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   3226篇
  免费   234篇
  国内免费   15篇
化学   2377篇
晶体学   12篇
力学   60篇
数学   425篇
物理学   601篇
  2023年   53篇
  2022年   75篇
  2021年   118篇
  2020年   168篇
  2019年   192篇
  2018年   83篇
  2017年   70篇
  2016年   210篇
  2015年   153篇
  2014年   166篇
  2013年   198篇
  2012年   287篇
  2011年   274篇
  2010年   157篇
  2009年   133篇
  2008年   204篇
  2007年   165篇
  2006年   158篇
  2005年   108篇
  2004年   67篇
  2003年   34篇
  2002年   36篇
  2001年   28篇
  2000年   20篇
  1999年   19篇
  1998年   13篇
  1997年   6篇
  1996年   17篇
  1995年   15篇
  1994年   10篇
  1993年   6篇
  1992年   12篇
  1991年   8篇
  1990年   8篇
  1988年   7篇
  1987年   12篇
  1986年   17篇
  1984年   8篇
  1983年   13篇
  1981年   12篇
  1980年   6篇
  1979年   7篇
  1978年   14篇
  1975年   7篇
  1973年   7篇
  1971年   7篇
  1967年   5篇
  1966年   5篇
  1939年   5篇
  1936年   6篇
排序方式: 共有3475条查询结果,搜索用时 0 毫秒
51.
Samples obtained as a result of the valleriite synthesis process under different conditions (temperature and proportion Cu:Fe:Mg in the initial mixture) were investigated by 57Fe M?ssbauer spectroscopy with attraction data of X-ray diffraction. Parameters of hyperfine interactions for valleriite were determined and crystal chemical identification of 57Fe subspectra was carried out. It was found that valleriite was formed in samples synthesized at 150°C and 180°C and not formed in samples synthesized at 250°C.  相似文献   
52.
The deposition of palladium on a novel, reversibly protonatable, pyridyl-terminated self-assembled monolayer on gold substrates has been studied by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS spectroscopy) and time of flight-secondary ion mass spectrometry (ToF-SIMS). For this purpose, 12-(pyridin-4-yl)dodecane-1-thiol, consisting of a surface-active head group, an unfunctionalized hydrocarbon backbone and a terminal pyridyl group, has been synthesized and deposited on gold surfaces. Coordination of Pd(II) ions to the pyridyl group was examined. Furthermore, a reversible protonation/deprotonation cycle has been applied, and the relation between protonation and the amount of complexed palladium was studied. Investigation of the SAM by angle-resolved NEXAFS spectroscopy revealed the aliphatic backbone to be preferentially upright oriented with the aromatic head group being not preferentially oriented. The palladium layer was further coordinated with a CF3-labeled terpyridine ligand in order to prove the accessibility of the Pd(II) ions to further complexation and the platform useful for deposition of further layers toward a multi-layered system.  相似文献   
53.
Bottom‐up assembly by dielectrophoresis (DEP) has emerged in recent years as a viable alternative to conventional top–down fabrication of electronic devices from nanomaterials, particularly carbon nanotubes and graphene. Here, we demonstrate how this technique can be extended to fabricate devices containing carbon nanotubes and graphene suspended between two electrodes over a back‐gate electrode. The suspended device geometry is critical for the development of nano‐electromechanical devices and to extract maximum performance out of electronic and optoelectronic devices. This technique allows for parallel assembly of devices over large scale. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)  相似文献   
54.
55.
We show that the nonequilibrium entropy production for a driven quantum system is larger than the Bures length, the geometric distance between its actual state and the corresponding equilibrium state. This universal lower bound generalizes the Clausius inequality to arbitrary nonequilibrium processes beyond linear response. We further derive a fundamental upper bound for the quantum entropy production rate and discuss its connection to the Bremermann-Bekenstein bound.  相似文献   
56.
We report measurements of the de Haas-van Alphen effect in CeIn(3) in magnetic fields extending to approximately 90 T, well above the Néel critical field of mu(0)H(c) approximately 61 T. The unreconstructed Fermi surface a sheet is observed in the high magnetic field polarized paramagnetic limit, but with its effective mass and Fermi surface volume strongly reduced in size compared to that observed in the low magnetic field paramagnetic regime under pressure. The spheroidal topology of this sheet provides an ideal realization of the transformation from a "large Fermi surface" accommodating f electrons to a "small Fermi surface" when the f-electron moments become polarized.  相似文献   
57.
58.
Resonance ionization laser ion source (RILIS) technique has been used in the β-decay studies of 59Mn and 58Zn. The importance of the RILIS for production of these elements is discussed. The properties of the low-lying levels of the studied nuclei are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
59.
60.
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