全文获取类型
收费全文 | 18923篇 |
免费 | 1916篇 |
国内免费 | 1907篇 |
专业分类
化学 | 1964篇 |
晶体学 | 35篇 |
力学 | 1292篇 |
综合类 | 432篇 |
数学 | 15310篇 |
物理学 | 3713篇 |
出版年
2024年 | 19篇 |
2023年 | 175篇 |
2022年 | 188篇 |
2021年 | 305篇 |
2020年 | 356篇 |
2019年 | 438篇 |
2018年 | 409篇 |
2017年 | 515篇 |
2016年 | 578篇 |
2015年 | 428篇 |
2014年 | 848篇 |
2013年 | 1349篇 |
2012年 | 868篇 |
2011年 | 1036篇 |
2010年 | 969篇 |
2009年 | 1236篇 |
2008年 | 1336篇 |
2007年 | 1419篇 |
2006年 | 1218篇 |
2005年 | 1123篇 |
2004年 | 899篇 |
2003年 | 898篇 |
2002年 | 837篇 |
2001年 | 704篇 |
2000年 | 686篇 |
1999年 | 643篇 |
1998年 | 569篇 |
1997年 | 477篇 |
1996年 | 375篇 |
1995年 | 271篇 |
1994年 | 245篇 |
1993年 | 176篇 |
1992年 | 154篇 |
1991年 | 135篇 |
1990年 | 102篇 |
1989年 | 80篇 |
1988年 | 73篇 |
1987年 | 63篇 |
1986年 | 56篇 |
1985年 | 85篇 |
1984年 | 85篇 |
1983年 | 30篇 |
1982年 | 60篇 |
1981年 | 31篇 |
1980年 | 38篇 |
1979年 | 43篇 |
1978年 | 22篇 |
1977年 | 25篇 |
1976年 | 19篇 |
1974年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
1.
2.
探讨了经济增长及金融发展与城乡收入差距之间互动影响,刻画了三者间的逻辑关系,并基于广西1990-2017年的统计数据,运用状态空间模型及卡尔曼滤波算法对三者间动态关系进行了实证分析.结果显示:经济增长对城乡收入差距呈现倒U型曲线形态,而金融发展则显示出具有不断缩小城乡收入差距的趋势. 相似文献
3.
4.
5.
《Mathematical Methods in the Applied Sciences》2018,41(9):3246-3269
The purpose of this paper is to describe the oscillatory properties of second‐order Euler‐type half‐linear differential equations with perturbations in both terms. All but one perturbations in each term are considered to be given by finite sums of periodic continuous functions, while coefficients in the last perturbations are considered to be general continuous functions. Since the periodic behavior of the coefficients enables us to solve the oscillation and non‐oscillation of the considered equations, including the so‐called critical case, we determine the oscillatory properties of the equations with the last general perturbations. As the main result, we prove that the studied equations are conditionally oscillatory in the considered very general setting. The novelty of our results is illustrated by many examples, and we give concrete new corollaries as well. Note that the obtained results are new even in the case of linear equations. 相似文献
6.
7.
In this paper, we study the local linear convergence properties of a versatile class of Primal–Dual splitting methods for minimizing composite non-smooth convex optimization problems. Under the assumption that the non-smooth components of the problem are partly smooth relative to smooth manifolds, we present a unified local convergence analysis framework for these methods. More precisely, in our framework, we first show that (i) the sequences generated by Primal–Dual splitting methods identify a pair of primal and dual smooth manifolds in a finite number of iterations, and then (ii) enter a local linear convergence regime, which is characterized based on the structure of the underlying active smooth manifolds. We also show how our results for Primal–Dual splitting can be specialized to cover existing ones on Forward–Backward splitting and Douglas–Rachford splitting/ADMM (alternating direction methods of multipliers). Moreover, based on these obtained local convergence analysis result, several practical acceleration techniques are discussed. To exemplify the usefulness of the obtained result, we consider several concrete numerical experiments arising from fields including signal/image processing, inverse problems and machine learning. The demonstration not only verifies the local linear convergence behaviour of Primal–Dual splitting methods, but also the insights on how to accelerate them in practice. 相似文献
8.
《Mathematische Nachrichten》2018,291(8-9):1177-1190
We introduce homogeneous Besov and Triebel–Lizorkin spaces with variable indexes. We show that their study reduces to the study of inhomogeneous variable exponent spaces and homogeneous constant exponent spaces. Corollaries include trace space characterizations and Sobolev embeddings. 相似文献
9.
In this paper we study the domain of the generator of stable processes, stable-like processes and more general pseudo- and integro-differential operators which naturally arise both in analysis and as infinitesimal generators of Lévy- and Lévy-type (Feller) processes. In particular we obtain conditions on the symbol of the operator ensuring that certain (variable order) Hölder and Hölder–Zygmund spaces are in the domain. We use tools from probability theory to investigate the small-time asymptotics of the generalized moments of a Lévy or Lévy-type process , for functions f which are not necessarily bounded or differentiable. The pointwise limit exists for fixed if f satisfies a Hölder condition at x. Moreover, we give sufficient conditions which ensure that the limit exists uniformly in the space of continuous functions vanishing at infinity. As an application we prove that the domain of the generator of contains certain Hölder spaces of variable order. Our results apply, in particular, to stable-like processes, relativistic stable-like processes, solutions of Lévy-driven SDEs and Lévy processes. 相似文献
10.
For a general dyadic grid, we give a Calderón–Zygmund type decomposition, which is the principle fact about the multilinear maximal function on the upper half‐spaces. Using the decomposition, we study the boundedness of . We obtain a natural extension to the multilinear setting of Muckenhoupt's weak‐type characterization. We also partially obtain characterizations of Muckenhoupt's strong‐type inequalities with one weight. Assuming the reverse Hölder's condition, we get a multilinear analogue of Sawyer's two weight theorem. Moreover, we also get Hytönen–Pérez type weighted estimates. 相似文献