首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   274432篇
  免费   2192篇
  国内免费   1388篇
化学   123033篇
晶体学   3846篇
力学   16387篇
综合类   109篇
数学   44873篇
物理学   89764篇
  2021年   2065篇
  2020年   2236篇
  2019年   2665篇
  2018年   11176篇
  2017年   11925篇
  2016年   8152篇
  2015年   2980篇
  2014年   4235篇
  2013年   7783篇
  2012年   10176篇
  2011年   18431篇
  2010年   12177篇
  2009年   12484篇
  2008年   16292篇
  2007年   19500篇
  2006年   6265篇
  2005年   10872篇
  2004年   7859篇
  2003年   7679篇
  2002年   6068篇
  2001年   5345篇
  2000年   4220篇
  1999年   3048篇
  1998年   2819篇
  1997年   2619篇
  1996年   2596篇
  1995年   2300篇
  1994年   2208篇
  1993年   2219篇
  1992年   2223篇
  1991年   2514篇
  1990年   2450篇
  1989年   2512篇
  1988年   2398篇
  1987年   2419篇
  1986年   2232篇
  1985年   2787篇
  1984年   2799篇
  1983年   2430篇
  1982年   2477篇
  1981年   2375篇
  1980年   2177篇
  1979年   2511篇
  1978年   2669篇
  1977年   2675篇
  1976年   2805篇
  1975年   2591篇
  1974年   2519篇
  1973年   2728篇
  1972年   2192篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
In this work, we have used the MuMax3 software to simulate devices consisting of a ferromagnetic thin film placed over a heavy metal thin film. The devices are two interconnected partial-disks where a Néel domain wall is formed in the disks junction. In our simulations we investigate devices with disk radius r=50 nm and different distance d between the disks centers (from d=12 nm to d=2R=100 nm). By applying strong sinusoidal external magnetic fields, we find a mechanism able to create, annihilate and even manipulate a skyrmion in each side of the device. This mechanism is discussed in terms of interactions between skyrmion and domain wall. The Néel domain wall formed in the center of the device interacts with the Néel skyrmion, leading to a process of transporting a skyrmion from one disk to the other periodically. Our results have relevance for potential applications in spintronics such as logical devices.  相似文献   
3.
4.
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   
5.
Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined.  相似文献   
6.
Kinetic, sorption and selectivity properties of commercial adsorbents are improved by adding petroleum residues (tar asphaltene concentrates) 13% of whole mass. Obtained adsorbents can be used for selective extraction of nobel metals from multicomponent polymetallic solutions of heavy metals and fro sewages purification for removing arsenic.  相似文献   
7.
Experimental data on the effect of thallium and sodium impurities on the lattice heat conductivity of PbTe at room temperature are reported. Because the lattice of lead chalcogenides is strongly polarized near charged impurities, the effect of impurities on the lattice heat conductivity depends substantially on their charge state. This property of the material has been used to determine the charge state of the thallium impurity in PbTe. The results obtained argue for a model of quasi-local thallium-impurity states which assumes low electron-correlation energy at an impurity center. Fiz. Tverd. Tela (St. Petersburg) 40, 1206–1208 (July 1998)  相似文献   
8.
9.
We prove a character formula for any finite-dimensional irreducible representationV of the “queer” Lie superalgebra g=q(n). It expresses chV in terms of the multiplicities of the irreducible g-subquotients of the cohomology groups of certain dominant g-bundles on the Π-symmetric projective spaces (i.e., on the homogeneous superspacesG/P whose reduced space is a projective space, whereG=Q(n)). We also establish recurrent relations for the above multiplicities, and this enables us to compute explicitly chV for any givenV. This provides a complete solution to the Kac character problem for the Lie superalgebraq(n). Finally, we consider the particular cases ofq(2), q(3), andq(4) in which we compare the new character formula with the generic character formula of [12]. Translated from Itogi Nauki i Tekhniki, Seriya Sovremennaya Matematika i Ee Prilozheniya. Tematicheskie Obzory. Vol. 41, Algebraic Geometry-7, 1997.  相似文献   
10.
The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures is discussed. Zh. Tekh. Fiz. 67, 97–99 (December 1997)  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号