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   733篇
  免费   15篇
  国内免费   1篇
化学   554篇
晶体学   15篇
力学   6篇
数学   18篇
物理学   156篇
  2021年   3篇
  2020年   8篇
  2019年   8篇
  2018年   6篇
  2017年   3篇
  2016年   6篇
  2015年   9篇
  2014年   9篇
  2013年   16篇
  2012年   32篇
  2011年   38篇
  2010年   26篇
  2009年   23篇
  2008年   50篇
  2007年   65篇
  2006年   32篇
  2005年   40篇
  2004年   42篇
  2003年   38篇
  2002年   29篇
  2001年   35篇
  2000年   29篇
  1999年   12篇
  1998年   8篇
  1997年   12篇
  1996年   8篇
  1995年   10篇
  1993年   6篇
  1992年   11篇
  1991年   4篇
  1990年   6篇
  1989年   8篇
  1988年   9篇
  1987年   6篇
  1986年   8篇
  1985年   11篇
  1984年   6篇
  1983年   9篇
  1982年   3篇
  1981年   4篇
  1980年   4篇
  1979年   6篇
  1978年   7篇
  1977年   6篇
  1976年   3篇
  1975年   8篇
  1974年   5篇
  1973年   3篇
  1966年   3篇
  1965年   4篇
排序方式: 共有749条查询结果,搜索用时 15 毫秒
51.
52.
Vortexlike turbulent structures in hot-ion mode plasmas with several keV are observed in the case with a radially produced weak shear of electric fields E(r). However, a strong E(r) shear formation due to a high ion-confining potential phi(c) production clears up these vortices together with plasma-confinement improvement and disappearance of both drift-wave and turbulencelike Fourier spectral signals. These findings are based on three-time progress in phi(c) in comparison to phi(c) attained 1992-2002. The significant advance of phi(c) is well extended in line with proposed potential-formation physics scalings.  相似文献   
53.
We elaborated a versatile experimental model of chromatin which consists of a single chain of long duplex DNA that interacts with well-defined cationic nanoparticles of various sizes. We found that the DNA compaction by nanoparticles is stepwise and progressive at the single-chain level. It is controlled by the ability of DNA to wrap nanoparticles, which is more efficient for larger particles and, similar to DNA-histone interaction, is optimal at a physiological salt concentration.  相似文献   
54.
55.
56.
57.
Four new aromatic constituents, rhododendroketoside, (-)-sakuraresinoside, acernikol, and nikoenoside, were isolated from a Japanese folk medicine, the stem bark of Acer nikoense MAXIM. The structures of the new constituents were determined on the basis of chemical and physicochemical evidence. The principle cyclic diarylheptanoids were found to show inhibitory effects on the release of beta-hexosaminidase in RBL-2H3 cells.  相似文献   
58.
Two new friedelane-type triterpenes, salasones D and E, a new norfriedelane-type triterpene, salaquinone B, and a new polyacylated eudesmane-type sesquiterpene, salasol B, were isolated from the stems of Salacia chinensis LINN. (S. prinoides DC., Hippocrateaceae) collected in Thailand. Their stereostructures were elucidated on the basis of chemical and physicochemical evidence. Some norfriedelane-type triterpene, lignan, and catechin constituents were found to show radical scavenging activity.  相似文献   
59.
We studied the stability and dynamics of a model of a nucleosome, the fundamental unit for the packing of long DNA in eukaryotes, using a Brownian dynamics simulation. For the proper folding of a stiff polymer on a core particle, moderate attractive interaction is shown to be essentially important, which explains the empirical experimental protocol for the reconstitution of nucleosomes. The effect of the chain end on the positioning of the core particle is examined and compared with the experimental data by atomic force microscopy measurement. It is also suggested that the core particle exhibits sliding motion along the chain as a manifestation of Brownian motion.  相似文献   
60.
Yoshikawa N  Yatagai T 《Optics letters》2000,25(19):1424-1426
We propose a novel three-dimensional (3-D) object-recognition method based on a Fourier-transform profilometry technique and a two-dimensional (2-D) correlation technique. Height information on 3-D objects is transformed to phase information on 2-D complex amplitude by use of the Fourier-transform profilometry technique. 3-D objects are recognized using correlation by use of the transformed complex amplitude.  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