全文获取类型
收费全文 | 10090篇 |
免费 | 863篇 |
国内免费 | 839篇 |
专业分类
化学 | 7704篇 |
晶体学 | 108篇 |
力学 | 286篇 |
综合类 | 66篇 |
数学 | 1689篇 |
物理学 | 1939篇 |
出版年
2024年 | 9篇 |
2023年 | 105篇 |
2022年 | 198篇 |
2021年 | 304篇 |
2020年 | 331篇 |
2019年 | 298篇 |
2018年 | 253篇 |
2017年 | 251篇 |
2016年 | 470篇 |
2015年 | 431篇 |
2014年 | 494篇 |
2013年 | 706篇 |
2012年 | 899篇 |
2011年 | 979篇 |
2010年 | 701篇 |
2009年 | 601篇 |
2008年 | 756篇 |
2007年 | 738篇 |
2006年 | 652篇 |
2005年 | 546篇 |
2004年 | 478篇 |
2003年 | 302篇 |
2002年 | 253篇 |
2001年 | 128篇 |
2000年 | 107篇 |
1999年 | 117篇 |
1998年 | 67篇 |
1997年 | 67篇 |
1996年 | 66篇 |
1995年 | 50篇 |
1994年 | 41篇 |
1993年 | 42篇 |
1992年 | 39篇 |
1991年 | 29篇 |
1990年 | 34篇 |
1989年 | 22篇 |
1988年 | 18篇 |
1987年 | 24篇 |
1986年 | 15篇 |
1985年 | 27篇 |
1984年 | 20篇 |
1983年 | 14篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1975年 | 6篇 |
1974年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 906 毫秒
941.
942.
943.
944.
Jorge J. Betancor Juan C. Fariña Eleonor Harboure Lourdes Rodríguez-Mesa 《Potential Analysis》2013,38(3):711-739
In this paper we prove that the variation operators of the heat semigroup and the truncations of Riesz transforms associated to the Schrödinger operator are bounded on a suitable BMO type space. 相似文献
945.
Lin Juan Wang Chuanrong Yan Kunmei 《Mathematical Methods in the Applied Sciences》2010,33(14):1762-1770
Let the elastic domain be a disk, and its boundary the unit circle. By dint of the stability of Cauchy‐type integral with respect to the perturbation of integral curve, this paper discusses the stability of the complex stress functions to the second fundamental problem in plane elasticity when smooth perturbation happens for the boundary curve. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
946.
947.
The technology of source space distribution imaging measurement is a passive object positioning method with high precision in the near field, which also can get the distribution image of ship's radiated noise sources and locate the ghts of the target. The sea trials have been carried out, and the results validate the feasibility and practicability of this tech-nology. The researches indicate that the measurement precision can be achieved at the meter level within the range of 200 m using the uniform linear array which has the length of 45 m and 10 elements, and the method shows good robustness. The results also provide that the general ship can be simplified as single highlight model at 2-10 kHz in the near field and the catamaran is double highlights while its two propellers are working at the same time. 相似文献
948.
José Fernández-Bertrán Luis M. Alfonso Juan C. Alvarez Edilso Reguera 《Journal of inclusion phenomena and macrocyclic chemistry》2000,37(1-4):131-136
The adducts of urea and solid alkyl derivatives can beobtained mechanochemically in good yields. Theproducts synthesized by grinding the solid reagentshave identical IR spectra and XRD powder patterns tothose obtained by crystallization from ethanolicsolutions. 相似文献
949.
Gil Garrote Herminia Domínguez Juan C. Parajó 《Applied biochemistry and biotechnology》2001,95(3):195-207
Milled corncob samples were mixed with water and heated to obtain a liquid phase containing oligosaccharides, sugars, and
acetic acid as main reaction products (autohydrolysis reaction). To hydrolyze the sugar oligomers to the correspondent monomers,
sulfuric acid was added to the autohydrolysis liquors to reach 0.5–2 wt% of solution, and the reaction media were heated at
101.5–135°C. With this operational procedure, sugar solutions suitable as fermentation media (containing xylose as the major
component) were obtained. The kinetics of the posthydrolysis step was characterized on the basis of experimental data concerning
the time courses of the concentrations of xylooligosaccharides, xylose, furfural, and acetic acid. The concentrations of other
reaction byproducts (glucose or arabinose) were also measured. 相似文献
950.
We have studied the magnetic and electronic properties of double perovskites A2FeReO6 with A=Ba and Ca using ab initio methods based on density functional theory. It has been shown that when changing Ba by Ca the system undergoes a metal–insulator transition coincidentally to a structural phase transition, even if conduction band fillings are not significantly changed. Our results suggest that only considering a quite large correlation term on the Re site could explain an insulating character for Ca2FeReO6. Instead, we found that small correlations could induce a bad metallic behavior as suggested in more recent experiments. 相似文献