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   57篇
  免费   1篇
  国内免费   2篇
化学   25篇
晶体学   2篇
力学   1篇
数学   22篇
物理学   10篇
  2022年   1篇
  2021年   2篇
  2020年   1篇
  2019年   1篇
  2016年   1篇
  2014年   1篇
  2013年   6篇
  2012年   2篇
  2011年   1篇
  2010年   1篇
  2009年   5篇
  2008年   1篇
  2007年   2篇
  2006年   5篇
  2005年   1篇
  2004年   5篇
  2003年   2篇
  2002年   4篇
  2001年   1篇
  2000年   1篇
  1998年   2篇
  1997年   1篇
  1996年   2篇
  1995年   3篇
  1992年   4篇
  1991年   1篇
  1990年   1篇
  1980年   2篇
排序方式: 共有60条查询结果,搜索用时 312 毫秒
21.
The correlation factor in the Nernst-Einstei equation for low sodium Na2OGeO2 glass determined from dc conductivity and 22Na diffusion coefficient measurements was found to be near unity. Values of the correlation factor were also compiled from the literature for higher alkali content germanate glasses as well as for sodium borate and alkali silicate glasses. In all three systems the correlation factor was found to depend primarily on the alkali content in the glass. Specifically, uncorrelated ionic diffusion (? ? 1) occurs in low alkali glasses while correlated motion (? < 1) takes place at higher alkali concentrations. This observation is consistent with the theory that many “holes” exist in low alkali glasses through which the diffusing cation can randomly jump.  相似文献   
22.
There is a possibility that not all alkali ions are mobile in glass at a given time, similar to the weak electrolyte aqueous solution. The applicability of the weak electrolyte theory was tested by two types of experiments; one is the concentration dependence of the equivalent conductance of GeO2 glasses containing small amounts of Na2O and the other is the high field conduction of commercial glasses. In both cases, the theory was found to be applicable in a limited range.  相似文献   
23.
In the present study, we show that the heterogeneous mixture of glycoforms of the basic salivary proline‐rich protein 3M, encoded by PRB3‐M locus, is a major component of the acidic soluble fraction of human whole saliva in the first years of life. Reversed‐phase high‐performance liquid chromatography with high‐resolution electrospray ionization mass spectrometry analysis of the intact proteoforms before and after N‐deglycosylation with Peptide‐N‐Glycosidase F and tandem mass spectrometry sequencing of peptides obtained after Endoproteinase GluC digestion allowed the structural characterization of the peptide backbone and identification of N‐ and O‐glycosylation sites. The heterogeneous mixture of the proteoforms derives from the combination of 8 different neutral and sialylated glycans O‐linked to Threonine 50, and 33 different glycans N‐linked to Asparagine residues at positions 66, 87, 108, 129, 150, 171, 192, and 213.  相似文献   
24.
In this paper we introduce a two-sided Arnoldi method for the reduction of high order linear systems and we propose useful extensions, first of all a stopping criterion to find a suitable order for the reduced model and secondly, a selection procedure to significantly improve the performance in the multi-input multi-output (MIMO) case. One application is in micro-electro-mechanical systems (MEMS). We consider a thermo-electric micro thruster model, and a comparison between the commonly used Arnoldi algorithm and the two-sided Arnoldi is performed.  相似文献   
25.
26.
In this work we discuss the problem of smooth and analytic regularity for hyperfunction solutions to linear partial differential equations with analytic coefficients. In particular we show that some well known “sum of squares” operators, which satisfy Hörmander’s condition and consequently are hypoelliptic, admit hyperfunction solutions that are not smooth (in particular they are not distributions).  相似文献   
27.
In this paper we deal with the existence of weak solutions for the following Neumann problem¶¶$ \left\{{ll} -\mathrm{div}(|\nabla u|^{p-2}\nabla u) + \lambda(x)|u|^{p-2}u = \alpha(x)f(u) + \beta(x)g(u) $ \left\{\begin{array}{ll} -\mathrm{div}(|\nabla u|^{p-2}\nabla u) + \lambda(x)|u|^{p-2}u = \alpha(x)f(u) + \beta(x)g(u) &; $ \mbox{in $ \mbox{in \Omega$}\\ {\partial u \over \partial \nu} = 0 $}\\ {\partial u \over \partial \nu} = 0 &; $ \mbox{on $ \mbox{on \partial \Omega$} \right. $}\end{array} \right. ¶¶ where $ \nu $ \nu is the outward unit normal to the boundary $ \partial\Omega $ \partial\Omega of the bounded open set _boxclose^N \Omega \subset \mathbb{R}^N . The existence of solutions, for the above problem, is proved by applying a critical point theorem recently obtained by B. Ricceri as a consequence of a more general variational principle.  相似文献   
28.
29.
The one-pot reaction of enolisable 1,3-dicarbonyls and N-methyl-1,3-oxazolium-5-olate derivatives provided enol lactones directly in good yield and with excellent regio- and diastereocontrol.  相似文献   
30.
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