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   314813篇
  免费   3762篇
  国内免费   1092篇
化学   170799篇
晶体学   4457篇
力学   13032篇
综合类   7篇
数学   36282篇
物理学   95090篇
  2020年   1988篇
  2019年   1958篇
  2018年   1972篇
  2017年   1880篇
  2016年   3874篇
  2015年   3240篇
  2014年   4429篇
  2013年   13988篇
  2012年   10740篇
  2011年   13383篇
  2010年   8278篇
  2009年   8263篇
  2008年   12351篇
  2007年   12586篇
  2006年   12224篇
  2005年   11169篇
  2004年   10045篇
  2003年   8867篇
  2002年   8713篇
  2001年   10123篇
  2000年   7720篇
  1999年   6126篇
  1998年   4904篇
  1997年   4740篇
  1996年   4780篇
  1995年   4375篇
  1994年   4127篇
  1993年   3951篇
  1992年   4445篇
  1991年   4296篇
  1990年   4023篇
  1989年   3834篇
  1988年   4128篇
  1987年   3789篇
  1986年   3680篇
  1985年   5323篇
  1984年   5402篇
  1983年   4383篇
  1982年   4756篇
  1981年   4806篇
  1980年   4552篇
  1979年   4669篇
  1978年   4675篇
  1977年   4649篇
  1976年   4603篇
  1975年   4511篇
  1974年   4359篇
  1973年   4527篇
  1972年   2573篇
  1971年   1880篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
The breakup of suspended, agglomerated submicron particles was studied by exposing the aerosol to weak shock waves of varying strength under conditions 400 ms?1?v?880 ms?1. A newly developed laser light-scattering diagnostic employing a top hat laser profile was used to size the particles passing through a very small scattering volume. By Comparing the optically measured particle size in front of and behind shock waves, the breakup of agglomerated particles could be clearly identified. The experiments indicate that the aerodynamic forces behind an incident shock overcome the particle binding force resulting in disintegration of the submicron agglomerates. The results are presented in form of a modified Weber number.  相似文献   
993.
994.
995.
We present two different approaches to detect and quantify phase synchronization in the case of coupled non-phase coherent oscillators. The first one is based on the general idea of curvature of an arbitrary curve. The second one is based on recurrences of the trajectory in phase space. We illustrate both methods in the paradigmatic example of the R?ssler system in the funnel regime. We show that the second method is applicable even in the case of noisy data. Furthermore, we extend the second approach to the application of chains of coupled systems, which allows us to detect easily clusters of synchronized oscillators. In order to illustrate the applicability of this approach, we show the results of the algorithm applied to experimental data from a population of 64 electrochemical oscillators.  相似文献   
996.
997.
About 40 epoxide-amine network polymers with glass transition temperatures ranging from 0 to 232°C were investigated, about one-third being reported for the first time. The glass transition temperature Tgl of the corresponding linear copolymers was first calculated by use of an additivity law whose physical validity was carefully checked. Then the contribution of crosslink mers was determined, and various physical and empirical approaches of the effect of crosslinking on Tg were compared. The results gave evidence in favor of the DiMarzio approach. A predictive relationship based on these considerations is proposed.  相似文献   
998.
Magnetic properties, electrical resistivity, specific heat and magnetic excitations have been investigated in Heusler phases CeInAg2–xCux. The hybridization continuously increases from CeInAg2 (antiferromagnetic Kondo lattice) to CeInCu2 (heavy fermion compound). The specific heat coefficient for this last compound is found to reach 1.2 J/mole. K2 at 1.4 K, the Kondo temperature is 6 K and the Wilson ratio is close to 2.  相似文献   
999.
The macroscopic approach for two-particle transfer reactions is applied in normal spherical nuclei and pairing deformation parameters βp are estimated. For Ni isotopes the macroscopic approach works reasonably well while for the lead region strong energy dependence of theβ p values has been observed. It is shown that alpha-transfer reactions can also be treated within this formalism as couplings of the two-neutron and two-proton channels.  相似文献   
1000.
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