全文获取类型
收费全文 | 9492篇 |
免费 | 801篇 |
国内免费 | 1301篇 |
专业分类
化学 | 107篇 |
力学 | 281篇 |
综合类 | 233篇 |
数学 | 9709篇 |
物理学 | 1264篇 |
出版年
2024年 | 14篇 |
2023年 | 88篇 |
2022年 | 95篇 |
2021年 | 132篇 |
2020年 | 205篇 |
2019年 | 260篇 |
2018年 | 259篇 |
2017年 | 277篇 |
2016年 | 305篇 |
2015年 | 194篇 |
2014年 | 429篇 |
2013年 | 719篇 |
2012年 | 401篇 |
2011年 | 537篇 |
2010年 | 524篇 |
2009年 | 725篇 |
2008年 | 707篇 |
2007年 | 734篇 |
2006年 | 620篇 |
2005年 | 571篇 |
2004年 | 449篇 |
2003年 | 535篇 |
2002年 | 465篇 |
2001年 | 315篇 |
2000年 | 351篇 |
1999年 | 344篇 |
1998年 | 270篇 |
1997年 | 264篇 |
1996年 | 168篇 |
1995年 | 93篇 |
1994年 | 86篇 |
1993年 | 52篇 |
1992年 | 54篇 |
1991年 | 34篇 |
1990年 | 26篇 |
1989年 | 25篇 |
1988年 | 24篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 21篇 |
1984年 | 34篇 |
1983年 | 20篇 |
1982年 | 33篇 |
1981年 | 25篇 |
1980年 | 23篇 |
1979年 | 20篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1973年 | 5篇 |
1936年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 562 毫秒
991.
Ionel Sorinel Ciuperca 《Journal of Dynamics and Differential Equations》1998,10(1):73-108
We consider the Schrödinger operator on two types of domains depending on a small parameter : dumbbell domains and thin domains with varying orders of thinness. In both situations we compare the eigenvalues and eigenvectors of the Schrödinger operator with the corresponding eigenvalues and eigenvectors of a limit operator defined on the limit domain. 相似文献
992.
郭兴明 《应用数学和力学(英文版)》1996,17(5):445-450
CHARACTERISTICSOFSUBDIFFERENTIALSOFFUNCTIONS(郭兴明)CHARACTERISTICSOFSUBDIFFERENTIALSOFFUNCTIONS¥GuoXingming(ReceivedJune16,1995... 相似文献
993.
Variable Order and Distributed Order Fractional Operators 总被引:1,自引:0,他引:1
Many physical processes appear to exhibit fractional order behavior thatmay vary with time or space. The continuum of order in the fractionalcalculus allows the order of the fractional operator to be considered asa variable. This paper develops the concept of variable and distributedorder fractional operators. Definitions based on the Riemann–Liouvilledefinition are introduced and the behavior of the new operators isstudied. Several time domain definitions that assign different argumentsto the order q in the Riemann–Liouville definition are introduced. Foreach of these definitions various characteristics are determined. Theseinclude: time invariance of the operator, operator initialization,physical realization, linearity, operational transforms, and memorycharacteristics of the defining kernels.A measure (m
2) for memory retentiveness of the order history isintroduced. A generalized linear argument for the order q allows theconcept of `tailored' variable order fractional operators whose m
2 memory may be chosen for a particular application. Memory retentiveness (m
2) andorder dynamic behavior are investigated and applications are shown.The concept of distributed order operators where the order of thetime based operator depends on an additional independent (spatial)variable is also forwarded. Several definitions and their Laplacetransforms are developed, analysis methods with these operators aredemonstrated, and examples shown. Finally operators of multivariable anddistributed order are defined and their various applications areoutlined. 相似文献
994.
计算具有区间参数结构的固有频率的优化方法 总被引:7,自引:0,他引:7
基于区间函数的单向包含性质,把具有区间非确定参数结构的固有频率所在区间范围问题
转化成两个全局优化问题,并采用一种实数编码遗传算法求取问题的全局解. 用一种能够求
得剪切型结构和弹簧质量系统特征值范围精确解的单调分析方法进行检验. 在一
些文献中,直接采用区间数运算法则和有限元法得到结构区间刚度阵和区间质量阵,并把关
于该区间刚度阵和区间质量阵的广义区间特征值问题的特征值区间作为待求的非确定性结构
的特征值所在的区间范围,该方法易于扩大问题的解域. 算例表明,可望得到结构
固有频率区间范围的准确解. 相似文献
995.
The kinetics of crack growth in a viscoelastic orthotropic plate made of a composite material is analyzed. The external load is the superposition of a cyclic load and a constant tensile load. The level of the tensile load is assumed to exceed the amplitude of the cyclic load. The kinetic curves are compared with the constant tension curves. The effect of the cyclic component is studied.Translated from Prikladnaya Mekhanika, Vol. 40, No. 9, pp. 116–122, September 2004. 相似文献
996.
T. A. Bodnar’ 《Journal of Applied Mechanics and Technical Physics》2007,48(6):818-823
An approximate solution ω = A[ω, μ] of the nonlinear integral Nekrasov equation is obtained by successive replacement of the
kernel of the integral operator by a close one. The solution is sought not directly at the bifurcation point μ1 = 3 of the linearized equation ω = μL[ω] but at the point μ = 1 at which operator A[ω, μ], remaining nonlinear in ω, is linear
in μ.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 6, pp. 50–56, November–December, 2007. 相似文献
997.
An inverse problem for identification of the coefficient in heat-conduction equation is considered. After reducing the problem to a nonlinear ill-posed operator equation, Newton type iterative methods are considered. The implicit iterative method is applied to the linearized Newton equation, and the key step in the process is that a new reasonable a posteriori stopping rule for the inner iteration is presented. Numerical experiments for the new method as well as for Tikhonov method and Bakushikskii method are given, and these results show the obvious advantages of the new method over the other ones. 相似文献
998.
MAXIMAL ELEMENTS OF A FAMILY OF GB-MAJORIZED MAPPINGS IN PRODUCT FC-SPACES AND APPLICATIONS 总被引:1,自引:1,他引:1
丁协平 《应用数学和力学(英文版)》2006,27(12):1607-1618
A new family of GB-majorized mappings from a topological space into a finite continuous topological spaces (in short, FC-space) involving a better admissible set-valued mapping is introduced. Some existence theorems of maximal elements for the family of GB-majorized mappings are proved under noncompact setting of product FCspaces. Some applications to fixed point and system of minimax inequalities are given in product FC-spaces. These theorems improve, unify and generalize many important results in recent literature. 相似文献
999.
This article focuses on the formulation of a hysteretic model used as anisolator restoring force model. The proposed model is based on operatorgoverning input and output functions that depend on the deflection andthe restoring force of the isolator. First, the mathematical formulationis demonstrated, then the hysteretic model proposed is applied toisolators having different types of behavior. The model parameters aresought using the experimental force-deflection loop of each of theisolators studied. Next, the transient response of a flexible structuremounted on an all-metal isolator is predicted by coupling the firstorder differential equation of the restoring force and the second orderdifferential equations of the structure's motion. The experimentalinvestigation validates the proposed hysteretic model applied to theall-metal mount. 相似文献
1000.
In this paper, we obtain that multilinear Calderón-Zygmund operators and their commutators with BMO functions are bounded on products of Herz-Morrey spaces with variable smoothness and integrability. The vector-valued setting of multilinear Calderón-Zygmund operators is also considered. 相似文献