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J. L. Lundberg E. J. Mooney C. E. Rogers 《Journal of Polymer Science.Polymer Physics》1969,7(5):947-962
Diffusion coefficients and solubilities of methane in polyisobutylene have been measured at four temperatures between 102 and 188°C. in the pressure range 23–341 atm. Diffusion coefficients extrapolated to atmospheric pressure range from 1.72 × 10?6 cm.2/sec. at 102°C. to 1.5 × 10?5 cm.2/sec. at 188°C. corresponding to an activation energy for diffusion of 8.7 ± 0.4 kcal./mole. Solubilities are small, about one molecule of methane for every forty carbon atoms in the polyisobutylene at 300 atm. partial pressure of methane. Solubilities vary little with temperature, but show an apparent minimum between 127 and 188°C. With improved methods of data analysis, diffusion coefficients and solubilities have been recalculated from previously reported studies on nitrogen in branched polyethylene and methane in branched polyethylene, linear polyethylene, and polystyrene. Recalculated diffusion coefficients are essentially the same as those reported previously, but the recalculated solubilities are decreased from 2 to 30%. The solubilities of all five systems show strong deviations from Henry's law, i.e., increases in partial pressure of methane and nitrogen with respect to solubility exceed linearity. The partial pressure (or fugacity)—solubility data may be interpreted in terms of a sorption model in which sorbed molecules are accommodated in widely dispersed, unoccupied volumes or sites in the polymer. An almost equivalent, solution model in which the first sorbed molecules to enter the polymer are accommodated to a large extent in existing volumes in the polymer, with successively sorbed molecules swelling the polymer to a greater extent (i.e., partial molal volume of sorbed molecules, V 1, increasing with concentration) can also account for these data. 相似文献
13.
Characterising the metric and topological evolution of OpenStreetMap network representations 总被引:3,自引:0,他引:3
OpenStreetMap (OSM) is a collaborative project to create a free editable map database of the world. This paper presents an analysis of the evolution of OSM street network representations. Three urban areas in Ireland were analysed where each evolves from containing little street network detail to a highly detailed street network. In order to characterise this evolution a number of metric and topological characteristics were computed. Some characteristics exhibited broadly similar behaviour in each region. This may be a attributed to similarities in the degree of contributor activity and intrinsic universal mapping procedures exhibited by contributors. 相似文献
14.
J. G. Grasselli M. Mehicic J. R. Mooney 《Fresenius' Journal of Analytical Chemistry》1986,324(6):537-543
Summary There have been many recent explosive advances in both IR and Raman spectroscopy which have developed in response to industrial problems of increasing complexity. Probably the biggest factor in these advances has been computerization, which has contributed not only to substantial improvements in data handling but to enormous gains in sensitivities of analyses as well.In this paper numerous examples of Raman and IR applications in industry are given using many of these recent advances, including in-situ techniques, microprobe analyses, unusual combinations of instruments — i.e., hyphenated methods — and new sample handling techniques. The bright future of FT-IR and Raman spectroscopy is also briefly discussed.
