全文获取类型
收费全文 | 53951篇 |
免费 | 3562篇 |
国内免费 | 3887篇 |
专业分类
化学 | 20098篇 |
晶体学 | 393篇 |
力学 | 4039篇 |
综合类 | 650篇 |
数学 | 16405篇 |
物理学 | 19815篇 |
出版年
2024年 | 77篇 |
2023年 | 472篇 |
2022年 | 1113篇 |
2021年 | 1131篇 |
2020年 | 1205篇 |
2019年 | 1247篇 |
2018年 | 1099篇 |
2017年 | 1268篇 |
2016年 | 1402篇 |
2015年 | 1082篇 |
2014年 | 1796篇 |
2013年 | 3397篇 |
2012年 | 2124篇 |
2011年 | 2355篇 |
2010年 | 1922篇 |
2009年 | 3092篇 |
2008年 | 3298篇 |
2007年 | 3740篇 |
2006年 | 3153篇 |
2005年 | 2494篇 |
2004年 | 2086篇 |
2003年 | 2370篇 |
2002年 | 2803篇 |
2001年 | 2160篇 |
2000年 | 2065篇 |
1999年 | 1741篇 |
1998年 | 1686篇 |
1997年 | 1037篇 |
1996年 | 955篇 |
1995年 | 815篇 |
1994年 | 855篇 |
1993年 | 630篇 |
1992年 | 685篇 |
1991年 | 470篇 |
1990年 | 455篇 |
1989年 | 337篇 |
1988年 | 296篇 |
1987年 | 296篇 |
1986年 | 266篇 |
1985年 | 251篇 |
1984年 | 254篇 |
1983年 | 153篇 |
1982年 | 213篇 |
1981年 | 201篇 |
1980年 | 134篇 |
1979年 | 166篇 |
1978年 | 144篇 |
1977年 | 130篇 |
1976年 | 84篇 |
1973年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
G. Tiana M.H. Jensen K. Sneppen 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):135-140
A feedback mechanism that involves the proteins p53 and mdm2, induces cell death as a controlled response to severe DNA damage.
A minimal model for this mechanism demonstrates that the response may be dynamic and connected with the time needed to translate
the mdm2 protein. The response takes place if the dissociation constant k between p53 and mdm2 varies from its normal value. Although it is widely believed that it is an increase in k that triggers the response, we show that the experimental behaviour is better described by a decrease in the dissociation
constant. The response is quite robust upon changes in the parameters of the system, as required by any control mechanism,
except for few weak points, which could be connected with the onset of cancer.
Received 8 May 2002 / Received in final form 9 July 2002 Published online 17 September 2002 相似文献
82.
83.
Patrick Dehornoy 《Algebra Universalis》2002,48(2):223-248
We solve the word problem of the identity x(yz) = (xy)(yz) by investigating a certain group describing the geometry of that identity. We also construct a concrete realization of the
one-generated free algebra relative to the above identity.
Received March 23, 2001; accepted in final form July 6, 2002. 相似文献
84.
85.
A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity. 相似文献
86.
A. Khrennikov 《Annalen der Physik》2003,12(10):575-585
We study the probabilistic consequences of the choice of the basic number field in the quantum formalism. We demonstrate that by choosing a number field for a linear space representation of quantum model it is possible to describe various interference phenomena. We analyse interference of probabilistic alternatives induced by real, complex, hyperbolic (Clifford) and p‐adic representations. 相似文献
87.
平行机半在线排序问题研究(Ⅰ) 总被引:15,自引:1,他引:14
对半在线平行机排序问题的研究进展作了详细综述和进一步探讨。文章给出半在线排序问题的背景、定义、分类和求解。介绍它们定义和在不同机器环境和目标函数下半在线排序问题分类,以及第一类半在线模型的近似算法的设计及其竞争比分析。 相似文献
88.
姜德元 《浙江大学学报(理学版)》2003,30(5):499-502
研究了NA序列重对数律收敛速度的一般形式,把Davis和Gut的结果推广到了NA的情形,并使梁汉营等人关于对数律一个结果成为特例;作为推论,得到了关于NA序列重对数律收敛速度的充分条件. 相似文献
89.
By further generalizing the skew-symmetric triangular splitting iteration method studied by Krukier, Chikina and Belokon (Applied Numerical Mathematics, 41 (2002), pp. 89–105), in this paper, we present a new iteration scheme, called the modified skew-Hermitian triangular splitting iteration method, for solving the strongly non-Hermitian systems of linear equations with positive definite coefficient matrices. We discuss the convergence property and the optimal parameters of this new method in depth. Moreover, when it is applied to precondition the Krylov subspace methods like GMRES, the preconditioning property of the modified skew-Hermitian triangular splitting iteration is analyzed in detail. Numerical results show that, as both solver and preconditioner, the modified skew-Hermitian triangular splitting iteration method is very effective for solving large sparse positive definite systems of linear equations of strong skew-Hermitian parts. 相似文献
90.
Teresa Regińska 《BIT Numerical Mathematics》2004,44(1):119-133
The paper concerns conditioning aspects of finite-dimensional problems arising when the Tikhonov regularization is applied
to discrete ill-posed problems. A relation between the regularization parameter and the sensitivity of the regularized solution
is investigated. The main conclusion is that the condition number can be decreased only to the square root of that for the
nonregularized problem. The convergence of solutions of regularized discrete problems to the exact generalized solution is
analyzed just in the case when the regularization corresponds to the minimal condition number. The convergence theorem is
proved under the assumption of the suitable relation between the discretization level and the data error. As an example the
method of truncated singular value decomposition with regularization is considered.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献