全文获取类型
收费全文 | 13703篇 |
免费 | 3389篇 |
国内免费 | 1647篇 |
专业分类
化学 | 10793篇 |
晶体学 | 149篇 |
力学 | 655篇 |
综合类 | 91篇 |
数学 | 1182篇 |
物理学 | 5869篇 |
出版年
2024年 | 54篇 |
2023年 | 193篇 |
2022年 | 384篇 |
2021年 | 452篇 |
2020年 | 611篇 |
2019年 | 560篇 |
2018年 | 466篇 |
2017年 | 516篇 |
2016年 | 850篇 |
2015年 | 853篇 |
2014年 | 953篇 |
2013年 | 1466篇 |
2012年 | 1070篇 |
2011年 | 1069篇 |
2010年 | 894篇 |
2009年 | 943篇 |
2008年 | 974篇 |
2007年 | 1026篇 |
2006年 | 852篇 |
2005年 | 782篇 |
2004年 | 641篇 |
2003年 | 542篇 |
2002年 | 359篇 |
2001年 | 295篇 |
2000年 | 301篇 |
1999年 | 248篇 |
1998年 | 217篇 |
1997年 | 178篇 |
1996年 | 104篇 |
1995年 | 126篇 |
1994年 | 98篇 |
1993年 | 88篇 |
1992年 | 74篇 |
1991年 | 53篇 |
1990年 | 49篇 |
1989年 | 43篇 |
1988年 | 52篇 |
1987年 | 40篇 |
1986年 | 37篇 |
1985年 | 44篇 |
1984年 | 34篇 |
1983年 | 10篇 |
1982年 | 28篇 |
1981年 | 24篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 12篇 |
1977年 | 12篇 |
1974年 | 7篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
在Brueckner-Hartree-Fock理论框架内, 研究了同位旋非对称核物质中质子和中子单粒子势的动量相关性及其随同位旋非对称度的变化, 在此基础上计算了同位旋对称势, 并讨论了三体核力的影响. 结果表明同位旋对称势对于同位旋非对称度的依赖性很弱, 但对于动量和密度均有较强的依赖性. 当密度固定时, 同位旋对称势随动量增加而减小. 尽管三体核力对于质子和中子单粒子势的动量相关性有较大影响, 但对同位旋对称势的影响很小. 还与目前重离子碰撞输运理论模型中所使用的各种参数化的唯象对称势进行了比较. 相似文献
113.
V. B. Kobychev N. M. Vitkovskaya I. L. Zaitseva B. A. Trofimov 《Journal of Structural Chemistry》2004,45(6):940-944
The profiles of reactions leading to pyrrole anion N-adducts with CO2 and CS2 have been studied by the ab initio (RHF/6-31+G*, MP2/6-31+G*) and density functional (B3LYP/6-31+G*) methods. Addition of the pyrrole anion to the carbon disulfide molecule is accompanied by the appearance of a minimum corresponding to a pre-reaction complex. The transformation of the complex to the N-pyrrolyldithiocarboxylate anion occurs via a low activation barrier, which is due to repolarization of the C=S bonds. The profile of the reaction leading to the pyrrole anion N-adduct with CO2 does not contain any intermediate stationary points throughout the whole route from reagents to products.Original Russian Text Copyright © 2004 by V. B. Kobychev, N. M. Vitkovskaya, I. L. Zaitseva, and B. A. Trofimov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 990–993, November–December, 2004. 相似文献
114.
115.
116.
Precipitate-forming chemical reactions have been studied in chemically cross-linked poly(vinyl alcohol) gel medium. One of the reactive components was incorporated into the gel, the other was allowed to diffuse into it. Depending on the experimental conditions the reaction-diffusion process often results in patterns of different type. Experiments performed in tubes and in thin layers were carried out in order to investigate the effects of various factors (cross-linking density, swelling degree as well as the concentrations of the outer and inner electrolytes) on the morphologies of the precipitate patterns. It was found that precipitation occurs not only in the Liesegang bands, but also between bands. Beside Liesegang-type structures, tree-like patterns have been observed, showing a characteristic periodicity in the density profile obtained by digitalized image analyses. 相似文献
117.
118.
Ro Jin Pak Ayanendranath Basu 《Annals of the Institute of Statistical Mathematics》1998,50(3):503-521
This paper deals with the minimum disparity estimation in linear regression models. The estimators are defined as statistical quantities which minimize the blended weight Hellinger distance between a weighted kernel density estimator of errors and a smoothed model density of errors. It is shown that the estimators of the regression parameters are asymptotic normally distributed and efficient at the model if the weights of the density estimators are appropriately chosen. 相似文献
119.
Spherically symmetric static cosmological models filled with black-body radiation are considered. The models are isotropic
about a central observer but inhomogeneous. It is suggested that the energy density of the free gravitational field, which
is coupled to the isotropic radiation energy density, might play an important role in generating sufficient field (vacuum)
energy (when converted into thermal energy) and initiate processes like inflation. On the central world line the energy density
of the free gravitational field vanishes whereas the proper pressure and density of the isotropic black-body radiation are
constants. Further, it is shown that the cosmological constant is no more arbitrary but given in terms of the central pressure
and density. Also, at its maximum value the energy density of the free gravitational field is proved to be equal to one third
of the combined value of radiation pressure and density. 相似文献
120.
研究了在美国BNL/AGS上能量10.7AGeV的197Au离子诱发核作用,报告了EMU–01国际合作实验关于射弹核碎裂和产生粒子密度等最新实验结果. 相似文献