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   742篇
  免费   20篇
  国内免费   2篇
化学   442篇
晶体学   10篇
力学   73篇
数学   100篇
物理学   139篇
  2023年   11篇
  2022年   8篇
  2021年   15篇
  2020年   12篇
  2019年   7篇
  2018年   13篇
  2017年   9篇
  2016年   11篇
  2015年   13篇
  2014年   13篇
  2013年   34篇
  2012年   30篇
  2011年   42篇
  2010年   15篇
  2009年   21篇
  2008年   28篇
  2007年   37篇
  2006年   29篇
  2005年   24篇
  2004年   23篇
  2003年   9篇
  2002年   23篇
  2001年   11篇
  2000年   9篇
  1999年   17篇
  1998年   9篇
  1996年   6篇
  1995年   9篇
  1994年   8篇
  1993年   10篇
  1992年   12篇
  1991年   6篇
  1990年   10篇
  1989年   8篇
  1988年   7篇
  1987年   9篇
  1986年   6篇
  1985年   14篇
  1984年   15篇
  1983年   15篇
  1982年   11篇
  1981年   10篇
  1980年   10篇
  1979年   13篇
  1977年   9篇
  1976年   18篇
  1975年   15篇
  1974年   13篇
  1973年   10篇
  1971年   8篇
排序方式: 共有764条查询结果,搜索用时 125 毫秒
81.
82.
83.
The foundation of a dynamic theory for the bargaining sets started withStearns, when he constructed transfer sequences which always converge to appropriate bargaining sets. A continuous analogue was developed byBillera, where sequences where replaced by solutions of systems of differential equations. In this paper we show that the nucleolus is locally asymptotically stable both with respect toStearns' sequences andBillera's solutions if and only if it is an isolated point of the appropriate bargaining set. No other point of the bargaining set can be locally asymptotically stable. Furthermore, it is always stable in these processes. As by-products of the study we derive the results ofBillera andStearns in a different fashion. We also show that along the non-trivial trajectories and sequences, the vector of the excesses of the payoffs, arranged in a non-increasing order, always decreases lexicographically, thus each bargaining set can be viewed as resulting from a certain monotone process operating on the payoff vectors.  相似文献   
84.
85.
Microwave spectra of 1,3-dithiole-2-one show that the molecule has a planar equilibrium conformation. IR and Raman spectra are analysed to give the normal modes of vibration.  相似文献   
86.
Carboxy-SNARF-1 is an emission-changing, pH-sensitive probe for measurements of intracellular pH. However, the protonated and deprotonated forms of the dye interact differently with intracellular constituents, and this imposes new requirements on the calibration of the system. Whole spectra of intracellular and extracellular C.SNARF-1 were analyzed and showed (1) intracellular quenching which was significantly greater for the deprotonated form of the dye than for the protonated state and (2) a detectable change in pK a. Importantly for avoiding damage to cells, this mathematical analysis allowed reference spectra for fully protonated and fully deprotonated dye to be obtained without a need for spectra measured at extreme values of pH. It is not known what constituent(s) of the intracellular milieu might be responsible for the changes in dye behavior in the cell. To address this question, preliminary experiments with cell-free buffers compared the pattern seen inside the cell with quenching by a protein (bovine serum albumin; BSA) or that due to ethanol. The BSA result was completely unlike the intracellular case in that the protonated form of the dye was quenched. Buffer containing ethanol, on the other hand, was able to mimic the essential features of the intracellular spectra.  相似文献   
87.
A novel synthesis of perazine (10-(4-methylpiperazinyl-3-propyl)phenothiazine), likely to be applicable to 10-dialkylaminopropyl phenothiazines generally, is described.  相似文献   
88.
We have looked for the decay ηπ0e+e? in an optical spark chamber experiment at the Rutherford Laboratory. Our observations are consistent with no events being seen and give an upper limit rate (ηπ0e+e?)/ rate (ηall) < 4.5 × 10?5 (90% C.L.).  相似文献   
89.
The infrared absorption spectra of ethyl fluoroformate and ethyl propiolate have been examined in the vapour, solution and solid states. For both esters evidence is found of rotational isomerism arising from internal rotation about the O-C2H5 bond, in close agreement with previous work on other ethyl esters.  相似文献   
90.
In an optical spark chamber experiment we have obtained a sample of 80 eta Dalitz decays (ηe+e?γ) and have measured the eta electromagnetic form factor to be F(X) = 1.0?(0.22 ±0.45)X, where X=Mee2/Mη2, and the branching ratio (ηe+e?γ/(ηπ+π?π0)= (0.0082 ± 0.0020).  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