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11.
High‐performance liquid chromatography separation of unsaturated organic compounds by a monolithic silica column embedded with silver nanoparticles 下载免费PDF全文
Yang Zhu Kei Morisato George Hasegawa Nirmalya Moitra Tsutomu Kiyomura Hiroki Kurata Kazuyoshi Kanamori Kazuki Nakanishi 《Journal of separation science》2015,38(16):2841-2847
The optimization of a porous structure to ensure good separation performances is always a significant issue in high‐performance liquid chromatography column design. Recently we reported the homogeneous embedment of Ag nanoparticles in periodic mesoporous silica monolith and the application of such Ag nanoparticles embedded silica monolith for the high‐performance liquid chromatography separation of polyaromatic hydrocarbons. However, the separation performance remains to be improved and the retention mechanism as compared with the Ag ion high‐performance liquid chromatography technique still needs to be clarified. In this research, Ag nanoparticles were introduced into a macro/mesoporous silica monolith with optimized pore parameters for high‐performance liquid chromatography separations. Baseline separation of benzene, naphthalene, anthracene, and pyrene was achieved with the theoretical plate number for analyte naphthalene as 36 000 m?1. Its separation function was further extended to cis/trans isomers of aromatic compounds where cis/trans stilbenes were chosen as a benchmark. Good separation of cis/trans‐stilbene with separation factor as 7 and theoretical plate number as 76 000 m?1 for cis‐stilbene was obtained. The trans isomer, however, is retained more strongly, which contradicts the long‐ established retention rule of Ag ion chromatography. Such behavior of Ag nanoparticles embedded in a silica column can be attributed to the differences in the molecular geometric configuration of cis/trans stilbenes. 相似文献
12.
S. N. Karmakar R. K. Moitra P. Chaudhuri 《Zeitschrift für Physik B Condensed Matter》1985,58(2):133-140
In this paper we present a new theory for including both short range order and long range order simultaneously in the well known cluster Bethe lattice method for binary alloys. We have used this theory for obtaining the Friedel criterion for the appearance of magnetic moments in disordered states using the single band Hubbard model. This is followed by a study of this criterion in a two-bands-d hybridised Hubbard model, which is considered as a simulation of real transition metals. A new technique for solving this problem in the Bethe lattice network is presented, which yields an analytic solution for the critical correlation strength in the presence of hybridisation and short range order. It is found that in all cases hybridisation tends to diminish the tendency for magnetisation, which is in accord with physical expectations. 相似文献
13.
Parikshit Mandal 《Physica B: Condensed Matter》2008,403(18):2967-2978
We explore the pattern of frequency-dependent linear and non-linear optical (NLO) response of one electron quantum dots harmonically confined in two dimensions. For some fixed values of transverse magnetic field strength (ωc), and harmonic confinement potential (ω0), the influence of effective mass (m*) of the system and the symmetry breaking anharmonic interaction on the frequency-dependent linear (α), and the first (β), and second (γ) NLO responses of the dot is computed through linear variational route. The investigation reveals interesting roles played by the anharmonic interaction and effective mass in modulating the response properties. 相似文献
14.
The growth of a new nonlinear optical material L‐valine by solvent evaporation method is reported here. To grow good quality crystals pH value of growth solution has been optimized and solubility of L‐valine in different solvents and different pH values was determined. The grown crystals were characterized by IR, single crystal XRD, DTA and TGA, optical transmission and second harmonic generation (SHG) efficiency measurement. SHG efficiency of L‐valine was found equivalent to KDP and its transmission is 75%‐80% from ultraviolet to near IR region. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The Anderson hamiltonian has been studied for arbitrarily filled bands using the real space renormalization group (RSRG) method. The ground state energy is determined in one dimension for the scale factors ns = 3 and ns = 5. Direct application of RSRG gives, for a certain ns, the results for only ns number of discrete cases of band-filling. We then devise an interpolation scheme which spans the entire region of the band and gives the ground state energy for any general filling. The results, as provided by our scheme, satisfy the desired particle-hole symmetry exactly and are always an upper bound to the exact one. The non-linear dependence of the band energy on its filling is represented correctly, even for small ns. Finally, we discuss how the results improve for large ns. 相似文献
17.
