全文获取类型
收费全文 | 8110篇 |
免费 | 751篇 |
国内免费 | 1094篇 |
专业分类
化学 | 75篇 |
力学 | 208篇 |
综合类 | 187篇 |
数学 | 8281篇 |
物理学 | 1204篇 |
出版年
2024年 | 9篇 |
2023年 | 81篇 |
2022年 | 79篇 |
2021年 | 126篇 |
2020年 | 170篇 |
2019年 | 231篇 |
2018年 | 233篇 |
2017年 | 242篇 |
2016年 | 260篇 |
2015年 | 181篇 |
2014年 | 385篇 |
2013年 | 622篇 |
2012年 | 340篇 |
2011年 | 485篇 |
2010年 | 459篇 |
2009年 | 647篇 |
2008年 | 618篇 |
2007年 | 641篇 |
2006年 | 541篇 |
2005年 | 483篇 |
2004年 | 397篇 |
2003年 | 429篇 |
2002年 | 400篇 |
2001年 | 273篇 |
2000年 | 293篇 |
1999年 | 277篇 |
1998年 | 231篇 |
1997年 | 218篇 |
1996年 | 141篇 |
1995年 | 72篇 |
1994年 | 68篇 |
1993年 | 40篇 |
1992年 | 36篇 |
1991年 | 24篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 19篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 16篇 |
1984年 | 28篇 |
1983年 | 15篇 |
1982年 | 23篇 |
1981年 | 14篇 |
1980年 | 20篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1936年 | 4篇 |
排序方式: 共有9955条查询结果,搜索用时 31 毫秒
51.
从量子力学诞生日起,它的经典对应(或类比)一直是物理学家关心的话题.本文以介观电路量子化的框架中,带有互感的两个介观电容-电感(LC)电路为例,首次讨论了量子纠缠的经典类比(或对应)问题.先用有序算符内的积分理论证明其互感是产生量子纠缠的源头;再推导出求解特征频率的公式,就发现它与一个经典系统的小振动频率的表达式有相似之处,该经典系统组成如下:两个墙壁各连一个相同的弹簧,两个弹簧之间接着一个滑动小车可以在光滑的桌面上运动,小车挂有一根单摆.用分析力学求此系统的小振动频率,发现与上述介观电路的特征频率形式类似,单摆的摆动会造成小车来回振动,摆、小车和弹簧的互相牵制效应反映了小车和摆的"纠缠". 相似文献
52.
In the present paper, we investigate the blow-up dynamics for local solutions to the semilinear generalized Tricomi equation with combined nonlinearity. As a result, we enlarge the blow-up region in comparison to the ones for the corresponding semilinear models with either power nonlinearity or nonlinearity of derivative type. Our approach is based on an iteration argument to establish lower bound estimates for the space average of local solutions. Finally, we obtain upper bound estimates for the lifespan of local solutions as byproduct of our iteration argument. 相似文献
53.
《Annals of Pure and Applied Logic》2022,173(3):103071
In standard epistemic logic, the names and the existence of agents are usually assumed to be common knowledge implicitly. This is unreasonable for various applications in computer science and philosophy. Inspired by term-modal logic and assignment operators in dynamic logic, we introduce a lightweight modal predicate logic where names can be non-rigid, and the existence of agents can be uncertain. The language can handle various de dicto/de re distinctions in a natural way. We characterize the expressive power of our language, obtain complete axiomatisations of the logics over several classes of varying-domain/constant-domain epistemic models, and show their (un)decidability. 相似文献
54.
We develop the exact WKB analysis of an M2P1T (merging two simple poles and one simple turning point) Schrödinger equation. In Part II, using a WKB-theoretic transformation to the algebraic Mathieu equation constructed in Part I, we calculate the alien derivative of its Borel transformed WKB solutions at each fixed singular point relevant to the simple poles through the analysis of Borel transformed WKB solutions of the Legendre equations. In the course of the calculation of the alien derivative we make full use of microdifferential operators whose symbols are given by the infinite series that appear in the coefficients of the algebraic Mathieu equation and the Legendre equation. 相似文献
55.
《Indagationes Mathematicae》2017,28(3):670-679
In this paper, we use the concept of quasi-compact operators, as a generalization of the class of Riesz operators, to improve the definition of the pseudo-Schechter essential spectrum of a closed densely defined operator acting on Banach space. Moreover, we discuss the incidence of some perturbation results on the behavior of pseudo-essential spectra of the sum of two bounded linear operators. 相似文献
56.
《Mathematische Nachrichten》2017,290(11-12):1732-1752
This paper provides various “contractivity” results for linear operators of the form where C are positive contractions on real ordered Banach spaces X . If A generates a positive contraction semigroup in Lebesgue spaces , we show (M. Pierre's result) that is a “contraction on the positive cone ”, i.e. for all provided that . We show also that this result is not true for 1 ⩽ . We give an extension of M. Pierre's result to general ordered Banach spaces X under a suitable uniform monotony assumption on the duality map on the positive cone . We deduce from this result that, in such spaces, is a contraction on for any positive projection C with norm 1. We give also a direct proof (by E. Ricard) of this last result if additionally the norm is smooth on the positive cone. For any positive contraction C on base‐norm spaces X (e.g. in real spaces or in preduals of hermitian part of von Neumann algebras), we show that for all where N is the canonical half‐norm in X . For any positive contraction C on order‐unit spaces X (e.g. on the hermitian part of a algebra), we show that is a contraction on . Applications to relative operator bounds, ergodic projections and conditional expectations are given. 相似文献
57.
《Mathematische Nachrichten》2017,290(16):2560-2566
In this paper, we describe a second main theorem of holomorphic curves in , of hyper‐order strictly less than 1, that involves a general linear operator . As an application, we derive a truncated second main theorem of degenerate holomorphic curves of hyper‐order strictly less than 1 using Nochka weights. 相似文献
58.
《Mathematische Nachrichten》2017,290(14-15):2388-2400
In this paper, we study the high‐dimensional Hausdorff type operators and establish their boundedness on the power weighted Hardy spaces for . As a consequence, we obtain that the Hausdorff type operator is bounded on if Φ is the Gauss function, or the Poisson function. 相似文献
59.
《Mathematische Nachrichten》2017,290(4):507-519
We show a picture of the relations among different types of summability of series in the space of integrable functions with respect to a vector measure m of relatively norm compact range. In order to do that, we study the class of the so‐called m‐1‐summing operators. We give several applications regarding the existence of copies of c 0 in , as well as on m‐1‐summing operators which are weakly compact, Asplund or weakly precompact. 相似文献
60.
《Mathematische Nachrichten》2017,290(1):37-49
We prove that Burenkov's extension operator preserves Sobolev spaces built on general Morrey spaces, including classical Morrey spaces. The analysis concerns bounded and unbounded open sets with Lipschitz boundaries in the n‐dimensional Euclidean space. 相似文献