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   21892篇
  免费   888篇
  国内免费   182篇
化学   14469篇
晶体学   146篇
力学   480篇
综合类   1篇
数学   4008篇
物理学   3858篇
  2023年   154篇
  2022年   181篇
  2021年   405篇
  2020年   471篇
  2019年   583篇
  2018年   448篇
  2017年   347篇
  2016年   729篇
  2015年   699篇
  2014年   684篇
  2013年   1279篇
  2012年   1381篇
  2011年   1664篇
  2010年   857篇
  2009年   740篇
  2008年   1244篇
  2007年   1180篇
  2006年   1146篇
  2005年   1116篇
  2004年   884篇
  2003年   771篇
  2002年   707篇
  2001年   363篇
  2000年   280篇
  1999年   276篇
  1998年   227篇
  1997年   257篇
  1996年   269篇
  1995年   249篇
  1994年   208篇
  1993年   176篇
  1992年   147篇
  1991年   149篇
  1990年   119篇
  1989年   108篇
  1988年   124篇
  1987年   106篇
  1986年   107篇
  1985年   154篇
  1984年   169篇
  1983年   110篇
  1982年   155篇
  1981年   150篇
  1980年   140篇
  1979年   122篇
  1978年   129篇
  1977年   120篇
  1976年   119篇
  1975年   91篇
  1974年   88篇
排序方式: 共有10000条查询结果,搜索用时 439 毫秒
61.
We consider the question of factorizability in tensor product spaces, and argue that the correlations associated with entangled states are even more problematic in the general case involving any tensor product of Hilbert spaces, than in the Einstein, Podolsky, and Rosen case with only two [1].  相似文献   
62.
This author wants to express his thanks to the School of Information Engineering at Teesside Polytechnic, Middlesbrough, England, for its support and hospitality during a visiting appointment of 3 months in 1989, when this paper was written.  相似文献   
63.
64.
An assembly of cation receptor 1 and anion receptor 2 via the hydrogen bonding melamine-barbiturate structural motif complexes sodium thiocyanate, sodium iodide, and sodium azide in apolar solvents.  相似文献   
65.
Dextran-modified iron oxide nanoparticles   总被引:1,自引:0,他引:1  
Ji 《中国颗粒学报》2007,5(1):162-168
Dextran-modified iron oxide nanoparticles were prepared by precipitation of Fe(Ⅱ) and Fe(Ⅲ) salts with ammonium hydroxide by two methods. Iron oxide was precipitated either in the presence of dextran solution, or the dextran solution was added after precipitation. In the second method, the iron oxide particle size and size distribution could be controlled depending on the concentration of dextran in the solution. The nanoparticles were characterized by size-exclusion chromatography, transmission electron microscopy and dynamic light scattering. Optimal conditions for preparation of stable iron oxide colloid particles were determined, The dextran/iron oxide ratio 0-0,16 used in precipitation of iron salts can be recommended for synthesis of nanoparticles suitable for biomedical applications, as the colloid does not contain excess dextran and does not coagulate.  相似文献   
66.
67.
The classical (first integral) methods of studying restrictions on the possible motion of gravitationally interacting bodies are reviewed. The simple and flexible inequality method is extended to a similar approach to the relationship between possible forbidden motion and (asymptotic) symmetries in the relativistic few-body problem. This extended method is used to reproduce the standard results of bounded motion for a test particle in a Schwarzschild geometry. The existence of bounded motion is shown for the general relativistic few-body problem and the difficulties in determining such bounded motion is analysed. The use of this approach to obtaining a relativistic alternative to the classical Roche lobe analysis in contact binaries is discussed.  相似文献   
68.
69.
70.
In this work a new reference wave method for solving parabolic-type equations is proposed. The performance of the method is demonstrated by applying it to the equation governing the propagation of the two-frequency mutual coherence function in a random medium. An analytic solution is presented for arbitrary correlation properties of the medium. It is shown that when approximating the transverse structure function of the medium by a quadratic form, the solution reduces to the exact result derived previously. Extensions to more general types of media are considered.  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