全文获取类型
收费全文 | 10389篇 |
免费 | 1066篇 |
国内免费 | 859篇 |
专业分类
化学 | 4149篇 |
晶体学 | 43篇 |
力学 | 685篇 |
综合类 | 81篇 |
数学 | 3207篇 |
物理学 | 4149篇 |
出版年
2024年 | 21篇 |
2023年 | 148篇 |
2022年 | 203篇 |
2021年 | 220篇 |
2020年 | 247篇 |
2019年 | 238篇 |
2018年 | 203篇 |
2017年 | 316篇 |
2016年 | 444篇 |
2015年 | 366篇 |
2014年 | 563篇 |
2013年 | 928篇 |
2012年 | 564篇 |
2011年 | 779篇 |
2010年 | 601篇 |
2009年 | 660篇 |
2008年 | 685篇 |
2007年 | 716篇 |
2006年 | 669篇 |
2005年 | 515篇 |
2004年 | 447篇 |
2003年 | 403篇 |
2002年 | 327篇 |
2001年 | 262篇 |
2000年 | 237篇 |
1999年 | 216篇 |
1998年 | 214篇 |
1997年 | 168篇 |
1996年 | 161篇 |
1995年 | 116篇 |
1994年 | 107篇 |
1993年 | 60篇 |
1992年 | 54篇 |
1991年 | 45篇 |
1990年 | 61篇 |
1989年 | 66篇 |
1988年 | 61篇 |
1987年 | 39篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1984年 | 27篇 |
1983年 | 13篇 |
1982年 | 19篇 |
1981年 | 13篇 |
1980年 | 17篇 |
1979年 | 17篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Summary Our purpose is to extend results due to P. Chandra and L. Leindler concerning the order of approximation by means of Fourier series for functions belonging to generalized Lipschitz-classes. 相似文献
52.
Nikolaos S. PAPAGEORGIOU Nikolaos YANNAKAKIS 《数学学报(英文版)》2005,21(5):977-996
This is the first part of a work on second order nonlinear, nonmonotone evolution inclusions defined in the framework of an evolution triple of spaces and with a multivalued nonlinearity depending on both x(t) and x(t). In this first part we prove existence and relaxation theorems. We consider the case of an usc, convex valued nonlinearity and we show that for this problem the solution set is nonempty and compact in C^1 (T, H). Also we examine the Isc, nonconvex case and again we prove the existence of solutions. In addition we establish the existence of extremal solutions and by strengthening our hypotheses, we show that the extremal solutions are dense in C^1 (T, H) to the solutions of the original convex problem (strong relaxation). An example of a nonlinear hyperbolic optimal control problem is also discussed. 相似文献
53.
Huimin Xie Biao Li Robert Geer Bai Xu James Castracane 《Optics and Lasers in Engineering》2003,40(3):163-177
A focused ion beam (FIB) Moiré method is proposed to measure the in-plane deformation of object in a micrometer scale. The FIB Moiré is generated by the interference between a prepared specimen grating and FIB raster scan lines. The principle of the FIB Moiré is described. The sensitivity and accuracy of deformation measurement are discussed in detail. Several specimen gratings with 0.14 and 0.20 μm spacing are used to generate FIB Moiré patterns. The FIB Moiré method is successfully used to measure the residual deformation in a micro-electro-mechanical system structure after removing the SiO2 sacrificial layer with a 5000 lines/mm grating. The results demonstrate the feasibility of this method. 相似文献
54.
The paper addresses the problem of a semi-infinite plane crack along the interface between two isotropic half-spaces. Two methods of solution have been considered in the past: Lazarus and Leblond [1998a. Three-dimensional crack-face weight functions for the semi-infinite interface crack-I: variation of the stress intensity factors due to some small perturbation of the crack front. J. Mech. Phys. Solids 46, 489-511, 1998b. Three-dimensional crack-face weight functions for the semi-infinite interface crack-II: integrodifferential equations on the weight functions and resolution J. Mech. Phys. Solids 46, 513-536] applied the “special” method by Bueckner [1987. Weight functions and fundamental fields for the penny-shaped and the half-plane crack in three space. Int. J. Solids Struct. 23, 57-93] and found the expression of the variation of the stress intensity factors for a wavy crack without solving the complete elasticity problem; their solution is expressed in terms of the physical variables, and it involves five constants whose analytical representation was unknown; on the other hand, the “general” solution to the problem has been recently addressed by Bercial-Velez et al. [2005. High-order asymptotics and perturbation problems for 3D interfacial cracks. J. Mech. Phys. Solids 53, 1128-1162], using a Wiener-Hopf analysis and singular asymptotics near the crack front.The main goal of the present paper is to complete the solution to the problem by providing the connection between the two methods. This is done by constructing an integral representation for Lazarus-Leblond's weight functions and by deriving the closed form representations of Lazarus-Leblond's constants. 相似文献
55.
Yakov Varshavsky 《Geometric And Functional Analysis》2007,17(1):271-319
The goal of this paper is to generalize a theorem of Fujiwara (Deligne’s conjecture) to the situation appearing in a joint
work [KV] with David Kazhdan on the global Langlands correspondence over function fields. Moreover, our proof is more elementary
than the original one and stays in the realm of ordinary algebraic geometry, that is, does not use rigid geometry. We also
give a proof of the Lefschetz–Verdier trace formula and of the additivity of filtered trace maps, thus making the paper essentially
self-contained.
The work was supported by the Israel Science Foundation (Grant No. 555/04)
Received: May 2005 Accepted: August 2005 相似文献
56.
57.
Auguet C. Martorell F. Moll F. Torra V: 《Journal of Thermal Analysis and Calorimetry》2002,70(1):277-290
The miniaturized calorimetric devices furnish a reduced working flat surface and permits measurements with extremely low-mass
quantities. The experimental sensitivity shows relevant position dependence with x-y surface coordinates and with z-distance. The device identification is realized via a 2-D model based in Fourier general equation.
Using the Marquardt method the experimental flat surface device can be identified and the fitted parameters used to simulate
the behavior of the experimental system. From the model, the effects of several dissipation configurations can be evaluated.
Also, via the RC-analogy, a way to 3-D experimental devices is roughly described.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
58.
We derive and analyse four algorithms for computing the current induced on a thin straight wire by a transient electric field.
They all involve solving the thin wire electric field integral equations (EFIEs) and consist of a very accurate differential
equations solver together with various schemes to approximate the vector potential integral equation. We carry out a rigorous
numerical stability analysis of each of these methods. This has not previously been done for solution schemes for the thin
wire EFIEs. Each scheme is shown to be stable and convergent provided the radius of the wire is small enough for the thin
wire equations to be a valid model. 相似文献
59.
Hans C. Fogedby 《Journal of statistical physics》1992,69(1-2):411-425
We elaborate in some detail on a new phase space approach to complexity, due to Y.-C. Zhang. We show in particular that the connection between maximal complexity and power law noise or correlations can be derived from a simple variational principle. For a 1D signal we find 1/f noise, in accordance with Zhang. 相似文献
60.
Polyethyleneimine (PEIM) samples crosslinked by a commercial epoxy resin (Epon 828) were prepared, and their adsorption capacity for acidic gases was studied. The swelling and deswelling characteristics of the crosslinked samples were also examined as part of this program. Reactivation of these adsorbents could be carried out by heat, or by a combination of heat and treatment in dilute alkalies. 相似文献