全文获取类型
收费全文 | 79219篇 |
免费 | 505篇 |
国内免费 | 544篇 |
专业分类
化学 | 25119篇 |
晶体学 | 820篇 |
力学 | 6784篇 |
综合类 | 15篇 |
数学 | 32078篇 |
物理学 | 15452篇 |
出版年
2022年 | 44篇 |
2021年 | 57篇 |
2020年 | 46篇 |
2019年 | 50篇 |
2018年 | 10466篇 |
2017年 | 10281篇 |
2016年 | 6099篇 |
2015年 | 907篇 |
2014年 | 360篇 |
2013年 | 415篇 |
2012年 | 3871篇 |
2011年 | 10600篇 |
2010年 | 5684篇 |
2009年 | 6091篇 |
2008年 | 6671篇 |
2007年 | 8820篇 |
2006年 | 276篇 |
2005年 | 1363篇 |
2004年 | 1590篇 |
2003年 | 2006篇 |
2002年 | 1050篇 |
2001年 | 288篇 |
2000年 | 339篇 |
1999年 | 186篇 |
1998年 | 210篇 |
1997年 | 168篇 |
1996年 | 226篇 |
1995年 | 135篇 |
1994年 | 94篇 |
1993年 | 117篇 |
1992年 | 79篇 |
1991年 | 84篇 |
1990年 | 70篇 |
1989年 | 65篇 |
1988年 | 64篇 |
1987年 | 65篇 |
1986年 | 62篇 |
1985年 | 51篇 |
1984年 | 51篇 |
1983年 | 39篇 |
1982年 | 41篇 |
1981年 | 41篇 |
1980年 | 48篇 |
1979年 | 45篇 |
1978年 | 35篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Thi Thu Van Nguyen Jean-Jacques Strodiot Van Hien Nguyen 《Journal of Global Optimization》2009,44(2):175-192
In this article we present a new and efficient method for solving equilibrium problems on polyhedra. The method is based on
an interior-quadratic proximal term which replaces the usual quadratic proximal term. This leads to an interior proximal type
algorithm. Each iteration consists in a prediction step followed by a correction step as in the extragradient method. In a
first algorithm each of these steps is obtained by solving an unconstrained minimization problem, while in a second algorithm
the correction step is replaced by an Armijo-backtracking linesearch followed by an hyperplane projection step. We prove that
our algorithms are convergent under mild assumptions: pseudomonotonicity for the two algorithms and a Lipschitz property for
the first one. Finally we present some numerical experiments to illustrate the behavior of the proposed algorithms. 相似文献
962.
Yan-nan LIU & Huai-yu JIAN Department of Mathematical Sciences Tsinghua University Beijing China 《中国科学A辑(英文版)》2007,50(2):231-239
In this paper, we study the evolution of hypersurface moving by the mean curvature minus an external force field. It is shown that the flow will blow up in a finite time if the mean curvature of the initial surface is larger than some constant depending on the boundness of derivatives of the external force field. For a linear force, we prove that the convexity of the hypersurface is preserved during the evolution and the flow has a unique smooth solution in any finite time and expands to infinity as the time tends to infinity if the initial curvature is smaller than the slope of the force. 相似文献
963.
Towards a unified recurrent neural network theory: The uniformly pseudo-projection-anti-monotone net
In the past decades, various neural network models have been developed for modeling the behavior of human brain or performing
problem-solving through simulating the behavior of human brain. The recurrent neural networks are the type of neural networks
to model or simulate associative memory behavior of human being. A recurrent neural network (RNN) can be generally formalized
as a dynamic system associated with two fundamental operators: one is the nonlinear activation operator deduced from the input-output
properties of the involved neurons, and the other is the synaptic connections (a matrix) among the neurons. Through carefully
examining properties of various activation functions used, we introduce a novel type of monotone operators, the uniformly
pseudo-projectionanti-monotone (UPPAM) operators, to unify the various RNN models appeared in the literature. We develop a
unified encoding and stability theory for the UPPAM network model when the time is discrete. The established model and theory
not only unify but also jointly generalize the most known results of RNNs. The approach has lunched a visible step towards
establishment of a unified mathematical theory of recurrent neural networks. 相似文献
964.
Zhong-hua Shen 《高校应用数学学报(英文版)》2008,23(3):371-376
In 2000, a remote user authentication scheme using smart cards was proposed and the masquerade attacks were proved successful on this scheme. Recently, Kumar has suggested the idea of check digits to overcome the above attacks with a new scheme that removes these threats well. In this paper it is pointed out that the weakness still exists in Kumar's scheme, and the intruder can login to the remote system through having some information. A new scheme which can overcome these attacks and appears more secure and efficient than Kumar's is presented. 相似文献
965.
