全文获取类型
收费全文 | 73篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
化学 | 51篇 |
力学 | 8篇 |
数学 | 4篇 |
物理学 | 12篇 |
出版年
2019年 | 1篇 |
2017年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2011年 | 3篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 4篇 |
2007年 | 1篇 |
2005年 | 2篇 |
2004年 | 3篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1967年 | 3篇 |
1964年 | 1篇 |
1929年 | 1篇 |
1927年 | 2篇 |
1891年 | 2篇 |
1883年 | 1篇 |
1879年 | 1篇 |
1872年 | 2篇 |
1871年 | 2篇 |
1870年 | 4篇 |
1863年 | 1篇 |
1862年 | 2篇 |
排序方式: 共有75条查询结果,搜索用时 15 毫秒
1.
2.
Chiral tridentate phosphines, R(2)P(CH(2))(3)PPh(CH(2))(2)PPh(2) where R = C(6)H(5), p-ClC(6)H(4), and p-FC(6)H(4), can be prepared from simple starting materials, (R(3)P, I(CH(2))(3)I, and Ph(2)P(CH(2))(2)PPh(2)), in a few stages involving phosphonium salts and phosphine oxides as intermediates. Crystalline diamagnetic complexes of nickel(II) and palladium(II) have been isolated. In solution these show first-order 12 line (31)P NMR spectra consistent with three nonequivalent phosphorus nuclei coupled to one another in a square planar geometry. A single X-ray crystallographic study of NiI(2){P(CH(2))(3)PPh(CH(2))(2)PPh(2)} showed that this was square pyramidal in the solid state with a weakly held apical iodo ligand. 相似文献
3.
4.
H. E. Roscoe 《Fresenius' Journal of Analytical Chemistry》1883,22(1):306-307
Ohne Zusammenfassung 相似文献
5.
D. F. Roscoe 《General Relativity and Gravitation》2002,34(5):577-603
This paper is essentially a speculation on the realization of Mach's Principle, and we came to the details of the present analysis via the formulation of two questions: (a) Can a globally inertial space &; time be associated with a non-trivial global matter distribution? (b) If so, what are the general properties of such a global distribution? These questions are addressed within the context of an extremely simple model universe consisting of particles possessing only the property of enumerability existing in a formless continuum.Since there are no pre-specified ideas of clocks and rods in this model universe, we are forced into two fundamental considerations, these being: What invariant meanings can be given to the concepts of spatial displacement and elapsed time in this model universe? Briefly, these questions are answered as follows: the spatial displacement of a particle is defined in terms of its changed relationship with the particle ensemble as a whole—this is similar to the man walking down a street who can estimate the length of his walk by reference to his changed view of the street. Once the concept of invariant spatial displacement is established, a corresponding concept of elapsed time then emerges in a natural way as ‘process’ within the system. Thus, unlike for example, general relativity, which can be considered as a theory describing the behaviour of specified clocks and rods in the presence of matter, the present analysis can be considered as a rudimentary—but fundamental—theory of what underlies the concepts of clocks and rods in a material universe. In answer to the original two questions, this theory tells us that a globally inertial space &; time can be associated with a non-trivial global matter distribution, and that this distribution is necessarily fractal with D = 2. This latter result is compared with the results of modern surveys of galaxy distributions which find that such distributions are quasi-fractal with D ? 2 on the small-to-medium scales, with the situation on the medium-to-large scales being a topic of considerable debate. Accordingly, and bearing in mind the extreme simplicity of the model considered, the observational evidence is consistent with the interpretation that the analysed point-of-view captures the cosmic reality to a good first-order approximation. We consider the implications of these results. 相似文献
6.
R. Roscoe 《Rheologica Acta》1980,19(6):737-743
Summary A simple modification of the stress-strain relation for a normal viscoelastic material has been derived for a gel with temporary structural bonds which is subjected to small deformations during gelation. This shows that the storage modulus should separate into two parts, one dependent on frequency and the other on the time for which the gel has been allowed to set. The loss modulus should depend only on frequency. These theoretical results, and others concerning creep under constant stress are in general agreement with observations on a number of gels. Exceptions occur, however, in the period immediately after preparation (before continuous structure has formed) and also after long periods of time during which irreversible changes can have occurred. Certain anomalies appear when the basic assumption of the theory are applied to structure formation in gels with permanent bonds, and a possible resolution of these is suggested.
With 3 figures 相似文献
Zusammenfassung Es wird eine einfache Modifikation der Spannungs-Dehnungs-Beziehungen normaler viskoelastischer Stoffe abgeleitet, durch die das Verhalten eines Gels mit temporärer Bindungsstruktur bei kleinen Deformationen während des Geliervorgangs beschrieben werden kann. Diese sagt voraus, daß der Speichermodul in zwei Teile aufspaltet, wobei der eine von der Frequenz und der andere von der Erstarrungszeit des Gels abhängt. Dagegen sollte der Verlustmodul nur von der Frequenz abhängig sein. Diese theoretischen Voraussagen, sowie die daraus abgeleiteten Folgerungen bezüglich des Kriechens unter konstanter Spannung, stimmen durchweg mit den an einer Anzahl von Gelen gemachten Beobachtungen überein. Abweichungen kommen dagegen in der Zeit unmittelbar nach der Herstellung vor (bevor sich eine durchgehende Struktur gebildet hat) und nach einer so langen Zeitspanne, daß irreversible Strukturänderungen entstanden sein können. Gewisse Anomalien treten in Erscheinung, wenn die Grundvoraussetzungen der Theorie auf die Strukturbildung bei Gelen mit permanenten Bindungen angewendet werden. Hierfür wird eine mögliche Deutung vorgeschlagen.
With 3 figures 相似文献
7.
8.
Frédérin abwergel Jacques Herbert Ballly Herbert Ballly H Beirao da Veiga VA Solonnikov 《偏微分方程通讯》2013,38(9-10):1323-1358
We study a class of stationary transport equation with nonlocal low-order tems We obtain the existence and uniqueness of a solution in sobolev spaces 相似文献
9.
10.
Peter K. Anastasovski T. E. Bearden C. Ciubotariu W. T. Coffey L. B. Crowell G. J. Evans M. W. Evans R. Flower S. Jeffers A. Labounsky D. Leporini B. Lehnert M. Mészáros J. K. Moscicki P. R. Molnár H. Múnera E. Recami D. Roscoe S. Roy 《Foundations of Physics Letters》1999,12(3):251-265
The general theory of gauge fields is used to develop a theory of electrodynamics in which the fundamental structure is non-Abelian and in which the internal gauge field symmetry is O(3), based on the existence of circular polarization and the third Stokes parameter. The theory is used to provide an explanation for the Sagnac effect with platform at rest and in motion. The Sagnac formula is obtained by considering the platform in motion to be a gauge transformation. The topological phases can be described straightforwardly with non Abelian electrodynamics, which produces a novel magnetic field component for all types of radiation, a component which is proportional to the third Stokes parameter. The theory provides a natural explanation for the inverse Faraday effect without phenomenology. 相似文献