全文获取类型
收费全文 | 4301篇 |
免费 | 131篇 |
国内免费 | 37篇 |
专业分类
化学 | 2741篇 |
晶体学 | 9篇 |
力学 | 172篇 |
数学 | 928篇 |
物理学 | 619篇 |
出版年
2023年 | 25篇 |
2022年 | 96篇 |
2021年 | 95篇 |
2020年 | 102篇 |
2019年 | 90篇 |
2018年 | 89篇 |
2017年 | 66篇 |
2016年 | 179篇 |
2015年 | 148篇 |
2014年 | 180篇 |
2013年 | 276篇 |
2012年 | 314篇 |
2011年 | 324篇 |
2010年 | 158篇 |
2009年 | 197篇 |
2008年 | 270篇 |
2007年 | 259篇 |
2006年 | 217篇 |
2005年 | 201篇 |
2004年 | 205篇 |
2003年 | 144篇 |
2002年 | 102篇 |
2001年 | 47篇 |
2000年 | 38篇 |
1999年 | 35篇 |
1998年 | 39篇 |
1997年 | 37篇 |
1996年 | 49篇 |
1995年 | 22篇 |
1994年 | 28篇 |
1993年 | 16篇 |
1992年 | 31篇 |
1991年 | 21篇 |
1990年 | 23篇 |
1989年 | 21篇 |
1988年 | 21篇 |
1987年 | 18篇 |
1986年 | 15篇 |
1985年 | 34篇 |
1984年 | 28篇 |
1983年 | 27篇 |
1982年 | 30篇 |
1981年 | 15篇 |
1980年 | 20篇 |
1979年 | 11篇 |
1978年 | 19篇 |
1977年 | 13篇 |
1976年 | 14篇 |
1974年 | 11篇 |
1967年 | 4篇 |
排序方式: 共有4469条查询结果,搜索用时 0 毫秒
921.
Carlos G. Dassori Julio A. Deiber Alberto E. Cassano 《International Journal of Multiphase Flow》1984,10(2):181-193
The two-phase flow through a symmetric sinusoidal channel is studied by means of a regular perturbation analysis, where the small parameter is defined as the ratio between the amplitude of variation of the channel wall and the average thickness of the non-wetting phase. Results are valid for Reynolds numbers of the same order of magnitude as that of the expansion parameter. It is thus found that the fluid-fluid interface presents a wavy shape characterized by an amplitude and a phase-shift with respect to the fixed solid-fluid interface. Instabilities of the two-phase flow can arise for large values of the viscosity, flow rate and phase thickness ratios. Results are expected to be a first step towards the understanding of the hydrodynamics of trickle bed reactors, where several flow regimes are possible. 相似文献
922.
The swinging of bells on belfries is a classical problem in structural dynamics and has been addressed in the Central European
specialized bibliography. To carry out our study, the different modalities of swinging bells have been classified in “systems”
according to their most relevant characteristics in three groups: Central European, English and Spanish systems. Each group
presents some singular characteristics of frequency and oscillation, unbalance and/or turning rate, which give rise to different
forces variable in time on their supporting structures. We have analyzed the three systems and, compared the maximum values
of the horizontal and vertical forces that appear on the structure as well as its main harmonics. Besides the parameters analyzed,
the complete dynamic study of the structure, and therefore the evaluation of its dynamic amplification factor (D.A.F.), requires
the knowledge of its dynamic characteristics: main frequencies and damping ratio. 相似文献
923.
924.
This note is related to a nice short paper of M. Ochiai. We prove in a very fast way that the two-parameter family of Heegaard diagrams, constructed by Ochiai, encodes the genuine three-sphere. The result is obtained, up to isotopy, by using a sequence of only three moves in this order: a Whitehead–Zieschang reduction, a band sum and a cancellation of a handle. 相似文献
925.
Alberto Cialdea 《Rendiconti del Circolo Matematico di Palermo》1986,35(1):32-49
Polynomials solutions of the elliptic equation (1.1) are considered in a domain whose boundary has edges but no cusps. It is shown that by using such solutions it is possible to built complete systems of vectors in suitable function spaces. 相似文献
926.
We consider general surfaces, S, of high degree containing a given complete intersection space curve, Y. We study integral curves in the subgroup of Pic(S) generated by Y and the plane section. We determine the cohomological invariants of these curves and classify the subcanonical ones. Then using these subcanonical curves we produce stable rank two vector bundles on P
3. 相似文献
927.
Enrico De Micheli Giovanni Alberto Viano 《Journal of Mathematical Analysis and Applications》2004,299(2):630-650
In this paper we study a class of Hausdorff-transformed power series whose convergence is extremely slow for large values of the argument. We perform a Watson-type resummation of these expansions, and obtain, by the use of the Pollaczek polynomials, a new representation whose convergence is much faster. We can thus propose a new algorithm for the numerical evaluation of these expansions, which include series playing a relevant role in the computation of the partition function in statistical mechanics. By the same procedure we obtain also a solution of the classical Hausdorff moment problem. 相似文献
928.
We study a noncommutative version of the bispectral problem and consider the corresponding ad-conditions in the case when
both operators have order one. These terms are explained in an extended abstract given below. 相似文献
929.
Alberto Cavicchioli Dušan Repovš Thomas L. Thickstun 《Journal of Mathematical Sciences》2007,144(5):4413-4422
In this paper, we describe the history and the present status of one of the main classical problems in low-dimensional geometric
topology—the recognition of topological 3-manifolds in the class of all generalized 3-manifolds (i.e., ANR homology 3-manifolds).
This problem naturally splits into the cell-like resolution problem for 3-manifolds by means of homology 3-manifolds and the
general-position problem for topological 3-manifolds. We have also included some open problems.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 4, pp. 71–84, 2005. 相似文献
930.
Alberto Seeger 《Aequationes Mathematicae》1991,42(1):47-71
Summary The Schur complement relative to the linear mappingA of a functionf is denotedAf and defined as the image off underA. In this paper we give some estimates for the second-order differential ofAf whenf is either a partially quadratic convex function or aC
2 convex function with a nonsingular second-order differential. We then consider an arbitrary convex functionf and study the second-order differentiability ofAf in a more general sense. 相似文献