Md. Mijanuddin Parikshit Chandra Mondal Mahammad Ali 《Journal of Molecular Structure》2007,826(1):17-23
A series of square-pyramidal copper(II) complexes, [Cu(LSe)(N∧N)] (H2LSe = seleno-bisphenolate; N∧N = bipyridyl, phenanthroline or N,N-dimethylethylenediamine) have been synthesized and characterized by elemental analyses, magnetic measurements, IR, EPR, and electronic spectral studies. Single crystal X-ray structures of [Cu(LSe)(bpy)]·H2O (2), [Cu(LSe)(phen)]·CH2Cl2 (3) and [Cu(LSe)(N,N-Me2en)] (4) showed that all the complexes have approximately square-pyramidal geometry. In complexes 2 and 3, the square plane is occupied by O(1), O(2), N(1) and N(2) and the apical position by Se atom of LSe 2− ligand. The asymmetric unit of complex 4 contains two crystallographically independent discrete molecules A and B with CuN2OSe chromophore comprising the square plane and the axial position being occupied by another phenolate oxygen atom. Complexes 2, 3 and 4 are found to be paramagnetic and EPR parameters extracted are: g∥ = 2.232, g⊥ = 2.069; 〈geff〉 = 1.95; and g∥ = 2.232, g⊥ = 2.083 for complexes 2, 3 and 4, respectively. Both the complexes 2 and 4 show three reduction processes: (a) a quasi-reversible reduction of CuII to CuI, (b) an irreversible reduction of CuI to Cu0 with the release of free ligand, and (c) a reduction process occurs at this coordinated ligand. They also show a well-defined quasi-reversible oxidation of CuII to CuIII and an irreversible oxidation peak at ∼1.30 and 1.40 V vs. Ag/AgCl for 4 and 2, respectively, with no cathodic counterpart, and were attributed to the oxidation of the metal coordinated ligand. 相似文献
18.
UV–vis absorption, steady state and time resolved fluorescence studies on the photo physical behavior of indomethacin, a traditional NSAID in binary water ethanol mixtures have been presented. Our results reveal that indomethacin can sense the micro heterogeneity in the binary mixtures forming ground state fluorescent complex with two predominant types of clusters viz. ethanol self-association clusters and hydrogen bonded water clusters. 相似文献
19.
Nanocomposite Made of an Oligo(p‐phenylenevinylene)‐Based Trihybrid Thixotropic Metallo(organo)gel Comprising Nanoscale Metal–Organic Particles,Carbon Nanohorns,and Silver Nanoparticles 下载免费PDF全文
Subham Bhattacharjee Dr. Suman K. Samanta Parikshit Moitra K. Pramoda Ram Kumar Prof. Dr. Santanu Bhattacharya Prof. Dr. C. N. R. Rao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5467-5476
A silver ion (Ag+)‐triggered thixotropic metallo(organo)gel of p‐pyridyl‐appended oligo(p‐phenylenevinylene) derivatives (OPVs) is reported for the first time. Solubilization of single‐walled carbon nanohorns (SWCNHs) in solutions of the pure OPVs as well as in the metallogels mediated by π–π interactions has also been achieved. In situ fabrication of silver nanoparticles (AgNPs) in the SWCNH‐doped dihybrid gel leads to the formation of a trihybrid metallogel. The mechanical strength of the metallogels could be increased stepwise in the order: freshly prepared gel<dihybrid gel<trihybrid gel. Microscopic studies of the trihybrid gel indicate the formation of three distinct morphologies, that is, nanoscale metal–organic particles (NMOPs), flowerlike aggregates of SWCNHs and AgNPs, and also their integration with each other. Detailed studies suggest lamellar organizations of the linear metal–ligand complexes in the NMOPs, which upon association create a three‐dimensional network that eventually immobilizes the solvent molecules. 相似文献
20.