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991.
Yuhong Oh Donggi Ahn Seunghoon Nam Byungwoo Park 《Journal of Solid State Electrochemistry》2010,14(7):1235-1240
The electrochemical properties of nanoscale Al2O3-coated LiCoO2 thin films were examined as a function of the coating coverage. Al2O3-coated LiCoO2 films showed enhanced cycle-life performance with increasing degree of coating coverage, which was attributed to the suppression
of Co dissolution and F− concentration in the electrolyte. Moreover, an Al2O3-coating layer with partial coverage clearly improved the electrochemical properties, even at 60 °C or with a water-contaminated
electrolyte. Even though metal-oxide coating on LiCoO2 has been actively investigated, the mechanisms of nanoscale coating have yet to be clearly identified. In this article, surface
analysis suggested that the Al2O3-coating layer had transformed to an AlF3
∙3H2O layer during cycling, which inhibited the generation of HF by scavenging H2O molecules present in the electrolyte. 相似文献
992.
Chi‐Ming Ho Dr. Sammi King‐Woon Yau Dr. Chun‐Nam Lok Dr. Man‐Ho So Chi‐Ming Che Prof. 《化学:亚洲杂志》2010,5(2):285-293
The oxidative dissolution of silver nanoparticles (AgNPs) plays an important role in the synthesis of well‐defined nanostructured materials, and may be responsible for their activities in biological systems. In this study, we use stopped‐flow spectrophotometry to investigate the kinetics and mechanism of the oxidative dissolution of AgNPs by H2O2 in quasi‐physiological conditions. Our results show that the reaction is first order with respect to both [Ag0] and [H2O2], and parallel pathways that involve the oxidation of H2O2 and HO2? are proposed. The order of the reaction is independent of the size of the AgNPs (≈5–20 nm). The rate of dissolution increases with increasing pH from 6.0 to 8.5. At 298 K and I=0.1 M , the value of kb is five orders of magnitude higher than that of ka (where ka and kb are the rate constants for the oxidative dissolution of AgNPs by H2O2 and HO2?, respectively). In addition, the effects of surface coating and the presence of halide ions on the dissolution rates are investigated. A possible mechanism for the oxidative dissolution of AgNPs by H2O2 is proposed. We further demonstrate that the toxicities of AgNPs in both bacteria and mammalian cells are enhanced in the presence of H2O2, thereby highlighting the biological relevance of investigating the oxidative dissolution of AgNPs. 相似文献
993.
We investigated the delamination problem at the metal‐polymer interface and the mechanical buckling of the metal layer at a localized area of the metallic shell under compression between two parallel plates. First, polystyrene (PS) beads were synthesized by dispersion polymerization and then their sulfonation process. After sequential electroless deposition, the average size of multi‐metal coated sulfonated polystyrene (SPS) bead was ca 4.95 µm. Using the electromechanical indentation, the electrical resistance of a single metal‐coated SPS bead decreased with increasing compressive strain without delamination at the metal‐polymer interface, and its electrical resistance showed 5.65 Ω. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
994.
The value-at-risk is an important risk measure that has been used extensively in recent years in portfolio selection and in
risk analysis. This problem, with its known bilevel linear program, is reformulated as a polyhedral DC program with the help
of exact penalty techniques in DC programming and solved by DCA. To check globality of computed solutions, a global method
combining the local algorithm DCA with a well adapted branch-and-bound algorithm is investigated. An illustrative example
and numerical simulations are reported, which show the robustness, the globality and the efficiency of DCA. 相似文献
995.
Boris S. Mordukhovich Nguyen Mau Nam Bingwu Wang 《Set-Valued and Variational Analysis》2009,17(4):359-387
The primary goal of this paper is to study some notions of normals to nonconvex sets in finite-dimensional and infinite-dimensional spaces and their images under single-valued and set-valued mappings. The main motivation for our study comes from variational analysis and optimization, where the problems under consideration play a crucial role in many important aspects of generalized differential calculus and applications. Our major results provide precise equality formulas (sometimes just efficient upper estimates) allowing us to compute generalized normals in various senses to direct and inverse images of nonconvex sets under single-valued and set-valued mappings between Banach spaces. The main tools of our analysis revolve around variational principles and the fundamental concept of metric regularity properly modified in this paper. 相似文献
996.
