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101.
In this paper, we address several optimization problems in satellite optical communications. We show that the inter-satellite links with swaying transmitters can be described as an equivalent fading model. We further indicate that the instantaneous signal-to-noise ratio follows the reciprocal Pareto distribution. Then we conduct the analysis on several performance metrics such as the first and second moments of signal-to-noise ratio, the amount of fading, as well as the outage probability. Based on these metrics, we establish optimization models and provide the corresponding solutions. 相似文献
102.
Jung A. Jung Young Baek Kim Young A. Kim Seung Bum Ryu Veronica Kim 《Journal of nanoparticle research》2011,13(6):2361-2374
Functional spherical solid and hollow particles of polysilsesquioxanes (PSQs) containing amine, thiol, and vinyl groups were
prepared by polymerizing organotrialkoxysilanes (OTASs) containing corresponding chemical groups. Fluorescent PSQ particles
were prepared by physically entrapping Rhodamine 6G, Coumarin 7, and Fluoresceine sodium salts. The intensity of fluorescent
light increased initially with increasing amount of entrapped fluorophores and then leveled off or decreased slightly after
reaching a maximum value. PSQ particles containing gold nanoparticles (GNPs), both inside and on the surface, were prepared
by the in situ reduction of gold ions by the PSQ particles. When the reduction reaction was carried out for extended periods
of time, the GNP that had formed inside the poly(3-mercaptopropyl)silsesquioxane (PMPSQ) and polyvinylsilsesequioxane (PVSQ)
particles underwent interesting morphological changes. PSQ particles containing amine and thiol groups fixed the GNPs on the
surface, which could be utilized further in binding amine-modified oligo-DNA strands. The aggregation of PSQ/GNP particles
combined with complementary oligo-DNA strands was examined to demonstrate that these particles could be applied to DNA assays
and isolation. The particles were characterized by scanning electron microscopy, transmission electron microscopy, solid state
nuclear magnetic resonance spectroscopy, ultraviolet/visible spectroscopy, and fluorescence microscopy. 相似文献
103.
The complex crossed structures with a polymorph of calcite, termed a chalky layer, which make up much of the shell of an oyster, are composed of flames and leaflets. Two layers, folia and the chalky layer in the giant Pacific oyster (Crassostrea gigas) were examined using SEM (scanning electron microscope), micro-area-XRD (X-ray diffraction) and FT-IR (Fourier transform infrared spectrometer) to determine their morphologies and component characteristics. The chalky layer was also tested using microindentation to assess its mechanical properties, and a microcrack was generated to study the fracture mechanism of the chalky layer. From an analysis of the secondary protein structure, it was shown that the ordered structures of the two layers, α-helix and β-structure, are similar but that the unordered structures are different. Moreover, the foliated rods at the interface of the chalky layer play a key role in the crystal growth of the chalky layers. Comparing the morphology and the preferred orientation of foliated laths, the advantages of the relatively high density and low hardness of the chalky layer have interesting implications regarding the development of sophisticated complex composites. 相似文献
104.
Susanne Friedreich D��niel Barna Andreas Dax Ryu Hayano Dezs? Horv��th Masaki Hori Bertalan Juh��sz Oswald Massiczek Anna S��t��r Thomas Pask Eberhard Widmann 《Hyperfine Interactions》2011,199(1-3):337-346
The spin magnetic moment $\mu^{\overline{p}}_{s}$ of the antiproton can be determined by comparing the measured transition frequencies in $\overline{p}^4$ He?+? with three-body QED calculations. A comparison between the proton and antiproton can then be used as a test of CPT invariance. The highest measurement precision of the difference between the proton and the antiproton spin magnetic moments to date is 0.3%. A new experimental value of the spin magnetic moment of the antiproton was obtained as $\mu^{\overline{p}}_{s} = -2.7862(83)\mu_{N}$ , slightly better than the previously best measurement. This agrees with $\mu^{p}_{s}$ within 0.24%. In 2009, a new measurement with antiprotonic 3He has been started. A comparison between the theoretical calculations and experimental results would lead to a stronger test of the theory and address systematic errors therein. A measurement of this state will be the first HF measurement on $\overline{p}^3$ He?+?. We report here on the new experimental setup and the first tests. 相似文献
105.
