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   359147篇
  免费   3390篇
  国内免费   844篇
化学   167516篇
晶体学   5446篇
力学   17931篇
综合类   1篇
数学   55140篇
物理学   117347篇
  2020年   2232篇
  2019年   2383篇
  2018年   11287篇
  2017年   12055篇
  2016年   8562篇
  2015年   3975篇
  2014年   4973篇
  2013年   12075篇
  2012年   13087篇
  2011年   22818篇
  2010年   14355篇
  2009年   14224篇
  2008年   20227篇
  2007年   23502篇
  2006年   9899篇
  2005年   15061篇
  2004年   11098篇
  2003年   10183篇
  2002年   8240篇
  2001年   7889篇
  2000年   6234篇
  1999年   4729篇
  1998年   3998篇
  1997年   3906篇
  1996年   3970篇
  1995年   3552篇
  1994年   3525篇
  1993年   3658篇
  1992年   3681篇
  1991年   3747篇
  1990年   3509篇
  1989年   3415篇
  1988年   3474篇
  1987年   3337篇
  1986年   3141篇
  1985年   4335篇
  1984年   4528篇
  1983年   3650篇
  1982年   3867篇
  1981年   3809篇
  1980年   3682篇
  1979年   3771篇
  1978年   3896篇
  1977年   3729篇
  1976年   3817篇
  1975年   3471篇
  1974年   3473篇
  1973年   3562篇
  1972年   2399篇
  1971年   2012篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
43.
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   
44.
Functional, degradable polymers were synthesized via the copolymerization of vinyl acetate (VAc) and 2‐methylene‐1,3‐dioxepane (MDO) using a macro‐xanthate CTA, poly(N‐vinylpyrrolidone), resulting in the formation of amphiphilic block copolymers of poly(NVP)‐b‐poly(MDO‐co‐VAc). The behavior of the block copolymers in water was investigated and resulted in the formation of self‐assembled nanoparticles containing a hydrophobic core and a hydrophilic corona. The size of the resultant nanoparticles was able to be tuned with variation of the hydrophilic and hydrophobic segments of the core and corona by changing the incorporation of the macro‐CTA as well as the monomer composition in the copolymers, as observed by Dynamic Light Scattering, Static Light Scattering, and Transmission Electron Microscopy analyses. The concept was further applied to a VAc derivative monomer, vinyl bromobutanoate, to incorporate further functionalities such as fluorescent dithiomaleimide groups throughout the polymer backbone using azidation and “click” chemistry as postpolymerization tools to create fluorescently labeled nanoparticles. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2699–2710  相似文献   
45.
46.
47.
48.
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   
49.
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   
50.
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   
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