全文获取类型
收费全文 | 1411篇 |
免费 | 38篇 |
国内免费 | 5篇 |
专业分类
化学 | 894篇 |
力学 | 39篇 |
数学 | 328篇 |
物理学 | 193篇 |
出版年
2022年 | 12篇 |
2021年 | 14篇 |
2020年 | 8篇 |
2019年 | 21篇 |
2018年 | 16篇 |
2017年 | 15篇 |
2016年 | 32篇 |
2015年 | 40篇 |
2014年 | 39篇 |
2013年 | 96篇 |
2012年 | 89篇 |
2011年 | 118篇 |
2010年 | 67篇 |
2009年 | 64篇 |
2008年 | 111篇 |
2007年 | 84篇 |
2006年 | 75篇 |
2005年 | 71篇 |
2004年 | 86篇 |
2003年 | 41篇 |
2002年 | 49篇 |
2001年 | 14篇 |
2000年 | 21篇 |
1999年 | 18篇 |
1998年 | 17篇 |
1997年 | 10篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 14篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1985年 | 9篇 |
1984年 | 12篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 19篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1971年 | 4篇 |
1936年 | 3篇 |
排序方式: 共有1454条查询结果,搜索用时 15 毫秒
91.
92.
Serge Lawrencenko Michael D. Plummer Xiaoya Zha 《Discrete and Computational Geometry》2002,28(3):313-330
Abstract. Let G be an infinite locally finite plane graph with one end and let H be a finite plane subgraph of G . Denote by a(H) the number of finite faces of H and by l(H) the number of the edges of H that are on the boundary of the infinite face or a finite face not in H . Define the isoperimetric constant h (G) to be inf
H
l(H) / a(H) and define the isoperimetric constant h (δ) to be inf
G
h (G) where the infimum is taken over all infinite locally finite plane graphs G having minimum degree δ and exactly one end. We establish the following bounds on h (δ) for δ ≥ 7 :
相似文献
93.
This paper provides computable representations for the evaluation of the probability content of cones in isotropic random fields. A decomposition of quadratic forms in spherically symmetric random vectors is obtained and a representation of their moments is derived in terms of finite sums. These results are combined to obtain the distribution function of quadratic forms in spherically symmetric or central elliptically contoured random vectors. Some numerical examples involving the sample serial covariance are provided. Ratios of quadratic forms are also discussed. 相似文献
94.
M. Serge Dubuc 《Probability Theory and Related Fields》1971,19(4):281-290
Sans résumé 相似文献
95.
An induction period has been observed in the pyrolysis of ethane in a continuous-flow stirred tank reactor at 530°C. The rate constants of the initiation, determining propagation and termination steps, have been determined. 相似文献
96.
Serge Vasilach 《Rendiconti del Circolo Matematico di Palermo》1979,28(3):377-386
In our preceding paper [2], we have studied the fundamental properties of the heterogeneous algebras, and constructed the projective limits in the category of these algebras and in the category of abstract automata. The present article is devoted to the study ofdirect limits in the same categories. 相似文献
97.
Serge Steinblatt 《Optics Communications》1983,47(6):391-394
An experimental method to measure the optical anisotropy profiles of optical fibers and preforms is presented. The local values of nz?nr and nz?n?, (r,?,z) being a cylindrical coordinate system associated with the fiber or preform, are obtained. 相似文献
98.
99.
Le Grand F George G Akoka S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,174(1):171-176
Deuterium site-specific natural isotope abundance (Ai) is routinely measured by NMR spectroscopy and quantified using an internal reference peak. This study demonstrates that the substitution of the chemical compound used as internal reference by an electronically generated signal (the ERETIC method) allows a dramatic reduction of the experimental time. Measurements of Ai on eight samples of methylsalicylate have been performed using either an internal reference (TMU) or ERETIC. No significant difference in accuracy or precision had been found between the two methods. However, because the method is applicable in partially saturated conditions, the experiment time was divided by a factor of 4 and the drawbacks associated with an internal chemical reference were avoided when ERETIC was used. 相似文献
100.