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41.
Double- and multi-1,3-alternate-calixcrowns were prepared by multistep syntheses. 相似文献
42.
Inside Cover: Selective Solid–Liquid and Liquid–Liquid Extraction of Lithium Chloride Using Strapped Calix[4]pyrroles (Angew. Chem. Int. Ed. 37/2018) 下载免费PDF全文
43.
Photoelectrochemical Cells: Carbon Nanotube–Graphitic Carbon Nitride Hybrid Films for Flavoenzyme‐Catalyzed Photoelectrochemical Cells (Adv. Funct. Mater. 24/2018) 下载免费PDF全文
44.
The development of lithium metal anodes for next generation batteries remains a challenge. Uncontrolled Li dendrite growth not only induces severe safety issues but also leads to capacity fading by continuously consuming the electrolyte. This study demonstrates the design and fabrication of a composite protective layer composed of a high dielectric polymer, inorganic particles, and an electrolyte to overcome these obstacles. This layer not only suppresses dendrite growth, but also prevents LiPF6 degradation. The electrolyte introduced in the protective layer remains within the coating layer after solvent removal and acts as an ion transport channel at the interface. This enables the protective layer to exhibit high ionic conductivity and mechanical strength. The composite protective layer, which exhibits synergistic soft‐rigid characteristics, is placed on the Li metal anode and facilitates superior interfacial stability during long‐term cycles. LiMn2O4/coated lithium full cells using the composite protective layer show a superior rate capability and enhanced capacity retention compared to the cells using a bare lithium anode. The proposed strategy opens new avenues to fabricate a sustainable composite protective layer that affords superior performance in lithium metal batteries. 相似文献
45.
As a novel sensing system, N-(1-pyrenylmethyl) amide-appended calix[4]crown-5 (2) and crown-6 (3) have been newly synthesized. Judging from the fluorescence changes upon the addition of cations, 3 having crown-6 ring showed the Pb2+ ion selectivity over other cations tested regarding fluorescence quenching. Upon the Pb2+ ion coordination to two amide oxygen atoms with aid of crown ring, a reverse-photo-induced electron transfer (PET) occurs in such a way that electrons transfer from the pyrene groups to the electron deficient amide oxygen atoms to give a quenched fluorescence. By the addition of either HClO4 or triethylamine in the solution of 3, the fluorescence intensity decreased because of the reverse-PET from pyrene groups to protonated amide oxygen atoms and because of normal PET from the nitrogen anion formed by triethylamine to pyrene groups, respectively. For 3, NOR logic gate in which the strong fluorescence signal appears at 395 nm (output: 1) is operated only when neither of triethylamine nor Pb(ClO4)2 (inputs A and B) is added (A=B: 0). XNOR gate is also operated only when both of two inputs are added (triethylamine and HClO4, A=B: 1) or when neither of two inputs is added (A=B: 0). Then, for 3, new INHIBIT gate system was also designed using such combinational inputs as HClO4, Pb(ClO4)2 and triethylamine. 相似文献
46.
Yun‐Hi Kim Seong‐Kuk Ahn Hyung Sun Kim Soon‐Ki Kwon 《Journal of polymer science. Part A, Polymer chemistry》2002,40(23):4288-4296
Two new pyromellitic dianhydrides, 1,4‐bis(4′‐t‐butylphenyl) pyromellitic dianhydride and 1,4‐bis(4′‐trimethylsilylphenyl) pyromellitic dianhydride, were synthesized via Suzuki coupling, oxidation, and dehydration. A series of new organosoluble polyimides were prepared from the obtained pyromellitic dianhydride and various aromatic diamines by the conventional polycondensation reaction followed by chemical imidization, as well as high‐temperature, one‐step polymerization. The structures of the dianhydrides and polymers were identified with various spectroscopies. The inherent viscosities of the resulting polymers were 0.62–1.89 dL/g. The synthesized polyimides showed good solubility in various organic solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, and p‐chlorophenol. These polymers had glass‐transition temperatures of 230–260 °C. Thermogravimetric analysis showed that all the polymers were stable, with 10% weight losses recorded above 490 °C in nitrogen. The polyimide films had good mechanical properties and high oxygen permselectivity to nitrogen. The oxygen permeability coefficient (P) and the permselectivity of oxygen to nitrogen (P/P) of the films were 13–56 barrer and 3.7–5.5, respectively. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4288–4296, 2002 相似文献
47.
