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1.
H. Ade 《The European physical journal. Special topics》2012,208(1):305-318
The use of soft X-rays near the carbon absorption edge (∼270–300 eV) for small angle X-ray scattering and X-ray reflectivity experiments has significantly expanded the scientific capabilities to investigate thin films of soft matter that are primarily composed of carbon and low Z heteroatoms. In this perspective, we will delineate the basic operating principles and underlying physics of these methods and exemplify their impact by discussing a few recent applications. An extension of these methods to the fluorine edge is also included, demonstrating that the general concepts are also applicable to absorption edges of hetero atoms in soft matter. A short perspective of some future developments is provided. 相似文献
2.
P. Thomsen-Schmidt K. Hasche G. Ulm K. Herrmann M. Krumrey G. Ade J. Stümpel I. Busch S. Schädlich A. Schindler W. Frank D. Hirsch M. Procop U. Beck 《Applied Physics A: Materials Science & Processing》2004,78(5):645-649
High-accuracy film thickness measurements in the range below 100 nm can be made by various complex methods like spectral ellipsometry (SE), scanning force microscopy (SFM), grazing incidence X-ray reflectometry (GIXR), or X-ray fluorescence analysis (XRF). The measurement results achieved with these methods are based on different interactions between the film and the probe. A key question in nanotechnology is how to achieve consistent results on a level of uncertainty below one nanometre with different techniques.Two different types of thickness standards are realised. Metal film standards for X-ray techniques in the thickness range 10 to 50 nm are calibrated by GIXR with monochromatised synchrotron radiation of 8048 eV. The results obtained at four different facilities show excellent agreement. SiO2 on Si standards for SE and SFM in the thickness range 6 to 1000 nm are calibrated by GIXR with monochromatised synchrotron radiation of 1841 eV and with a metrological SFM. Consistent results within the combined uncertainties are obtained with the two methods. Surfaces and interfaces of both types of standards are additionally investigated by transmission electron microscopy (TEM). PACS 61.10.Kw; 68.55.Jk; 06.20.Fn; 06.60.Mr; 07.79.Lh 相似文献
3.
Synthesis,Single Crystal Growth and Crystal Structure of Ta7Cu10Ga34 – a 8 × 4 × 2 Super Structure of CsCl
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Single crystals of Ta7Cu10Ga34 were grown from the elements in a Cu/Ga melt. Ta7Cu10Ga34 represents the first ternary compound of the system Ta/Cu/Ga. The crystal structure (Cmmm, oC102, Z = 2, a = 23.803(1), b = 12.2087(4), c = 5.7487(2) Å, 1291 refl. 78 parameters, R1 = 0.037, wR2 = 0.070). The crystal structure is characterized by rods of pentagonal prisms MGa10, which are alternatingly occupied by Ta and Cu. Four of these rods are connected to columns running in direction (001). These columns are linked by cubic units TaGa8, CuGa8, and GaGa8. According to the characteristic structural elements and the size of the unit cell Ta7Cu10Ga34 represents a 8 × 4 × 2 super structure of CsCl or bcc. With respect to the underlying CsCl structure the formula can be written as [Ta7Cu10Ga2□13]Ga32, i.e. a cubic primitive packing of 32 Ga atoms with Ta, Cu, and Ga in cubic voids and 13 vacancies. The pentagonal‐prismatic coordination of Ta and Cu can formally be obtained from the cubic primitive packing of Ga atoms by a 45° rotation of a part of the Ga8 cubes. There is a close similarity to the binary compounds Ta8Ga41 and Ta2–xGa5+x. The first one is also related to a CsCl‐like structure, the latter one contains rods of pentagonal prisms, which form the same columns. There are also relations to the ternaries V2Cu3Ga8 and V11Cu9Ga46, whose cubic structures are more or less complex variants of CsCl. 相似文献
4.
Hans Ade 《Rendiconti del Circolo Matematico di Palermo》1979,28(2):191-204
With Schauder's fixpoint principle we establish an existence theorem for solutions of two simultaneous nonlinear operator equations of the formL iu=Miu, i=1,2, Li linear,M i continous. By applying this result to boundary value problems with ordinary differential equations we generalize results of Conti and Ehrmann in various directions. 相似文献
5.
