全文获取类型
收费全文 | 618篇 |
免费 | 19篇 |
国内免费 | 1篇 |
专业分类
化学 | 286篇 |
晶体学 | 3篇 |
力学 | 41篇 |
数学 | 164篇 |
物理学 | 144篇 |
出版年
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 29篇 |
2020年 | 34篇 |
2019年 | 16篇 |
2018年 | 20篇 |
2017年 | 22篇 |
2016年 | 21篇 |
2015年 | 24篇 |
2014年 | 29篇 |
2013年 | 53篇 |
2012年 | 43篇 |
2011年 | 44篇 |
2010年 | 40篇 |
2009年 | 35篇 |
2008年 | 40篇 |
2007年 | 26篇 |
2006年 | 31篇 |
2005年 | 25篇 |
2004年 | 18篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有638条查询结果,搜索用时 15 毫秒
71.
Dumitru Ceau?escu Victor Eliu-Ceau?escu 《Fresenius' Journal of Analytical Chemistry》1976,282(1):45-46
Ohne Zusammenfassung
The reliability of results in case of linear physio-chemical titration curves. The interval of confidence of the equivalence point相似文献
72.
Dumitru Ceauescu Victor Eliu-Ceauescu und Marina Eliu-Ceauescu 《Fresenius' Journal of Analytical Chemistry》1984,319(1):78-80
Ohne Zusammenfassung
Diese Arbeit kann im Zusammenhang mit unseren vorangehenden Beiträgen [1–3] über das Vertrauensintervall von Analysenergebnissen gesehen werden 相似文献
Calculation of the content of individual components and their confidence intervals in indirect analysis
Diese Arbeit kann im Zusammenhang mit unseren vorangehenden Beiträgen [1–3] über das Vertrauensintervall von Analysenergebnissen gesehen werden 相似文献
73.
Barbero G Freire FC Scalerandi M Alexe-Ionescu AL 《The journal of physical chemistry. B》2006,110(36):17889-17897
We analyze the influence of the adsorption of ions at the interfaces on the transient phenomena occurring in an electrolytic cell submitted to a steplike external voltage. In the limit of small amplitude of the applied voltage, where the equation of the problem can be linearized, we obtain an analytical solution for the bulk and surface densities of ions and for the electrical potential. We also obtain, in this limit, the relaxation time for the transient phenomena. 相似文献
74.
Sami I. Muslih Om P. Agrawal Dumitru Baleanu 《International Journal of Theoretical Physics》2010,49(8):1746-1752
This paper presents a fractional Schrödinger equation and its solution. The fractional Schrödinger equation may be obtained using a fractional variational principle and a fractional Klein-Gordon equation; both methods are considered here. We extend the variational formulations for fractional discrete systems to fractional field systems defined in terms of Caputo derivatives to obtain the fractional Euler-Lagrange equations of motion. We present the Lagrangian for the fractional Schrödinger equation of order α. We also use a fractional Klein-Gordon equation to obtain the fractional Schrödinger equation which is the same as that obtained using the fractional variational principle. As an example, we consider the eigensolutions of a particle in an infinite potential well. The solutions are obtained in terms of the sines of the Mittag-Leffler function. 相似文献
75.
Israr Ahmad Kamal Shah Ghaus ur Rahman Dumitru Baleanu 《Mathematical Methods in the Applied Sciences》2020,43(15):8669-8682
The main objective of this research work is to establish existence results as well as to study qualitative aspects of the proposed coupled system of fractional hybrid delay differential equations (FHDDEs). Using the hybrid fixed point theory, we establish appropriate results for the existence of at least one solution to our problem. The powerful tools of functional analysis and dynamical systems are applied to derive different kinds of stability analysis. These include Ulam-Hyers (UH), generalized Ulam-Hyers (GUH), Ulam-Hyers-Rassias (UHR), and generalized Ulam-Hyers-Rassias (GUHR). In order to provide the authenticity of the our results, an illustrative example is given to wind up the present research work. 相似文献
76.
Nguyen Huy Tuan Nguyen Hoang Tuan Dumitru Baleanu Tran Ngoc Thach 《Mathematical Methods in the Applied Sciences》2020,43(3):1292-1312
In the present paper, we study the initial inverse problem (backward problem) for a two-dimensional fractional differential equation with Riemann-Liouville derivative. Our model is considered in the random noise of the given data. We show that our problem is not well-posed in the sense of Hadamard. A truncated method is used to construct an approximate function for the solution (called the regularized solution). Furthermore, the error estimate of the regularized solution in L2 and Hτ norms is considered and illustrated by numerical example. 相似文献
77.
In this short note, our aim is to investigate the inverse problem of parameter identification in quasi-variational inequalities. We develop an abstract nonsmooth regularization approach that subsumes the total variation regularization and permits the identification of discontinuous parameters. We study the inverse problem in an optimization setting using the output-least squares formulation. We prove the existence of a global minimizer and give convergence results for the considered optimization problem. We also discretize the identification problem for quasi-variational inequalities and provide the convergence analysis for the discrete problem. We give an application to the gradient obstacle problem. 相似文献
78.
Anca Daniela M?cinic 《Journal of Pure and Applied Algebra》2010,214(10):1818-1826
We analyze k-stage formality and relate resonance with this type of formality properties. For instance, we show that, for a finitely generated nilpotent group that is k-stage formal, the resonance varieties are trivial up to degree k. We also show that the cohomology ring, truncated up to degree k+1, of a finitely generated nilpotent, k-stage formal group is generated in degree 1; this criterion is necessary and sufficient for a finitely generated, 2-step nilpotent group to be k-stage formal. We compute resonance varieties for Heisenberg-type groups and deduce the degree of partial formality for this class of groups. 相似文献
79.
We prove a theorem unifying three results from combinatorial homological and commutative algebra, characterizing the Koszul property for incidence algebras of posets and affine semigroup rings, and characterizing linear resolutions of squarefree monomial ideals. The characterization in the graded setting is via the Cohen-Macaulay property of certain posets or simplicial complexes, and in the more general nongraded setting, via the sequential Cohen-Macaulay property. 相似文献
80.
We consider a class of elliptic inclusions under Dirichlet boundary conditions involving multifunctions of Clarke's generalized gradient. Under conditions given in terms of the first eigenvalue as well as the Fu?ik spectrum of the p ‐Laplacian we prove the existence of a positive, a negative and a sign‐changing solution. Our approach is based on variational methods for nonsmooth functionals (nonsmooth critical point theory, second deformation lemma), and comparison principles for multivalued elliptic problems. In particular, the existence of extremal constant‐sign solutions plays a key role in the proof of sign‐changing solutions (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献