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   52629篇
  免费   1713篇
  国内免费   72篇
化学   33458篇
晶体学   250篇
力学   1690篇
数学   8209篇
物理学   10807篇
  2023年   384篇
  2022年   323篇
  2021年   539篇
  2020年   705篇
  2019年   678篇
  2018年   1065篇
  2017年   871篇
  2016年   1601篇
  2015年   1470篇
  2014年   1471篇
  2013年   3071篇
  2012年   3563篇
  2011年   3695篇
  2010年   2227篇
  2009年   1846篇
  2008年   3116篇
  2007年   3136篇
  2006年   2761篇
  2005年   2684篇
  2004年   2297篇
  2003年   1859篇
  2002年   1612篇
  2001年   967篇
  2000年   810篇
  1999年   569篇
  1998年   433篇
  1997年   400篇
  1996年   496篇
  1995年   321篇
  1994年   380篇
  1993年   370篇
  1992年   405篇
  1991年   347篇
  1990年   331篇
  1989年   325篇
  1988年   267篇
  1987年   270篇
  1986年   234篇
  1985年   407篇
  1984年   366篇
  1983年   263篇
  1982年   346篇
  1981年   338篇
  1980年   293篇
  1979年   283篇
  1978年   266篇
  1976年   283篇
  1975年   256篇
  1974年   267篇
  1973年   261篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Microarrays are a popular technology to study genes that are differentially expressed between two conditions. In this Note, we propose an iterative procedure to determine the biggest subset of non-differentially expressed genes. We prove a pseudo Markov relationship that allows practical computations. We obtain explicit expressions for FDR and the level of the proposed test at each step. To cite this article: A. Bar-Hen, S. Robin, C. R. Acad. Sci. Paris, Ser. I 337 (2003).  相似文献   
93.
94.
95.
96.
This paper presents a method to estimate reflected and transmitted wave amplitude spectra in a bounded domain such as a wave tank, when available data signals must be shortened due to interferences and wall effects. This paper extends the well known Goda and Suzuki two-probe method to three probes. The paper also suggests solutions to compute reliable transmission and reflection coefficients in spite of problems linked to higher harmonics and to the interference between different wave trains propagating in the tank. To cite this article: G. Duclos, A.H. Clément, C. R. Mecanique 331 (2003).  相似文献   
97.
Delauré  B.  Beck  M.  Golovko  V. V.  Kozlov  V.  Phalet  T.  Schuurmans  P.  Severijns  N.  Vereecke  B.  Versyck  S.  Beck  D.  Quint  W.  Ames  F.  Reisinger  K.  Forstner  O.  Deutsch  J.  Bollen  G.  Schwarz  S. 《Hyperfine Interactions》2003,150(1-4):91-105
We present data from three seasons of experimental field work designed to recreate ancient Andean coastal ceramic firing techniques. Based on the recent discovery of two different archaeological ceramic production sites in the La Leche river valley of northern coastal Peru, the opportunity arose to apply Mössbauer spectroscopy and other analytical methods to reconstruct ancient firing procedures. Two sets of firings took place in 1993 and 1997 in Batán Grande using a partially restored Formative kiln from about 800 BC, local hardwood and cow dung as fuel. A third experiment followed in 2000 after the discovery of a Middle Sicán ceramics workshop in use between ca. AD 950 and 1050 at Huaca Sialupe, where an exact replica of an ancient kiln was built from local clay, and fired with local wood and cow dung. Additionally, inverted urns found at Huaca Sialupe were tested for their potential use as furnaces for metal working. Mössbauer spectroscopy was used to compare the physical and chemical state of specimens produced in the field experiments with ancient ceramics and with specimens produced in controlled laboratory experiments.  相似文献   
98.
We consider a SOS type model of interfaces on a substrate which is both heterogeneous and rough. We first show that, for appropriate values of the parameters, the differential wall tension that governs wetting on such a substrate satisfies a generalized law which combines both Cassie and Wenzel laws. Then in the case of an homogeneous substrate, we show that this differential wall tension satisfies either the Wenzel's law or the Cassie's law, according to the values of the parameters.  相似文献   
99.
This article is concerned with the equations governing the steady motion of a viscoelastic incompressible second‐order fluid in a bounded domain. A new proof of existence and uniqueness of strong solutions is given. In addition, using appropriate finite element methods to approximate a coupled equivalent problem, sharp error estimates are obtained using a fixed point argument. The method is applied to the two‐dimensional lid‐driven cavity problem, at low Reynolds number and in a certain range of values of the viscoelastic parameters, to analyze the combined effects of inertia and viscoelasticity on the flow. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007  相似文献   
100.
A new time integrated method for the study of resonant nuclear scattering of synchrotron radiation in the forward direction or in Bragg directions is introduced. This method gives in principle similar information as the well known time differential method. A brief comparison of both methods is presented. The idea is to excite coherently the nuclei incorporated in two absorbers, one moving with respect to the other. The fields radiated by the nuclei from both absorbers interfere and each time the nuclear energy in one absorber matches, by Doppler modulation, the nuclear energy of the other, an extremum in the time integrated intensity is observed. The results of the first experiments at the Advanced Photon Source at the Argonne National Laboratory will be presented. This revised version was published online in August 2006 with corrections to the Cover Date.  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