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121.
In this study, the photocatalytic dye degradation efficiency of KTi0.5Te1.5O6 synthesized through solid‐state method was enhanced by cation (Ag+/Sn+2) doping at potassium site via ion exchange method. As prepared materials were characterized by XRD, SEM‐EDS, IR, TGA and UV–Vis Diffuse reflectance spectroscopic (DRS) techniques. All the compounds were crystallized in cubic lattice with space group. The bandgap energies of parent, Ag+‐ and Sn+2‐doped KTi0.5Te1.5O6 materials obtained from DRS profiles were found to be 2.96, 2.55 and 2.40 eV, respectively. Photocatalytic efficiency of parent, Ag+‐ and Sn+2‐doped materials was evaluated against the degradation of methylene blue (MB) and methyl violet (MV) dyes under visible light irradiation. The Sn+2‐doped KTi0.5Te1.5O6 showed higher activity toward the degradation of both MB and MV dyes and its higher activity is ascribed to the lower bandgap energy compared to the parent and Ag+‐doped KTi0.5Te1.5O6. The mechanistic degradation pathway of methylene blue (MB) was studied in the presence of Sn2+‐doped KTi0.5Te1.5O6. Quenching experiments were performed to know the participation of holes, super oxide and hydroxyl radicals in the dye degradation process. The stability and reusability of the catalysts were studied.  相似文献   
122.
A series of N–thiocyanatoacetyl derivatives of 3–alkyl–2,6–diarylpiperidin–4–ones has been synthesized by the reaction between the N–chloroacetyl derivatives of the respective piperidin–4–ones and the ambident thiocyanate nucleophile. The synthesized compounds have been characterized through FT–IR, 1H, 13C, 1H–1H COSY, 1H–13C COSY and NOESY spectra. The spectral data reveal the conformational priority of the six-membered heterocyclic ring.  相似文献   
123.
Colorimetric detection of anions (HSO4? and CN?) was achieved via analyte triggered colour changing of the dipodal and tripodal sensors in CH3CN–H2O (1:1). The sensors exhibited very sharp visual colour changes and fluorescence quenching–enhancing effect upon addition of the HSO4? and CN?. The large downfield shift of the NH proton signals in 1H-NMR complexation studies and quantum chemical DFT calculations proved the formation of hydrogen-bonded complexes where no proton transfer mechanism was found.  相似文献   
124.
A solvent-free, eco-friendly and facile approach for the synthesis of highly functionalized tetrasubstituted pyrroles has been reported through one-pot four-component reaction of aldehyde, amine, nitroalkane and 1,3-diketone using silica gel supported polyphosphoric acid (PPA–SiO2) under microwave condition. The reaction occured through the in situ formation of β-keto enamine and nitrostyrene analog following Michael addition and finally intramolecular annulation affording the products in good yields. The key features of the present method include clean reaction, mild conditions, low catalyst loading, straightforward, high to excellent yields, short reaction time, avoiding use of harmful metal catalyst and organic solvent, environmentally friendly compared to the existing methods, recovery and reusability of catalyst and easy workup procedure.  相似文献   
125.
The optical response time of a nematic liquid crystal (NLC) decreases due to incorporation of carbon nanotubes (CNTs) in the liquid-crystal host. Such reduction is believed to be due to an increase in the elastic constant of the nanotube-doped LC system. In this paper, we present the effect on optical response due to doping an NLC with octadecylamine functionalised single-walled carbon nanotubes (ODA-SWCNT) in a twisted alignment mode. The electro-optic switching amplitude of ODA-SWCNT nanocomposites of NLC decreases compared to pure NLC. A fast response time is observed with an increase in the concentration of ODA-SWCNT in NLC host. Additionally, optical response of pure NLC in a twisted nematic (TN) cell fabricated using mixtures of polyimide (PI) and ODA-SWCNT as an alignment layer is investigated. The optical response time decreased by ~75% in a TN cell fabricated with a mixture of PI and ODA-SWCNT compared to that of a TN cell prepared using a pure PI alignment layer. The presence of ODA-SWCNT in the alignment layer enhances the surface anchoring of the NLC molecules leading to an increase in the elastic constant and a decrease in the optical response time of NLC.  相似文献   
126.
