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31.
N. Venugopalan Pillai R. Vinodkumar V. Ganesan Peter Koshy V. P. Mahadevan Pillai 《Pramana》2010,75(6):1157-1161
BaWO4 doped with ZnO (2, 3, 5, 7 and 10 wt%) nanostructured films are prepared on quartz substrates by pulsed laser ablation. The
films are post annealed at 900°C. GIXRD analysis of the post-annealed films reveal the change of orientation of scheelite
tetragonal crystal growth from 1 1 2 reflection plane to 0 0 4 planes when doping concentration is more than 3 wt%. The AFM
images show that film with 7 wt% ZnO doping concentration has good ceramic pattern with surface features giving a minimum
value of rms surface roughness suitable for optoelectronic device applications. The optical transmittance and band-gap energy
of the films are found to decrease considerably on postannealing which can be due to the increase in grain size of the crystallites
on annealing. Thus doping with ZnO improves the surface features of the films and increases the optical band-gap energy. 相似文献
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Quantum dots (3–4?nm) of Zn1? x Cd x S (both free of Mn2+ and with Mn2+ incorporated) were synthesized through a novel solvothermal-microwave irradiation technique. Detailed structural analysis of the Zn1? x Cd x S and Zn1? x Cd x S:Mn2+ (x?=?0, 0.25, 0.5, 0.75 and 1) materials was carried out using powder X-ray diffraction technique. For all the compositions, the crystallite size was controlled to less than 1.5?nm. The optical energy gap for Zn1? x Cd x S was found to vary from 3.878 to 2.519?eV and for Zn1?x Cd x S:Mn2+ it varies from 3.830 to 2.442?eV when x is increased from 0 to 1. Overall, the optical energy gap could be tuned from a minimum of 2.442?eV to a maximum of 3.878?eV. DC conductivity analysis (from 40°C to 150°C) and electrical energy gap analysis for all the compositions were also performed. The dc conductivity for Zn1? x Cd x S solid solutions varies from 0.3840?×?10?10 to 8.7782?×?10?10?mho/m at 150°C and for Zn1? x Cd x S:Mn2+ it varies from 0.5751?×?10?10 to 9.8078?×?10?10 mho /m at 150°C (for x?=?0 to x?=?1). The method of synthesis and the results observed in this investigation may assist in the fabrication of optical devices when the required operational performance falls under the range observed in the study. 相似文献
35.
36.
P. Kuppusamy P. T. Manoharan C. Mahadevan M. Seshasayee 《Journal of chemical crystallography》1985,15(4):359-376
The crystal and molecular structure of the title compound, C21H11N6S4Ni, is reported. The crystals are triclinic:P¯1 (No. 2),Z=4,a=8.768(1),b=11.817(3),c=22.131(3) Å,=97.44(1),=91.90(1), and =94.04(1)°. The structure was solved by the heavy-atom method, and refined by full-matrix least squares toR=0.039 for 3213 unique reflections. The Ni atoms of both anions in the asymmetric unit have an approximately square-planar configuration. Anions and cations form segregated stacks alonga. The stacking of the anions along this direction is dimeric, with alternating Ni-Ni distances 4.111(2) and 7.593(2) Å for molecule I and 4.208(1) and 8.155(2) Å for molecule II. Static susceptibility measurements show strong antiferromagnetic coupling (2J=-241 cm–1) between the two anions of the dimers. 相似文献
37.
Results are reported of measurements of the glass transition temperature (Tg), conductivity and density (d) for glasses of the AsSbSe system, with compositions (As, Sb)40Se60 and AsxSb15Se85?x. The results are compared with glasses of similar compositions of the AsxSe100?x about compositions in the GexSb15Se85?x and AsxSe100?x glasses, in the case of AsxSb15Se85?x glasses, the As-rich compositions exhibit higher values of Tg and d compared to the stoichiometric composition As25Sb15Se60. These results are discussed in the light of a chemically ordered structural arrangement in these glasses. 相似文献
38.
Aswathanarayana Srinivasa Kittappa Malavalli Mahadevan Kallappa Mahadevappa Hosamani Vijaykumar Hulikal 《Monatshefte für Chemie / Chemical Monthly》2008,139(2):141-145
Summary. 4-Nitrophthalic acid was found to be an effective catalyst for the imino Diels-Alder reaction of N-benzylideneanilines with 3,4-dihydro-2H-pyran and 2,3-dihydrofuran to afford pyrano- and furanoquinolines in good yields. It was also found that aryl amines react
smoothly with 3,4-dihydro-2H-pyran and 2,3-dihydrofuran under the same condition to afford the corresponding pyrano- and furanoquinolines in high yields.
This catalyst is inexpensive, easily available, water soluble, and stable to aqueous reaction conditions. 相似文献
39.
Aswathanarayana Srinivasa Kittappa M. Mahadevan Vijaykumar Hulikal 《Monatshefte für Chemie / Chemical Monthly》2008,10(1):255-259
Antimony(III) sulfate is found to catalyze the imino Diels-Alder reaction of Schiff’s bases with N-vinylpyrrolidin-2-one to afford 2-aryl-4-(2′-oxopyrrolidinyl-1′)-1,2,3,4-tetrahydroquinolines. One-pot synthesis of 1,2,3,4-tetrahydroquinolines
from 3-nitro benzaldehyde and aromatic amines with N-vinylpyrrolidin-2-one catalyzed by antimony(III) sulfate is also reported. This catalyst is inexpensive, easily available,
and it was also found that catalyst could be recovered quantitatively and reused without much loss of catalytic activity. 相似文献
40.
Sreeram Kalarical Janardhanan Indumathy Ramasamy Balachandran Unni Nair 《Transition Metal Chemistry》2008,33(1):127-131
Natural polymers like chitosan and starch have been employed as templates for the preparation of iron oxide nanoparticles.
The templates offer selective binding sites for Fe(II) under aqueous conditions. Controlled drying and subsequent removal
of the template backbone enables the synthesis of spatially separated iron oxide nanoparticles. The crystalline character
of the iron oxide and near narrow particle size distribution pattern have been confirmed through powder XRD, Photon Correlation
Spectroscopy, and TEM measurements. The crystallite sizes of the particles were found to be 26–35 nm irrespective of the nature
of the template. 相似文献