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991.
A flow injection catechol biosensor based on tyrosinase entrapped in carbon nanotube modified polypyrrole biocomposite film on a glassy carbon surface has been developed. Amperometric response was measured as a function of concentration of catechol, at a fixed bias voltage of −50 mV at a flow rate of 1 mL/min. The proposed biosensor exhibited impressive analytical performance such as a linear range between 3 and 50 μM, a short response time (10 s), a detection limit of 0.671 μM and an excellent operational (with a relative standard deviation of 0.54%) and long-term stability (85% remained after 10th week). A comparison of the analytical parameters of the developed biosensor with polypyrrole/tyrosinase film electrode was performed in the study. CNT was shown to enhance the electron transfer between the electrode and enzyme and capable to carry higher bioactivity owing to its intensified surface area.  相似文献   
992.
In the previous paper, we report line strength measurements for 58 bands of 12CO2 between 4550 and 7000 cm−1 [R.A. Toth, L.R. Brown, C.E. Miller, V. Malathy Devi, D. Chris Benner, J. Mol. Spectrosc., this issue, doi:10.1016/j.jms.2006.008.001.]. In the present study, self-broadenedwidth and self-induced pressure shift coefficients are determined in two intervals:
(a) between 4750 and 5400 cm−1for bands of the Fermi triad (20011 ← 00001, 20012 ← 00001, 20013 ← 00001), three corresponding hot bands (21111 ← 01101, 21112 ← 01101, 21113 ← 01101) and the 01121← 00001 combination band;
(b) between 6100 and 7000 cm−1 for the Fermi tetrad (30014 ← 00001, 30013 ← 00001, 30012 ← 00001, 30011 ← 00001), two associated hot bands (31113 ← 01101, 31112 ← 01101), as well as 00031 ← 00001 and its hot band 01131 ← 01101.
Least-squares fits of the experimental width and pressure shift coefficients are modeled using empirical expressions:
  相似文献   
993.
A simple approach is proposed for the synthesis of cobalt hexacyanoferrate nanoparticles (CoNPs) with uniform shape and size controlled by ethylene diamine tetraacetic acid (EDTA) as a stabilizer. A sensitive amperometric biosensor for insulin has been prepared using glassy carbon electrodes by solubilization of carbon nanotubes (CNTs) in chitosan (CHIT) together with CoNPs synthesized by the new methodology. The CoNP-CNT-CHIT organic–inorganic system exerts a synergistic effect, resulting in the remarkably enhanced insulin currents owing to the superior electron-transfer ability of CNTs and the excellent reversible redox centers of CoNPs. High-resolution transmission electron microscopy (HRTEM) was used to provide closer inspection of the CoNPs. The effects of alkali metal cations and the concentrations of CNTs and CoNPs on the voltammetric behavior of the film-modified electrode were also investigated. In pH 6.98 phosphate buffer (PB) at +0.7 V (vs. SCE) the insulin biosensor exhibits a linear response range of 0.1–3 μM with a correlation coefficient of 0.98, and the detection limit (S/N=3) is determined to be 40 nM, the stability of the biosensor was tested and found satisfactory. There is great promise for in vivo measurements of this important hormone.  相似文献   
994.
A method has been developed for rapidly separating and detecting strychnine and brucine using a poly(dimethysiloxane) (PDMS) microchip and electrochemical (EC) detection. PDMS microchannels dynamically modified by Brij35 are shown to be more efficient than native ones. The two analytes are well separated within 90 s in 70 mmol/L acetate buffer (pH 5.5) containing 0.01% (v/v) Brij35. Detection limits were found to be 1.0 μmol/L for strychnine and 0.2 μmol/L for brucine at S/N=3. The method was used to determine trace strychnine and brucine in rat serum, and the results obtained correlate well with those obtained via high-performance liquid chromatography (HPLC).   相似文献   
995.
The magnetic behaviors of ferromagnetic single-walled nanotubes are systematically investigated by use of the many-body Green's function method of quantum statistical theory. The spontaneous magnetization, absolute value of ferromagnetic energy, area of hysteresis loop and coercivity increase with diameter of the tubes and spin quantum number, and decrease with temperature. Curie temperature increases with diameter and spin quantum number. As the diameter of the tube tends to infinity, all the numerical results approach to those of a two-dimensional monolayer. The dependences of initial susceptibility on temperature and diameter below and above Curie point are contrary. The calculated results are compared with experimental results where possible, and are qualitatively in agreement with the latter. The Curie temperature is determined by the tube diameter and independent of rolling helicities.  相似文献   
996.
