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   7450篇
  免费   995篇
  国内免费   499篇
化学   2306篇
晶体学   86篇
力学   564篇
综合类   62篇
数学   474篇
物理学   2948篇
综合类   2504篇
  2024年   32篇
  2023年   75篇
  2022年   189篇
  2021年   216篇
  2020年   242篇
  2019年   187篇
  2018年   203篇
  2017年   208篇
  2016年   300篇
  2015年   270篇
  2014年   337篇
  2013年   521篇
  2012年   409篇
  2011年   469篇
  2010年   364篇
  2009年   424篇
  2008年   439篇
  2007年   483篇
  2006年   436篇
  2005年   390篇
  2004年   320篇
  2003年   320篇
  2002年   241篇
  2001年   214篇
  2000年   220篇
  1999年   181篇
  1998年   170篇
  1997年   134篇
  1996年   150篇
  1995年   100篇
  1994年   118篇
  1993年   90篇
  1992年   66篇
  1991年   68篇
  1990年   73篇
  1989年   60篇
  1988年   55篇
  1987年   38篇
  1986年   26篇
  1985年   21篇
  1984年   9篇
  1982年   9篇
  1981年   5篇
  1980年   8篇
  1979年   14篇
  1978年   9篇
  1974年   4篇
  1973年   8篇
  1971年   4篇
  1970年   4篇
排序方式: 共有8944条查询结果,搜索用时 15 毫秒
141.
Pierre Turq has made decisive contributions to the theory and to the multiscale simulation of charged systems, such as molten salts, electrolyte solutions and colloidal suspensions, in the bulk, at interfaces and under confinement. His research line focussed on dynamical properties and was characterised by constant efforts to connect his theoretical work to both experiments and practical applications. In this article, his colleagues and former students pay a tribute to his past and current research interests by illustrating some recent developments accomplished in his laboratory.  相似文献   
142.
《Physics letters. A》2014,378(5-6):561-564
Using first-principles density functional theory and non-equilibrium Greenʼs function formalism for quantum transport calculation, we have investigated the effect of gate voltage on the electronic transport properties of BDC60-based molecular junction. The results show that the transport properties are strongly modulated by the applied gate voltage, and the current–voltage curve displays an obvious rectifying behavior at much low bias region. The mechanism for the rectifying behavior is analyzed by the bias-dependent transmission spectrum, projected density of states, spatial distribution of molecular projected self-consistent Hamiltonian orbitals and voltage drop over the junction.  相似文献   
143.
144.
We review some of our recent efforts in developing upscaling methods for simulatingthe flow transport through heterogeneous porous media. In particular, the steady flowtransport through highly heterogeneous porous media driven by extraction wells and theflow transport through unsaturated porous media will be considered.  相似文献   
145.
We investigate the full counting statistics of a voltage-driven normal metal(N)–superconductor(S) contact. In the low-bias regime below the superconducting gap, the NS contact can be mapped onto a purely normal contact, albeit with doubled voltage and counting fields. Hence in this regime the transport characteristics can be obtained by the corresponding substitution of the normal metal results. The elementary processes are single Andreev transfers and electron- and hole-like Andreev transfers. Considering Lorentzian voltage pulses we find an optimal quantization for half-integer Levitons.  相似文献   
146.
We systematically studied the influence of magnetic field on zero-line modes (ZLMs) in graphene and demonstrated the physical origin of their enhanced robustness by employing nonequilibrium Green’s functions and the Landauer–Büttiker formula. We found that a perpendicular magnetic field can separate the wavefunctions of the counter-propagating kink states into opposite directions. Specifically, the separation vanishes at the charge neutrality point and increases as the Fermi level deviates from the charge neutrality point and can reach a magnitude comparable to the wavefunction spread at a moderate field strength. Such spatial separation of oppositely propagating ZLMs effectively suppresses backscattering and is more significant under zigzag boundary condition than under armchair boundary condition. Moreover, the presence of magnetic field enlarges the bulk gap and suppresses the bound states, thereby further reducing the scattering. These mechanisms effectively increase the mean free paths of the ZLMs to approximately 1 μm in the presence of a disorder.  相似文献   
147.
Using first-principles density functional theory and non-equilibrium Green′s function formalism for quantum transport calculation, we have investigated the electronic transport properties of the boron/nitrogen-doped C131-based molecular junction. Our results show that an obvious rectifying behavior is observed. Moreover, the rectifying performance can be tuned by adjusting the doping sites. The mechanism for the rectifying phenomenon is suggested. The present findings could be helpful for the application of the C131 molecule in the field of single molecular devices or nanometer electronics.  相似文献   
148.
曾晓雄  周史薇  刘文彪 《中国物理 B》2012,21(9):90402-090402
The recent work of Nation et al., in which the Hawking radiation energy and entropy flow from a black hole is considered to be produced in a one-dimensional Landauer transport process, is extended to the case of a Reissner- Nordstrom black hole. The energy flow contains not only the contribution of the thermal flux but also that of the particle flux. It is found that the charge can also be transported via the one-dimensional quantum tunnel. Because of the existence of the electrostatic potential, the entropy production rate is shown to be smaller than that of the Schwarzschild black hole.  相似文献   
149.
150.
为探究凡纳滨对虾养殖尾水处理过程中互花米草湿地的净化效果和沉积物古菌群落的组成与分布,基于16S rRNA基因的高通量测序技术,从沉积物环境因子、古菌群落结构和多样性、环境因子与古菌群落间的相互关系进行分析.结果表明:互花米草人工湿地深层沉积物的古菌群落多样性显著高于表层和根际沉积物;门水平上,互花米草人工湿地优势古菌为泉古菌门、广古菌门和奇古菌门;纲水平上,优势古菌为深古菌纲、甲烷微菌纲和热源体纲;目水平上,互花米草人工湿地中含3种氨氧化古菌和7种产甲烷古菌.非度量多维尺度分析(NMDS)表明,互花米草根际沉积物与深层沉积物古菌群落差异显著(P<0.05),与表层更为相似.冗余分析(RDA)及Mantel检验表明,影响古菌群落的主要环境因子包括p H、铵氮(NH4+-N)、总有机碳(TOC)和总磷(TP).相关性热图表明奇古菌门和其中的亚硝基菌纲与环境因子的相关性最强.氨氧化古菌群落与pH、NH4+-N、总氮(TN)和TP呈显著相关(P<0.01),产甲烷古菌与环境因子则无显著相关性....  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