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51.
A. Dakshinamoorthy T. Kumar K. K. Nandy R. H. Iyer J. N. Mathur S. B. Manohar 《Journal of Radioanalytical and Nuclear Chemistry》2000,245(3):595-598
In a preliminary study performed with the waste rocks from the future uranium mine to be explored in Brazil, 106 samples were taken from the eight main lithologies found in the massif and analysed by instrumental neutron activation analysis (INAA) for 20 elements. For samples from the same lithology, a high variability in the concentration of most of the elements was found (coefficient of variation larger than 20%), which might be attributed to either insufficient homogenisation of minerals or to local variation within lithology. The hypothesis that the variability within the lithology does not have an influence to the total variability was tested by analysing 5 replicates of the 5 most contrasting samples from the predominant lithology (plagioclase-microcline-gneiss), chosen after applying statistical evaluation (principal components and cluster analyses). Results indicated that homogenisation of samples was adequate due to low variation among replicates. The hypothesis tested was rejected with a confidence level higher than 99% for all the elements, corroborating the large intra-lithology variability. 相似文献
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Philip Dimitrov Pradeep Iyer Marcel Van Beylen Thieo E. Hogen‐Esch 《Journal of polymer science. Part A, Polymer chemistry》2009,47(8):2198-2206
The anionic polymerization of butadiene initiated with 1,4‐dilithio‐1,1,4,4‐tetraphenylbutane (LiTPB) in diethyl ether (DEE) gives polybutadiene (PBD) with high 1,2 content (>70%), narrow polydispersities (1.04 < Mw/Mn < 1.20), and predicted molecular weights. In THF, this polymerization does not work very well. After removal of DEE and addition of THF, the PBD dianion is end capped quantitatively by addition of 1,1‐diphenylethylene (DPE) to give the diphenylalkyl end capped PBD dianion. Subsequent addition of methyl methacrylate at low temperatures results in the formation of well‐defined PMMA‐b‐PBD‐b‐PMMA triblock copolymers. The results are accounted for by taking into account the effects of Li ion solvation on the BD initiation and end capping of the PBD anion by DPE. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2198–2206, 2009 相似文献
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Yang Z Chak P Bristow AD van Driel HM Iyer R Aitchison JS Smirl AL Sipe JE 《Optics letters》2007,32(7):826-828
Highly efficient second-harmonic generation can be achieved by harnessing resonance effects in microring resonator structures. We propose an angular quasi-phase-matching scheme based on the position dependence of polarization inside the ring resonator. 相似文献
56.
Zou J Martin AD Zdyrko B Luzinov I Raston CL Iyer KS 《Chemical communications (Cambridge, England)》2011,47(18):5193-5195
p-Phosphonic acid calix[4]arenes render high stability to exfoliated graphenes in water. These calix[4]arenes modified graphenes can be used as highly effective substrates to nucleate ultra-small Pd nanoparticles, which in turn serve as galvanic reaction templates for the generation of high density 2D arrays of Pt nanoparticles. 相似文献
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J. T. Kunjappu A. J. Singh R. M. Iyer 《Journal of photochemistry and photobiology. A, Chemistry》1987,41(1)
Improved lasing efficiency and long-term photostability of laser dye 7-amino-4-methylcoumarin (C120) has been demonstrated in zone-refined material. Among the impurities found segregated, a high molecular weight compound, 7-acetylamino-4-methylcoumarin, was identified by mass spectrometry. Melting and spectral characteristics of the zone-melted fractions showed the migration of impurities to be in the direction of the zone movement. 相似文献
60.
Balaji V. S. Iyer Sachin Shanbhag Vinay A. Juvekar Ashish K. Lele 《Journal of Polymer Science.Polymer Physics》2008,46(21):2370-2379
In a topologically constraining environment the size of a flexible nonconcatenated ring polymer (macrocycles) and its dynamics are known to differ from that of linear polymers. Hence, the diffusion coefficient of ring polymers can be expected to be different from linear chains. We present here scaling arguments for the concentration and molecular weight dependence of self‐diffusion coefficient of ring polymers in semidilute solutions, and show that contrary to expectations these scaling relations are identical to what is known for linear polymers. At higher concentrations excluded volume interactions arising from possibilities of segmental overlap can become effective for large ring polymers. In this regime the diffusion coefficient of large ring polymers shows a relatively weaker dependence on concentration and molecular weight. ©2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2370–2379, 2008 相似文献