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141.
Pramod P Sudeep PK Thomas KG Kamat PV 《The journal of physical chemistry. B》2006,110(42):20737-20741
Design of nanohybrid systems possessing several ruthenium trisbipyridine (Ru(bpy)(3)(2+)) chromophores on the surface of gold nanoparticles, by adopting a place exchange reaction, was reported and their photophysical properties were tuned by varying the density of chromophores. The charge shift between the excited and ground-state Ru(bpy)(3)(2+) chromophores was reported for the first time, leading to the formation of Ru(bpy)(3)(+) and Ru(bpy)(3)(3+). Electron-transfer products were not observed on decreasing the concentration of Ru(bpy)(3)(2+) functionalized on Au nanoparticles or in a saturated solution of unbound chromophores. The close proximity of the chromophores on periphery of the gold core may lead to an electron transfer reaction and the products sustained for several nanoseconds before undergoing recombination, probably due to the stabilizing effect of the polar ethylene glycol moieties embedded between the chromophore groups. 相似文献
142.
Elliptic problems with parameters in the boundary conditions are called Steklov problems. With the tool of computational approximation
(finite-element method), we estimate the solution of a nonlinear Steklov eigenvalue problem for a second-order, self-adjoint,
elliptic differential problem. We discussed the behavior of the nonlinear problem with the help of computational results using
Matlab. 相似文献
143.
K.S. Subrahmanyam Prashant Kumar Angshuman Nag C.N.R. Rao 《Solid State Communications》2010,150(37-38):1774-1777
It has been demonstrated that acid-treated graphene samples as well as reduced graphene oxide show fairly intense blue emission centered around 440 nm. Reduction of graphene oxide can be carried out either chemically or by using different types of radiations. Blue emission from graphene-based materials can be combined with the yellow emission from materials like ZnO to produce white light sources. 相似文献
144.
Sahu PK Kulkarni BD Khomane RB Pardhy SA Phalgune UD Rajmohanan P Pasricha R 《Chemical communications (Cambridge, England)》2003,(15):1876-1877
Barium hexaaluminate (BHA) synthesized by coupling of sol-gel process in reverse microemulsions shows a unique nanowhisker morphology and high surface area, which are retained after calcination at 1300 degrees C. 相似文献
145.
Excited-state interactions between chlorophyll a (Chla) and gold nanoparticles have been studied. The emission intensity of Chla is quenched by gold nanoparticles. The dominant process for this quenching has been attributed to the process of photoinduced electron transfer from excited Chla to gold nanoparticles, although because of a small overlap between fluorescence of Chla and absorption of gold nanoparticles, the energy-transfer process cannot be ruled out. Photoinduced electron-transfer mechanism is supported by the electrochemical modulation of fluorescence of Chla. In absence of an applied bias, Chla cast on gold film, as a result of electron transfer, exhibits a very weak fluorescence. However, upon negatively charging the gold nanocore by external bias, an increase in fluorescence intensity is observed. The negatively charged gold nanoparticles create a barrier and suppress the electron-transfer process from excited Chla to gold nanoparticles, resulting in an increase in radiative process. Nanosecond laser flash experiments of Chla in the presence of gold nanoparticles and fullerene (C60) have demonstrated that Au nanoparticles, besides accepting electrons, can also mediate or shuttle electrons to another acceptor. Taking advantage of these properties of gold nanoparticles, a photoelectrochemical cell based on Chla and gold nanoparticles is constructed. A superior performance of this cell compared to that without the gold film is due to the beneficial role of gold nanoparticles in accepting and shuttling the photogenerated electrons in Chla to the collecting electrode, leading to an enhancement in charge separation efficiency. 相似文献
146.
