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   1038篇
  免费   13篇
  国内免费   2篇
化学   702篇
晶体学   16篇
力学   5篇
数学   46篇
物理学   284篇
  2022年   8篇
  2021年   4篇
  2020年   5篇
  2019年   9篇
  2018年   6篇
  2016年   11篇
  2015年   8篇
  2014年   7篇
  2013年   29篇
  2012年   44篇
  2011年   30篇
  2010年   17篇
  2009年   23篇
  2008年   47篇
  2007年   53篇
  2006年   49篇
  2005年   46篇
  2004年   46篇
  2003年   51篇
  2002年   43篇
  2001年   19篇
  2000年   19篇
  1999年   7篇
  1998年   17篇
  1997年   5篇
  1996年   22篇
  1995年   15篇
  1994年   17篇
  1993年   15篇
  1992年   27篇
  1991年   11篇
  1990年   15篇
  1989年   14篇
  1988年   11篇
  1987年   10篇
  1986年   8篇
  1985年   24篇
  1984年   22篇
  1983年   12篇
  1982年   27篇
  1981年   17篇
  1980年   25篇
  1979年   15篇
  1978年   17篇
  1977年   28篇
  1976年   22篇
  1975年   16篇
  1974年   10篇
  1973年   22篇
  1965年   3篇
排序方式: 共有1053条查询结果,搜索用时 203 毫秒
91.
Nanoscale patterns of modified oligonucleotides are produced on octadecyltrimethoxysilane self-assembled monolayers at a silicon surface by electron beam lithography. DNA structures with feature sizes of the order of 250 nm were detected by epi-fluorescence microscopy.  相似文献   
92.
We report a search for CP-violating asymmetry in B0-->D(*+/-)D-/+ decays. The analysis employs two methods of B0 reconstruction: full and partial. In the full reconstruction method all daughter particles of the B0 are required to be detected; the partial reconstruction technique requires a fully reconstructed D- and only a slow pion from the D(*+)-->D0pi(+)(slow) decay. From a fit to the distribution of the time interval corresponding to the distance between two B meson decay points we calculate the CP-violating parameters and find the significance of nonzero CP asymmetry to be 2.7 standard deviations.  相似文献   
93.
The radiative decay B-->phi K gamma is observed for the first time. The branching fraction for the charged B--->phi K- gamma decay mode is measured to be B(B--->phi K- gamma)=(3.4+/-0.9+/-0.4)x10(-6). The photon energy distribution for the B--->phi K- gamma decay is presented. The signal for the neutral B(0)-->phi K(0)gamma decay mode is not statistically significant and an upper limit, B(B(0)-->phi K(0)gamma)<8.3x10(-6) at 90% C.L., is set. The analysis is based on a data set of 90 fb(-1) collected by the Belle experiment at the e(+)e(-) asymmetric collider KEKB.  相似文献   
94.
We report measurements of branching fractions for charged and neutral B-->eta(c)K decays where the eta(c) meson is reconstructed in the K(0)(S)K+/-pi(-/+), K+K-pi(0), K(*0)K-pi(+), and pp; decay channels. The neutral B0 channel is a CP eigenstate and can be used to measure the CP violation parameter sin(2phi(1). We also report the first observation of the B0-->eta(c)K(*0) mode. The results are based on an analysis of 29.1 fb(-1) of data collected by the Belle detector at KEKB.  相似文献   
95.
Methods to prepare fractions of poly(epsilon-caprolactone) with a narrow molecular mass distribution in large quantities have been examined using high osmotic pressure chromatography under the theta condition. Effects of column dimension and coupling columns in series on the separation resolution were studied. We found that use of a thicker column can improve the resolution if adverse effects of viscous fingering are avoided. We also demonstrated that coupling the columns results in a better separation if the second column does not adsorb high-molecular-mass components purified in the first column.  相似文献   
96.
In order to solve the issues in Si nanoelectronics such as fluctuation in the device functions and poor reliability of devices due to relative increase in mass transport in nm size structures and to yield novel functions by rather taking advantage of the nm size, we need to understand the phenomena peculiar to nm size structures. Based on the fact that a practical method to fabricate nm structures in terms of throughput, process time, and cost is to combine modification of solid surfaces with energetic particles (especially with single ions) and subsequent chemical processing in solutions, we describe single ion irradiation effects as a tool to modify solid surfaces in nm scale, a method for nm scale in-situ observation of solid surfaces, and some examples of the acquired knowledge.  相似文献   
97.
We obtain a “Kronecker limit formula” for the Epstein zeta function. This is done by introducing a generalized gamma function attached to the Epstein zeta function. The methods involve generalizing ideas of Shintani and Stark. We first show that a generalized gamma function appears as the value at s=0 of the first derivative of the associated Epstein zeta function. Then this is used to yield Kronecker's limit formula and its “s=0”-version.  相似文献   
98.
Group 9 metal compounds in organic synthesis have two characteristic reactions. The first occurs because the group 9 metals have a high affinity to carbon–carbon or carbon–nitrogen π‐bonds. The first type of characteristic reactions in these group 9 metal compounds includes Pauson–Khand reactions, the Pauson–Khand‐type reactions ([2 + 2 + 1] cyclization), the other cyclizations and coupling reactions. The second occurs because the group 9 metals have a high affinity to carbonyl groups. The second type of characteristic reactions includes carbonylations such as hydroformylations, the carbonylations of methanol, amidocarbonylations and other carbonylations. The first characteristic reactions are applied for the synthesis of fine chemicals such as pharmaceuticals and agrochemicals. However, the second characteristic reactions are utilized not only for fine chemicals but also for important bulk commodity chemicals such as aldehydes, carboxylic acids and alcohols. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
99.
100.
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