Lone S Kim SH Nam SW Park S Cheong IW 《Langmuir : the ACS journal of surfaces and colloids》2010,26(23):17975-17980
We present a simple fabrication of photo- and thermoresponsive microparticles with a narrow size distribution in the PDMS-based microfluidic device. The monodisperse water-in-oil (W/O) droplets of poly(N-isopropylacrylamide-co-spironaphthoxazine methacryloyl) (PNIPA-SPO) were formed at the T-junction channel of the device by adjusting the flow conditions of two immiscible solutions. Subsequently, the droplets were polymerized downstream of the channel under 365 nm UV irradiation in the presence of 2,2'-diethoxyacetophenone (DEAP, photoinitiator) and N,N'-methylenebisacrylamide (MBA, monomer and cross-linker). Being photosensitive, the polymerized microparticles progressively change their color when subjected to UV-vis irradiation. Above the LCST of the copolymer, the microparticles exhibited volume shrinkage accompanied by color deterioration. In addition, the UV light-driven clustering of the PNIPA-SPO copolymer was observed within the W/O droplet in the absence of photoinitiator, which contributed to variable microstructures from Janus to acorn-like and snowman-like morphologies. This work is the first attempt to unveil the photocontrolled asymmetric particle morphology by using the photoresponsive polymer. 相似文献
997.
E. V. Nam A. E. Zhirnov E. A. Litmanovich N. S. Melik-Nubarov I. D. Grozdova 《Polymer Science Series A》2010,52(9):907-913
Covalent modification of poly(alkylene oxides), block copolymers of ethylene oxide and propylene oxide with M ∼ 2000, with fluororescein isothiocyanate or 7-nitrobenzo-2-oxadiazole taken in a ratio of 0.6–1.0 mol of label/mole of polymer
leads to changes in the physical state of polymers and their solubility in water decreases, as well as the partition coefficient
in the hexane-water system and the critical concentration of aggregation and dimensions of the formed particles. 相似文献
998.
Potentiometric properties of cholic and deoxycholic acid derivatives substituted with various ion-recognizing moieties, such as dithiocarbamate, bipyridyl, glycolic and malonic diamides, urea and thiourea, and trifluoroacetophenons (TFAP), have been studied using solvent polymeric membranes. The dithiocarbamate and bipyridyl group containing ionophores exhibit high silver ion selectivity. The cholic acid derivatized with glycolic diamides exhibited high calcium selectivity, but its complex formulation constant was 105 times smaller than that of ETH 1001. The reduced calcium binding ability of the glycolic diamide-substituted ionophore was advantageous for eliminating anionic interference. The bi- or tripodal malonic diamide-substituted ionophores exhibited substantially increased magnesium selectivity. Anion-selective ionophores have been designed by substituting urea and thiourea group containing chains to the hydroxyl linkers of chenodeoxycholic acid frames; their selectivity closely followed the sequence of Hoffmeister series, except the unusually large response of the thiourea-substituted ionophore to sulfate. The most successful examples of cholic or deoxycholic acid frame-based ionophores are those functionalized with two carbonate-selective TFAP groups: bipodal TFAP groups behaves like a tweezers for the incoming carbonate, and exhibit analytically interference free and quantitative responses to the carbonate in serum and seawater samples. 相似文献
999.
Hydroxyzine hydrochloride forms two 1:1 inclusion complexes with β‐cyclodextrin in aqueous solution as confirmed by the 1H NMR titration and ROESY studies. One complex is formed by the deep penetration of the chlorophenyl ring from the wider rim side, while the mode of entry of the phenyl ring into the β‐CD cavity is not clear. The stoichiometry and overall association constant of the complexes have been determined by the treatment of 1H NMR shift data. Some chiral discrimination by the host between the two enantiomers of hydroxyzine hydrochloride is also indicated. 相似文献
1000.
Jae Kyun Park Gyoung Seok Hwang Byung Doo Chin Nam Su Kang Tae-Woo Lee 《Current Applied Physics》2012
The light emitting behavior of the electrophosphorescent devices with solution-processible hole transport layer and light emitting layer was characterized. We have introduced the hole-transporting stacked layer composed of poly(3,4-ethylenedioxy thiophene): poly(4-styrenesulfonate) [PEDOT:PSS] and thin perfluorinated ionomer, aiming for the improvement of charge injection and transport with corresponding high efficiency behavior. In order to provide a suitable work function, composition and thickness of the ultra-thin perfluorinated ionomer was optimized for being an interfacial layer condition; 34 cd/A of green phosphorescent device was obtained while the control device without ionomer shows the luminous efficiency of 29 cd/A. Both for devices with vacuum-deposited and solution-processed electrophosphorescent emitters, change of the device efficiencies were analyzed in terms of the work function, surface chemical composition, and charge conduction behavior. 相似文献