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101.
Spectroscopic characterization of zinc oxide nanorods synthesized by solid-state reaction 总被引:2,自引:0,他引:2
Prasad V D'Souza C Yadav D Shaikh AJ Vigneshwaran N 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,65(1):173-178
Well-crystallized zinc oxide nanorods have been fabricated by single step solid-state reaction using zinc acetate and sodium hydroxide, at room temperature. The sodium lauryl sulfate (SLS) stabilized zinc oxide nanorods were characterized by using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and photoluminescence spectroscopy. The X-ray diffraction revealed the wurtzite structure of zinc oxide. The size estimation by XRD and TEM confirmed that the ZnO nanorods are made of single crystals. The growth of zinc oxide crystals into rod shape was found to be closely related to its hexagonal nature. The mass ratio of SLS:ZnO in the nanorods was found to be 1:10 based on the thermogravimetric analysis. Blue shift of photoluminescence emission was noticed in the ZnO nanorods when compared to that of ZnO bulk. FT-IR analysis confirmed the binding of SLS with ZnO nanorods. Apart from ease of preparation, this method has the advantage of eco-friendliness since the solvent and other harmful chemicals were eliminated in the synthesis protocol. 相似文献
102.
Kabir-ud-Din Sharma D Khan ZA Aswal VK Kumar S 《Journal of colloid and interface science》2006,302(1):315-321
Clouding phenomenon in aqueous micellar solutions of an anionic surfactant tetra-n-butylammonium dodecylsulfate (TBADS) has been observed as a function of surfactant concentration. Small-angle neutron scattering (SANS) experiments in these systems show clustering of micelles as the temperature approaches the cloud point (CP). The individual micelles and the clusters of micelles coexist at CP. The clustering of micelles depends on the surfactant concentration and temperature. It is proposed that clustering is due to depletion of H-bonded water present around the butyl chains at the micellar surface. This is associated with entropy gain which is considered to be the major thermodynamic factor related to micellar aggregation. The structures (clusters) that emerge depend on the relative lengths of the alkyl chains of the counterion and can be tuned by the temperature. 相似文献
103.
[reaction: see text] An expeditious synthesis of unsymmetrical biaryls functionalized with electron-withdrawing or -donating substituents is described and illustrated by carbanion-induced ring transformation of 2H-pyran-2-one using acetyltrimethylsilane (ATMS) as a novel reagent in good yield. The novelty of the reaction lies in the creation of an aromatic ring from 2H-pyran-2-ones via two-carbon insertion from ATMS used as a source of carbanion. 相似文献
104.
Libraries of 2-substituted-benzimidazoles, benzoxazoles, benzothiazoles as well as quinazolin-4(3H)-ones were synthesized
via potassium persulfate–CuSO4-mediated oxidative coupling of aldehydes with o-phenylenediamines, o-aminophenols, o-aminothiophenols, and anthranilamide, respectively, in aqueous micelles. The strategy opens a way for rapid generation of
libraries of small heterocycles for biological screening. The reagent is commercially available, cheap, and highly chemoselective.
The yields were superior in aqueous micelles to those in organic solvents. Short reaction times, large-scale synthesis, excellent
chemoselectivity, excellent yields, as well as environmental friendliness are the main advantages of this diversity-oriented
synthesis. 相似文献
105.
R. K. Moudgil Vinayak Garg P. K. Ahluwalia 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,74(4):517-525
The effect of mass-asymmetry on the ground-state of coupledelectron-hole quantum wire system is investigated within thequantum version of the self-consistent mean-field approximationof Singwi, Tosi, Land, and Sjölander. The pair-correlationfunctions, static density susceptibility, and correlation energy arecalculated over a range of wire parameters.We find that themass-asymmetry affects appreciably both the intra- and inter-wire correlations,which in turn bring in a marked change in the e-h ground-state.Below a critical density, the e-h correlations now favor theliquid-Wigner crystal phase transition at a sufficiently large wirespacing. This result is in striking difference with the correspondingstudy on the mass-symmetric e-h wire model since here transition to theWigner crystal phase occurs in the adequately closeproximity of two wires at a much lower density, and there also occurs acrossover from Wigner to a charge-density-wave phase at relatively higherdensities. We find that for a GaAsbased e-h wire the critical density for Wignercrystallization is enhanced by a factor of about 2.6.As an important result, our theory captures nicely the recentexperimental observation of Wigner crystallization in anun-equal density GaAs based e-h wire by Steinberg et al.[Phys. Rev. B 73, 113307 (2006)]. 相似文献
106.