Photovoltaic cells using composite nanoclusters of porphyrins and fullerenes with gold nanoparticles
Hasobe T Imahori H Kamat PV Ahn TK Kim SK Kim D Fujimoto A Hirakawa T Fukuzumi S 《Journal of the American Chemical Society》2005,127(4):1216-1228
Novel organic solar cells have been prepared using quaternary self-organization of porphyrin (donor) and fullerene (acceptor) units by clusterization with gold nanoparticles on nanostructured SnO2 electrodes. First, porphyrin-alkanethiolate monolayer-protected gold nanoparticles (H2PCnMPC: n is the number of methylene groups in the spacer) are prepared (secondary organization) starting from the primary component (porphyrin-alkanethiol). These porphyrin-modified gold nanoparticles form complexes with fullerene molecules (tertiary organization), and they are clusterized in acetonitrile/toluene mixed solvent (quaternary organization). The highly colored composite clusters can then be assembled as three-dimensional arrays onto nanostructured SnO2 films to afford the OTE/SnO2/(H2PCnMPC+C60)m electrode using an electrophoretic deposition method. The film of the composite clusters with gold nanoparticle exhibits an incident photon-to-photocurrent efficiency (IPCE) as high as 54% and broad photocurrent action spectra (up to 1000 nm). The power conversion efficiency of the OTE/SnO2/(H2PC15MPC+C60)m composite electrode reaches as high as 1.5%, which is 45 times higher than that of the reference system consisting of the both single components of porphyrin and fullerene. 相似文献
147.
Poly(p-phenylene sulfide) films coated on conducting SnO2 and Pt surfaces were found to attain p-type semiconducting properties on electrochemical cycling. Upon illumination of these films with visible light (λ < 500 nm) a photoelectrochemical effect was observed. The performance of a photoelectrochemical cell employing this polymer film coated electrode is discussed. 相似文献
148.
Ordered assembly of protonated porphyrin driven by single-wall carbon nanotubes. J- and H-aggregates to nanorods 总被引:1,自引:0,他引:1
Ordered assemblies of protonated porphyrin in the form of J- and H-type aggregates have been achieved on the single-wall carbon nanotube (SWCNTs) surface. This unusual molecular aggregation phenomenon driven by SWCNTs further enables macroscopic assembly in the form of linear bundles. 相似文献
149.
Hydroxyl radical reactions of selected chlorinated aromatic phenols (2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol) and chlorinated phenoxyacetic acids [2,4-dichlorophenoxyacetic acid (2,4-D), 2,4-D methyl ester, 2-(2,4-dichlorophenoxy)propionic acid (2,4-DP)] were studied using the radiolysis techniques of pulse radiolysis and gamma radiolysis. Hydroxyl radical addition was the prominent reaction pathway for the chlorinated phenoxyacetic acids and also for the chlorinated phenols at pH values below the pK(a) of the compounds. A very prominent change in (*)OH reactivity was observed with the chlorinated phenoxide ions in high pH solutions. Two different reaction pathways were clearly present between the hydroxyl radical and the chlorinated phenoxide ions. One of the reaction pathways was suppressed when the concentration of chlorinated phenoxide ions was increased 10-fold. Amid a greater electron-withdrawing presence on the aromatic ring (higher chlorinated phenoxide ions), the hydroxyl radical reacted preferably by way of addition to the aromatic ring. Steady-state experiments utilizing gamma radiolysis also showed a substantial decrease in oxidation with an increase in pH of substrate. 相似文献
150.
The mechanistic details of the hydroxyl radical-induced transformations of quinoline have been elucidated. The nature and distribution of the final products have provided insight into the preferential attack of the hydroxyl radicals at different sites on the aromatic rings. Hydroxylated products at all of the carbon atoms but one, C2, have been observed and quantified following controlled radiolysis of N2O-purged aqueous quinoline solutions. The difference in the growth pattern and the lifetime of the monohydroxylated products under radiolytic conditions, as well as the formation of high-molecular-weight products (e.g., quinoline dimers), shows the complexity of the OH reaction pathways. The radiolytic yields (G values) for the degradation of the quinoline and the formation of the hydroxylated products are calculated in the absence and in the presence of an oxidant, K3Fe(CN)6. The addition of K3Fe(CN)6 changes only the distribution of the hydroxylated products. These experiments indicate that the nature of the hydroxylated products is determined in the initial addition step of the reaction of the hydroxyl radical with quinoline, whereas the chemistry of the OH adducts is relevant to the distribution of the final products. The discrepancy between the products of -radiolysis and the photo-Fenton reaction of quinoline is also discussed. 相似文献