全文获取类型
收费全文 | 6501篇 |
免费 | 1124篇 |
国内免费 | 1192篇 |
专业分类
化学 | 3616篇 |
晶体学 | 53篇 |
力学 | 707篇 |
综合类 | 91篇 |
数学 | 1114篇 |
物理学 | 3236篇 |
出版年
2024年 | 25篇 |
2023年 | 95篇 |
2022年 | 187篇 |
2021年 | 216篇 |
2020年 | 217篇 |
2019年 | 209篇 |
2018年 | 202篇 |
2017年 | 285篇 |
2016年 | 280篇 |
2015年 | 247篇 |
2014年 | 335篇 |
2013年 | 549篇 |
2012年 | 451篇 |
2011年 | 453篇 |
2010年 | 356篇 |
2009年 | 447篇 |
2008年 | 437篇 |
2007年 | 440篇 |
2006年 | 387篇 |
2005年 | 351篇 |
2004年 | 344篇 |
2003年 | 281篇 |
2002年 | 272篇 |
2001年 | 220篇 |
2000年 | 229篇 |
1999年 | 202篇 |
1998年 | 193篇 |
1997年 | 134篇 |
1996年 | 103篇 |
1995年 | 94篇 |
1994年 | 95篇 |
1993年 | 81篇 |
1992年 | 69篇 |
1991年 | 45篇 |
1990年 | 44篇 |
1989年 | 31篇 |
1988年 | 27篇 |
1987年 | 22篇 |
1986年 | 19篇 |
1985年 | 24篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 21篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 23篇 |
1978年 | 8篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1973年 | 8篇 |
排序方式: 共有8817条查询结果,搜索用时 15 毫秒
1.
Yuta Yamamoto Shogo Nakano Fumio Seki Yasuteru Shigeta Sohei Ito Hiroaki Tokiwa Makoto Takeda 《Molecules (Basel, Switzerland)》2021,26(5)
Infection of hosts by morbilliviruses is facilitated by the interaction between viral hemagglutinin (H-protein) and the signaling lymphocytic activation molecule (SLAM). Recently, the functional importance of the n-terminal region of human SLAM as a measles virus receptor was demonstrated. However, the functional roles of this region in the infection process by other morbilliviruses and host range determination remain unknown, partly because this region is highly flexible, which has hampered accurate structure determination of this region by X-ray crystallography. In this study, we analyzed the interaction between the H-protein from canine distemper virus (CDV-H) and SLAMs by a computational chemistry approach. Molecular dynamics simulations and fragment molecular orbital analysis demonstrated that the unique His28 in the N-terminal region of SLAM from Macaca is a key determinant that enables the formation of a stable interaction with CDV-H, providing a basis for CDV infection in Macaca. The computational chemistry approach presented should enable the determination of molecular interactions involving regions of proteins that are difficult to predict from crystal structures because of their high flexibility. 相似文献
2.
3.
用密耦方法计算了非对称同位素替代分子与氦原子碰撞(He-HD,HT,DT)转动激发,当入射能量E=0.3 eV时,得到了上述碰撞体系的微分散射截面或角分布.基于上述理论计算,讨论了原子与双原子分子碰撞的同位素效应. 相似文献
4.
A Dirac picture perturbation theory is developed for the time evolution operator in classical dynamics in the spirit of the Schwinger–Feynman–Dyson perturbation expansion and detailed rules are derived for computations. Complexification formalisms are given for the time evolution operator suitable for phase space analyses, and then extended to a two-dimensional setting for a study of the geometrical Berry phase as an example. Finally a direct integration of Hamilton's equations is shown to lead naturally to a path integral expression, as a resolution of the identity, as applied to arbitrary functions of generalized coordinates and momenta. 相似文献
5.
直流稳压电源可以将交流电压变换为直流电压,并使之稳定,在我们现实生活中应用很广泛,在实验中我们利用的电学知识,设计制造了一种直流稳压电源。本文简要介绍了这种直流稳压电源波形演示器的设计目的和电路原理,重点阐述了它的制作流程、滤波和稳压原理以及性能测试输出波形。 相似文献
6.
S. K. Godunov V. T. Zhukov O. B. Feodoritova 《Computational Mathematics and Mathematical Physics》2006,46(6):971-982
An algorithm is constructed for calculating invariant subspaces of symmetric hyperbolic systems arising in electromagnetic, acoustic, and elasticity problems. Discrete approximations are calculated for subspaces that correspond to minimal eigenvalues and smooth eigenfunctions. Difficulties related to the presence of an infinite-dimensional kernel in the differential operator are successfully handled. The efficiency of the algorithm is demonstrated using acoustics equations. 相似文献
7.
用经验赝势方法计算了体ZnSe以及ZnSe/GaAs单异质结系统中ZnSe外延层г、X、L等特殊对称点导带底能量随压力的变化。结果表明,同Si、Ge、GaAs等半导体材料不同,ZnSe的X点导带底具有正的压力系数,但比г点的压力系数小,这是ZnSe材料以及ZnSe基异质结构材料发生直接禁带向间接禁带的转变时所需转变压力较大的根本原因。研究了ZnSe/GaAs异质结构中晶格失配造成的应变对外延层г、X、L对称点压力系数的影响,表明这种晶格失配造成的应变可以极大地减小ZnSe外延层材料由直接禁带向间接禁带的转变压力。 相似文献
8.
Examples are worked out using a new equation proposed in the previous paper to show that it has new physical predictions for mesoscopic systems. 相似文献
9.
What Is Its Real Existing Form?——Theoretical and Experimental Studies on 2-Mercaptobenzothiazole 总被引:1,自引:0,他引:1
1 INTRODUCTION The study of heterocyclic molecules with aroma- tic rings and their absorptions on metals is of con- siderable importance from both theoretical and te- chnological points of view. These molecules are in- teresting because of their applications as corrosion inhibitors and flotation collectors, and their abilities to form self-assembly layers[1]. 2-Mercaptobenzo- thiazole (C7H5NS2, in the following MBT) is an important heterocyclic molecule, which can be used as corrosion … 相似文献
10.