127.
In the Ni(II)–S(IV)–O2 system in the region of pH > 8.4, both Ni(II) and S(IV) are simultaneously autoxidized, and when sulfur is consumed fully NiOOH precipitates. At pH > 8.4, ethanol has no effect on the rate, whereas ammonia strongly inhibits the reaction when pH > 7.0. The kinetics of the reaction, in both the presence and the absence of ethanol, is defined by the rate law where k is the rate constant, KO is the equilibrium constant for the adsorption of O2 on ? Ni(OH)2 particle surface. In ammonia buffer, the factor F is defined by where K, KOH, K1, K2, K3, and K4 are the stability constants of NiSO3, NiOH+, Ni(NH3)2+, Ni(NH3), Ni(NH3), and Ni(NH3), respectively. In unbuffered medium, the factor F reduces to The values of k and Ksp were found to be (1.3 ± 0.08) × 10?1 s?1 and (4.2 ± 3.5) × 10?16, respectively, at 30°C. A nonradical mechanism that assumes the adsorption of both SO32? and O2 on the ? Ni(OH)2 particle surface has been proposed. At pH ≤ 8.2, Ni(II) displays no catalytic activity for sulfur(IV)‐autoxidation and it is also not oxidized to NiOOH. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 464–478, 2010  相似文献   
128.
Terbium ion doped MO–Al2O3 (M = Mg, Ca, Sr and Ba) series phosphors have been synthesized through combustion technique and their luminescence properties have been studied and compared. Terbium ion in different phosphors has shown different fluorescence properties due to the presence of different ratios of Tb3+ and Tb4+ states in different samples. The UV/Visible absorption and XPS techniques have been used to probe the existence of Tb3+ and Tb4+ states. The host sensitive 4f–5d and the charge transfer transitions enabled the use of terbium ion as an indicator of the structure.  相似文献   
129.
Measurement of densities ρ, viscosities η, and ultrasonic speeds u has been carried out for binary mixtures of N,N-diethylaniline (N,N-DEA) with acetophenone, cyclopentanone, cyclohexanone (CH), and 2-methylcyclohexanone (Me-CH) and their pure liquids at (303.15 and 308.15) K. These experimental data have been used to calculate the excess molar volume V E, deviation in ultrasonic velocity ?u, deviation in isentropic compressibility ?κ s , and deviation in viscosity ?η. The variation of these properties with composition of the mixtures suggests dipole–dipole interactions and charge-transfer complex formation between N,N-diethylaniline and dipolar ketones. The magnitude of the property is found to depend on the chain length of the ketones’ molecule. The viscosity data have been correlated using three equations: Grunberg and Nissan (Nature 164:799–800, 1949), Katti and Chaudhri (J Chem Eng Data 9:442–443, 1964), and Hind et al. (Trans Faraday Soc 56:328–330, 1960). These results have been fitted to the Redlich–Kister polynomial using multiparametric nonlinear regression analysis to estimate the binary coefficients and standard errors.  相似文献   
130.
Bis-β-cyclodextrin connected via ethylene diamine on the primary side of the β-cyclodextrin was synthesized and used for the supramolecular non-covalent inclusion complex with C60 in a mixed solvent system at room temperature. The apparent association constant of the 2:2 inclusion complex determined by combination of UV–Vis absorbance and Benesi–Hildebrand equation was found to be 1.78 × 106 M?1. The product obtained was highly water-soluble and superior in stability in aqueous medium as compared to previously known β-cyclodextrin/C60 complex. The non-covalent self-assembly of bis-β-cyclodextrin and C60 was characterized and confirmed from FT-IR, UV–Vis, XRD and TGA. The supramolecular aggregation behavior and particle size of the inclusion complex was found from transmission electron microscope and static light scattering measurements. The size of the inclusion complex was found to be ~30 ± 5 nm.  相似文献   
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