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   113917篇
  免费   55篇
  国内免费   30篇
化学   39800篇
晶体学   1686篇
力学   7706篇
综合类   3篇
数学   26362篇
物理学   38445篇
  2018年   9798篇
  2017年   10769篇
  2016年   4546篇
  2015年   1022篇
  2014年   215篇
  2013年   341篇
  2012年   4946篇
  2011年   14031篇
  2010年   8017篇
  2009年   8169篇
  2008年   11938篇
  2007年   15899篇
  2006年   361篇
  2005年   7709篇
  2004年   3973篇
  2003年   3906篇
  2002年   1699篇
  2001年   285篇
  2000年   446篇
  1999年   133篇
  1998年   104篇
  1997年   77篇
  1996年   260篇
  1995年   171篇
  1994年   166篇
  1993年   142篇
  1992年   147篇
  1991年   154篇
  1990年   157篇
  1989年   144篇
  1988年   137篇
  1987年   150篇
  1986年   141篇
  1985年   154篇
  1984年   188篇
  1983年   186篇
  1982年   172篇
  1981年   182篇
  1980年   192篇
  1979年   185篇
  1978年   212篇
  1977年   127篇
  1976年   140篇
  1975年   107篇
  1974年   101篇
  1973年   140篇
  1972年   74篇
  1969年   111篇
  1968年   129篇
  1966年   84篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
21.
The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi-LAT) started a pivotal period in indirect detection of dark matter. By outperforming expectations, for the first time a robust and stringent test of the paradigm of weakly interacting massive particles (WIMPs) is within reach. In this paper, we discuss astrophysical targets for WIMP detection and the challenges they present, review the analysis tools which have been employed to tackle these challenges, and summarize the status of constraints on and the claimed detections in the WIMP parameter space. Methods and results will be discussed in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook on short term and longer term developments.  相似文献   
22.
The structure and properties of 12Cr1MoV steel irradiated with a zirconium ion beam were studied by optical microscopy, scanning electron microscopy, and micro- and nanoindentation. It is shown that the modification covers the entire cross-section of the irradiated specimens to a depth of 1 mm. The data on irradiation-induced structural changes are used to interpret the changes in mechanical properties of the irradiated specimens under static and cyclic loading. Particular attention is given to analysis of strain estimation by the digital image correlation method.  相似文献   
23.
24.
25.
26.
Submicron CaZrO3 powder is obtained in combustion reactions (solution combustion synthesis—SCS) with glycine. It is found that SCS reduces the sintering temperature of CaZrO3 powders. The dielectric properties of calcium zirconate ceramics are studied by the electrochemical impedance method. It is shown that a ceramics of powders obtained by the SCS method has high dielectric characteristics.  相似文献   
27.
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   
28.
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   
29.
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   
30.
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   
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