全文获取类型
收费全文 | 10847篇 |
免费 | 1057篇 |
国内免费 | 781篇 |
专业分类
化学 | 2393篇 |
晶体学 | 32篇 |
力学 | 835篇 |
综合类 | 225篇 |
数学 | 6284篇 |
物理学 | 2916篇 |
出版年
2024年 | 10篇 |
2023年 | 109篇 |
2022年 | 124篇 |
2021年 | 222篇 |
2020年 | 279篇 |
2019年 | 289篇 |
2018年 | 260篇 |
2017年 | 329篇 |
2016年 | 425篇 |
2015年 | 286篇 |
2014年 | 535篇 |
2013年 | 951篇 |
2012年 | 469篇 |
2011年 | 665篇 |
2010年 | 590篇 |
2009年 | 665篇 |
2008年 | 673篇 |
2007年 | 710篇 |
2006年 | 619篇 |
2005年 | 566篇 |
2004年 | 484篇 |
2003年 | 476篇 |
2002年 | 436篇 |
2001年 | 352篇 |
2000年 | 317篇 |
1999年 | 252篇 |
1998年 | 245篇 |
1997年 | 192篇 |
1996年 | 180篇 |
1995年 | 154篇 |
1994年 | 116篇 |
1993年 | 100篇 |
1992年 | 88篇 |
1991年 | 84篇 |
1990年 | 45篇 |
1989年 | 53篇 |
1988年 | 37篇 |
1987年 | 31篇 |
1986年 | 33篇 |
1985年 | 35篇 |
1984年 | 26篇 |
1983年 | 15篇 |
1982年 | 24篇 |
1981年 | 24篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 14篇 |
1977年 | 17篇 |
1974年 | 7篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
91.
Julia Novak Barbara Kensington-Miller Tanya Evans 《International Journal of Mathematical Education in Science & Technology》2017,48(5):647-658
This paper describes students’ perspectives of a one-off flipped lecture in a large undergraduate mathematics service course. The focus was on calculating matrix determinants and was designed specifically to introduce debate and argumentation into a mathematics lecture. The intention was to promote a deeper learning and understanding through engagement with the added hope of instilling some passion for the subject. During the lecture, students were asked to vote with their feet, literally moving around the lecture theatre to form groups according to their shared favourite technique for calculating matrix determinants. Group discussions were then followed by a whole class debate facilitated by the lecturers, before they wrapped up the lecture by resolving the professional disagreements that had come to light during the debate. Following the lecture, data on student perspectives was gathered using both surveys and focus groups. Within this paper, we share the data and reveal the interesting results that emerged from our analysis. Despite remaining unconvinced as to whether flipped lectures are better for learning, students reported greater engagement and increased understanding of the material covered. 相似文献
92.
Juan Carlos Pardo José-Luis Pérez Victor Pérez-Abreu 《Journal of Functional Analysis》2017,272(1):339-362
We investigate the process of eigenvalues of a fractional Wishart process defined by , where B is the matrix fractional Brownian motion recently studied in [18]. Using stochastic calculus with respect to the Young integral we show that, with probability one, the eigenvalues do not collide at any time. When the matrix process B has entries given by independent fractional Brownian motions with Hurst parameter , we derive a stochastic differential equation in the Malliavin calculus sense for the eigenvalues of the corresponding fractional Wishart process. Finally, a functional limit theorem for the empirical measure-valued process of eigenvalues of a fractional Wishart process is obtained. The limit is characterized and referred to as the non-commutative fractional Wishart process, which constitutes the family of fractional dilations of the free Poisson distribution. 相似文献
93.
94.
Yeliz Kara 《代数通讯》2017,45(8):3627-3635
In this article, we focus on modules with the property that every projection invariant submodule is essential in a fully invariant direct summand. In contrast to π-extending condition, it is shown that the former property is inherited by direct summands and Morita invariant. An application of our results yields that the endomorphism ring of a free module enjoys the property. Moreover, we characterize generalized triangular matrix rings with the aforementioned property and apply to somewhat special cases. 相似文献
95.
In this paper, we investigate the mean squared derivative cost functions that arise in various applications such as in motor control, biometrics and optimal transport theory. We provide qualitative properties, explicit analytical formulas and computational algorithms for the cost functions. We also perform numerical simulations to illustrate the analytical results. In addition, as a by‐product of our analysis, we obtain an explicit formula for the inverse of a Wronskian matrix that is of independent interest in linear algebra and differential equations theory. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
96.
Bilender P. Allahverdiev Hüseyin Tuna 《Mathematical Methods in the Applied Sciences》2017,40(18):7287-7306
In this paper, we introduce a q‐analog of 1‐dimensional Dirac equation. We investigate the existence and uniqueness of the solution of this equation. Later, we discuss some spectral properties of the problem, such as formally self‐adjointness, the case that the eigenvalues are real, orthogonality of eigenfunctions, Green function, existence of a countable sequence of eigenvalues, and eigenfunctions forming an orthonormal basis of . Finally, we give some examples. 相似文献
97.
98.
Pavel Trojovský 《Journal of Difference Equations and Applications》2017,23(10):1737-1746
This paper is devoted to a generalization of some previous results, as we completely solve a linear homogeneous difference equation of the second order with an exponential coefficient. 相似文献
99.
Ryusuke Kon 《Journal of Difference Equations and Applications》2017,23(10):1747-1759
In a certain class of semelparous Leslie matrix models, either a positive equilibrium is stable and an invariant set on the boundary of the nonnegative cone is unstable or vice versa generically if the model dimension is two or three. This dynamic dichotomy is expected to be failed in the four-dimensional case. Our study focuses on a semelparous Leslie matrix model with specific nonlinearities and rigorously proves that the dynamic dichotomy does not hold in the four-dimensional case. This result is derived by showing that the four-dimensional semelparous Leslie matrix model can be uniformly persistent with respect to the boundary of the nonnegative cone even if there exists an unstable positive equilibrium. In such a situation, there are no missing age-classes but population oscillation occurs. 相似文献
100.
由于近年来实际问题特别是大数据应用的发展,矩阵优化问题越来越得到优化研究者,甚至是其他领域的研究者的高度关注,成为热点问题.优化问题的扰动性分析是优化理论研究的基础与核心,为包括算法设计在内的优化研究提供重要的理论基础.由于矩阵优化问题的非多面体性,使得相应扰动分析理论的研究本质上与经典的多面体优化问题(非线性规划)不同.结合文献[1,2],简要介绍矩阵优化扰动性分析方面取得的若干最新进展. 相似文献