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   569018篇
  免费   6005篇
  国内免费   1625篇
化学   274547篇
晶体学   8001篇
力学   29243篇
综合类   13篇
数学   96166篇
物理学   168678篇
  2021年   3848篇
  2020年   4255篇
  2019年   4619篇
  2018年   20306篇
  2017年   20564篇
  2016年   16573篇
  2015年   6921篇
  2014年   9027篇
  2013年   20791篇
  2012年   21655篇
  2011年   36087篇
  2010年   23189篇
  2009年   23451篇
  2008年   30541篇
  2007年   34485篇
  2006年   16697篇
  2005年   20806篇
  2004年   17397篇
  2003年   16180篇
  2002年   13720篇
  2001年   13782篇
  2000年   10602篇
  1999年   8095篇
  1998年   6771篇
  1997年   6474篇
  1996年   6368篇
  1995年   5667篇
  1994年   5546篇
  1993年   5358篇
  1992年   5948篇
  1991年   6050篇
  1990年   5768篇
  1989年   5604篇
  1988年   5626篇
  1987年   5500篇
  1986年   5212篇
  1985年   6693篇
  1984年   6832篇
  1983年   5423篇
  1982年   5518篇
  1981年   5489篇
  1980年   5088篇
  1979年   5478篇
  1978年   5621篇
  1977年   5435篇
  1976年   5403篇
  1975年   4982篇
  1974年   4941篇
  1973年   4984篇
  1972年   3508篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
This paper analyzes the compromise social choice correspondence derived from the τ-value of digraph games. Monotonicity of this correspondence is shown. A connection between several properties of social choice correspondences based on game theoretical solutions and game theoretical properties of the underlying solutions is given. Applications to several game theoretic solutions are provided.  相似文献   
922.
923.
924.
The PARRNe facility has been used to produce neutron-rich isotopes 83,84Gaby the ISOL method. Their decay has been studied, and β-γ coincidence and γ-γ coincidence data were collected as a function of time. The first two excited levels in 83Ge and the first excited level in 84Ge have been measured for the first time.  相似文献   
925.
The steady motion of a spheroidal aerosol particle with inner nonuniformly distributed heat sources (sinks) that is placed in an external temperature gradient is theoretically studied in the Stokes approximation. The mean temperature of the particle surface is assumed to differ slightly from that of the gaseous environment. An analytic expression for the force and rate of thermophoresis are found by solving the gas-dynamic equations in view of the motion of the environment.  相似文献   
926.
The problem of finding the Euclidean distance between two convex polyhedra can be reduced to the combinatorial optimization problem of finding the minimum distance between their faces. This paper presents a global optimality criterion for this problem. An algorithm (QLDPA) for the fast computation of the distance between convex and bounded polyhedra is proposed as an application of it. Computer experiments show its fast performance, especially when the total number of vertices is large.  相似文献   
927.
928.
929.
930.
An experiment was designed to determine whether normally sighted human subjects would be able to adapt to the handicapping effects of sudden deprivation of visual cues on horizontal plane sound localization. Two groups of sighted normal-hearing young adults participated. One group was allowed the benefit of sight. The other group was blindfolded. Measurements of accuracy and the time to respond were made daily over the course of five consecutive days, in a semi-reverberant sound proof booth that modeled listening in a small office. Sound localization was assessed using an array of eight speakers that surrounded the subject in space. Each day, one block of 120 trials was presented for each of three stimuli, two one-third octave noise bands, centred at 0.5 and 4 kHz, and broadband noise, to assess the utilization of interaural temporal difference cues, interaural level difference cues and binaural and spectral cues in combination. Blindfolded subjects were relatively less accurate than sighted subjects. Both groups showed gains with practice, the blindfolded group to a greater degree, largely due to improvements in the use of spectral cues. The blindfolded group took longer to respond than the sighted group, but showed greater decrements in response time with practice.  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