Zhao Qiaoling Yan Guojun 《高校应用数学学报(英文版)》2007,22(3):343-352
In this paper,the stochastic flow of mappings generated by a Feller convolution semigroup on a compact metric space is studied.This kind of flow is the generalization of superprocesses of stochastic flows and stochastic diffeomorphism induced by the strong solutions of stochastic differential equations. 相似文献
966.
Yan-Ning Liu Xiao-Long Weng Peng Zhang Wen-Xin Li Yu Gong Li Zhang Tian-Cheng Han Pei-Heng Zhou Long-Jiang Deng 《中国物理快报》2021,(3):44-49
Infrared metamaterial absorber(MMA) based on metal-insulator-metal(MIM) configuration with flexible design,perfect and selective absorption,has attracted much attention recently for passive radiative cooling applications.To cool objects passively,broadband infrared absorption(i.e.8-14 μm) is desirable to emit thermal energy through atmosphere window.We present a novel MMA composed of multilayer MIM resonators periodically arranged on a PbTe/MgF_2 bilayer substrate.Verified by the rigorous coup led-wave analysis method,the proposed MMA shows a relative bandwidth of about 45%(from 8.3 to 13.1 μm with the absorption intensity over 0.8).The broadband absorption performs stably over a wide incident angle range(below 50°) and predicts 12 K cooling below ambient temperature at nighttime.Compared with the previous passive radiative coolers,our design gets rid of the continuous metal substrate and provides an almost ideal transparency window(close to 100%)for millimeter waves over 1 mm.The structure is expected to have potential applications in thermal control of integrated devices,where millimeter wave signal compatibility is also required. 相似文献
967.
Myocardial infarction results from the rupture of an atherosclerotic plaque, which occurs in response to both mechanical stress
and inflammatory processes. In order experimentally observe flow into atherosclerotic coronary artery morphologies, a novel
technique for molding realistic compliant phantom featuring injection-molded inclusions and multiple layers has been developed.
This transparent phantom allows for particle image velocimetry (PIV) flow analysis and can supply experimental data to validate
computational fluid dynamics algorithms and hypothesis. 相似文献
968.
Background
The morphological development of neurons is a very complex process involving both genetic and environmental components. Mathematical modelling and numerical simulation are valuable tools in helping us unravel particular aspects of how individual neurons grow their characteristic morphologies and eventually form appropriate networks with each other.Methods
A variety of mathematical models that consider (1) neurite initiation (2) neurite elongation (3) axon pathfinding, and (4) neurite branching and dendritic shape formation are reviewed. The different mathematical techniques employed are also described.Results
Some comparison of modelling results with experimental data is made. A critique of different modelling techniques is given, leading to a proposal for a unified modelling environment for models of neuronal development.Conclusion
A unified mathematical and numerical simulation framework should lead to an expansion of work on models of neuronal development, as has occurred with compartmental models of neuronal electrical activity.969.
970.
Jason Miller 《Communications in Mathematical Physics》2011,308(3):591-639
We study the massless field on \({D_n = D \cap \tfrac{1}{n} \mathbf{Z}^2}\), where \({D \subseteq \mathbf{R}^2}\) is a bounded domain with smooth boundary, with Hamiltonian \({\mathcal {H}(h) = \sum_{x \sim y} \mathcal {V}(h(x) - h(y))}\). The interaction \({\mathcal {V}}\) is assumed to be symmetric and uniformly convex. This is a general model for a (2 + 1)-dimensional effective interface where h represents the height. We take our boundary conditions to be a continuous perturbation of a macroscopic tilt: h(x) = n x · u + f(x) for \({x \in \partial D_n,\,u \in \mathbf{R}^2}\), and f : R 2 → R continuous. We prove that the fluctuations of linear functionals of h(x) about the tilt converge in the limit to a Gaussian free field on D, the standard Gaussian with respect to the weighted Dirichlet inner product \({(f,g)_\nabla^\beta = \int_D \sum_i \beta_i \partial_i f_i \partial_i g_i}\) for some explicit β = β(u). In a subsequent article, we will employ the tools developed here to resolve a conjecture of Sheffield that the zero contour lines of h are asymptotically described by SLE(4), a conformally invariant random curve. 相似文献