全文获取类型
收费全文 | 49篇 |
免费 | 0篇 |
专业分类
化学 | 31篇 |
力学 | 1篇 |
数学 | 14篇 |
物理学 | 3篇 |
出版年
2023年 | 1篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2014年 | 1篇 |
2013年 | 2篇 |
2012年 | 1篇 |
2011年 | 3篇 |
2009年 | 1篇 |
2007年 | 1篇 |
2006年 | 1篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1977年 | 2篇 |
1969年 | 1篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1935年 | 2篇 |
1933年 | 2篇 |
1931年 | 5篇 |
1930年 | 2篇 |
排序方式: 共有49条查询结果,搜索用时 15 毫秒
1.
The time-optimal control of a soft spring is discussed. The domain of controllability and the switching locus are described. It is shown that the switching locus changes in a discontinuous manner as the nonlinearity varies continuously.This research was partially supported by the Joint Services Electronics Program, Grant No. (4711) N00014-67-A-0226 ARPA 1129, and by NASA, Grant No. NGR 15-005-021. 相似文献
2.
John Frith Anneliese Schauerte 《Topology and its Applications》2011,158(17):2322-2331
This paper is the first part of a two-part investigation. It introduces full and balanced biframes which capture useful properties of the reals viewed as a biframe (or bitopological space). The subsequent paper will apply these concepts to the study of completions of quasi-nearness biframes.We start with the smallest dense quotient for biframes. Next we discuss the reals as a biframe and introduce the key ideas of balanced, full and stable biframes. The crucial tool here is the frame pseudocomplement. We include a discussion of the relations between the newly introduced ideas and regularity. Order topology biframes are all regular, normal and balanced but not necessarily full. We consider the plane and various examples related to zero-dimensionality. We provide methods of transferring fullness and balancedness from domain to codomain and conversely under various kinds of maps.Of particular importance to our later study of completions is the idea of a biframe map whose right adjoint preserves the first and second parts of the biframe. We give a result providing sufficient conditions for a map to have a part-preserving right adjoint. We present an example of a dense onto map (which is in fact a compactification) between normal, regular biframes whose right adjoint is not part-preserving. The paper concludes with internal properties of full and balanced biframes showing the particularly close connection between the first and second parts and ends with a final visit to the biframe of reals. 相似文献
3.
4.
Peter Schramel Anneliese Wolf und Gisela Lill 《Fresenius' Journal of Analytical Chemistry》1984,317(3-4):471-477
Zusammenfassung Indicatoren für lang- und kurzzeitige Umweltbelastungen in verschiedenen geographischen Regionen mit ihren verschiedenartigen Belastungsgraden (z. B. Industrie, Landwirtschaft u. a.) sind weltweit mehr und mehr von Interesse. Die wichtigste Frage dabei ist, wie aussagefähig ein bestimmter Indicator für den Stand der Umweltbelastung betrachtet werden kann.Verschiedene Materialien wie Pflanzen, Tiere (Ganztiere bzw. Organe), Organe des Menschen (z. B. Placenta) und Böden wurden in den letzten Jahren als geeignete Indicatoren diskutiert. In verschiedenen Forschungsprogrammen unserer Arbeitsgruppe sind wir mit diesen Fragestellungen intensiv beschäftigt. Materialien wie menschliche Placenta, verschiedene Tierarten und deren Organe, Pflanzen und Böden wurden dabei untersucht, um geeignete Indicatormaterialien zu finden. An Hand einiger ausgewählter Beispiele soll die Aussagefähigkeit dieser Materialien diskutiert werden, wobei der Schwerpunkt auf die Unterscheidung zwischen normaler biologischer Streuung der Daten und dem Einfluß der Umwelt gelegt werden soll. Etwa 20 Elemente mit essentiellen Spurenelementen wie Cu, Fe, Mn, Zn usw. und toxischen Elementen wie Pb, Cd, Hg, As usw. wurden dabei untersucht.