Young Kwan Park Sang Beom Choi Hyunuk Kim Kimoon Kim Prof. Byoung‐Ho Won Kihang Choi Prof. Jung‐Sik Choi Wha‐Seung Ahn Prof. Nayoun Won Sungjee Kim Prof. Dong Hyun Jung Dr. Seung‐Hoon Choi Dr. Ghyung‐Hwa Kim Sun‐Shin Cha Dr. Young Ho Jhon Dr. Jin Kuk Yang Prof. Jaheon Kim Prof. 《Angewandte Chemie (International ed. in English)》2007,46(43):8091-8091
48.
Electron‐transfer transparency of graphene: Fast reduction of metal ions on graphene‐covered donor surfaces 下载免费PDF全文
Du Won Jeong Serin Park Won Jin Choi Giyeol Bae Yun Jang Chung Cheol‐Soo Yang Young Kuk Lee Ju‐Jin Kim Noejung Park Jeong‐O. Lee 《固体物理学:研究快报》2015,9(3):180-186
The mechanism of charge transfer through nanomaterials such as graphene remains unclear, and the amount of charge that can be transferred from/to graphene without damaging its structural integrity is unknown. In this communication, we show that metallic nanoparticles can be decorated onto graphene surfaces as a result of charge transfer from the supporting substrate to an adjoining solution containing metal ions. Au or Pt nanoparticles were formed with relatively high yield on graphene‐coated substrates that can reduce these metal ions, such as Ge, Si, GaAs, Al, and Cu. However, metal ions were not reduced on graphene surfaces coated onto non‐reducing substrates such as SiO2 or ZnO. These results confirm that graphene can be doped by exploiting charge transfer from the underlying substrate; thus graphene is not only transparent with respect to visible light, but also with respect to the charge transfer. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
49.
Waste tire powder subjected to allylamine modification in the presence of ultraviolet (UV) radiation has been used to prepare polypropylene based thermoplastic vulcanizates with maleic anhydride polypropylene (MA‐PP) as compatibilizer. The effect of increasing the concentration of MA‐PP on performance characteristics like tensile strength, elongation and rheological properties have been investigated. X‐ray diffraction studies of the PP/waste tire powder blend indicate the disappearance of β crystalline peaks on addition of waste tire powder in the PP, whereas it is observed in the allylamine modified rubber powder loaded PP. Differential scanning calorimetry results further supported the above fact. The improvement in mechanical properties of the PP/allylamine modified rubber powder loaded thermoplastic vulcanizates has been explained in terms of βα transformation of PP crystals during straining of the samples and uniform dispersion of allylamine coated rubber powder in the PP matrix. The melt rheological properties of the thermoplastic vulcanizates loaded with modified rubber powder are higher than its counterpart due to the higher dispersion as a result of chemical interaction between the rubber powder surface with the MA‐PP. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
50.
A precursor, 1,2,4-trimethylbenzene, seeded in a large amount of an inert carrier gas, helium, was electrically discharged in a corona-excited supersonic expansion using a pinhole-type glass nozzle. The blue-green colored fluorescence emanating from the downstream jet was recorded with a long path monochromator to observe the vibronic emission spectrum of the benzyl-type radical formed. Analysis of the spectrum suggests that the most dominant product of the corona discharge is the 3,4-dimethylbenzyl radical formed by extracting a hydrogen atom from the methyl group at the 4-position. The electronic energies of the D1 and D2 states and the vibrational mode frequencies of the 3,4-dimethylbenzyl radical were accurately obtained for the first time by comparison with those from an ab initio calculation as well as those of the known vibrational mode frequencies of the precursor. 相似文献