全文获取类型
收费全文 | 24680篇 |
免费 | 3274篇 |
国内免费 | 2448篇 |
专业分类
化学 | 11883篇 |
晶体学 | 369篇 |
力学 | 878篇 |
综合类 | 104篇 |
数学 | 1037篇 |
物理学 | 16131篇 |
出版年
2024年 | 24篇 |
2023年 | 147篇 |
2022年 | 428篇 |
2021年 | 417篇 |
2020年 | 456篇 |
2019年 | 520篇 |
2018年 | 554篇 |
2017年 | 637篇 |
2016年 | 795篇 |
2015年 | 721篇 |
2014年 | 1033篇 |
2013年 | 2101篇 |
2012年 | 1317篇 |
2011年 | 1605篇 |
2010年 | 1174篇 |
2009年 | 1641篇 |
2008年 | 1606篇 |
2007年 | 1813篇 |
2006年 | 1567篇 |
2005年 | 1302篇 |
2004年 | 1171篇 |
2003年 | 1056篇 |
2002年 | 1040篇 |
2001年 | 850篇 |
2000年 | 854篇 |
1999年 | 729篇 |
1998年 | 639篇 |
1997年 | 486篇 |
1996年 | 504篇 |
1995年 | 499篇 |
1994年 | 398篇 |
1993年 | 363篇 |
1992年 | 383篇 |
1991年 | 248篇 |
1990年 | 172篇 |
1989年 | 151篇 |
1988年 | 167篇 |
1987年 | 120篇 |
1986年 | 90篇 |
1985年 | 101篇 |
1984年 | 98篇 |
1983年 | 50篇 |
1982年 | 74篇 |
1981年 | 55篇 |
1980年 | 42篇 |
1979年 | 41篇 |
1978年 | 30篇 |
1977年 | 22篇 |
1976年 | 35篇 |
1973年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
71.
It is shown that the potential perturbation that shifts a chosen standing wave in space is a block of potential barrier and well for every wave bump between neighbouring knots. The algorithms shifting the range of the primary localization of a chosen bound state in a potential well of finite width are as well applicable to the scattering functions if states of the continuous spectrum are considered as bound states normalized to unity but distributed on an infinite interval with vanishing density. The potential perturbations of the same type on the half-axis concentrate the scattering wave at the origin, thus creating a bound state embedded into the continuous spectrum (zero width resonance). 相似文献
72.
T. K. Solovykh 《Journal of Applied Spectroscopy》1997,64(5):654-657
The role of impurity ions in formation of the optical properties of rare-earth orthoferrites is investigated. Optical spectra
of the substituted against unsubstituted orthoferrites are presented. The influence of different isovalent substitutions on
the optical absorption of orthoferrites that are promising for magnetooptics is studied.
Institute of Solid-State and Semiconductor Physics of the Academy of Sciences of Belarus, 17, P. Brovka St., Minsk, 220072,
Belarus. Translated from zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 5, pp. 642–645, September–October, 1997. 相似文献
73.
Absolute total electron scattering cross sections for carbon dioxide have been measured at low electron energies using a photoelectron
source. The measurements have been carried out at 27 electron energies varying from 0.91–9.14 eV with an accuracy of ±3%.
The cross sections obtained in the present experiment have been compared with other measurements and theoretical computations. 相似文献
74.
We show that, contrary to earlier reports, application of the one-parameter variational technique to the classical (image) model for H in front of an Al surface leads to energy shifts for the ground state which are very close to those obtained numerically with a more sophisticated model of the system. 相似文献
75.
本文报道了在Zn0.76Cd0.24Se/ZnSe多量子阱(MQWs)中,用不同的Ar+激光线激发,观察到了共振增强的喇曼散射。首次在室温和77K的条件下,用Ar+的457.9nm谱线激发,观察到分别来自ZnSe垒层和Zn0.76Cd0.24Se阱层的限制纵光学声子模(LO)的喇曼散射,并对上述不同的光学模的起因进行了分析。 相似文献
76.
对溴分子在68800-7200cm^-1范围内的两个被观察到的[^2Π3/2]4d偶宇称里堡态的转动光谱进行了计算模拟,确定了转动常数,并且证实了原先对实验光谱的传动结构和电子角动量的标识。 相似文献
77.
讨论了浅海中波导的声波散射问题,我们将该问题归结为一个第一类边界积分方程,利用正同化方法求解,并证明了该方法的收敛性,数值例子表明了该方法的简单与有效性。 相似文献
78.
本文系统研究了MFX体系中Eu3+荧光光谱特征,着重讨论了X-,M2+及杂质缺陷(主要为O2-)对Eu3+发光的影响. 相似文献
79.
W. Kockelmann M. Hofmann O. Moze S.J. Kennedy K.H.J. Buschow 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(1):25-32
The element distributions and the magnetic ordering behaviour of compounds RNi10Si2 (R
=
Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize
in an ordered variant of the ThMn12 structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively,
corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn12 structure. TbNi10Si2 orders antiferromagnetically below T
N
= 4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) /Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi10Si2 do not carry any ordered magnetic moments. The compounds with R
=
Dy, Ho, Er, and Tm are paramagnetic down to 1.6 K and 3.0 K, respectively.
Received 10 July 2002 / Received in final form 12 September 2002 Published online 29 October 2002 相似文献
80.
A simple model has been developed to describe the Zeeman patterns of far-infrared laser magnetic resonance spectra of the monobromomethyl radical CH2Br observed at 447.3 and 671.1μm. A satisfactory agreement between the experimental spectra of the radical and their simulation with this simple model has been achieved. This approach can be used to gain further information about the structure and the spectrum of this interesting radical. 相似文献