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151.
E. Süske T. Scharf P. Schaaf E. Panchenko D. Nelke M. Buback H. Kijewski H.-U. Krebs 《Applied Physics A: Materials Science & Processing》2004,79(4-6):1295-1297
The structural and mechanical properties of polymethyl methacrylate (PMMA) thin films produced by pulsed laser deposition in ultra-high vacuum were investigated by infrared spectroscopy, electron microscopy, size-exclusion chromatography and microhardness measurements. After preparation, the film hardness and elastic modulus are found to be increased. This is caused by a reduced chain length of the polymer film to values of 5800 g/mol and by cross links of an amount of about 20% of the polymer, while the chemical structure of the deposited films is comparable to the target material. During annealing, relaxation processes lead to a reduction of the film hardness, without changing the cross-linked part in the samples. PACS 81.05.Lg; 81.15.Fg; 68.55.Jk; 68.60.Bs; 68.60.Dv 相似文献
152.
Schaaf Peter Müller Alexander Carpene Ettore Kahle Michael 《Hyperfine Interactions》2002,144(1-4):129-139
Hyperfine Interactions - Thin films are playing a more and more important role for technological applications and there are many aspects of materials surface processing and thin film production,... 相似文献
153.
G. A. MÜller K. P. Lieb E. Carpene K. Zhang P. Schaaf J. Faupel H. U. Krebs 《Hyperfine Interactions》2004,158(1-4):137-143
Modifications of magnetic properties upon heavy-ion irradiation have been recently investigated for films of ferromagnetic 3d-elements (Fe, Ni, Co) and alloys (permendur, permalloy), in relation to changes of their microstructure. Here we report on Xe-ion irradiation of a highly textured iron film prepared via pulsed-laser deposition on a MgO(100) single crystal and containing a thin 57Fe marker layer for magnetic orientation Mössbauer spectroscopy (MOMS). We compare the results with those obtained for a polycrystalline Fe/Si(100) sample produced by electron evaporation and premagnetized before Xe-irradiation in a 300 Oe external field. Characterization of the samples also included magneto-optical Kerr effect (MOKE), Rutherford backscattering spectroscopy (RBS) and X-ray diffraction (XRD). 相似文献
154.
155.
de Saint-Aubin C Hemmerlé J Boulmedais F Vallat MF Nardin M Schaaf P 《Langmuir : the ACS journal of surfaces and colloids》2012,28(23):8681-8691
Although never emphasized and increasingly used in organic electronics, PEDOT-PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)) layer-by-layer (lbl) film construction violates the alternation of polyanion and polycation rule stated as a prerequisit for a step-by-step film buildup. To demonstrate that this alternation is not always necessary, we studied the step-by-step construction of films using a single solution containing polycation/polyanion complexes. We investigated four different systems: PEDOT-PSS, bPEI-PSS (branched poly(ethylene imine)-poly(sodium 4-styrene sulfonate)), PDADMA-PSS (poly(diallyl dimethyl ammonium)-PSS), and PAH-PSS (poly(allylamine hydrochloride)-PSS). The film buildup obtained by spin-coating or dipping-and-drying process was monitored by ellipsometry, UV-vis-NIR spectrophotometry, and quartz-crystal microbalance. The surface morphology of the films was characterized by atomic force microscopy in tapping mode. After an initial transient regime, the different films have a linear buildup with the number of deposition steps. It appears that, when the particles composed of polyanion-polycation complex and complex aggregates in solution are more or less liquid (case of PEDOT-PSS and bPEI-PSS), our method leads to smooth films (roughness on the order of 1-2 nm). On the other hand, when these complexes are more or less solid particles (case of PDADMA-PSS and PAH-PSS), the resulting films are much rougher (typically 10 nm). Polycation/polyanion molar ratios in monomer unit of the liquid, rinsing, and drying steps are key parameters governing the film buildup process with an optimal polycation/polyanion molar ratio leading to the fastest film growth. This new and general lbl method, designated as 2-in-1 method, allows obtaining regular and controlled film buildup with a single liquid containing polyelectrolyte complexes and opens a new route for surface functionalization with polyelectrolytes. 相似文献
156.
157.