Herrn Prof. Dr. W. Fresenius zum 70. Geburtstag gewidmet 相似文献
Examinations on the suitability of different types of samples as indicators for heavy metal pollution
Summary Indicators for long- and short-term environmental pollution in different regions with different environmental influences (agriculture, industry, etc.) become world-wide more and more of interest. The main question in this connection is how a substance can give evidence for environmental research.Different materials like human placenta, animals (or some organs of these), plants and soils have been discussed in the last few years for use as indicator substances. The use of bioindicators will be discussed in this paper by means of some examples from the research work of our laboratory. About twenty elements, including nearly all the heavy metals like As, Hg, Cd, Pb, etc. and essential trace elements like Cu, Fe, Mn, Zn, etc. have been investigated in these experiments. Main emphasis is laid on the differentiation between normal biological scattering of data and the environmental influence.
Herrn Prof. Dr. W. Fresenius zum 70. Geburtstag gewidmet 相似文献
5.
Ohne ZusammenfassungHerrnHermann Schmidt zum 60. Geburtstag 相似文献
6.
Ohne Zusammenfassung 相似文献
7.
Quasi-nearness biframes provide an asymmetric setting for the study of nearness; in Frith and Schauerte (Quaest Math 33:507–530, 2010) a completion (called a quasi-completion) was constructed for such structures and in Frith and Schauerte (Quaest Math, 2012) completeness was characterized in terms of the convergence of regular Cauchy bifilters. In this paper questions of functoriality for this quasi-completion are considered and one sees that having enough regular Cauchy bifilters plays an important rôle. The quasi-complete strong quasi-nearness biframes with enough regular Cauchy bifilters are seen to form a coreflective subcategory of the strong quasi-nearness biframes with enough regular Cauchy bifilters. Here a significant difference between the symmetric and asymmetric cases emerges: a strong (even quasi-uniform) quasi-nearness biframe need not have enough regular Cauchy bifilters. The Cauchy filter quotient leads to further characterizations of those quasi-nearness biframes having enough regular Cauchy bifilters. The fact that the Cauchy filter quotient of a totally bounded quasi-nearness biframe is compact shows that any totally bounded quasi-nearness biframe with enough regular Cauchy bifilters is in fact quasi-uniform. The paper concludes with various examples and counterexamples illustrating the similarities and differences between the symmetric and asymmetric cases. 相似文献
8.
The paircover approach is used to explore the links between quasi-uniform and proximal biframes. The Samuel compactification for quasi-uniform biframes is constructed and its universal property discussed. 相似文献
9.
G. Klein Gertrud Pollauf Marie Krisch Elisabeth Farkass F. Schusta Anneliese Niethammer G. D. Lander C. K. Glycart M. Wagenaar F. Pavelka L. van Itallie A. J. Steenhauer A. L. W. E. van der Veen G. Denigès L. Rosenthaler D. Krüger E. Tschirch H. Tangl R. Fischer F. Stauder F. Dangl L. Kofler H. Hilbck C. Griebel F. Weiß A. Hinrichs L. Klemm O. Mohr H. Alber M. Gläser Th. Morawski und J. A. Rose 《Fresenius' Journal of Analytical Chemistry》1933,91(1-2):48-68
Ohne Zusammenfassung 相似文献
10.
G. Klein Gertrud Pollauf Marie Krisch Elisabeth Farkass F. Schusta Anneliese Niethammer G. D. Lander C. K. Glycart M. Wagenaar F. Pavelka L. van Itallie A. J. Steenhauer A. L. W. E. van der Veen G. Denigès L. Rosenthaler D. Krüger E. Tschirch H. Tangl R. Fischer F. Stauder F. Dangl L. Kofler H. Hilbck C. Griebel F. Weiß A. Hinrichs L. Klemm O. Mohr H. Alber M. Gläser Th. Morawski J. A. Rose 《Analytical and bioanalytical chemistry》1933,91(1-2):48-68