The emission spectra of the A2П-X2Σ+ (red) system of 12C14N have been reinvestigated in the 3500-22 000 cm−1 region at high resolution using a Fourier transform spectrometer. In total, spectra of 63 bands involving vibrational levels up to v′ = 22 of the A2П state and v″ = 12 of the X2Σ+ ground state have been measured and rotationally analyzed providing an improved set of spectroscopic constants. The present measurements of the Δv = −2 sequence bands of 12C14N and those of 13C14N from Ram et al. (2010) [36] allow for a much improved identification of these two isotopologues in the near infrared spectra of carbon stars.  相似文献   
997.
In a previous contribution [Kassi S, Song KF, Campargue A. High sensitivity CW-cavity ring down spectroscopy of 12CO2 near 1.35 μm (I): line positions. JQSRT 110 (2009) 1801-1814], the line positions analysis of the high sensitivity absorption spectrum of carbon dioxide has been reported in the 7123-7793 cm−1 region. In this second contribution, the spectral region investigated by CW-cavity ring down spectroscopy has been extended up to 7917 cm−1. It added about 400 lines to our previous list of about 2500 transitions. These additional lines include transitions belonging to six newly observed 12C16O2 bands for which we provide the spectroscopic parameters. Over the whole 7123-7917 cm−1 region, the accurate intensities of about 2900 lines belonging to four isotopologues (12C16O2, 13C16O2, 16O12C18O and 16O12C17O) were retrieved with an average accuracy of 3%. Intensity values range between 1.2×10−29 and 4.1×10−25 cm/mol. Compared to the present version of the carbon dioxide spectroscopic databank recently adopted for the HITRAN database, important deviations were evidenced for some weak bands of the main isotopologue. The CW-CRDS intensity data relative to a total of 46 12C16O2 bands together with selected intensity information available in the literature for nine bands have been fitted simultaneously using the effective operators approach. The ΔP=11 set of the 12C16O2 effective dipole moment parameters has been refined leading to a much better agreement with the measured intensity values. In addition, the ΔP=10 effective dipole moment parameters of the 16O12C18O minor isotopologue were determined for the first time. The obtained results will help to improve the carbon dioxide spectroscopic databank (CDSD).  相似文献   
998.
Development and application of a database for the Spectral-Line Moment-Based (SLMB) modeling of the full spectrum radiative properties of mixtures of carbon dioxide and nitrogen is presented. The critical issue of the definition of a reference thermophysical condition is addressed together with the suggestion of a coherent and precise methodology to derive parameters of the model for any other configuration. The database is built accordingly from the CDSD-1000 high temperature spectroscopic databank for gas and blackbody-weighting temperatures in the range [300; 2700 K]. Accuracy of both the modeling and the database is assessed through comparisons with LBL results in terms of full spectrum k-distributions and emission functions. Results obtained from the application of FSK correlations and the Leckner's formula are also provided for extended analyses.  相似文献   
999.
The adsorption of carbon monoxide is studied on Au/Pd(1 0 0) alloys by means of reflection-absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD). The alloy was formed by adsorbing a four-monolayer thick gold film on a Pd(1 0 0) substrate and by heating to various temperatures to form alloys with a range of palladium coverages. The alloy was characterized using X-ray photoelectron spectroscopy and the composition of the outermost layer measured using low-energy ion scattering spectroscopy. CO adsorbs on palladium bridge sites only for palladium coverages greater than 0.5 monolayers (ML) suggesting that next-nearest neighbor sites are preferentially populated by palladium atoms. CO adsorbs on atop palladium sites and desorbs at ∼350 K corresponding to a desorption activation energy of ∼117 kJ/mol. However, at lower palladium coverages, these sites are not occupied and CO desorption states are detected 170 and 112 K corresponding to desorption activation energies of ∼53 kJ/mol and ∼35 kJ/mol, respectively, for these states. It is suggested that these states are due to a restructuring of the surface to form low-coordination gold sites that obscure the atop palladium site.  相似文献   
1000.
Thorn-like, organometallic-functionalized carbon nanotubes were successfully developed via a novel microwave hydrothermal route. The organometallic complex with methyl orange and iron (III) chloride served as reactive seed template, resulting in the oriented polymerization of pyrrole on the modified carbon nanotubes without the assistance of other oxidants. Morphological and structural characterizations of the carbon nanotube/methyl orange-iron (III) chloride and polypyrrole/carbon nanotube composites were examined using transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), infrared spectroscopy and X-ray diffraction (XRD). The electrochemical property of the polypyrrole/carbon nanotube composite was elucidated by cyclic voltammetry and galvanostatic charge-discharge. A specific capacitance of 304 F g−1 was obtained within the potential range of −0.5-0.5 V in 1 M KCl solution.  相似文献   
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