to afford the pyrrolyl derivatives 3a‐c . Compound 3a was chosen as intermediate for the synthesis of poly fused heterocycles incorporated furopyrimidines moiety 4–11 . Some of the synthesized compounds were screened for their antibacterial and antifungal activities. 相似文献
5.
Wen Zhang Hui Huang Yu Ding Margherita Gavagnin Ernesto Mollo Guido Cimino Yue‐Wei Guo 《Helvetica chimica acta》2006,89(4):813-820
Three new polyoxygenated steroids, muricesteroid ( 1 ), and menellsteroids A ( 2 ) and B ( 3 ), were isolated from two species of the South China Sea gorgonian Muricella flexuosa and Menella verrucosa Brundin , respectively. The structures of these new compounds were elucidated on the basis of extensive spectroscopic analysis, chemical methods and comparison with known related compounds. 相似文献
6.
It is proved that the variety of relevant disjunction lattices has the finite embeddability property. It follows that Avron's relevance logic RMI min has a strong form of the finite model property, so it has a solvable deducibility problem. This strengthens Avron's result that RMI min is decidable. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
Al.Th. Kermanidis D.G. Stamatelos G.N. Labeas Sp.G. Pantelakis 《Theoretical and Applied Fracture Mechanics》2006,45(2):148-158
The synergetic effect of corrosion and corrosion induced hydrogen embrittlement damage processes which occur at local scale has been found to result in a dramatic macroscopic tensile ductility loss of the 2024 aluminum alloy. In the present work, the tensile behaviour of corroded 2024 T351 specimens has been estimated on the basis of FE analysis by taking into account the local material properties in the damaged areas. A parametric study is involved to account for the effect of thickness in the results. Calculated tensile properties obtained with the analysis agree well with experimental data. 相似文献
8.
9.
A graph G is N2‐locally connected if for every vertex ν in G, the edges not incident with ν but having at least one end adjacent to ν in G induce a connected graph. In 1990, Ryjá?ek conjectured that every 3‐connected N2‐locally connected claw‐free graph is Hamiltonian. This conjecture is proved in this note. © 2004 Wiley Periodicals, Inc. J Graph Theory 48: 142–146, 2005 相似文献
10.
The inhomogeneous Dirichlet problems concerning divergence form elliptic equations are studied. Optimal regularity requirements on the coefficients and domains for the W1,p theory, 1 < p < ∞, are obtained. The principal coefficients are supposed to be in the John‐Nirenberg space with small BMO seminorms. The domain is a Reifenberg domain. These conditions for the W1,p theory not only weaken the requirements on the coefficients but also lead to a more general geometric condition on the domains. In fact, these domains might have fractal dimensions. © 2004 Wiley Periodicals, Inc. 相似文献