全文获取类型
收费全文 | 4500篇 |
免费 | 739篇 |
国内免费 | 911篇 |
专业分类
化学 | 2432篇 |
晶体学 | 27篇 |
力学 | 432篇 |
综合类 | 83篇 |
数学 | 1392篇 |
物理学 | 1784篇 |
出版年
2024年 | 18篇 |
2023年 | 55篇 |
2022年 | 133篇 |
2021年 | 145篇 |
2020年 | 136篇 |
2019年 | 145篇 |
2018年 | 127篇 |
2017年 | 162篇 |
2016年 | 187篇 |
2015年 | 160篇 |
2014年 | 233篇 |
2013年 | 337篇 |
2012年 | 305篇 |
2011年 | 322篇 |
2010年 | 256篇 |
2009年 | 315篇 |
2008年 | 302篇 |
2007年 | 317篇 |
2006年 | 271篇 |
2005年 | 259篇 |
2004年 | 244篇 |
2003年 | 219篇 |
2002年 | 206篇 |
2001年 | 171篇 |
2000年 | 173篇 |
1999年 | 150篇 |
1998年 | 142篇 |
1997年 | 96篇 |
1996年 | 102篇 |
1995年 | 86篇 |
1994年 | 65篇 |
1993年 | 47篇 |
1992年 | 53篇 |
1991年 | 28篇 |
1990年 | 25篇 |
1989年 | 20篇 |
1988年 | 17篇 |
1987年 | 16篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 16篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 16篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1973年 | 4篇 |
排序方式: 共有6150条查询结果,搜索用时 31 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.
杨晓光 《应用数学学报(英文版)》1997,13(4):337-341
1.IntroductionIntillspaperweanalyzetheconvergenceonmultiplicativeiterativealgorithmsfortheIninimizationofadiffcrentiablefunctiondefinedonthepositiveorthantofR".ThealgorithmissllggestedbyEggermolltl'],andisrelatedtotheEM[2](Expextation--Maximization)algoritllnlforPositronemissiontonlography[']andimagereconstructi..14].Wecollsidertheproblenl"linf(x)s.t.x20.Themultiplicativeiterativealgorithmshavethel'orlniforj=l,2,',n,withAhdeterminedthroughalinesearch.Whilelusem[5]establishedanelegantconv… 相似文献
3.
4.
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
5.
6.
曾六川 《数学物理学报(A辑)》2002,22(1):99-106
该文研究Banach空间中一类强增生型变分包含解的存在性及其具误差的Ishikawa迭代程序的收敛性问题.该文结果是几位作者早期与最近的相应结果的改进和推广. 相似文献
7.
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
8.
Johan Helsing 《BIT Numerical Mathematics》2006,46(2):307-323
A sparse mesh-neighbour based approximate inverse preconditioner is proposed for a type of dense matrices whose entries come
from the evaluation of a slowly decaying free space Green’s function at randomly placed points in a unit cell. By approximating
distant potential fields originating at closely spaced sources in a certain way, the preconditioner is given properties similar
to, or better than, those of a standard least squares approximate inverse preconditioner while its setup cost is only that
of a diagonal block approximate inverse preconditioner. Numerical experiments on iterative solutions of linear systems with
up to four million unknowns illustrate how the new preconditioner drastically outperforms standard approximate inverse preconditioners
of otherwise similar construction, and especially so when the preconditioners are very sparse.
AMS subject classification (2000) 65F10, 65R20, 65F35, 78A30 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.
The semi‐iterative method (SIM) is applied to the hyper‐power (HP) iteration, and necessary and sufficient conditions are given for the convergence of the semi‐iterative–hyper‐power (SIM–HP) iteration. The root convergence rate is computed for both the HP and SIM–HP methods, and the quotient convergence rate is given for the HP iteration. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献