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   498044篇
  免费   6338篇
  国内免费   1460篇
化学   235918篇
晶体学   6516篇
力学   18875篇
综合类   13篇
数学   50322篇
物理学   133892篇
无线电   60306篇
  2021年   4315篇
  2020年   4818篇
  2019年   5150篇
  2018年   6559篇
  2017年   6345篇
  2016年   9722篇
  2015年   6001篇
  2014年   9482篇
  2013年   21819篇
  2012年   16707篇
  2011年   20498篇
  2010年   14783篇
  2009年   15338篇
  2008年   20111篇
  2007年   20437篇
  2006年   19093篇
  2005年   17337篇
  2004年   16153篇
  2003年   14430篇
  2002年   14087篇
  2001年   15794篇
  2000年   12409篇
  1999年   10052篇
  1998年   8621篇
  1997年   8290篇
  1996年   7980篇
  1995年   7219篇
  1994年   7120篇
  1993年   6755篇
  1992年   7389篇
  1991年   7481篇
  1990年   7126篇
  1989年   6796篇
  1988年   6626篇
  1987年   6010篇
  1986年   5651篇
  1985年   7202篇
  1984年   7278篇
  1983年   5823篇
  1982年   5825篇
  1981年   5807篇
  1980年   5368篇
  1979年   5668篇
  1978年   5791篇
  1977年   5691篇
  1976年   5577篇
  1975年   5145篇
  1974年   5111篇
  1973年   5126篇
  1972年   3626篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
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   
993.
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   
994.
995.
996.
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   
997.
A self-consistent, completely quantum calculation of the structure of the inner crust of neutron stars is carried out in the Wigner-Seitz approximation with a realistic phenomenological nuclear energy functional, where pair correlations of neutrons and protons are included in the explicit form. It has been shown that the superfluidity of neutrons and protons affects the structure of the ground state of the crust.  相似文献   
998.
Journal of Statistical Physics - We study high-energy asymptotics of the steady velocity distributions for model kinetic equations describing various regimes in dilute granular flows. The main...  相似文献   
999.
The kinetics of formation and relaxation of transient holographic gratings recorded in a system of saturable three-level centers is studied. Distortions in the shape of the profile of recorded and decaying structures of population and of the refractive index are taken into account. The analysis of the time dependences of diffraction efficiencies of different orders is performed for phase (thermal) and amplitude (concentration) gratings.  相似文献   
1000.
We examine several interesting relationships and expressions involving Fourier-Feynman transform, convolution product and first variation for functionals in the Fresnel class F(B) of an abstract Wiener space B. We also prove a translation theorem and Parseval's identity for the analytic Feynman integral. This revised version was published online in June 2006 with corrections to the Cover Date.  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