全文获取类型
收费全文 | 5586篇 |
免费 | 653篇 |
国内免费 | 501篇 |
专业分类
化学 | 134篇 |
晶体学 | 2篇 |
力学 | 898篇 |
综合类 | 128篇 |
数学 | 4447篇 |
物理学 | 1131篇 |
出版年
2024年 | 10篇 |
2023年 | 67篇 |
2022年 | 68篇 |
2021年 | 98篇 |
2020年 | 120篇 |
2019年 | 157篇 |
2018年 | 161篇 |
2017年 | 158篇 |
2016年 | 186篇 |
2015年 | 125篇 |
2014年 | 210篇 |
2013年 | 482篇 |
2012年 | 228篇 |
2011年 | 247篇 |
2010年 | 255篇 |
2009年 | 304篇 |
2008年 | 360篇 |
2007年 | 403篇 |
2006年 | 365篇 |
2005年 | 302篇 |
2004年 | 268篇 |
2003年 | 294篇 |
2002年 | 272篇 |
2001年 | 203篇 |
2000年 | 200篇 |
1999年 | 189篇 |
1998年 | 176篇 |
1997年 | 176篇 |
1996年 | 108篇 |
1995年 | 96篇 |
1994年 | 58篇 |
1993年 | 55篇 |
1992年 | 50篇 |
1991年 | 47篇 |
1990年 | 35篇 |
1989年 | 25篇 |
1988年 | 27篇 |
1987年 | 28篇 |
1986年 | 19篇 |
1985年 | 19篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1982年 | 14篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 14篇 |
1977年 | 4篇 |
1976年 | 10篇 |
1975年 | 2篇 |
排序方式: 共有6740条查询结果,搜索用时 15 毫秒
81.
具有转向点超曲面的奇摄动椭圆型方程边值问题 总被引:5,自引:0,他引:5
本文利用多重尺度法和比较定理,研究了n维空间中一类具有转向点超曲面的奇摄动椭圆方程边值问题,研究了该值问题解的渐近性态。 相似文献
82.
A numerical method based on cubic splines with nonuniform grid is given for singularly-perturbed nonlinear two-point boundary-value problems. The original nonlinear equation is linearized using quasilinearization. Difference schemes are derived for the linear case using a variable-mesh cubic spline and are used to solve each linear equation obtained via quasilinearization. Second-order uniform convergence is achieved. Numerical examples are given in support of the theoretical results. 相似文献
83.
We study Hamiltonians with singular spectra of Cantor type with a constant ratio of dissection. The decay properties of the states in such systems depend on the nature of the dissection rate that can be characterized in terms of the algebraic number theory. We show that in spite of simplicity of the considered model the computational modeling of nondecaying states is in general impossible. 相似文献
84.
In the present paper, we solve three boundary value problems related to the temperature field in oil strata — the fractional
extensions of the incomplete lumped formulation and lumped formulation in the linear case and the fractional generalization
of the incomplete lumped formulation in the radial case. By using the Caputo differintegral operator and the Laplace transform,
the solutions are obtained in integral forms where the integrand is expressed in terms of the convolution of some auxiliary
functions of Wright function type. A generalization of the Laplace transform convolution theorem, known as Efros’ theorem
is widely used. 相似文献
85.
本文用另一方法证明了非对称矩阵的奇异值是处处强半光滑的,并利用这一性质给出求解逆奇异值问题的相对广义牛顿法,该方法具有Q-二阶收敛速度. 相似文献
86.
含余割核奇异积分修改的反演问题 总被引:1,自引:0,他引:1
针对含余害核奇异积分反演问题在指κ<0时一般无解的情况,本文提出并求解两种修改的反演问题,而后一种修改反演问题的提法与此前类似问题颇不相同,由于运用了推广的留数定理和Bertrand型换序公式使本问题及类似问题解法得以简化。 相似文献
87.
88.
T. Linss 《BIT Numerical Mathematics》2007,47(2):379-391
A non-monotone FEM discretization of a singularly perturbed one-dimensional reaction-diffusion problem whose solution exhibits
strong layers is considered. The method is shown to be maximum-norm stable although it is not inverse monotone. Both a priori
and a posteriori error bounds in the maximum norm are derived. The a priori result can be used to deduce uniform convergence
of various layer-adapted meshes proposed in the literature. Numerical experiments complement the theoretical results.
AMS subject classification (2000) 65L10, 65L50, 65L60 相似文献
89.
为了求解各向异性接合材料界面端部奇异性应力场,建立了一种新型杂交元模型.该模型的独特之处在于:基于有限元特征法得到的奇异性场数值特征解建立了一种新型界面端奇异单元.通过算例证明,新型杂交元模型能够利用较少的单元数获得较为精确的数值结果.当前模型应用范围广泛,能够用于复杂结构的界面端部场求解. 相似文献
90.
Consider discrete storage processes that are modulated by environmental processes. Environmental processes cause interruptions in the input and/or output processes of the discrete storage processes. Due to the difficulties encountered in the exact analysis of such discrete storage systems, often Poisson flow and/or fluid flow models with the same modulating environmental processes are proposed as approximations for these systems. The analysis of Poisson flow and fluid flow models is much easier than that of the discrete storage processes. In this paper we give sufficient conditions under which the content of the discrete storage processes can be bounded by the Poisson flow and the fluid flow models. For example, we show that Poisson flow models and the fluid flow models developed by Kosten (and by Anick, Mitra and Sondhi) can be used to bound the performance of infinite (finite) source packetized voice/data communication systems. We also show that a Poisson flow model and the fluid flow model developed by Mitra can be used to bound the buffer content of a two stage automatic transfer line. The potential use of the bounding techniques presented in this paper, of course, transcends well beyond these examples.Supported in part by NSF grant DMS-9308149. 相似文献