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91.
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93.
Finite element simulation for estimating the mechanical properties of multi-walled carbon nanotubes 总被引:2,自引:0,他引:2
C. W. Fan Y. Y. Liu Chyanbin Hwu 《Applied Physics A: Materials Science & Processing》2009,95(3):819-831
A finite element simulation technique for estimating the mechanical properties of multi-walled carbon nanotubes is developed.
In the present modeling concept, individual carbon nanotube is simulated as a frame-like structure and the primary bonds between
two nearest-neighboring atoms are treated as beam elements, the beam element properties are determined via the concept of
energy equivalence between molecular dynamics and structural mechanics. As to the simulation of the interlayer van der Waals
force which has intrinsic nonlinearity and complicated applying region, a simplifying method is proposed that the interlayer
pressure caused by van der Waals force instead of the force itself is to be considered, and we make use of the linear part
of the interlayer pressure near the equilibrium condition to avoid the nonlinearity in problem, then linear spring elements
whose stiffness is determined by equivalent force concept can be utilized to simulate the interlayer van der Waals force such
that significant modeling and computing effort is saved in performing the finite element analysis. Numerical examples for
estimating the mechanical properties of nanotubes, such as axial and radial Young’s modulus, shear modulus, natural frequency,
buckling load, etc., are presented to illustrate the accuracy of this simulation technique. By comparing to the results found
in the literature and the possible analytical solutions, it shows that the obtained mechanical properties of nanotubes by
the present method agree well with their comparable results. In addition, the relations between these mechanical properties
and the nanotube size are also discussed. 相似文献
94.
A new family of cuprates, Li2Cu3(SiO3)4 (1) and Na2Cu3(GeO3)4 (2), was isolated in molten salt media. The extended lattices contain ladderlike periodic arrays of [Cu3O8]10- magnetic nanostructures. Magnetic properties of the Na2Cu3Ge(4-x)SixO12 series, where x = 0, 0.86, and 1.72, were systematically studied. The geometrically induced magnetic couplings are tunable upon cation substitution. 相似文献
95.
K. G. Sanjaya Ranmohotti Wendy L. Queen J. Palmer West Don VanDerveer Shiou-Jyh Hwu 《Journal of chemical crystallography》2009,39(4):303-307
Abstract A new barium chlorovanadate, Ba5(V2O7)2Cl2, was isolated by a high-temperature (850 °C) reaction employing a CsCl/RbCl flux. The structure was determined by single
crystal X-ray diffraction methods. This compound crystallizes in an orthorhombic crystal system, Pmmn (No. 59), with a = 11.558(2) ?, b = 15.164(3) ?, c = 10.023(2) ?, Z = 4 and V = 1756.7(6) ?3. The structure of Ba5(V2O7)2Cl2 was determined by full-matrix, least-squares methods with R
1 = 0.0398, wR
2 = 0.1069 and GOF = 1.048 for all data. This new structure can be described as a composite lattice made up of mixed covalent
and ionic moities. The extended framework is orchestrated by stacked [Ba(V2O7)Cl]3− slabs that are interconnected by Ba2+ cations through Ba–O bonds to the [V2O7] units. The Ba2+ and Cl- ions form BN-type “[BaCl]” sheets with pseudo-hexagonal windows that are centered by [V2O7]4− pyrovanadate units.
Graphical Abstract The structure of a new chlorovanadate, Ba5(V2O7)2Cl2, exhibits an interesting BN-type salt lattice that consists of an extended [BaCl] sheet containing pseudo-hexagonal windows
that are centered by [V2O7] pyrovanadate units.
相似文献
96.
