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991.
992.
Modelling of the impedimetric responses of an aflatoxin B1 immunosensor prepared on an electrosynthetic polyaniline platform 总被引:1,自引:0,他引:1
Owino JH Ignaszak A Al-Ahmed A Baker PG Alemu H Ngila JC Iwuoha EI 《Analytical and bioanalytical chemistry》2007,388(5-6):1069-1074
Aflatoxins are a group of mycotoxins that have deleterious effects on humans and are produced during fungal infection of plants
or plant products. An electrochemical immunosensor for the determination of aflatoxin B1 (AFB1) was developed with AFB1antibody (AFB1-Ab) immobilized on Pt electrodes modified with polyaniline (PANi) and polystyrene sulphonic acid (PSSA). Impedimetric analysis
shows that the electron transfer resistances of the Pt/PANi–PSSA electrode, the Pt/PANi–PSSA/AFB1-Ab immunosensor and Pt/PANi–PSSA/AFB1-Ab incubated in bovine serum albumin (BSA) were 0.458, 720 and 1,066 kΩ, respectively. These results indicate that electrochemical
impedance spectroscopy (EIS) is a suitable method for monitoring the change in electron transfer resistance associated with
the immobilization of the antibody. Modelling of EIS data gave equivalent circuits which showed that the electron transfer
resistance increased from 0.458 kΩ for the Pt/PANi–PSSA electrode to 1,066 kΩ for the Pt/PANi–PSSA/AFB1-Ab immunosensor, indicating that immobilization of the antibody and incubation in BSA introduced an electron transfer barrier.
The AFB1 immunosensor had a detection limit of 0.1 mg/L and a sensitivity of 869.6 kΩ L/mg. 相似文献
993.
994.
Azadani AN Lopez JM Hirsa AH 《Langmuir : the ACS journal of surfaces and colloids》2007,23(10):5227-5230
We have observed 2D protein crystallization under conditions where in the absence of flow, crystallization fails to occur. Even under conditions where crystallization does occur in quiescent systems, we have found that flow can accelerate the crystallization process. By interrogating the flow responsible for this enhanced crystallization, we have correlated the enhancement with large shear in the plane of the interface. Some possible mechanisms for why interfacial shear can enhance the crystallization process are proposed. 相似文献
995.
Benchmark total atomization energies (TAE0 values) were obtained, by means of our recent W4 theory [Karton, A.; Rabinowitz, E.; Martin, J. M. L.; Ruscic, B. J. Chem. Phys. 2006, 125, 144108], for the molecules Be2, BeF2, BeCl2, BH, BF, BH3, BHF2, B2H6, BF3, AlF, AlF3, AlCl3, SiH4, Si2H6, and SiF4. We were then able to deduce "semi-experimental" heats of formation for the elements beryllium, boron, aluminum, and silicon by combining the calculated TAE0 values with experimental heats of formation obtained from reactions that do not involve the species Be(g), B(g), Al(g), and Si(g). The elemental heats of formation are fundamental thermochemical quantities that are required whenever a molecular heat of formation has to be derived from a calculated binding energy. Our recommended DeltaH degrees f,0 [A(g)] values are Be 76.4+/-0.6 kcal/mol, B 135.1+/-0.2 kcal/mol, Al 80.2+/-0.4 kcal/mol, and Si 107.2+/-0.2 kcal/mol. (The corresponding values at 298.15 K are 77.4, 136.3, 80.8, and 108.2 kcal/mol, respectively.) The Be value is identical to the CODATA recommendation (but with half of the uncertainty), while the B, Al, and Si values represent substantial revisions from established earlier reference data. The revised B and Si values are in agreement with earlier semi-ab initio derivations but carry much smaller uncertainties. 相似文献
996.
997.
998.
[reaction: see text]. A proline-based N-oxide is identified that serves as an effective catalyst for the reaction of allyltrichlorosilane with aryl and alpha,beta-unsaturated aldehydes at room temperature to afford the desired homoallylic alcohols in up to 92% ee. The chiral catalyst can be easily prepared from optically pure proline in three simple steps and 60% overall yield. 相似文献
999.
A general approach is introduced to calculate field emission properties of any kind of nanostructure based on the first-principles local density of states (LDOS) and effective potentials. The experimental field emission spectroscopy images are explained as LDOS at the structure-vacuum barrier, weighted by the probability of electron tunneling. The method excellently reproduces the experimental field emission patterns of pristine capped carbon nanotubes. We show that cesium adsorbates even with a low doping ratio of one dopant per nanotube increase the emission current around 2.5 times, due to a generated dipole field. 相似文献
1000.
Inscription of optical waveguides in crystalline silicon by mid-infrared femtosecond laser pulses 总被引:1,自引:0,他引:1
Nejadmalayeri AH Herman PR Burghoff J Will M Nolte S Tünnermann A 《Optics letters》2005,30(9):964-966
For the first time to the authors' knowledge, optical waveguides have been inscribed in bulk crystalline silicon by ultrafast laser radiation. Femtosecond laser pulses of 40-nm spectral bandwidth, 1-kHz repetition rate, and 1.7-microJ on-target energy were applied at a mid-infrared wavelength of 2.4 microm to induce nonlinear absorption in the focal volume of the beam. By scanning the laser beam with respect to the sample, buried optical waveguides have been created that were single mode at 1550 and 1320 nm and guided light only with its polarization perpendicular to the sample's surface. Propagation losses with an upper limit of 1.2 dB/cm or less were observed throughout the optical telecommunications band. 相似文献