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   839篇
  免费   46篇
  国内免费   26篇
化学   481篇
晶体学   21篇
力学   42篇
综合类   1篇
数学   161篇
物理学   205篇
  2023年   11篇
  2022年   8篇
  2021年   8篇
  2020年   16篇
  2019年   19篇
  2018年   24篇
  2017年   33篇
  2016年   36篇
  2015年   26篇
  2014年   45篇
  2013年   80篇
  2012年   77篇
  2011年   58篇
  2010年   49篇
  2009年   34篇
  2008年   40篇
  2007年   43篇
  2006年   42篇
  2005年   32篇
  2004年   35篇
  2003年   22篇
  2002年   19篇
  2001年   5篇
  2000年   16篇
  1999年   11篇
  1998年   7篇
  1997年   5篇
  1996年   17篇
  1995年   15篇
  1994年   10篇
  1993年   2篇
  1992年   5篇
  1991年   6篇
  1987年   3篇
  1986年   2篇
  1985年   4篇
  1984年   4篇
  1983年   1篇
  1982年   7篇
  1981年   3篇
  1980年   3篇
  1979年   6篇
  1978年   4篇
  1976年   3篇
  1975年   5篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
  1968年   1篇
  1937年   2篇
排序方式: 共有911条查询结果,搜索用时 15 毫秒
771.
Incomplete-Fusion-Fragmentation Model is used to analyze the multifragmentation of the projectile remnant in 600MeV/u Au+Au reaction.The theoretical resultsof the mass number,the excitation energy and the thermodynamical temperature of the projectile remnant agree well with experimental data.The backbending structure in the curve of temperature as a function of the excitation energy per nucleon,i.e. the evidence of liquid-gas phase transition,is reproduced and reasonably related to the decay modes phase transformation from dominance of the multifragmentation mode to the vaporization mode.  相似文献   
772.
The increase of effective string tension as a result of the hard gluon kinks on a string is investigated using a parametrization form. In this form the effective string tension increasing with energies in hadron-hadron collisions is due to the mini-jet (gluon) production in the collisions. The data for the energy dependence of the strange quark suppression factor in hadron-hadron collisions are very well reproduced with this mechanism. Meanwhile, the experimental phenomena of approximate energy independence of the strange quark suppression factor in e+e -annihilations are discussed.  相似文献   
773.
A systematic investigation on the effect of substrate temperature on the structure, optical absorption and density of states of vacuum evaporated gallium monoselenide (GaSe) thin films is reported. The X‐ray diffraction analysis shows an occurrence of amorphous to polycrystalline transformation in the films deposited at higher‐temperature substrates (573K). The compositional analysis is made with Auger Electron Spectroscopy (AES). The thickness of the film (175nm) is measured by a multiple beam interferometery. Optical characteristics of the GaSe sample have been analyzed using spectrophotometer in the photon energy range of 1.0 ‐ 4 eV. The absorption mechanism has been recognized and the allowed indirect as well as forbidden direct transitions have been found. As‐deposited films show two indirect and allowed transitions due to spin‐orbit splitting of the valence band, as reported here for the first time. Low field conduction have enabled us to determine the density of states in amorphous and poly‐GaSe films. The amorphous and polycrystalline GaSe thin films have localized states density values of N (EF) = 1.686 × 1017 cm‐3 eV‐1 and 1.257 × 1015 cm‐3 eV‐1 respectively. The experimental results are interpreted in terms of variations in the density of localized states due to progressive decrease of the unsaturated bonds during deposition. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   
774.
775.
776.
In numerous recent papers plasma chemistry of non equilibrium plasma sources operating at atmospheric pressure has been linked to plasma medical effects including sterilization. In this paper we present a study of the effectiveness of an atmospheric pressure plasma source, known as plasma needle, in inhibition of the growth of biofilm produced by methicillin resistant Staphylococcus aureus (MRSA). Even at the lowest powers the biofilms formed by inoculi of MRSA of 104 and 105 CFU have been strongly affected by plasma and growth in biofilms was inhibited. The eradication of the already formed biofilm was not achieved and it is required to go to more effective sources.  相似文献   
777.
In this work, we carried out detailed investigation of a Cd1?xMnxTe/CdTe/Cd1?xMnxTe diluted magnetic semiconductor based quantum well. Our theoretical results are based on an accurate self-consistent resolution of the one-dimension Schrödinger and Poisson’s equations in the framework of the mean-field approximation for spin-up and spin-down orientations of carriers coupled via the sp–d exchange interaction. From the calculation of spin-dependent carrier densities for ferromagnetic and anti-ferromagnetic coupling, we evidence the spin-up and spin-down space separation for holes in quantum well for different values of band offsets. From deduced spin polarizations, we show that the CdTe region acts as a layer of spin rearrangement and spin reversal, respectively, in the ferromagnetic and anti-ferromagnetic coupling. The transmittance coefficients T+ and T? of injected spin-up and spin-down carriers are evaluated as a preliminary work to assess the spin-dependent currents in devices consisting of alternatively layers of non-magnetic and diluted magnetic semiconductors.  相似文献   
778.
779.
A calculation scheme based on density functional theory generalized to the case of periodic structures is used to calculate the electron energy spectrum and the imaginary part of the permittivity of single-layer 2D structures based on silicon dioxide with the surface functional groups X ≡ OH, CH3, NH2, NO2, CHO, and COOH. The dependences of the energy corresponding to the energy-band edges, valence-band widths, and the positions of the characteristic peaks of the density of states on the degree of replacement by surface groups The peculiarities of the optical absorption bands in the absorbed photon energy region ?ω < 14 eV are revealed.  相似文献   
780.
Xiong  Rui  Yang  Honglei  Peng  Qiong  Sa  Baisheng  Wen  Cuilian  Wu  Bo  Sun  Zhimei 《Research on Chemical Intermediates》2017,43(9):5271-5282
Research on Chemical Intermediates - One typical two-dimensional transition metal dichalcogenide (TMDC) called the TcSe2 monolayer has been predicted to be a potential photocatalyst for water...  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