Anwendungen der Infrarot- und Ramanspektroskopie in der Industrie
Zusammenfassung Infrarot- und in geringerem Maße Raman-Spektroskopie sind etablierte und wirklich alltägliche Techniken in einem gut ausgerüsteten Industrielabor. Sie werden routinemäßig bei Problemen eingesetzt, die von großer Bedeutung für den Erfolg einer Forschungs- und Entwicklungsindustrie sind.Die Untersuchung von Katalysatorstrukturen und der Oberflächenadsorptionsstellen in Hinblick auf Katalysevorgänge kann Isotopensubstitution und in situ Bestimmungen bei mittleren bis hohen Drücken und Temperaturen einschließen. Für die in situ Untersuchungen von Katalysatoren ist Raman-Spektroskopie die einfachere Methode, da das Trägermaterial keinen Einfluß hat.Untersuchungen bei hohen Drücken sind wichtig für Modellstudien bei der Ölproduktionsforschung, da hier Bandenpositionen und -intensitäten von gasförmigen/flüssigen Mischungen von Kohlenwasserstoffen mit dem Druck korreliert und für die Analyse der Zusammensetzung verwendet werden.Relativ neue Entwicklungen in der Schwingungsspektroskopie, wie Mikrotechniken und Mikroskopanordnungen, berühren alle Gebiete der Forschung und Entwicklung, die für die Ölindustrie typisch sind. Dazu gehören in der Raman-Spektroskopie die räumliche Trennung von Probe und Detektionssystem, die durch optische Fibern überbrückt wird, und viele Probentechniken in der IR-Spektroskopie wie IRAS, DRIFT und FTIR-PAS. In situ IRAS ist eine sehr leistungsstarke Methode bei der Untersuchung von beschichteten Metalloberflächen, Adhäsionsschichten und des zeitlichen Verhaltens von Beschichtungen bei Wärmebehandlung.Bei vielen analytischen Problemen liegen komplexe Gemische vor, zu deren Lösung Verbundverfahren wie GC/ FT-IR oder TGA/FT-IR beitragen können. Ebenso ist ein mobiles FT-IR-Spektrometer ein interessantes und sehr nützliches Konzept. Schließlich werden Beispiele für spektroskopische Einzelanalysen gezeigt, die entweder die besonderen oder auch die sich ergänzenden Möglichkeiten der FT-IR- und Raman-Spektroskopie ausnutzen.相似文献
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A. Brandl M. Pfitzner J. D. Mooney B. Durst W. Kern 《Flow, Turbulence and Combustion》2005,75(1-4):335-350
In order to simulate the turbulent combustion process occurring in spark-ignition (IC) engines, it is necessary to provide
suitable and numerically economical models, the latter being particularly important in the application to industrial problems.
Moreover, these models must deliver sufficiently accurate results for the unsteady operation of spark combustion engines,
concerning variable geometries, temperatures, pressures and charge development in different configurations. In this work different
turbulent combustion models for premixed hydrocarbon combustion are compared with respect to their ability to accurately predict
the propagation of turbulent perfectly premixed flames.
As a first configuration a cylinder of constant volume was studied. Transient calculations were used to simulate the propagation
of the turbulent flame and to evaluate the resulting turbulent burning velocity. These calculations were performed for a perfect
mixture of air and hydrocarbons at stoichiometric mixture and different initial conditions concerning pressure, temperature
and turbulence intensity. As a second configuration a stationary turbulent bunsen-type flame with methane fuel was used to
validate the turbulent combustion model of [Lindstedt and Vaos, Combust. Flame 116 (1999) 461] at different pressures. Calculated results were then compared to experimental data of [Kobayashi, Tamura,
Maruta and Niioka. In: Proceedings of the 26th Symposium on Combustion, 1996, p. 389] and show excellent agreement for the turbulent burning velocity at several pressure levels using only a single
set of model parameters. 相似文献
17.
The large intrinsic band gap of NiO has hindered severely its potential application under visible-light irradiation. In this Letter, we have performed first-principles calculations on the electronic properties of N- and C-doped NiO to ascertain if its band gap may be narrowed theoretically. It was found that impurity bands driven by N 2p or C 2p states appear in the band gap of NiO and that some of these locate at the conduction band minimum, which leads to a significant band gap narrowing. Our results show that N-doped NiO may serve as a potential photocatalyst relative to C-doped NiO, due to the presence of some recombination centres in C-doped NiO. 相似文献
18.
The principal and engineering aspects of a dedicated synchrotron radiation beamline under construction at the Advanced Photon Source for nuclear resonant scattering purposes are explained. The expected performance in terms of isotopes to be studied, flux, and timing properties is discussed.This work is supported by the US-DOE-BES Materials Sciences, under Contract No. W-31-109-ENG-38. 相似文献
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