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   239204篇
  免费   2409篇
  国内免费   599篇
化学   113732篇
晶体学   3588篇
力学   10702篇
综合类   11篇
数学   22879篇
物理学   67600篇
无线电   23700篇
  2021年   2743篇
  2020年   2883篇
  2019年   3501篇
  2018年   4563篇
  2017年   4479篇
  2016年   5956篇
  2015年   2962篇
  2014年   5479篇
  2013年   10508篇
  2012年   8331篇
  2011年   9603篇
  2010年   7706篇
  2009年   7964篇
  2008年   9180篇
  2007年   9252篇
  2006年   8171篇
  2005年   7349篇
  2004年   6864篇
  2003年   6290篇
  2002年   6140篇
  2001年   6548篇
  2000年   5032篇
  1999年   3979篇
  1998年   3407篇
  1997年   3498篇
  1996年   3173篇
  1995年   2817篇
  1994年   2896篇
  1993年   2812篇
  1992年   3105篇
  1991年   3199篇
  1990年   3127篇
  1989年   3132篇
  1988年   2981篇
  1987年   2820篇
  1986年   2663篇
  1985年   3382篇
  1984年   3392篇
  1983年   2844篇
  1982年   2755篇
  1981年   2694篇
  1980年   2511篇
  1979年   2866篇
  1978年   2815篇
  1977年   3001篇
  1976年   2997篇
  1975年   2765篇
  1974年   2687篇
  1973年   2812篇
  1972年   2145篇
排序方式: 共有10000条查询结果,搜索用时 750 毫秒
101.
Journal of Analytical Chemistry - Studies on the separation of the Se and Te trace components from Co, Ni, Cu, Fe, Cr, Mo, and W macrocomponents for their determination by inductively coupled...  相似文献   
102.
ABSTRACT

The authors present the results of an investigation in Fe–Ni-Cr austenitic alloys of the low-temperature deformation-induced segregations of nickel that form in the micro regions being (i) located close to grain- and subgrain boundaries and (ii) characteristic of the concentration and magnetic inhomogeneities indicated by the appearance of a dark diffraction contrast at the electron diffraction patterns taken from these regions typical (at the same time) of an enhanced value of Curie temperature. The observed effects were connected with the micro distortions caused by the local change of lattice parameter because of an increase in nickel concentration, as well as in the result of a magnetostriction dilatation. Using methods of the X-ray energy dispersive spectroscopy (XEDS) and atomic-probe body-section radiography (tomography – APT) has made it possible to determine the borders of those regions of austenite that were characteristic of an enhanced concentration of nickel in the fields of the localisation of a deformation-induced segregation of nickel in the vicinity of grain (subgrain) boundaries of austenitic alloys of the types Fe–13Cr–30Ni and Fe–37Ni–3Ti.  相似文献   
103.
104.
Journal of Experimental and Theoretical Physics - The nature of the training effect in exchange-biased compounds is studied. This effect consists in a decrease in the exchange bias field (HEB)...  相似文献   
105.
106.
Bruzy  N.  Coret  M.  Huneau  B.  Kermouche  G.  Mondon  M.  Bertrand  E.  Stainier  L. 《Experimental Mechanics》2019,59(8):1145-1157

The allotropic phase change from ferrite to austenite represents a moment of massive interplay between the microstructural and mechanical states of iron. The difference of compacity between the two phases induces a microplastic accommodation in the material at grain scale. However, mechanical heterogeneities resulting from the transformation process remain challenging to characterise due to the high temperature conditions it is associated with. We developed experimental equipment for in situ observation of α ? γ and γ ? α transformations. Images of the surface of an iron sample taken by an optical camera were used as input for a Digital Image Correlation (DIC) routine. Special care was taken to maximize image resolution to capture sub-grain phenomena. Observations show that, at the mesoscopic scale, shear strain fields exhibit strong localisations that are evidence of transformations that are occurring.

  相似文献   
107.
Russian Journal of General Chemistry - Highly dispersed CaO has been synthesized by heating an aqueous solution of calcium nitrate and D-glucose up to 800°C. Calcium oxide is formed with an...  相似文献   
108.
Russian Journal of Organic Chemistry - Methyl (Z)-3-[(2R,3R,4S,5S)-5-(2-methoxy-2-oxoethyl)-3,4-(isopropylidenedioxy)tetrahydrofuran-2-yl]-prop-2-enoate was synthesized, and its intramolecular...  相似文献   
109.
110.
Syrovatka  R. A.  Lipaev  A. M.  Naumkin  V. N.  Klumov  B. A. 《JETP Letters》2022,116(12):869-874
JETP Letters - A quasi-two-dimensional plasma crystal in (3 + 1) dimensions has been experimentally observed for the first time; i.e., three spatial coordinates of each microparticles of the...  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