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991.
Tae-Yeon Cho Kwan-Woo Ko Soon-Gil Yoon Satpal Singh Sekhon Man Gu Kang Young-Sik Hong Chi-Hwan Han 《Current Applied Physics》2013,13(7):1391-1396
We investigated the effect of a Nb2O5 blocking layer formed through the sol–gel method introduced to a titanium metal foil electrode in a flexible dye sensitized solar cell. The blocking layer formed directly on the working electrode physically separates the working electrode from the electrolyte, and prevents back transfer of electrons from the electrode to the electrolyte. The gel processing conditions (sol reaction time) and heat treatment temperature used in formation of the Nb2O5 blocking layer have been shown to affect the performance of the dye sensitized solar cell and optimal values of these parameters have been determined. A sol reaction time of 45 min and heat treatment temperature of 550 °C has been observed to result in optimal cell performance (η = 6.185%, Jsc = 13.233 mA/cm2, Voc = 0.672 V, ff = 0.694). Introduction of an Nb2O5 blocking layer enhances solar cell efficiency by 39.7%, which is much greater than the increase of 24.6% observed in a similar cell containing a TiO2 blocking layer under standard illumination conditions. The results obtained via Nb2O5 have been observed to be superior to those obtained via a TiO2 blocking layer. 相似文献
992.
Min-Seok Jeong Jae Hyun Kim Jae-Hyeon Ko Young Ho Ko Kwang Joo Kim 《Current Applied Physics》2013,13(8):1774-1777
The pressure dependences of the longitudinal sound velocity and the refractive index of amorphous Kel F-800 copolymer were investigated for pressures up to 13 GPa using high-pressure Brillouin spectroscopy combined with a diamond-anvil-cell technique. The sound velocity increased rapidly with increasing pressure at pressures below ~2 GPa, whereas it showed a mild change at higher pressure values. This was attributed to substantial collapse of effective free volume in this amorphous material. The refractive index could be measured by comparing the Brillouin spectra measured from backward and forward, symmetric scattering geometries. The pressure–density relationship could be obtained by using Lorentz–Lorenz equation based on an assumption of constant polarizability, which was consistent with that reported by previous study. 相似文献
993.
Two amino acid derived synthons were combined to give homopropargylic amines 2. Platinum dichloride was used to cyclize these intermediates into pyrroles 3 which collapsed to the target secondary structure mimics 1 on treatment with base. Side chains of these compounds overlay with an idealized type 1 β-turn and with an inverse γ-turn. 相似文献
994.
Frančič N Košak A Lyagin I Efremenko EN Lobnik A 《Analytical and bioanalytical chemistry》2011,401(8):2631-2638
In this work, we report on the development of a bio-sensing film for the detection of organophosphorous compounds using sol–gel
technology. A novel sol–gel immobilization method employing tetraethoxysilane/3-glycidoxypropyltrimethoxysilane/water hybrid
material was developed and used to immobilize the hexahistidine-tagged organophosphorous hydrolase enzyme (His6-OPH). Bio-sensing layers with encapsulated His6-OPH of various structures (water/silane, precursor ratios) have been prepared. The optimal (P = 5:1, R = 188) bio-sensing layers retained 90% of the initial enzyme activity. Furthermore, the bio-sensing layer prepared by this
method was able to maintain its activity at or above 80% of its initial activity for 2 weeks. The bio-hybrid film also showed
excellent reusability and improved activity at neutral pH in comparison to the same enzyme in solution. 相似文献
995.
Dye-doped silica nanoparticles (C dots) were synthesized in reverse microemulsions and used to quantitatively examine DNA cleavage in the presence of transition metal ions. The cores were synthesized as fluorescein isothiocyanate (FITC)-doped silica nanoparticles and the shells' surfaces were modified with single-stranded DNA oligomers tagged with Cy5 fluorophores. DNA cleavage induced by heavy metal ions was estimated by comparing the fluorescence of Cy5 before and after reaction with metal ions. For this, a lab-built laser-induced fluorescence microscope equipped with a charge coupled device (CCD) camera, for imaging, and photomultiplier tube, for photon counting, was used. FITC fluorescence from the core was measured as an internal standard to compensate for possible loss of the beads during the treatment. The cleavage of DNA in air in the presence of Pb(2+), Cd(2+), and Hg(2+) at 1 ng/mL was found to be 14%, 6%, and 20%, respectively, and was significantly reduced to below 9% under N(2) gas, indicating that the main cleavage source was oxygen in air. The most significant DNA cleavage was observed with the addition of hydrogen peroxide. This analytical method using dye-doped C dots provided convenient handling and quantification of the estimation of metal-DNA interaction with a detection limit of 34.9 pmol/mL. 相似文献
996.
997.
