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141.
Collisional relaxation dynamics of UF6 following excitation in the first electronic absorption band is studied by an investigation of the red-shifted emission. A comparison with dissociation data is made and a simple kinetic model proposed previously is improved. 相似文献
142.
143.
The addition of water vapor has a strong positive effect on the rate of ethane oxidation at 575°C. This effect is attributed to the role of H2O as a third body in the decomposition of H2O2 to OH radicals. Carbon tetrafluoride likewise enhances the rate of ethane conversion, although not to the extent realized with H2O. A kinetic model, based on known elementary reactions, adequately accounts for the conversions and selectivities observed as a function of H2O pressure, temperature, contact time, and O2 pressure. © 1994 John Wiley & Sons, Inc. 相似文献
144.
This paper reports a new layer-by-layer assembly approach to fabricate multilayers of cofacially aligned porphyrins on solid supports by a selective siloxane formation utilizing tetraphenylporphyrinatosilicon(IV) chloride as the building block. 相似文献
145.
The article describes the concentration of isoflavones (genistin, genistein and daidzein) in a Spanish commercial tofu treated under high-pressure. The tofu was subjected to pressure of 400 MPa, in cycles of 10 min each with a total of 4 cycles with the progression of 10, 20, 30 and 40 min, and a temperature of about 10-12 °C. The isoflavones were extracted from tofu with aqueous methanol solution (80:20). The content of isoflavones went up directly proportional to the pressure applied for the first 30 minutes. Afterwards, at 40 min, the values dropped close to the control. Significant differences were found in genistein, genistin and daidzein treated for 20 and 30 min in comparison to control values. Finally, we came to the conclusion that, the isoflavones (genistin, genistein and daidzein) of treated tofu were not destroyed at 400 Mpa for 30 min and a major extraction was observed when compared with the untreated tofu. 相似文献
146.
R. Lozada‐Morales A. Cid‐Garcia G. Lpez‐Calzada Ma. E. Zayas O. Zelaya‐Angel J. Carmona‐Rodriguez E. Rubio‐Rosas R. Palomino‐Merino O. Portillo‐Moreno S. Jimnez‐Sandoval 《physica status solidi (a)》2012,209(11):2281-2285
The melt‐quenching method was used to prepare two groups of samples using CdO and V2O5 as starting materials. Taking into account that a crystalline‐amorphous phase transition would be expected for the CdO–V2O5 system, a first batch was prepared varying the proportions of CdO and V2O5 in the intervals 60–95 and 40–5 wt%, respectively. With the aim of investigating the effect of erbium in the phase transition and crystalline quality of the first group of samples, a second batch was fabricated with the same proportions of CdO and V2O5, with the addition of 5 wt% of Er(NO3)5H2O as source of Er3+ ions. It was found that crystalline or amorphous samples could be obtained depending on the relative concentrations of CdO and V2O5, and that the borderline between amorphous and crystalline samples was affected by the incorporation of Er. From X‐ray diffraction, it was possible to identify the formation of the ternary compound Cd2V2O7 in the crystalline cases. The Raman and infrared bands in these samples were in agreement with the lattice modes of Cd2V2O7. Additionally, an improvement in the crystalline quality of Cd2V2O7 was obtained for the Er‐doped samples. The effect of the local environment around the Er3+ ions on the room temperature photoluminescence was also investigated for the amorphous and crystalline samples. 相似文献
147.
Jean‐Luc Bischoff Hussein Mortada Didier Dentel Mickael Derivaz Chiraz Ben Azzouz Abdelwahab Akremi Chaabanne Chefi Francisco Miguel Morales Miriam Herrera Jos Manuel Mnuel Rafael Garcia Mustapha Diani 《physica status solidi (a)》2012,209(4):657-662
We present a comparative structural study of the growth of Si and Ge deposited by molecular beam epitaxy (MBE) on a c(2 × 2) reconstructed LaAlO3(001) substrate. Our findings are based on complementary experimental techniques such as in situ X‐ray photoelectron spectroscopy (XPS), reflection high‐energy electron diffraction (RHEED), low energy electron diffraction (LEED) and ex situ atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). While the layers are amorphous and wet uniformly the substrate in a low deposition temperature range, above 500 °C both Si and Ge growths proceed in a Volmer–Weber (VW) mode leading to the formation of nanocrystals (NCs). The islands are found to be composed of pure Si and Ge and to have abrupt interfaces with the substrate. Both semiconductors (SCs) crystallize in their own diamond structure leading to relaxed NCs. No facets could be observed on the crystalline islands. An epitaxial relationship is established for which the (001) planes of Si and Ge are parallel to the LaAlO3(001) surface but are rotated by 45° around the [001] growth axis. The Ge lattice undergoes a second rotation of 6° with respect to the (001) growth axis. This 6° tilt is an original mechanism to partially compensate the strain in the Ge islands induced by the large misfit. Whereas a unique epitaxial relationship is pointed out for Si NCs, many Ge NCs are randomly orientated on the surface. This is interpreted by the fact that the Ge islands are less anchored to the substrate due to a large misfit and to the fact that the Ge O bonds are weaker than the Si O ones. 相似文献
148.
J.L. Martínez‐Morales 《Annalen der Physik》2006,15(9):653-662
Properties of the eigentensors of the Lichnerowicz Laplacian for the Euclidean Schwarzschild metric are discussed together with possible applications to the linear stability of higher‐dimensional instantons. The main statement of the article is that any eigentensor of the Lichnerowicz operator in a Euclidean (possibly higher‐dimensional) Schwarzschild metric is essentially singular at infinity. 相似文献
149.
Morales S Guesalaga A Fernández MP Guarini M Irarrázaval P 《Magnetic resonance imaging》2004,22(3):403-412
This work explores the use of magnetic resonance imaging (MRI) for nondestructive determination of wood characteristics and for 3D wood modeling. In this context, one of the applications under development is the automatic recognition and reconstruction of rings from transversal images obtained from MRI scanners. The algorithm analyzes a set of transversal MRI images, detecting and reconstructing growth ring edges. The information generated is then interpolated in order to obtain an accurate 3D picture of the log and its fundamental constituents (individual rings, knots, defects, etc). Results also show that the technique has potential for defect recognition, providing a powerful tool for future developments in wood analysis. The results are encouraging and further research is needed to develop automatic detection not only of rings, but also of different types of defects that are of paramount importance in the sawmill and plywood industries. 相似文献
150.
V. Sagredo P. Silva M. Díaz L.M. de Chalbaud J. Morales 《physica status solidi b》2000,220(1):237-241
The magnetic behavior of the Zn1–xMnxIn2Te4 compounds with 0.1 ≤ x ≤ 0.9 has been studied in the temperature range 1.8 to 300 K by means of electron paramagnetic resonance (EPR). We have found that the peak to peak linewidth decreases when the Mn concentration increases and when the temperature increases. The signal has a Lorentzian shape in the high temperature region and is slightly asymmetrically broadened when the temperature goes down to 10 K except for x = 0.1. The observed magnetic behavior is intimately related with the exchange between magnetic ions. The magnetic properties were studied by an ac susceptometer for the low temperature range (1.8 to 80 K). 相似文献