全文获取类型
收费全文 | 8043篇 |
免费 | 349篇 |
国内免费 | 651篇 |
专业分类
化学 | 758篇 |
晶体学 | 7篇 |
力学 | 371篇 |
综合类 | 54篇 |
数学 | 6724篇 |
物理学 | 1129篇 |
出版年
2023年 | 80篇 |
2022年 | 73篇 |
2021年 | 85篇 |
2020年 | 151篇 |
2019年 | 162篇 |
2018年 | 191篇 |
2017年 | 195篇 |
2016年 | 225篇 |
2015年 | 148篇 |
2014年 | 310篇 |
2013年 | 546篇 |
2012年 | 320篇 |
2011年 | 341篇 |
2010年 | 316篇 |
2009年 | 496篇 |
2008年 | 580篇 |
2007年 | 520篇 |
2006年 | 477篇 |
2005年 | 421篇 |
2004年 | 300篇 |
2003年 | 366篇 |
2002年 | 336篇 |
2001年 | 250篇 |
2000年 | 260篇 |
1999年 | 264篇 |
1998年 | 209篇 |
1997年 | 233篇 |
1996年 | 123篇 |
1995年 | 116篇 |
1994年 | 99篇 |
1993年 | 68篇 |
1992年 | 59篇 |
1991年 | 60篇 |
1990年 | 66篇 |
1989年 | 50篇 |
1988年 | 53篇 |
1987年 | 39篇 |
1986年 | 38篇 |
1985年 | 50篇 |
1984年 | 56篇 |
1983年 | 18篇 |
1982年 | 37篇 |
1981年 | 32篇 |
1980年 | 33篇 |
1979年 | 26篇 |
1978年 | 30篇 |
1977年 | 38篇 |
1976年 | 25篇 |
1974年 | 16篇 |
1973年 | 16篇 |
排序方式: 共有9043条查询结果,搜索用时 0 毫秒
991.
In this paper we consider a collocation method for solving Fredholm integral equations of the first kind, which is known to be an ill-posed problem. An “unregularized” use of this method can give reliable results in the case when the rate at which smallest singular values of the collocation matrices decrease is known a priori. In this case the number of collocation points plays the role of a regularization parameter. If the a priori information mentioned above is not available, then a combination of collocation with Tikhonov regularization can be the method of choice. We analyze such regularized collocation in a rather general setting, when a solution smoothness is given as a source condition with an operator monotone index function. This setting covers all types of smoothness studied so far in the theory of Tikhonov regularization. One more issue discussed in this paper is an a posteriori choice of the regularization parameter, which allows us to reach an optimal order of accuracy for deterministic noise model without any knowledge of solution smoothness. 相似文献
992.
Julián Aguirre 《Journal of Mathematical Analysis and Applications》2005,304(1):189-197
We find an error bound for the pseudospectral approximation of a function in terms of Hermite functions, hn(x)=e−x2Hn(x), in certain weighted Sobolev spaces. We use properties of Hermite polynomials, as well as an asymptotic expression for their largest zeroes to achieve the mentioned estimate. 相似文献
993.
994.
设A和B为无限维复Banach空间上的标准算子代数,记Δ~R(·)为下列谱函数之一:σ~R(·),σ_l~R(·),σ_r~R(·),σ_l~R(·)∩σ_r~R(·),(?)σ~R(·),(?)σ~R(·),σ_p~R(·),σ_c~R(·),σ_(ap)~R(·),σ_s~R(·),σ_(ap)~R(·)∩σ_s~R(·),σ_p~R(·)∩σ_c~R(·),σ_p~R(·)∪σ_c~R(·),其中R=A或B.证明了A和B之间的每个保持算子Jordan三乘积(算子乘积)之谱函数△~R(·)的满射Φ必有形式Φ=(?)π,其中(?)是1的立方根(1的平方根)而π或者是A和B之间的代数同构,或者是代数反同构.也获得不定度规空间上的标准算子代数之间保持算子斜乘积之谱函数的映射的完全刻画. 相似文献
995.
In this paper, the authors study monotonicity and convexity of the generalized elliptic integrals and certain combinations of these special functions, such as ma(r) and μa(r). Making use of these results, the authors obtain some sharp inequalities for the so-called Ramanujan's generalized modular functions. 相似文献
996.
Arpi A. Stepanyan 《Journal of Contemporary Mathematical Analysis (Armenian Academy of Sciences)》2007,42(3):151-160
The paper proves that every almost everywhere finite measurable function is representable by an absolute convergent series in the Franklin systems generated by quasi-dyadic, weakly regular partitions. 相似文献
997.
Árpád Baricz 《Journal of Mathematical Analysis and Applications》2007,327(2):1202-1213
This paper is motivated by an open problem of Anderson, Vamanamurthy, and Vuorinen. We prove a chain of inequalities for hypergeometric functions, generalized and normalized Bessel functions, Kummer functions and for some general power series. Some particular cases and refinements are given. 相似文献
998.
If f(z) is an entire function with ρ
1 > 0 as its exponent of convergence of zeros and if 0 ≤ α < ρ
1, then we prove the existence of entire functions each having α as its exponent of convergence of zeros.
相似文献
999.
Potential Analysis - Assume that a bounded domain Ω??N (N ≥ 2) has the property that there exists a signed measure µ with compact support in Ω such that, for every... 相似文献
1000.
L. Kuntz 《Journal of Optimization Theory and Applications》1995,86(1):263-270
A new implicit function theorem for a class of nonsmooth functions is proved. It is used to improve the directional implicit function theorem of Demidova and Demyanov (Ref. 1). 相似文献