全文获取类型
收费全文 | 800篇 |
免费 | 11篇 |
国内免费 | 3篇 |
专业分类
化学 | 455篇 |
晶体学 | 9篇 |
力学 | 30篇 |
数学 | 109篇 |
物理学 | 211篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 14篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 15篇 |
2015年 | 13篇 |
2014年 | 16篇 |
2013年 | 44篇 |
2012年 | 44篇 |
2011年 | 55篇 |
2010年 | 21篇 |
2009年 | 31篇 |
2008年 | 39篇 |
2007年 | 41篇 |
2006年 | 50篇 |
2005年 | 42篇 |
2004年 | 46篇 |
2003年 | 32篇 |
2002年 | 29篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 6篇 |
1998年 | 14篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 6篇 |
1979年 | 14篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1974年 | 9篇 |
1971年 | 3篇 |
1967年 | 4篇 |
1961年 | 3篇 |
排序方式: 共有814条查询结果,搜索用时 281 毫秒
1.
Papert's (1978) appeal to reconsider the power and possibilities of the aesthetic in mathematics learning is often ignored in mathematics education research. This paper begins with the premise, put forth by Dewey (1934), that the aesthetic structures many dimensions of inquiry and experience. In the same way that using particular paintings, musical compositions, or even everyday experiences has been instrumental to attempts by philosophers to understand the aesthetic dimensions of meaning and experience in artistic domains, I propose that analysing a particular encounter with mathematics may help reveal the nature and role of the often nebulous responses of elegance, beauty, and `fit' to which mathematicians lay claim in their mathematical activity. To achieve this, I draw on and adapt the defining features of the aesthetic character of experience set forth by the aesthetician Beardsley (1982). This, in turn, sheds light on the role thataesthetics can play in mathematical inquiry and experience, and provides initial categories and conjectures that can be used to investigate the potential roles of aesthetics in mathematics learning contexts.This revised version was published online in September 2005 with corrections to the Cover Date. 相似文献
2.
Let
d−1{(x1,…,xd)
d:x21+···+x2d=1} be the unit sphere of the d-dimensional Euclidean space
d. For r>0, we denote by Brp (1p∞) the class of functions f on
d−1 representable in the formwhere dσ(y) denotes the usual Lebesgue measure on
d−1,
and Pλk(t) is the ultraspherical polynomial.For 1p,q∞, the Kolmogorov N-width of Brp in Lq(
d−1) is given bythe left-most infimum being taken over all N-dimensional subspaces XN of Lq(
d−1).The main result in this paper is that for r2(d−1)2,where ANBN means that there exists a positive constant C, independent of N, such that C−1ANBNCAN.This extends the well-known Kashin theorem on the asymptotic order of the Kolmogorov widths of the Sobolev class of the periodic functions. 相似文献
3.
P.A. Sinclair 《Discrete Mathematics》2004,286(3):177-184
Let G be a connected graph with minimum degree at least 3. We prove that there exists an even circuit C in G such that G−E(C) is either connected or contains precisely two components one of which is isomorphic to a 1-bond. We further prove sufficient conditions for there to exist an even circuit C in a 2-connected simple graph G such that G−E(C) is 2-connected. As a consequence of this, we obtain sufficient conditions for there to exist an even circuit C in a 2-connected graph G for which G−E(C) is 2-connected. 相似文献
4.
Philip Sinclair 《Discrete Mathematics》2004,286(3):171-175
Let G be a 2-connected graph with minimum degree at least 3. We prove that there exists an even circuit C in G with factorization F={F1,F2} such that G−E(F1) is 2-connected. 相似文献
5.
Al2O3 incorporated HfO2 films grown by atomic layer deposition (ALD) were investigated by high-resolution X-ray photoelectron spectroscopy (HRXPS). The core level energy state of a 15 Å thick film showed a shift to higher binding energy, as the result of a silicate formation and Al2O3 incorporation. The incorporation of Al2O3 into the HfO2 film had no effect on silicate formation at the interface between the film and Si, while the ionic bonding characteristics and hybridization effects were enhanced compared to a pure HfO2 film. The dissociation of the film in an ultrahigh vacuum (UHV) is effectively suppressed compared to a pure HfO2 film, indicating an enhanced thermal stability of Hf-Al-O. Any dissociated Al2O3 on the film surface was completely removed into the vacuum by vacuum annealing treatment over 850 °C, while HfO2 contributed to Hf silicide formation on the film surface. 相似文献
6.
7.
Gavin D. Henry Author Vitae 《Tetrahedron》2004,60(29):6043-6061
8.
We couple a morphological study of an immiscible binary AB mixture with a micromechanical simulation to determine how the spatial distribution of the A and B domains and the interfacial region (interphase) affects the mechanical behavior of the blend. The morphological studies are conducted through a three-dimensional Cahn-Hilliard (CH) simulation. Through the CH calculations, we obtain the size and structure of the domains for different blend compositions. The output of the CH model serves as the input to the Lattice Spring Model (LSM), which consists of a three-dimensional network of springs. In particular, the location of the different phases is mapped onto the LSM lattice and the appropriate force constants are assigned to the LSM sites. A stress is applied to the LSM lattice and we calculate the elastic response of the material. We find that the local stress and strain fields are highly dependent on the morphology of the system. By integrating the morphological and mechanical models, we can isolate how modifications in the composition of the mixture affect the macroscopic behavior. Thus, we can establish how choices made in the components affect the ultimate performance of the material. 相似文献
9.