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51.
S. Schweizer M. Secu J. -M. Spaeth L. W. Hobbs A. Edgar G. V. M. Williams 《Radiation measurements》2004,38(4-6):633-638
We found a significant PSL effect in Eu2+-doped fluorozirconate glasses (ZBLAN) which were additionally doped with Br− or Cl− ions. The PSL is attributed to the characteristic emission of Eu2+ present in nano-crystallites of BaBr2 or BaCl2, which form in the glass upon annealing. The metastable hexagonal form of BaX2 (X=Br,Cl) is always formed first before it is converted into the stable orthorhombic form. The particle size increases upon annealing and so does the PSL efficiency of the glass ceramic. However, there is a saturation of the PSL efficiency, which is for Br− doping about 9% and for Cl−-doping about 80% of the Eu-doped BaFBr standard. The particle size was determined by transmission electron microscopy (TEM). The TEM results show a clear tendency for bigger particles for longer annealing at the expense of its number. The particle size for the most efficient phosphor is about 100 nm. 相似文献
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In this study, a genetically encoded bioluminescent indicator for ERK2 dimer was developed with the split Renilla luciferase complementation method, in which the formation of ERK2 dimer induces a spontaneous emission of bioluminescence in living cells. In response to extracellular stimuli, such as epidermal growth factor (EGF) or 17β‐estradiol (E2), extracellular signal‐regulated kinase 2 (ERK2) is phosphorylated by its upstream kinase MEK, and also phosphorylates its substrates in various regions of the cell, including the nucleus. Phosphorylated ERK2 is led to form its dimer, thereby transporting itself into the nucleus. We demonstrated with the indicator that stimulation with EGF or E2 induces the formation of ERK2 dimer in living MCF‐7 cells. The dynamics of this dimer formation was examined and discussed. 相似文献
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The luminescence of the terpyridine-Eu3+-complex associated with poly(ethyleneoxide) or poly(propyleneoxide) chains has been studied in various fluid or solid environments including silica/poly(alkyleneoxide) nanocomposite materials. Strongly luminescent materials are obtained. Their emission can be tuned by varying the organic/inorganic content and, generally, the structure of the host material. In this respect, the complex luminescence itself is a sensor of the structural aspects of the host material. 相似文献
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制备了Er3 、Yb3 共掺的SiO2-A12O3-PbF2-CdF2系统玻璃,并进行相应的微晶化热处理,研究了氟氧化物微晶玻璃中Er3 离子的上转换发光特性.研究结果表明:原始玻璃经热处理后得到的β-PbF2相氟氧化物微晶玻璃,Er3 和Yb3 所在局域基质声子能量的降低,使微晶玻璃中Er3 上转换发光强度显著提高,而微晶化后Er3 、Yb3 离子局域环境发生变化,导致微晶玻璃中Er3 离子的绿光上转换荧光强度较强,而红光上转换荧光强度相对较弱. 相似文献
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The mechanism of the slowly opened Q-switch operation was investigated thoroughly. Maximum energy extraction from the resonator
could be optimized, and the smallest output beam divergence could be achieved. In this article, we present a detailed analysis
that has numerically verified the mode-selection mechanism in the slowly opened Q-switch operation, and the degree of the
smaller output laser beam divergence that has been achieved. The mechanism of the slowly opened Q-switch operation is the
inherent advantage of the passive saturable absorber in this operation. We can use the maximum energy extraction and the smallest
output beam divergence results of the slowly opened Q-switch operation to design and optimize various passive saturable absorbers:
plastic dye sheets, LiF:F2− color center crystals, Cr4+: YAG crystals, RG1000 color glass filters, and the single crystal semiconductor saturable absorber wafers that are in developed
in our microchip laser systems. 相似文献
60.
David A. Stone Youngkyu Chang Harry R. Allcock 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):69-76
A new type of cyclolinear polymer, poly(phenylene vinylene‐alt‐cyclotriphosphazene), was synthesized through Heck‐type coupling reactions to produce π‐conjugated macromolecules with excellent solubility and precise electronic control of the band‐gap energy. This synthesis method is capable of producing well‐defined alternating polymers. The method is highly adaptable and can be readily used for other chromophore systems. The resulting polymers were also capable of accommodating a wide variety of substituents on the cyclophosphazene rings with minimal effect on the electronic properties. The band gap and electron affinities of the polymer were varied through the manipulation of the π‐conjugated unit located between the insulating phosphazene rings. Each chromophore matched the intended conjugation length consistently throughout the macromolecules. The polymers were good film formers because of the chosen substituents on the phosphazene rings. The absorbance of the polymers indicated minimal spectral shift from the monomer absorbance. This suggested an effective insulation of each chromophore unit from its neighbors by the phosphazene rings. Solution photoluminescence efficiencies were found to be up to 44.1%. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 69–76, 2006 相似文献