全文获取类型
收费全文 | 1632篇 |
免费 | 57篇 |
国内免费 | 169篇 |
专业分类
化学 | 438篇 |
晶体学 | 9篇 |
力学 | 20篇 |
综合类 | 12篇 |
数学 | 1209篇 |
物理学 | 170篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 32篇 |
2021年 | 31篇 |
2020年 | 46篇 |
2019年 | 66篇 |
2018年 | 45篇 |
2017年 | 61篇 |
2016年 | 34篇 |
2015年 | 32篇 |
2014年 | 40篇 |
2013年 | 449篇 |
2012年 | 40篇 |
2011年 | 59篇 |
2010年 | 38篇 |
2009年 | 66篇 |
2008年 | 68篇 |
2007年 | 86篇 |
2006年 | 80篇 |
2005年 | 62篇 |
2004年 | 56篇 |
2003年 | 54篇 |
2002年 | 102篇 |
2001年 | 49篇 |
2000年 | 37篇 |
1999年 | 44篇 |
1998年 | 32篇 |
1997年 | 22篇 |
1996年 | 35篇 |
1995年 | 20篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有1858条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Tony Forbes. 《Mathematics of Computation》2002,71(237):449-452
We describe a successful search for a sequence of fifteen consecutive integers, each the product of exactly four prime factors. Fifteen is best possible.
5.
ZhenFengZHANG 《数学学报(英文版)》2005,21(1):155-168
In this paper, we extend a classical result of Hua to arithmetic progressions with large moduli. The result implies the Linnik Theorem on the least prime in an arithmetic progression. 相似文献
6.
We construct a new family of cyclic difference sets with parameters ((3
d
– 1)/2, (3
d – 1 – 1)/2, (3
d – 2 – 1)/2) for each odd d. The difference sets are constructed with certain maps that form Jacobi sums. These new difference sets are similar to Maschietti's hyperoval difference sets, of the Segre type, in characteristic two. We conclude by calculating the 3-ranks of the new difference sets. 相似文献
7.
The periodic precipitation pattern formation in gelatinous media is interpreted as a moving boundary problem. The time law,
spacing law and width law are revisited on the basis of the new scenario. The explicit dependence of the geometric structure
on the initial concentrations of the reactants is derived. Matalon—Packter law, which relates the spacing coefficient with
the initial concentrations is reformulated removing many ambiguities and impractical parameters. Experimental results are
discussed to establish the significance of moving boundary concept in the diffusion controlled pattern forming systems 相似文献
8.
Weimin Xue 《中国科学A辑(英文版)》1997,40(7):673-679
A ringR is left co-semihereditary (strongly left co-semihereditary) if every finitely cogenerated factor of a finitely cogenerated
(arbitrary) injective leftR-module is injective. A left co-semihereditary ring, which is not strongly left co-semihereditary, is given to answer a question
of Miller and Tumidge in the negative. If
R
U
S
defines a Morita duality,R is proved to be left co-semihereditary (left semihereditmy) if and only ifS is right semihereditary (right co-semihereditary). Assuming thatS⩾R is an almost excellent extension,S is shown to be (strongly) right co-semihereditary if and only ifR is (strongly) right co-semihereditary.
Project supported by the National Natural Science Foundation of China. 相似文献
9.
本文给出Om×GLn作用于Cm,n上的复多项式环上的最高权向量环的Krull维数公式,从而改正了Aslaksen,Tan及Zhu的一个错误. 相似文献
10.
The FRS-ESR facility at GSI provides one of the most efficient methods for direct mass measurements. In the present experiment,
exotic nuclei were produced via fragmentation of 152Sm projectiles in a thick beryllium target at 500-600 MeV/u, separated in-flight with the fragment separator FRS, and injected
into the storage-cooler ring ESR. Time-resolved Schottky Mass Spectrometry was applied for mass measurements of stored and
electron-cooled bare and few-electron ions. 373 different nuclides were identified by means of the spectra of their revolution
frequencies. Masses for 18 nuclides (84Zr, 92Ru, 94Rh, 107,108,110Sb, 111,112,114I, 118Ba, 122,123La, 124Ce, 127Pr, 129Nd, 132Pm, 134Sm, 137Eu) have been determined for the first time. Masses for 111,112I and 113Xe have been obtained via known α-decay energies. The experiment and first results will be presented. 相似文献