全文获取类型
收费全文 | 231篇 |
免费 | 3篇 |
国内免费 | 4篇 |
专业分类
化学 | 151篇 |
晶体学 | 5篇 |
力学 | 3篇 |
数学 | 54篇 |
物理学 | 25篇 |
出版年
2022年 | 3篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 13篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 8篇 |
2007年 | 11篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
排序方式: 共有238条查询结果,搜索用时 109 毫秒
101.
Lilli Paama Ilkka Pitk nen Hannu R nkk m ki Paavo Per m ki 《Thermochimica Acta》1998,320(1-2):127-133
The characterization of historical mortars was performed by thermal analysis (TG-DTG), simultaneous infrared spectroscopy (TG-FTIR) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The samples were taken from St. John Church (Tartu, Estonia), built in the 13th–14th centuries. The analyses are important for the restoration of the church.
In reality, mortar is a very difficult system, the lime is accompanied with different hydraulic components. TG-DTG analysis and FTIR methods can be used to identify various components of mortar and to observe the reactions associated with the controlled heating at 25–900°C in dynamic air and nitrogen atmosphere. The elemental composition of the acid-soluble components (ASC) was determined by using the ICP-AES techniques. 相似文献
102.
This paper describes a method for monitoring the degradation of hydrogen peroxide by cells immobilized on a beaded support. The detection is based on the voltammetric reduction of hydrogen peroxide on a mercury film working electrode, whilst combining the concept of sequential injection (SI) with the lab-on-valve (LOV) manifold allows the measurements to be carried out in real time and automatically, in well-defined conditions. The method is shown to be capable of simultaneously monitoring hydrogen peroxide in the 10-1000 microM range and oxygen in the 160-616 microM range. A correction algorithm has been used to ensure reliable H2O2 results in the presence of varying oxygen levels. The method has been successfully applied to monitoring the degradation of H2O2 by wild-type cells and by catalase-overexpressing mouse embryonic fibroblasts. Since the technique allows the monitoring of the initial response rate, it provides data not accessible by current methods that are end-point-based measurements. 相似文献
103.
Carleman estimates and inverse problems for Dirac operators 总被引:1,自引:0,他引:1
We consider limiting Carleman weights for Dirac operators and prove corresponding Carleman estimates. In particular, we show
that limiting Carleman weights for the Laplacian also serve as limiting weights for Dirac operators. As an application we
consider the inverse problem of recovering a Lipschitz continuous magnetic field and electric potential from boundary measurements
for the Pauli Dirac operator.
M. Salo is supported by the Academy of Finland. L. Tzou is supported by the Doctoral Post-Graduate Scholarship from the Natural
Science and Engineering Research Council of Canada. This article was written while L. Tzou was visiting the University of
Helsinki and TKK, whose hospitality is gratefully acknowledged. The authors would like to thank András Vasy and Lauri Ylinen
for useful comments. 相似文献
104.
Ilkka Holopainen 《Israel Journal of Mathematics》2000,115(1):363-379
We studyL
q-Liouville properties of nonnegativep-superharmonic and, respectively,p-subharmonic functions on a complete Riemannian manifoldM. In particular, we prove that everyp-harmonic functionu ∈L
q (M) is constant ifq>p−1.
Supported by the Academy of Finland, Project 6355. 相似文献
105.
106.
Francis J. Chung Petri Ola Mikko Salo Leo Tzou 《Annales de l'Institut Henri Poincaré (C) Analyse Non Linéaire》2018,35(3):605-624
In this article we consider an inverse boundary value problem for the time-harmonic Maxwell equations. We show that the electromagnetic material parameters are determined by boundary measurements where part of the boundary data is measured on a possibly very small set. This is an extension of earlier scalar results of Bukhgeim–Uhlmann and Kenig–Sjöstrand–Uhlmann to the Maxwell system. The main contribution is to show that the Carleman estimate approach to scalar partial data inverse problems introduced in those works can be carried over to the Maxwell system. 相似文献
107.
Salo Gronowitz Anders Hallberg Christer Glennow 《Journal of heterocyclic chemistry》1980,17(1):171-174
The reaction of 3-bromo-2-iodothiophene with sodium methoxide in methanol, pyridine or hexamethylphosphoric triamide and the same reaction of 4-bromo-2-iodo- and 4-bromo-3-iodo-thiophene in pyridine led to a halogen-dance, giving the same mixture of 3-bromothiophene, bromo-iodothiophenes, diiodo-bromothiophenes and triiodo-bromothiophenes. The reaction of all three isomeric bromo-iodothiophenes with sodium methoxide in methanol in the presence of cupric oxide gave 4-bromo-2-methoxythiophene. 相似文献
108.
Ilkka Moring Heikki Ailisto
Visa Koivunen
Risto Myllyl 《Optics and Lasers in Engineering》1989,10(3-4):149-160Three-dimensional computer vision can be useful in applications like gauging and inspection of shapes. In this paper an approach for model-based shape inspection of large objects using active 3-D vision is presented. The 3-D vision sensor developed is based on the direct measurement of the time-of-flight of a laser pulse. Inspection software, including methods for comparison of the acquired shape information to a CAD model, is described. Results of preliminary tests are reported. 相似文献
109.
In any Carnot (nilpotent stratified Lie) group G of homogeneous dimension Q, Green's function u for the Q-Laplace equation exists and is unique. We prove that there exists a constant so that is a homogeneous norm in G. Then the extremal lengths of spherical ring domains (measured with respect to N) can be computed and used to give estimates for the extremal lengths of ring domains measured with respect to the Carnot-Carathéodory
metric. Applications include regularity properties of quasiconformal mappings and a geometric characterization of bi-Lipschitz
mappings.
Received: 18 September 2000/ revised version: 19 November 2001 / Published online: 17 June 2002 相似文献
110.
A fluid queue receiving its input from the output of a precedingM/M/1 queue is considered. The input can be characterized as a Markov modulated rate process and the well known spectral decomposition technique can be applied. The novel features in this system relate to the nature of the spectrum, which is shown to be composed of a continuous part and one or two discrete points depending on whether the load of the fluid queue is less or greater than the output to input rate ratio. Explicit expressions of the generalized eigenvectors are given in terms of Chebyshev polynomials of the second kind, and the resolution of unity is determined. The solution for the buffer content distribution is obtained as a simple integral expression. Numerical examples are given. 相似文献