We have carried out Monte Carlo simulations in Gibbs ensemble for two-and three-dimensional double Yukawa fluid. We have compared
liquid-vapour equilibrium curve with that of Lennard-Jones, when parameters occurring in double Yukawa potential are chosen
to fit Lennard-Jones potential. The results are in good agreement. The role of repulsive and attractive contributions for
the potential on the liquid-vapour coexistence region as well as on critical temperature and critical density has been studied.
The critical temperature is found to be more sensitive than the critical density to the variation in repulsive and attractive
parts of the potential. Also, the range of the attractive interaction directly influences range of the liquid vapour coexistence
region. It has been found that smaller the values of the attractive parameter, larger is the coexistence region. 相似文献
107.
Jagjeet Kaur Deepti Singh Vikas Dubey N. S. Suryanarayana Yogita Parganiha Pooja Jha 《Research on Chemical Intermediates》2014,40(8):2737-2771
In this review different methods of preparing lanthanum aluminate (LaAlO3) phosphors are discussed. The molten salt method, the combustion method, the sucrose method, and the coprecipitation technique are the best methods for preparing LaAlO3 phosphors with small particle size and high surface area by low-temperature synthesis. LaAlO3 usually has a rhombohedral structure. It has good dielectric properties and, hence, is regarded as an attractive alternative to SiO2 in microelectronic devices. LaAlO3 phosphors have excellent chemical and thermal stability, mechanical durability, and exploitable optical and electronic properties, leading to a wide range of potential applications. LaAlO3 phosphors doped with rare-earth ions have luminescence properties and can, hence, be used in optical display systems. 相似文献
108.
Eun Joo Shin Soon Mo Choi Deepti Singh Sun Mi Zo Yang Hun Lee Joon Ho Kim Sung Soo Han 《Cellulose (London, England)》2014,21(5):3515-3525
Providing a conclusive microenvironment for cell growth, proliferation and differentiation is a major developmental strategy in the tissue engineering and regenerative medicine. This is usually achieved in the laboratory by culturing cells in three-dimensional polymer-based scaffolding materials. Here, we describe the fabrication of a cellulose scaffold for tissue engineering purposes from cellulose fiber using a salt leaching method. The 1-n-allyl-3-methylimidazolium chloride (AmimCl) IL was used as a solvent for cellulose. The leaching methodology used in this study offers the unique advantage of providing effective control of scaffold porosity by simply varying cellulose concentration. Morphologic testing of the scaffolds produced revealed pore sizes of 200–500 μm. In addition, the scaffolds had high water adsorption rates and slow degradation rates. To further investigate the suitability of these scaffolds for tissue engineering applications, biocompatibility was checked using an MTT assay and confirmed by Live/Dead® viability testing. In addition, scanning electron microscopy and DAPI studies and in vivo experiment demonstrated the ability of cells to attach to scaffold surfaces, and a biocompatibility of matrices with cells, respectively. The authors describe the environmentally friendly fabrication of a novel cellulose-based tissue engineering scaffold. 相似文献
109.
A novel rearrangement of 3, 4-dihydro-2, 2-dimethyl-2H, 5H-pyrano [2, 3-b] [1] benzopyran-5-ones (dihydropyranochromones) has been observed during the dehydrogenation with DDQ. The products obtained are found to be 2, 2-dimethyl-2H, 5H-pyrano [3, 2-c] [1] benzopyran-5-ones (pyranocoumarins). 相似文献
110.
The Aurivillius phase-based composition bearing chemical formula Bi4Pb2Zr2TiFeNbO18 (termed as BPZTFNO) was synthesized by a solid-state method. The structural analysis as obtained from the X-ray pattern has depicted an orthorhombic phase. The various size and morphology of grains are distributed throughout the natural surface as revealed from microstructure analysis. The dielectric and electrical study of the BPZTFNO is taken at a various sweep of frequency (1 kHz–1 MHz) and temperatures (25–400 °C). The ferroelectric-paraelectric phase transition is well illustrated from the temperature-dependent dielectric constant. The complex impedance analysis suggests the association of grain effect. The relaxation of non-Debye nature is shown in the impedance study. The formed sample is subjected to an electric field and further its excitation performance is examined suggesting its possible usage in devices. 相似文献