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   3185篇
  免费   50篇
  国内免费   12篇
化学   1475篇
晶体学   25篇
力学   127篇
数学   519篇
物理学   1101篇
  2021年   35篇
  2020年   51篇
  2019年   52篇
  2018年   73篇
  2017年   50篇
  2016年   79篇
  2015年   59篇
  2014年   90篇
  2013年   129篇
  2012年   126篇
  2011年   153篇
  2010年   131篇
  2009年   108篇
  2008年   142篇
  2007年   145篇
  2006年   116篇
  2005年   114篇
  2004年   108篇
  2003年   92篇
  2002年   107篇
  2001年   50篇
  2000年   47篇
  1999年   29篇
  1998年   35篇
  1997年   42篇
  1996年   44篇
  1995年   27篇
  1994年   32篇
  1993年   28篇
  1992年   34篇
  1991年   32篇
  1990年   35篇
  1987年   27篇
  1984年   45篇
  1983年   36篇
  1982年   37篇
  1981年   38篇
  1980年   35篇
  1979年   32篇
  1978年   30篇
  1977年   60篇
  1976年   37篇
  1975年   29篇
  1974年   42篇
  1973年   32篇
  1972年   35篇
  1971年   26篇
  1968年   27篇
  1967年   39篇
  1966年   27篇
排序方式: 共有3247条查询结果,搜索用时 15 毫秒
1.
The relationship between magnetoelectricity and electromagnetism is a subject of a strong interest and numerous discussions in microwave and optical wave physics and material sciences. The definition of the energy and momentum of the electromagnetic (EM) field in a magnetoelectric (ME) medium is not a trivial problem. The question of whether electromagnetism and magnetoelectricity can coexist without an extension of Maxwell's theory arises when the effects of EM energy propagation are studied and the group velocity of the waves in an ME medium is considered. The energy balance equation reveals unusual topological structure of fields in ME materials. Together with certain constraints on the constitutive parameters of a medium, definite constraints on the local field structure should be imposed. Analyzing the EM phenomena inside an ME material, the question “what kind of the near fields arising from a sample of such a material can be measured?” should be answered. The visualization of the ME states requires an experimental technique that is based on an effective coupling to the violation of spatial as well as temporal inversion symmetry. To observe the ME energy in a subwavelength region, it is necessary to assume the existence of first-principle near fields—the ME fields. These are non-Maxwellian near fields with specific properties of violation of spatial and temporal inversion symmetry. A particular interest to the ME fields arises in studies of metamaterials with “artificial-atoms” ME elements.  相似文献   
2.
Bulletin of the Lebedev Physics Institute - Abstract—The self-similarity effect during rarefied water vapor flow between two finite-volume vessels is repeatedly recorded with a similarity...  相似文献   
3.
Technical Physics - The ballistic resistance of a combined cermet material based on a high-hardness ceramic bound with an intermetallide on a high-strength metal substrate, (TiB2 + NiTi) + Ti, is...  相似文献   
4.
5.
6.
A class of acceptor–donor–acceptor chromophoric small-molecule non-fullerene acceptors, 1–4, with difluoroboron(iii) β-diketonate (BF2bdk) as the electron-accepting moiety has been developed. Through the variation of the central donor unit and the modification on the peripheral substituents of the terminal BF2bdk acceptor unit, their photophysical and electrochemical properties have been systematically studied. Taking advantage of their low-lying lowest unoccupied molecular orbital energy levels (from −3.65 to −3.72 eV) and relatively high electron mobility (7.49 × 10−4 cm2 V−1 s−1), these BF2bdk-based compounds have been employed as non-fullerene acceptors in organic solar cells with maximum power conversion efficiencies of up to 4.31%. Moreover, bistable resistive memory characteristics with charge-trapping mechanisms have been demonstrated in these BF2bdk-based compounds. This work not only demonstrates for the first time the use of a boron(iii) β-diketonate unit in constructing non-fullerene acceptors, but also provides more insights into designing organic materials with multi-functional properties.

Boron(iii) β-diketonates have been demonstrated to serve as multi-functional materials in NFA-based OPVs and organic resistive memories.  相似文献   
7.
The isochoric heat capacity of the n-hexane–water system was studied on an adiabatic calorimeter at 300–600 K and molar fractions of water of 0.256–0.935 in a wide range of densities. The experimental critical curves of the liquid–vapor phase equilibrium were described by the equation corresponding to the theory of critical phenomena.  相似文献   
8.
A series of luminescent polynuclear alkynylgold(I) complexes with different lengths of alkyl chains attached at the N‐heterocyclic carbene moieties has been synthesised and demonstrated to display intriguing self‐assembly behaviours through a cooperative growth mechanism. Variation of the alkyl chain length was found to cause drastic morphological differences in the aggregates and to strongly affect the thermodynamic parameters as revealed by the nucleation–elongation model.  相似文献   
9.
10.
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