全文获取类型
收费全文 | 88056篇 |
免费 | 7021篇 |
国内免费 | 6073篇 |
专业分类
化学 | 27242篇 |
晶体学 | 1849篇 |
力学 | 3676篇 |
综合类 | 459篇 |
数学 | 23480篇 |
物理学 | 44444篇 |
出版年
2023年 | 248篇 |
2022年 | 302篇 |
2021年 | 555篇 |
2020年 | 833篇 |
2019年 | 1201篇 |
2018年 | 1136篇 |
2017年 | 861篇 |
2016年 | 630篇 |
2015年 | 590篇 |
2014年 | 1353篇 |
2013年 | 2614篇 |
2012年 | 1419篇 |
2011年 | 2090篇 |
2010年 | 2615篇 |
2009年 | 7268篇 |
2008年 | 8389篇 |
2007年 | 7023篇 |
2006年 | 6295篇 |
2005年 | 4402篇 |
2004年 | 4168篇 |
2003年 | 4398篇 |
2002年 | 5568篇 |
2001年 | 4037篇 |
2000年 | 3798篇 |
1999年 | 3608篇 |
1998年 | 2989篇 |
1997年 | 2111篇 |
1996年 | 1885篇 |
1995年 | 2288篇 |
1994年 | 2247篇 |
1993年 | 1665篇 |
1992年 | 1176篇 |
1991年 | 882篇 |
1990年 | 714篇 |
1989年 | 644篇 |
1988年 | 603篇 |
1987年 | 442篇 |
1985年 | 980篇 |
1984年 | 634篇 |
1983年 | 498篇 |
1982年 | 655篇 |
1981年 | 809篇 |
1980年 | 728篇 |
1979年 | 565篇 |
1978年 | 591篇 |
1977年 | 549篇 |
1976年 | 544篇 |
1975年 | 318篇 |
1974年 | 357篇 |
1973年 | 465篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
K. Batra V. Prasad M. Mohan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):191-198
The scattering of heavy ion with a multilevel Rydberg atom in the presence of an electromagnetic field is studied. The interaction
of Rydberg atom and the e.m field is explored using non-perturbative quasi-energy technique. Although the results are presented
for selected excitations but in actual calculations we have included many levels of the atom. The effect of various parameters
are shown on collisional excitation process. As an illustration detailed calculations are performed for the inelastic proton-Na
Rydberg atom collision accompanied by the transfer of photons and the effects of dressing due to the field are considered.
The emphasis of the present work is on collision induced transitions especially the case that involves change of orbital as
well as principal quantum number.
Received 26 December 2001 / Received in final form 8 April 2002 Published online 19 July 2002 相似文献
112.
F. Iachello S. Oss 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):307-314
We present a brief review of algebraic techniques developed and applied in molecular spectroscopy in the last five years.
We also outline perspectives for new applications of the Lie algebraic method in the first decade of the new century.
Received 21 November 2001 相似文献
113.
114.
关于康托集类光栅的实验探究 总被引:1,自引:1,他引:0
设计制作了康托集分形衍射光栅,通过对康托集分形光栅3个阶段的夫琅禾费衍射现象的观察,根据惠更斯-菲涅耳原理,得到了一维康托集分形光栅的夫琅禾费衍射光强分布特性. 相似文献
115.
利用红外特征峰波数偏移值与单体含量间的非线性定量关系,BP人工神经网络-FTIR法在较宽的含量范围(10%-90%之间)之内,准确测定了苯乙烯-丙烯酸丁酯共聚物中丙烯酸丁酯单体含量,回收率在97.3%-101.8%之间. 相似文献
116.
Ludmila C. Fidale Sarah Köhler Martin H.G. Prechtl Thomas Heinze Omar A. El Seoud 《Cellulose (London, England)》2006,13(5):581-592
The concentrations of water, W, and electrolytes present in solutions of LiCl in N,N-dimethylacetamide, LiCl/DMAc, and of tetrabutylammonium fluoride. x-hydrate in DMSO, TBAF.xW/DMSO can be accurately and expediently determined by three independent methods, UV–vis, FTIR and EMF measurement. The first relies on the use of solvatochromic probes whose spectra are sensitive to solution composition. It is applicable to W/LiCl/DMAc solutions but not to TBAF.xW/DMSO, because the charge-transfer complex bands of the probes are suppressed by strong interactions with the latter electrolyte. Integration of νOH band of water may be employed in order to determine [W], hence [electrolyte] by weight difference. EMF measurement uses ion-selective electrodes in order to determine [electrolyte], hence [W] by weight difference. Results of the latter method were in excellent agreement with those of FTIR. The reason for the failure of Karl Fischer titration is addressed, and the relevance of the results obtained to functionalization of cellulose under homogenous solution conditions is briefly commented on. 相似文献
117.
在聚合物基体中掺入少量的层状硅酸盐所制备的聚合物/粘土纳米复合材料,其阻隔性能明显地优于纯聚合物及其传统的复合材料。实验及分析结果表明,聚合物/粘土纳米复合材料的微观结构和阻隔性能主要受控于粘土剥离后的径厚比.一简单的重整化群模型被用来评估粘土几何因素(诸如径厚比、取向、剥离程度等)对聚合物/粘土纳米复合材料阻隔性能的影响,所得到的逾渗阈值及最佳粘土含量与实验结果吻合。 相似文献
118.
不完全信息群体决策专家权重的集结 总被引:8,自引:5,他引:3
本文对于属性权重信息和属性效用信息都不完全的群体多属性决策问题,通过构造属性值区间和运用系统聚类分析法,对群体决策中的专家进行分类,并确定每位专家的权重. 相似文献
119.
120.
Newton-Leibniz integration rule only applies to commuting functions of continuum variables, while operators made of Dirac’s symbols (ket versus bra, e.g., |q〉〈q| of continuous parameter q) in quantum mechanics are usually not commutative. Therefore, integrations over the operators of type |〉〈| cannot be directly performed by Newton-Leibniz rule. We invented an innovative technique of integration within an ordered product (IWOP) of operators that made the integration of non-commutative operators possible. The IWOP technique thus bridges this mathematical gap between classical mechanics and quantum mechanics, and further reveals the beauty and elegance of Dirac’s symbolic method and transformation theory. Various applications of the IWOP technique, including constructing the entangled state representations and their applications, are presented. 相似文献