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991.
Sb doped sol-gel SnO2 single layers (thickness 100 nm) were prepared from alcoholic solution and deposited via a dip coating process on fused silica substrates. The coatings have been sintered at a typical rate of 10–15 cm2/s by CO2 laser irradiation. The laser spot was scanned in one direction at a speed of 15,000 cm/s and the sample was moved in a perpendicular one at a speed up to 250 mm/s. The temperature of the topmost 10 m layer was monitored by a fast pyrometer (s resolution). The following properties of the coatings have been determined: the electrical resistivity , the carrier density n, and mobility , the structure, the thickness, the mesoscopic and micromorphology and the density. The sintering by CO2 laser radiation is mainly a thermal driven process. At T 500°C it allows to obtain coatings with a smaller resistivity (6.8×10–3 cm) than those produced by conventional furnace firing (el2.9×10–2 cm). The results are discussed in terms of particle size and packing density. 相似文献
992.
Trevor J. Davies Craig E. Banks Richard G. Compton 《Journal of Solid State Electrochemistry》2005,9(12):797-808
Recent advances are overviewed which enable simulation of the voltammetric behaviour of surfaces which respond in an electrochemically
spatially heterogeneous fashion. By use of the concept of a “diffusion domain” computationally expensive three-dimensional
simulations may be reduced to tractable two-dimensional equivalents. In this way the electrochemical response of partially
blocked electrodes and microelectrode arrays may be predicted, and are found to be consistent with experimental data. It is,
furthermore, possible to adapt the “blocked” electrode analysis to enable the voltammetric sizing of inert particles present
on an electrode surface. Finally theory of this type predicts the voltammetric behaviour of electrochemically heterogeneous
electrodes—for example composites whose different spatial zones display contrasting electrochemical behaviour toward the same
redox couple. 相似文献
993.
A novel calix[4]arene derivative containing benzothiazole group was coated on glassy carbon electrode (GCE) and then applied to the recognition of mercury ion. Cyclic and square wave voltammetric results showed that the modified electrode selectively recognizes Hg2+ ion in aqueous media. A new anodic stripping peak at −0.3 V (vs. Ag/Ag+) can be obtained by scanning the potential from −0.6 to 0.6 V, and the peak currents are proportional to the Hg2+ concentration. The modified electrode in a 0.1 M H2SO4+0.01 M NaCl solution shows linear voltammetric response in the range of 25-300 μg l−1 and detection limit of 5 μg l−1 (ca. 2.5×10−8 M). This modified GCE does not present any significant interference from alkali, alkaline and transition metal ions except for Pb2+, Ag+ and Cu2+ ions. Only 500, 50 and 100-fold molar excess of Pb2+, Ag+ and Cu2+ ions, respectively, can lead to voltammetric response comparable with that of Hg2+. The proposed method was successfully applied to determine mercury in natural water. 相似文献
994.
《Electroanalysis》2003,15(2):97-102
The oxidation of dimethyl sulfoxide (DMSO) to dimethyl sulfone (DMSO2) is representative of numerous anodic oxygen‐transfer reactions of organosulfur compounds that suffer from slow kinetics at noble metal electrodes. Anodic voltammetric data for DMSO are examined at various RuO2‐film electrodes prepared by thermal deposition on titanium substrates. The response for DMSO is slightly larger at RuO2 films prepared in a flame as compared with films prepared in a furnace; however, temperature is more easily controlled in the furnace. Doping of the RuO2 films with Fe(III) further improves the sensitivity of anodic response for DMSO. Optimal response is obtained at an Fe(III)‐doped RuO2‐film electrode prepared using a deposition solution of 50 mM RuCl3 and 10 mM FeCl3 in a 1 : 1 mixture of isopropanol and 12 M HCl at an annealing temperature of 450 °C. The Levich plot (i vs. ω1/2) and Koutecky‐Levich plot (1/i vs. 1/ω1/2) of amperometric data for the oxidation of DMSO at an Fe(III)‐doped RuO2‐film electrode configured as a rotated disk are consistent with an anodic response controlled by mass‐transport processes at low rotational velocities. Flow injection data demonstrate that Fe(III)‐doped RuO2‐film electrodes exhibit detection capability for methionine and cysteine in addition to DMSO. Detection limits for 100‐μL injections of the three compounds are ca. 3.2×10?4 mM, i.e., ca. 32 pmol. 相似文献
995.
Sung-Ho Jin Hyun-Nam Cho Sam-Kwon Choi 《Journal of polymer science. Part A, Polymer chemistry》1993,31(1):69-74
The polymerization of dipropargyl isopropylidene malonate (DPIPM) was polymerized by WCl6 and MoCl5 associated with various organometallic cocatalysts. MoCl5 was found to be the most effective catalyst and Ph4Sn was observed to have a high cocatalyst activity. Structure and physical properties of poly(DPIPM) were investigated. The spectral data indicated that poly(DPIPM) contains alternating double and single bonds along the polymer backbone and a cyclic recurring unit. The poly(DPIPM) was partially soluble in common organic solvents. The M?n values of the polymer from soluble fraction were in the range of 5100–8000 relative to polystyrene standards by GPC. In addition, poly(DPIPM) possesses good stability to air oxidition. When poly(DPIPM) is exposed to iodine vapor, the electrical conductivity was increased from 4.5 × 10?11 to 7 × 10?2 S/cm. © 1993 John Wiley & Sons, Inc. 相似文献
996.