Ravindar Tadi Yong-Il KimDebasish Sarkar CheolGi KimKwon-Sang Ryu 《Journal of magnetism and magnetic materials》2011,323(5):564-568
BaTiO3+MgFe2O4 material system was synthesized by hybrid chemical process using chlorides and nitrates of barium, titanium, iron, and magnesium. Magnetic properties of the composite samples measured as a function of annealing conditions indicated soft magnetic behavior. Saturation specific magnetization from 8 21 emu/g was observed for samples annealed at temperature between 950 and 1150 °C. Variation of specific saturation magnetization with respect to annealing temperature was related with the distribution of Fe cations in the tetrahedral and octahedral sites of MgFe2O4. Electrical properties of the samples annealed at different temperatures were measured to analyze the coexistence of ferroelectric phase. Dielectric constant varying from 15 to 200 with respect to frequency was observed for samples annealed from 950 to 1150 °C. 相似文献
106.
Chung-jong BongKwon-sang Ryu Seung-hoon NahmEun Kyu Kim 《Journal of magnetism and magnetic materials》2011,323(5):379-382
We present a magnetic and nondestructive method to evaluate the remanent life of modified 9Cr-1Mo steel by measuring the reversible magnetic permeability. Specimens with ten different kinds of aging periods were prepared using an isothermal heat treatment at 690 °C. The Larson-Miller parameter (LMP) was calculated and the peak interval of reversible magnetic permeability (PIRMP) was measured using the surface type probe. PIRMP was inversely proportional to LMP. We can evaluate the remanent life of modified 9Cr-1Mo steel using the relationship between PIRMP and LMP. Also, we present the possibility that the tensile strength and yield strength measured by destructive methods could be estimated by PIRMP measured nondestructively. 相似文献
107.
Summary We introduce a shared random-effect model, derived from frailty models to account for informative dropout. We extend the iterative
weighted least squares algorithm for hierarchical generalized linear models to shared random-effect models. Monte-Carlo simulations
are carried out to illustrate that the proposed method works well whether the random-effect distribution is correctly specified
or not.
This study was supported by a grant of the Korea Health 21 R & D Project, Ministry of Health & Welfare, Republic of Korea.
(01-PJ1-PG3-51200-0002). 相似文献
108.
109.
Sarah Lastella Hoichang Yang David Rider Ian Manners Pulickel M. Ajayan Chang Y. Ryu 《Journal of Polymer Science.Polymer Physics》2007,45(7):758-765
Catalyst formation kinetics of a ferrocene‐containing homopolymer, polyferrocenylethylmethylsilane (PFEMS), is investigated as it relates to the catalysis of single walled carbon nanotubes (SWNTs) through a chemical vapor deposition (CVD) process. The formation and efficiency of the PFEMS‐based iron catalyst is compared with that of the corresponding polystyrene (PS)‐b‐PFEMS diblock copolymer. The PFEMS homopolymer contains 23 wt % iron, while PS‐b‐PFEMS, with a 25 vol % PFEMS content, is only 6% iron. Despite its lower iron content, spin‐cast PS‐b‐PFEMS films on SiO2/Si substrates produce more active iron sites than spin‐cast PFEMS films during CVD growth of SWNTs. This is related to the self‐assembly of the block copolymer, where PFEMS domains are well dispersed in the PS matrix, which degrades at a CVD temperature of 920 °C to leave catalytically active elemental iron behind. On the contrary, the pure PFEMS films contain a high percentage of iron and silicon, which tend to transform into ceramic‐coated iron at this high temperature, thus rendering the iron inactive towards SWNT growth. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 758–765, 2007 相似文献
110.