Automatic white blood cell segmentation using stepwise merging rules and gradient vector flow snake 总被引:1,自引:0,他引:1
This study aims at proposing a new stained WBC (white blood cell) image segmentation method using stepwise merging rules based on mean-shift clustering and boundary removal rules with a GVF (gradient vector flow) snake. This paper proposes two different schemes for segmenting the nuclei and cytoplasm of WBCs, respectively. For nuclei segmentation, a probability map is created using a probability density function estimated from samples of WBC's nuclei and sub-images cropped to include a nucleus based on the fact that nuclei have a salient color against the background and red blood cells. Mean-shift clustering is then performed for region segmentation, and a stepwise merging scheme applied to merge particle clusters with a nucleus. Meanwhile, for cytoplasm segmentation, morphological opening is applied to a green image to boost the intensity of the granules and canny edges detected within the sub-image. The boundary edges and noise edges are then removed using removal rules, while a GVF snake is forced to deform to the cytoplasm boundary edges. When evaluated using five different types of stained WBC, the proposed algorithm produced accurate segmentation results for most WBC types. 相似文献
998.
CO(2) emissions, from fossil-fuel-burning power plants, the breathing, etc., influence the global worming on large scale and the man's work efficiency on small scale. The reversible capture of CO(2) is a prominent feature of CO(2) organic-inorganic hybrid adsorbent to sequester CO(2). Herein, (3-aminopropyl) trimethoxysilane (APTMS), [3-(methylamino)propyl] trimethoxysilane (MAPTMS), and [3-(diethylamino) propyl] trimethoxysilane (DEAPTMS) are immobilized on highly ordered mesoporous silicas (SBA-15) to catch CO(2) as primary, secondary, and tertiary aminosilica adsorbents. X-ray photoelectron spectroscopy was used to analyze the immobilized APTMS, MAPTMS, and DEAPTMS on the SBA-15. We report an interesting discovery that the CO(2) adsorption and desorption on the adsorbent depend on the amine type of the aminosilica adsorbent. The adsorbed CO(2) was easily desorbed from the adsorbent with the low energy consumption in the order of tertiary, secondary, and primary amino-adsorbents while the adsorption amount and the bonding-affinity increased in the reverse order. The effectiveness of amino-functionalized (1(o), 2(o), and 3(o) amines) SBA-15s as a CO(2) capturing agent was investigated in terms of adsorption capacity, adsorption-desorption kinetics, and thermodynamics. This work demonstrates apt amine types to catch CO(2) and regenerate the adsorbent, which may open new avenues to designing "CO(2) basket". 相似文献
999.
The possibility of comparing inkjet printing inks by micellar electrokinetic capillary electrophoresis (MECC) with diode array detection was studied. An analytical procedure was designed and successfully applied to discriminate between the electrophoretic profiles of inks (extracted from paper) produced by five well-known manufacturers. The separation process was conducted in a polyimide-coated fused silica capillary (ID 50 μm, 60 cm total/50 cm effective length) with +30 kV high voltage applied. Background electrolyte was used of the following optimum composition: 40 mM sodium borate buffer, 20 mM sodium dodecyl sulphate(IV) (SDS) and 10% (v/v) acetonitrile (pH 9.56). The experimental conditions were adjusted in terms of resolution and analysis time. The best results were obtained at 10 and 25 °C storage and capillary temperature, respectively, using 25 dots (ø 0.8 mm) cut from printouts as the sample and BGE diluted with water (1:99, v/v) as the injecting solution. The MECC separation of main printing ink components by the proposed method showed excellent precision - the RSD value of the migration time calculated for each of the investigated peaks did not exceed 3.3%. The optimized method was applied to group identification and differentiation of: (a) three colours of printing inks, (b) inks from different manufacturers (Hewlett-Packard, Epson, Brother, Lexmark and Canon) and (c) inks from different printer models. In all these cases, inks were successfully differentiated on the basis of position (migration time) and shape of their characteristic peaks. 相似文献
1000.
An automatic sequential injection system, combining monosegmented flow analysis, sequential injection analysis and sequential injection titration is proposed for acidity determination. The system enables controllable sample dilution and generation of standards of required concentration in a monosegmented sequential injection manner, sequential injection titration of the prepared solutions, data collecting, and handling. It has been tested on spectrophotometric determination of acetic, citric and phosphoric acids with sodium hydroxide used as a titrant and phenolphthalein or thymolphthalein (in the case of phosphoric acid determination) as indicators. Accuracy better than |4.4|% (RE) and repeatability better than 2.9% (RSD) have been obtained. It has been applied to the determination of total acidity in vinegars and various soft drinks. The system provides low sample (less than 0.3 mL) consumption. On average, analysis of a sample takes several minutes. 相似文献