全文获取类型
收费全文 | 1375篇 |
免费 | 151篇 |
国内免费 | 71篇 |
专业分类
化学 | 72篇 |
晶体学 | 1篇 |
力学 | 421篇 |
综合类 | 16篇 |
数学 | 814篇 |
物理学 | 273篇 |
出版年
2024年 | 2篇 |
2023年 | 12篇 |
2022年 | 19篇 |
2021年 | 29篇 |
2020年 | 39篇 |
2019年 | 27篇 |
2018年 | 29篇 |
2017年 | 58篇 |
2016年 | 65篇 |
2015年 | 46篇 |
2014年 | 53篇 |
2013年 | 106篇 |
2012年 | 84篇 |
2011年 | 82篇 |
2010年 | 73篇 |
2009年 | 65篇 |
2008年 | 78篇 |
2007年 | 70篇 |
2006年 | 88篇 |
2005年 | 74篇 |
2004年 | 64篇 |
2003年 | 54篇 |
2002年 | 43篇 |
2001年 | 31篇 |
2000年 | 26篇 |
1999年 | 29篇 |
1998年 | 27篇 |
1997年 | 32篇 |
1996年 | 23篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 19篇 |
1992年 | 23篇 |
1991年 | 18篇 |
1990年 | 15篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1957年 | 1篇 |
排序方式: 共有1597条查询结果,搜索用时 78 毫秒
81.
设${\cal F}$为开平面内的区域$D$上的亚纯函数族, ${\cal F}$中任何函数$f(z)\in{\cal F}$, $f$的零点竽数至少为$k+1$.对于$D$内不等于零的解析函数$a(z)$.若$f(z)$与其微分多项式$D(f)$ IM分担$a(z)$,本文不仅得到${\cal F}$在$D$上正规, 而且得到相应于正规函数的结果. 相似文献
82.
Jérôme Demange 《Journal of Functional Analysis》2008,254(3):593-611
We apply the method of [J. Demange, From porous media equation to generalized Sobolev inequalities on a Riemannian manifold, preprint, http://www.lsp.ups-tlse.fr/Fp/Demange/, 2004] and [J. Demange, Porous Media equation and Sobolev inequalities under negative curvature, preprint, http://www.lsp.ups-tlse.fr/Fp/Demange/, 2004], based on the curvature-dimension criterion and the study of Porous Media equation, to the case of a manifold M with strictly positive Ricci curvature. This gives a new way to prove classical Sobolev inequalities on M. Moreover, this enables to improve non-critical Sobolev inequalities as well. As an application, we study the rate of convergence of the solutions of the Porous Media equation to the equilibrium. 相似文献
83.
Yaping Liu 《Proceedings of the American Mathematical Society》2005,133(12):3619-3626
The global stability of a multi-species interacting system has apparently important biological implications. In this paper we study the global stability of Gause-type predator-prey models by providing new criteria for the nonexistence of cycles and limit cycles. Our criteria have clear geometrical interpretations and are easier to apply than other methods employed in recent studies. Using these criteria and related techniques we are able to develop new results on the existence and uniqueness of cycles in Gause-type models with various growth and response functions.
84.
LIU Fu-Su CHEN Wan-Fang 《理论物理通讯》2008,50(11):1237-1240
Abstract This paper points out that the Landau criterion for macroscopic superfluidity of He H is only a criterion for microscopic superfluidity of ^4He, extends the Landau criterion to microscopic superconductivity in fermions (electron and hole) system and system with Cooper pairs without long-range phase coherence. This paper gives another three non-superconductive systems that are of microscopic superconductivity. This paper demonstrates that one application of microscopic superconductivity is to establish room temperature electronics of the high-To cuprates. 相似文献
85.
首先给出了Jam es-S te in估计优于岭估计的充分条件,随后在P itm an准则下给出了Jam es-S te in估计优于最小二乘估计的简短证明. 相似文献
86.
In order to overcome the deficiency in classical method of low order spectral model, a new method for low order spectral model was advanced. Through calculating the multiple correlation coefficients between combinations of different functions and the recorded data under the least square criterion, the truncated functions which can mostly reflect the studied physical phenomenon were objectively distilled from these data. The new method overcomes the deficiency of artificially selecting the truncated functions in the classical low order spectral model. The new method being applied to study the inter-annual variation of summer atmospheric circulation over Northern Hemisphere, the truncated functions were obtained with the atmospheric circulation data of June 1994 and June 1998. The mechanisms for the two-summer atmospheric circulation variations over Northern Hemisphere were obtained with two-layer quasi-geostrophic baroclinic equation. 相似文献
87.
An optimal slewing program is designed within the class of Euler rotations for a spacecraft with elastic elements. The mathematical model constructed accounts for an arbitrary number of partial modes of elastic vibrations. An optimal reorientation problem is formulated using a nontraditional performance criterion, which minimizes the dynamic overloads of the elastic elements in relative motion. An algorithm for solving the corresponding nonlinear boundary-value problem is developed and implemented in a software package of FORTRAN-programs. A neural network is generated in the space of slew parameters; it may be trained during a preflight period. Known radial basis functions are used to model the process of fast in-flight computation of the optimal reorientation program 相似文献
88.
本文采用俞茂宏双剪统一屈服准则求解部分均匀荷载下简支圆板的塑性极限,已有的最大主应力准则、Tresca准则,Mises准则的解答均是该解答的特例或线性逼近。该解答可以适合于多种工程材料,具有普遍性和适用性,从得出的解析解和图示中可得出一些新的有益的认识 相似文献
89.
Zhuang Tao 《Acta Mechanica Sinica》1987,3(1):73-81
In recent years, some investigators discussed the applicability of the HRR theory for engineering materials based on the results
of numerical analyses and experimental studies. In the present paper, the finite element method is employed to analyze the
crack tip fields of the engineering elastic-plastic material with a variety of geometry configurations of cracked specimens
from elastic state to intensely general yielded state in the plane strain case. The results indicate that the HRR theory loses
its validity of application for engineering elastic-plastic materials in the plane strain case. The reasons for this are analyzed.
A dual-parameter fracture criterion is suggested for this case. 相似文献
90.
CANTWELL W J 《中国科学:物理学 力学 天文学(英文版)》2011,(6)
Structural impact tests were first presented to cover typical fibre metal laminates (FMLs) subjected a low velocity projectile impact,which produced the corresponding load-displacement traces and deformation/failure modes for the validation of numerical models.Finite element (FE) models were then developed to simulate the impact behaviour of FMLs tested.The aluminium (alloy grade 2024-0) layer was modelled as an isotropic elasto-plastic material up to the on-set of post failure stage,followed by shear failu... 相似文献