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   244166篇
  免费   1472篇
  国内免费   416篇
化学   111971篇
晶体学   3481篇
力学   12973篇
综合类   3篇
数学   37996篇
物理学   79630篇
  2021年   1019篇
  2020年   1181篇
  2019年   1251篇
  2018年   10470篇
  2017年   11333篇
  2016年   6595篇
  2015年   2412篇
  2014年   2478篇
  2013年   6161篇
  2012年   9150篇
  2011年   18481篇
  2010年   11349篇
  2009年   11422篇
  2008年   16250篇
  2007年   19689篇
  2006年   5571篇
  2005年   11735篇
  2004年   7929篇
  2003年   7550篇
  2002年   5453篇
  2001年   5711篇
  2000年   4288篇
  1999年   3117篇
  1998年   2158篇
  1997年   2184篇
  1996年   2092篇
  1995年   1974篇
  1994年   1952篇
  1993年   1753篇
  1992年   2244篇
  1991年   2317篇
  1990年   2174篇
  1989年   2146篇
  1988年   2149篇
  1987年   2153篇
  1986年   1962篇
  1985年   2431篇
  1984年   2473篇
  1983年   1972篇
  1982年   1983篇
  1981年   1825篇
  1980年   1808篇
  1979年   2113篇
  1978年   2203篇
  1977年   2073篇
  1976年   2039篇
  1975年   1903篇
  1974年   1884篇
  1973年   1961篇
  1972年   1265篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
91.
92.
The real structure of bulk Zn1 – хМхSe (S) crystals of diluted magnetic semiconductors with М = V, Cr, Fe, Co, Ni 3d impurities is characterized by neutron diffraction. These impurities are known to greatly destabilize even the initial lattices of pure zinc chalcogenides. Data on the resulting non-uniform microstrain field induced by atomic displacements are obtained from the structural peaks along the tangential and radial directions on the above crystals within a dopant concentration range of 0.01 ≤ х ≤ 0.10. Additional nodes with q = (1/3 1/3 1/3) 2π/a (q is the wave vector and a is the cubic unit cell) emerging in the reciprocal lattice of the cubic structure are considered as evidence for a pre-transition to the fcc (face-centered cubic)–hcp (hexagonal close-packed) phase state, which implies transitions from the fcc lattice along an 8-ray non-Lifshitz star with the wave vector k5 = μ(b1 + b2 + b3), where b1, b2, b3 are the reciprocal lattice vectors and μ ≈ 1/3.  相似文献   
93.
Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques - A method for studying the magnetic dynamics of endofullerenes M@C2n (2n = 60, 70, …) and their derivatives,...  相似文献   
94.
95.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films were investigated using a number of techniques. A high saturation magnetic induction up to B s = 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed, which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of the composition. The text was submitted by the authors in English.  相似文献   
96.
Methods for phase stabilization of ammonium nitrate were sought for in order to considerably expand the application area of this oxidizing agent in various-purpose self-combustible formulations, including that in a new generation of gas-generating formulations for automobile air bags. New methods for stabilization of ammonium nitrate were studied and, in particular, a search was made for organic compounds that can stabilize ammonium nitrate even at their low content. The mechanism of phase state stabilization of ammonium nitrate by compounds of this kind was examined.  相似文献   
97.
Kinetic, sorption and selectivity properties of commercial adsorbents are improved by adding petroleum residues (tar asphaltene concentrates) 13% of whole mass. Obtained adsorbents can be used for selective extraction of nobel metals from multicomponent polymetallic solutions of heavy metals and fro sewages purification for removing arsenic.  相似文献   
98.
All 3-dimensional convex polytopes are known to be rigid. Still their Minkowski differences (virtual polytopes) can be flexible with any finite freedom degree. We derive some sufficient rigidity conditions for virtual polytopes and present some examples of flexible ones. For example, Bricard's first and second flexible octahedra can be supplied by the structure of a virtual polytope.  相似文献   
99.
100.
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