J. Streib H. -J. Kluge H. Kremmling R. B. Moore H. W. Schaaf K. Wallmeroth 《Zeitschrift für Physik A Hadrons and Nuclei》1985,321(4):537-547
The isotope shift between197Au (stable) and the radioactive Au isotopes190Au,191Au,192Au and193Au were determined by resonance fluorescence spectroscopy in the 6s 2 S 1/2–6p 2 P 1/2.λ=267.6nm line. The unstable Au isotopes were produced at the ISOLDE mass separator at CERN. The nuclei were investigated semi on-line in a resonance vessel, heated to 1,400°C. The results areδν 190,197=?11.12(39) GHz,δν 191,197=?9.67(12) GHz,δν 192,197=?8.32(15) GHz,δν 193,197=?6.29(11) GHz, corresponding to a change of the mean-square charge radius byδ〈r 2〉190,197 =0.261(12) fm2,δ〈r 2〉191,197=0.227(5) fm2,δ〈r 2〉192,197=0.195(5) fm2,δ〈r 2〉193,197 =0.148(4) fm2. 相似文献
158.
P. Schaaf G. Rixecker E. Yang C. N. J. Wagner U. Gonser 《Hyperfine Interactions》1994,94(1):2239-2244
The process of mechanical alloying consists of intimate mixing and mechanical working of elemental powders in a high-energy ball mill. It has been well established that this process is able to produce nanocrystalline and amorphous material. In this study, the structural effects of mechanical alloying of pure Fe, Fe50W50 and Fe50Mo50 powders were investigated by X-ray diffraction and Mössbauer spectroscopy. For all cases, nanocrystalline and/or amorphous fractions were found after milling. The resulting particle size was determined by X-ray diffraction. Pure Fe does not amorphize even after prolonged milling times. For the nanocrystalline powder, significant changes in the linewidth and the hyperfine field are found. Powder mixtures of Fe50Mo50 and Fe50W50 are completely amorphous after milling times of 10 h, as seen by Mössbauer spectroscopy, but nanocrystalline fractions of the non-iron part are still found in X-ray diffraction. Also in the amorphous state, further changes in the hyperfine parameters are found with increasing milling time. 相似文献
159.
Zusammenfassung Eine formalkinetische Auswertung nichtisothermer TG-Kurven des Polyphenylens ist mit Hilfe der Methode von Flynn und Wall und der von Zsakó durchgeführt worden. Die Auswertung nach diesen Methoden führt zunächst zu unrealen Ergebnissen, da festgestellt werden konnte, daß der thermooxidative Abbau des Polyphenylens durch das System zweier sich überlagernder, unabhängig verlaufender Reaktionen bestimmt wird. Durch die Anwendung einer speziellen Beziehung zwischen dem Umsatzgrad der Bruttoreaktion und dem der beiden Komponenten gelingt es, die formalkinetischen Parameter beider Teilreaktionen mit Hilfe der Methode von Zsakó zu bestimmen.
Kinetic values from non-isothermal thermogravimetric curves of polyphenylene have been calculated using the method of Flynn and Wall and that of Zsakó. These methods at first give unreal kinetic parameters, for it has been established that the degradation of polyphenylene is a system of two mutually independent reactions occurring simultaneously. With the use of a special relation between the degree of conversion of the unit reaction and that of the components, the kinetic parameters of the two reactions could be investigated by the method of Zsakó.
Résumé On a calculé les paramètres cinétiques du polyphénylène à partir des courbes thermogravimétriques non-isothermes en se servant de méthodes de Flynn et Wall et de celle de Zsakó. Ces méthodes ont d'abord donné des paramètres cinétiques non-réels, du fait qu'il a été établi que la dégradation du polyphénylène pouvait être définie par un systè me à deux réactions mutuellement indépendantes qui ont lieu simultanément. En utilisant une relation spéciale entre le degré de conversion de la réaction de base et celui des composants, il devient possible d'étudier les paramètres cinétiques des deux réactions par la méthode de Zsakó.
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160.
R. van Dantzig F. W. N. de Boer A. van der Schaaf 《Czechoslovak Journal of Physics》1986,36(8):982-984
Commets are presented concerning hadronically stable clusters of negatively charged pions and neutrons (pineuts) with reference to recent theoretical and experimental studies on the subject.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985. 相似文献