《Electroanalysis》2004,16(4):275-281
An investigation into the hemo‐biocompatibility of calix[4]resorcinarenetetrathiol and calix‐PEG derivative coatings on gold electrodes is reported, with respect to the detection of the ascorbate ion in aqueous solution. The electrochemical behavior of the ascorbate ion at calix‐modified electrodes is also discussed. Findings show that a facilitated adsorption of ascorbate from solution is seen at calix‐modified gold electrodes. Following exposure to whole human blood, calix‐PEG derivative coatings were seen to offer some protection against both outer‐surface biofouling and electrode passivation effects in comparison to calix[4]resorcinarenetetrathiol counterparts. The individual effects of outer surface biofouling and electrode passivation on exposure to whole blood have been investigated. Our findings suggest that PEG moieties help prevent sorption of the biofouling film, thus possibly minimizing the release of a number of low molecular weight solutes which are thought to be involved with the passivation of electrode responses within clinical bio‐ and chemical sensors. 相似文献
997.
Ahmed Galal 《Journal of Solid State Electrochemistry》1998,2(1):7-15
Conducting poly(3-methylthiophene) electrodes were electrochemically prepared. The resulting polymer films were modified
with an inorganic complex, ferrocene. The incorporation of the ferrocene/ferrocenium moiety into the polymer film resulted
in enhanced charge transfer towards the oxidation of some organic molecules of biological interest. The electrochemical response
of the complex-containing polymer electrode was compared to that of the unmodified polymer electrode and that of the substrate.
Apparent diffusion coefficients of the redox species were estimated from the cyclic voltammetric data for different biological
molecules at the ferrocene-containing polymer electrode. Infra-red spectroscopic measurements for the “as-grown” films revealed
the presence of the inorganic complex within the polymer. The modified polymer electrode showed noticeable enhancement for
the charge transfer across the film interface and can be used as an electrochemical sensor for biological compounds.
Received: 3 June 1997 / Accepted: 7 July 1997 相似文献
998.
Mazloum Ardakani M Jalayer M Naeimi H Zare HR Moradi L 《Analytical and bioanalytical chemistry》2005,381(6):1186-1192
A potentiometric ion-selective electrode based on new compound, as a carrier, has been successfully developed for detection of perchlorate anion in aqueous solution. Within the perchlorate ion concentration range 1.0×10–6 to 1.0 mol L–1 the electrode had a linear response with a Nernstian slope of 60.6±1.0 mV per decade . The limit of detection as determined from the intersection of the extrapolated linear segments of the calibration plot was 8.0×10–7 mol L–1. The proposed electrode has fairly a good discriminating ability towards ClO4– ion in comparison to other anions. The sensor has a response time of 10 s and can be used for at least 2 months without substantial divergence in potential. It was successfully applied to direct determination of perchlorate in urine and water. 相似文献
999.
《Electroanalysis》2005,17(1):54-58
A disposable biosensor based on acetylcholinesterase‐functionalized acid purified multi‐wall carbon nanotubes (CNTs) modified thick film strip electrode for organophosphorus (OP) insecticides was developed. The degree of inhibition of the enzyme acteylcholinesterase (AChE) by OP compounds was determined by measuring the electrooxidation current of the thiocholine generated by the AChE catalyzed hydrolysis of acteylthiocholine (ATCh). The large surface area and electro‐catalytic activity of carbon nanotubes lowered the overpotential for thiocholine oxidation to 200 mV (vs. Ag/AgCl) without the use of mediating redox species and enzyme immobilization by physical adsorption. The biosensor detected as low as 0.5 nM (0.145 ppb) of the model organophosphate nerve agent paraoxon with good precision, electrode to electrode reproducibility and stability. Analysis of real water sample using the sensor demonstrated the feasibility of the application of the sensor for on site monitoring of OP compounds. 相似文献
1000.
《Electroanalysis》2005,17(4):319-326
Thallium hexacyanoferrate films have been prepared from various aqueous electrolyte solutions using consecutive cyclic voltammetry. The cyclic voltammograms recorded the direct deposition of thallium hexacyanoferrate films from the mixing of Tl3+ and [Fe(CN)6]3? ions from solutions of seven cations: Li+, Na+, K+, Rb+, Cs+, H+, and Tl+. An electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry were used to study the in situ growth of the thallium hexacyanoferrate films. The thallium hexacyanoferrate film shows a single redox couple with a formal potential between +0.6 V and +1.2 V, and shows a cation effect (H+, Li+, Na+, K+, Rb+, Cs+, and Tl+). A mixed film and a two‐layered modified electrodes composed of a thallium hexacyanoferrate film with cobalt(II) hexacyanoferrate film were prepared. 相似文献