Wang Y Rafailovich M Sokolov J Gersappe D Araki T Zou Y Kilcoyne AD Ade H Marom G Lustiger A 《Physical review letters》2006,96(2):028303
Strong dependence of the crystal orientation, morphology, and melting temperature (Tm) on the substrate is observed in the semicrystalline polyethylene thin films. The Tm decreases with the film thickness decrease when the film is thinner than a certain critical thickness, and the magnitude of the depression increases with increasing surface interaction. We attribute the large Tm depression to the decrease in the overall free energy on melting, which is caused by the substrate attraction force to the chains that competes against the interchain force which drives the chains to crystallization. 相似文献
6.
A. P. Smith C. Bai H. Ade R. J. Spontak C. M. Balik C. C. Koch 《Macromolecular rapid communications》1998,19(11):557-561
Incorporation of liquid crystalline polymers (LCPs) into commodity polymers remains a challenge in the design of high-performance, low-cost polymeric blends. Blends of a thermoplastic polymer and a nematic LCP are produced here by mechanical alloying. Functionality sensitive X-ray microscopy reveals LCP dispersions as small as 100 nm in diameter. Intimate mixing remains upon subsequent melt processing, indicating that mechanical alloying is suited for applications such as recycling. 相似文献
7.
Stabilized by the tailor-made coordination in the crystal , B4 tetrahedra were characterized for the first time in a solid-state structure (shown on the right). Some of the Al atoms are replaced by B4 tetrahedra in the cubic τ-boride Ni20AlB14. The B–B distances of 1.681(15) Å are similar to those in the molecular structures of B4Cl4 and B4(tBu)4, which contain tetrahedral B4 units. 相似文献
8.
Synthesis and Crystal Structure of Ti12Sn3O10 – a Low Valent Oxide of Titanium with an Oxidic Network and Intermetallic ”︁Islands”︁”︁ The new ternary compound Ti12Sn3O10 is obtained by the reaction of Ti, TiO2 and Sn at 1500 °C. According to the single crystal structure analysis (cubic, space group Fm3m, a = 13.5652(9) Å, Z = 8, wR2(I) = 0.048, R1(F) = 0.020) the air stable compound represents a new structure type combining structural features of oxides and intermetallics. While tin is surrounded only by titanium the five different Ti atoms have oxidic and metallic coordination spheres as well, explaining the quite low averaged oxidation number. The crystal structure is characterized by a threedimensional net of Ti4O‐tetrahedra and trigonal bipyramides Ti5O. In the voids there are intermetallic ”︁islands”︁”︁ of a composition Ti33Sn6 with a diameter of about 10 Å. 相似文献
9.
C. Dal Savio K. Pierz G. Ade H.-U. Danzebrink E.O. Göbel A. Hangleiter 《Applied physics. B, Lasers and optics》2006,84(1-2):317-322
Single self-assembled InAs quantum dots embedded in a In0.12Ga0.88As quantum well and emitting in the near infrared have been optically investigated. The dependence on the excitation power
of the single quantum dot photoluminescence has been used to identify the emission of the biexciton complex. The biexciton
binding energy, which has been measured for a dozen dots, increases with increasing exciton transition energy for the dot
sizes investigated in the present work, as a consequence of stronger confinement in a smaller quantum dot. The obtained data
is compared with experimental results available in the literature for InAs quantum dots.
PACS 78.67.Hc; 73.21.La; 78.55.Cr 相似文献
10.
Experimental data conclusively shows that the weak van der Waals interactions between alkane molecules, <1.5% the strength of covalent bonding on a per carbon atom basis, modify the carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectrum significantly in ordered solids, both in intensity, spectral shape, peak position, and dichroic signature. This constitutes a further breakdown of the ‘building block’ model, or, more precisely, even a molecular model in interpreting NEXAFS spectra. These observations have significant implications for the interpretation and use of NEXAFS spectra from any crystalline or semi-crystalline macromolecules, small molecules, or other weakly interacting systems. 相似文献