全文获取类型
收费全文 | 310977篇 |
免费 | 2123篇 |
国内免费 | 329篇 |
专业分类
化学 | 144228篇 |
晶体学 | 4670篇 |
力学 | 17164篇 |
综合类 | 3篇 |
数学 | 43836篇 |
物理学 | 103528篇 |
出版年
2021年 | 3206篇 |
2020年 | 3584篇 |
2019年 | 4295篇 |
2018年 | 6376篇 |
2017年 | 6591篇 |
2016年 | 8287篇 |
2015年 | 3836篇 |
2014年 | 7182篇 |
2013年 | 12700篇 |
2012年 | 10702篇 |
2011年 | 12489篇 |
2010年 | 10276篇 |
2009年 | 10401篇 |
2008年 | 12054篇 |
2007年 | 11821篇 |
2006年 | 10563篇 |
2005年 | 9103篇 |
2004年 | 8749篇 |
2003年 | 8144篇 |
2002年 | 8375篇 |
2001年 | 7960篇 |
2000年 | 6299篇 |
1999年 | 4687篇 |
1998年 | 4439篇 |
1997年 | 4305篇 |
1996年 | 3919篇 |
1995年 | 3478篇 |
1994年 | 3521篇 |
1993年 | 3561篇 |
1992年 | 3567篇 |
1991年 | 3936篇 |
1990年 | 3910篇 |
1989年 | 3917篇 |
1988年 | 3648篇 |
1987年 | 3753篇 |
1986年 | 3451篇 |
1985年 | 3995篇 |
1984年 | 4255篇 |
1983年 | 3637篇 |
1982年 | 3850篇 |
1981年 | 3545篇 |
1980年 | 3279篇 |
1979年 | 3765篇 |
1978年 | 3849篇 |
1977年 | 4007篇 |
1976年 | 4057篇 |
1975年 | 3796篇 |
1974年 | 3649篇 |
1973年 | 3795篇 |
1972年 | 3218篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
192.
Differential inequalities for polynomials generalizing the well-known Smirnov, Rahman, Schmeisser, and Bernstein inequalities are obtained.
相似文献193.
Dr. Man-Bo Li Daniels Posevins Dr. Karl P. J. Gustafson Dr. Cheuk-Wai Tai Dr. Andrey Shchukarev Dr. Youai Qiu Dr. Jan-E. Bäckvall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(1):210-215
A highly selective and efficient oxidative carbocyclization/borylation of enallenols catalyzed by palladium immobilized on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was developed for diastereoselective cyclobutenol synthesis. The heterogeneous palladium catalyst can be recovered and recycled without any observed loss of activity or selectivity. The high diastereoselectivity of the reaction is proposed to originate from a directing effect of the enallenol hydroxyl group. Optically pure cyclobutenol synthesis was achieved by the heterogeneous strategy by using chiral enallenol obtained from kinetic resolution. 相似文献
194.
Tereshchenko E. D. Cherniakov S. M. Yurik R. Yu. Rietveld M. T. Häggström I. 《Radiophysics and Quantum Electronics》2020,62(10):667-676
Radiophysics and Quantum Electronics - We present the results of comparing the total electron content measurements based on GLONASS satellite signals and the EISCAT UHF incoherent scatter radar... 相似文献
195.
Driven and non-equilibrium quantum states of matter have attracted growing interest in both theoretical and experimental studies in condensed matter physics. Recent progress in realizing transient collective states in driven or pumped Dirac materials (DMs) is reviewed herein. In particular, the focus is on optically pumped DMs which are a promising platform for transient excitonic instabilities. Optical pumping combined with the linear (Dirac) dispersion of the electronic spectrum offers a knob for tuning the effective interaction between the photoexcited electrons and holes, and thus provides a way of reducing the critical coupling for excitonic instability. As a result, a transient excitonic condensate could be achieved in a pumped DM while it is not feasible in equilibrium. A unifying theoretical framework is provided for describing transient collective states in 2D and 3D DMs. The experimental signatures are described and numerical estimates of the size of the dynamically induced excitonic gaps and the values of the critical temperatures for several specific systems, are summarized. In addition, general guidelines for identifying promising material candidates are discussed. Finally, comments are provided regarding recent experimental efforts in realizing transient excitonic condensate in pumped DMs, and outstanding issues and possible future directions are outlined. 相似文献
196.
Radiophysics and Quantum Electronics - We consider whether it is possible in principle to retrieve the key parameters of the mixed layer in the upper ocean (its thickness, bulk eddy viscosity and... 相似文献
197.
Lebedev V. T. Serebrov A. P. 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2020,14(1):1-5
Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques - A method for studying the magnetic dynamics of endofullerenes M@C2n (2n = 60, 70, …) and their derivatives,... 相似文献
198.
Doklady Mathematics - Integro-differential equations with unbounded operator coefficients in a Hilbert space are studied. The equations under consideration are abstract hyperbolic equations... 相似文献
199.
Stadnyk V. Yo. Shchepanskyi P. A. Rudysh M. Ya. Kogut Z. A. 《Journal of Applied Spectroscopy》2021,88(4):831-837
Journal of Applied Spectroscopy - The temperature dependence of the refractive indices of K2SO4 with copper impurity was investigated. It was found that introduction of the copper impurity leads to... 相似文献
200.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献