K.S. Prasad Nien‐Chu Fan Li‐Chen Wu Heng‐Chia Chang Li‐Sheng Wang Kuo‐Chu Hwang Reuben Jih‐Ru Hwu Jia‐Cherng Horng Chun‐Cheng Lin Ja‐an Annie Ho 《中国化学会会志》2012,59(6):802-808
We herein report a straightforward soot‐based synthesis and characterization of the negatively charged, hydrophilic, photoluminescent nanocarbon. The photoluminescent nanocarbon was prepared by refluxing castor oil soot in nitric acid. The as‐obtained fluorescent nanocarbon shows multiple colors under UV exposure and was characterized with surface morphological and spectral studies. Additionally, the photoluminescence nature of the nanocarbon was tunable by changing the pH or the dilution factor. During the course of the investigation, it has been found that, the photoluminescence nature observed here is not attributed to the presence of poly aromatic hydrocarbons, but solely due to the trait of the fluorescent nanocarbon. These results indicate that interparticle surface plasmon resonance plays a key role in the exhibition of photoluminescence. Furthermore, the feasibility of photoluminescent nanocarbon as a plausible tool for cell imaging and electrochemical application of the oxidized nanocarbon has also been examined. 相似文献
97.
Polyoxometallates (POMs) are desirable in materials applications ranging from uses as catalysts in selective oxidation reactions to molecular-like building blocks for the preparation of new extended solids. With the use of an unprecedented approach involving high temperature, molten salt methods, a fascinating series of salt-inclusion solids (SISs) that contain high nuclearity POMs has been isolated for the first time. Cs(11)Na(3)(V(15)O(36))Cl(6) (1) was synthesized using the eutectic NaCl/CsCl flux (mp 493 °C) which serves as a reactive solvent in crystal growth and allows for the SIS formation. Its framework can be viewed as an "ionic" lattice composed of alternately packed counterions of Cl-centered [V(15)O(36)Cl](9-) clusters (V15; S = 11/2) and multinuclear [Cs(9)Na(3)Cl(5)](7+) cations. In light of the structural analysis, 1 was proven to be soluble in water giving rise to a dark green solution that is similar in color to single crystals of the title compound. Infrared spectroscopy of the solid formed from fast evaporation of the solution supports the presence of dissolved V15 clusters. Also noteworthy is the magnetization of 1 at 2 K, which reveals an s-shaped plot resembling that of superparamagnetic materials. 相似文献
98.
Lai SF Chen WC Wang CL Chen HH Chen ST Chien CC Chen YY Hung WT Cai X Li E Kempson IM Hwu Y Yang CS Tok ES Tan HR Lin M Margaritondo G 《Langmuir : the ACS journal of surfaces and colloids》2011,27(13):8424-8429
We describe a simple and effective method to obtain colloidal surface-functionalized Au nanoparticles. The method is primarily based on irradiation of a gold solution with high-flux X-rays from a synchrotron source in the presence of 11-mercaptoundecanoic acid (MUA). Extensive tests of the products demonstrated high colloidal density as well as excellent stability, shelf life, and biocompatibility. Specific tests with X-ray diffraction, UV-visible spectrometry, visible microscopy, Fourier transform infrared spectroscopy, dark-field visible-light scattering microscopy, and transmission electron microscopy demonstrated that MUA, being an effective surfactant, not only allows tunable size control of the nanoparticles, but also facilitates functionalization. The nanoparticle sizes were 6.45 ± 1.58, 1.83 ± 1.21, 1.52 ± 0.37 and 1.18 ± 0.26 nm with no MUA and with MUA-to-Au ratios of 1:2, 1:1, and 3:1. The MUA additionally enabled functionalization with l-glycine. We thus demonstrated flexibility in controlling the nanoparticle size over a large range with narrow size distribution. 相似文献
99.
Cai X Chen HH Wang CL Chen ST Lai SF Chien CC Chen YY Kempson IM Hwu Y Yang CS Margaritondo G 《Analytical and bioanalytical chemistry》2011,401(3):809-816
Well-dispersed gold nanoparticles (NP) coated with tiopronin were synthesized by X-ray irradiation without reducing agents. High-resolution transmission electron microscopy shows that the average core diameters of the NPs can be systematically controlled by adjusting the tiopronin to Au mole ratio in the reaction. Three methods were used to study the NP uptake by cells: quantitative measurements by inductively coupled plasma mass spectrometry, direct imaging with high lateral resolution transmission electron microscopy and transmission X-ray microscopy. The results confirmed that the NP internalization mostly occurred via endocytosis and concerned the cytoplasm. The particles, in spite of their small sizes, were not found to arrive inside the cell nuclei. The synthesis without reducing agents and solvents increased the biocompatibility as required for potential applications in analysis and biomedicine in general. 相似文献
100.