全文获取类型
收费全文 | 3733篇 |
免费 | 468篇 |
国内免费 | 389篇 |
专业分类
化学 | 246篇 |
晶体学 | 2篇 |
力学 | 217篇 |
综合类 | 111篇 |
数学 | 3257篇 |
物理学 | 757篇 |
出版年
2024年 | 2篇 |
2023年 | 55篇 |
2022年 | 70篇 |
2021年 | 86篇 |
2020年 | 119篇 |
2019年 | 92篇 |
2018年 | 119篇 |
2017年 | 115篇 |
2016年 | 131篇 |
2015年 | 68篇 |
2014年 | 170篇 |
2013年 | 320篇 |
2012年 | 155篇 |
2011年 | 208篇 |
2010年 | 193篇 |
2009年 | 241篇 |
2008年 | 234篇 |
2007年 | 267篇 |
2006年 | 257篇 |
2005年 | 222篇 |
2004年 | 180篇 |
2003年 | 169篇 |
2002年 | 173篇 |
2001年 | 136篇 |
2000年 | 125篇 |
1999年 | 115篇 |
1998年 | 103篇 |
1997年 | 80篇 |
1996年 | 67篇 |
1995年 | 57篇 |
1994年 | 49篇 |
1993年 | 29篇 |
1992年 | 25篇 |
1991年 | 15篇 |
1990年 | 17篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 18篇 |
1985年 | 19篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 3篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1957年 | 3篇 |
排序方式: 共有4590条查询结果,搜索用时 234 毫秒
11.
Manuel
Bernard Ghislain Lartigue Guillaume Balarac Vincent Moureau Guillaume Puigt 《国际流体数值方法杂志》2020,92(11):1551-1583
In this article, a new framework to design high-order approximations in the context of node-centered finite volumes on simplicial meshes is proposed. The major novelty of this method is that it relies on very simple and compact differential operators, which is a critical point to achieve good performances in the High-performance computing context. This method is based on deconvolution between nodal and volume-average values, which can be conducted to any order. The interest of the new method is illustrated through three different applications: mesh-to-mesh interpolation, levelset curvature computation, and numerical scheme for convection. Higher order can also be achieved within the present framework by introducing high-rank tensors. Although these tensors feature much symmetries, their manipulation can quickly become an overwhelming task. For this reason and without loss of generality, the present articles are limited to third-order expansion. This method, although tightly connected to the k-exact schemes theory, does not rely on successive corrections: the high-order property is obtained in a single operation, which makes them more attractive in terms of performances. 相似文献
12.
13.
14.
15.
We consider the problem of sending a message from a sender to a receiver through an unreliable network by specifying in a protocol what each vertex is supposed to do if it receives the message from one of its neighbors. A protocol for routing a message in such a graph is finite if it never floods with an infinite number of copies of the message. The expected reliability of a given protocol is the probability that a message sent from reaches when the edges of the network fail independently with probability .We discuss, for given networks, the properties of finite protocols with maximum expected reliability in the case when is close to 0 or 1, and we describe networks for which no one protocol is optimal for all values of . In general, finding an optimal protocol for a given network and fixed probability is challenging and many open problems remain. 相似文献
16.
A novel microfluidic droplet generator is proposed, which can control the droplet size through turning an integrated micrometer head with ease, and the size of the produced micro-droplet can be automatically and real-time monitored by an open-sourced software and off-the-shelf hardware. 相似文献
17.
We generalize Nagel’s formula for the Szegö kernel and use it to compute the Szegö kernel on a class of non-compact CR manifolds whose tangent space decomposes into one complex direction and several totally real directions. We also discuss the control metric on these manifolds and relate it to the size of the Szegö kernel. 相似文献
18.
19.
Rishikesh Yadav Ramakanta Meher Vishnu Narayan Mishra 《Mathematical Methods in the Applied Sciences》2019,42(18):7172-7191
In this paper, we study the approximation properties of bivariate summation‐integral–type operators with two parameters . The present work deals within the polynomial weight space. The rate of convergence is obtained while the function belonging to the set of all continuous and bounded function defined on ([0],∞)(×[0],∞) and function belonging to the polynomial weight space with two parameters, also convergence properties, are studied. To know the asymptotic behavior of the proposed bivariate operators, we prove the Voronovskaya type theorem and show the graphical representation for the convergence of the bivariate operators, which is illustrated by graphics using Mathematica. Also with the help of Mathematica, we discuss the comparison by means of the convergence of the proposed bivariate summation‐integral–type operators and Szász‐Mirakjan‐Kantorovich operators for function of two variables with two parameters to the function. In the same direction, we compute the absolute numerical error for the bivariate operators by using Mathematica and is illustrated by tables and also the comparison takes place of the proposed bivariate operators with the bivariate Szász‐Mirakjan operators in the sense of absolute error, which is represented by table. At last, we study the simultaneous approximation for the first‐order partial derivative of the function. 相似文献
20.
Smooth backfitting has been shown to have better theoretical properties than classical backfitting for fitting additive models based on local linear regression. In this article, we show that the smooth backfitting procedure in the local linear case can be alternatively performed as a classical backfitting procedure with a different type of smoother matrices. These smoother matrices are symmetric and shrinking and some established results in the literature are readily applicable. The connections allow the smooth backfitting algorithm to be implemented in a much simplified way, give new insights on the differences between the two approaches in the literature, and provide an extension to local polynomial regression. The connections also give rise to a new estimator at data points. Asymptotic properties of general local polynomial smooth backfitting estimates are investigated, allowing for different orders of local polynomials and different bandwidths. Cases of oracle efficiency are discussed. Computer-generated simulations are conducted to demonstrate finite sample behaviors of the methodology and a real data example is given for illustration. Supplementary materials for this article are available online. 相似文献