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301.
David Nečas Daniel Franta Ivan Ohlídal Aleš Poruba Petr Wostrý 《Surface and interface analysis : SIA》2013,45(7):1188-1192
Variable‐angle spectroscopic ellipsometry is employed for the optical characterization of non‐stoichiometric silicon nitride thin films exhibiting inhomogeneity formed by refractive index and extinction index changes through the film thickness. For all the film samples, the best fit of the experimental data is achieved if, in addition to the inhomogeneity, an overlayer or roughness of the upper boundary is included. However, distinguishing of these two defects is found not to be possible. The influence of working gas ratio, deposition temperature and on/off time on the film properties is studied. The refractive index and extinction coefficient is found to increase with increasing working gas ratio and less significantly with decreasing deposition temperature. It is also found that the inhomogeneity increases with decreasing deposition temperature, and the deposition rate of the films decreases with increasing working gas ratio. The influence of the on/off time on the film properties is practically unimportant. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
302.
Aleš Marek Robert Pepin Bo Peng Kenneth J. Laszlo Matthew F. Bush František Tureček 《Journal of the American Society for Mass Spectrometry》2013,24(11):1641-1653
Gas-phase conformations and electron transfer dissociations of pentapeptide ions containing the photo-Leu residue (L*) were studied. Exhaustive conformational search including molecular dynamics force-field, semi-empirical, ab initio, and density functional theory calculations established that the photo-Leu residue did not alter the gas-phase conformations of (GL*GGK? + ?2H)2+ and (GL*GGK-NH2?+?H)+ ions, which showed the same conformer energy ranking as the unmodified Leu-containing ions. This finding is significant in that it simplifies conformational analysis of photo-labeled peptide ions. Electron transfer dissociation mass spectra of (GL*GGK? + ?2H)2+, (GL*GGK-NH2?+?2H)2+,(GL*GGKK?+?2H)2+, (GL*GLK?+?2H)2+, and (GL*LGK?+?2H)2+ showed 16 %–21 % fragment ions originating by radical rearrangements and cleavages in the diazirine ring. These side-chain dissociations resulted in eliminations of N2H3, N2H4, [N2H5], and [NH4O] neutral fragments and were particularly abundant in long-lived charge-reduced cation-radicals. Deuterium labeling established that the neutral hydrazine molecules mainly contained two exchangeable and two nonexchangeable hydrogen atoms from the peptide and underwent further H/D exchange in an ion–molecule complex. Electron structure calculations on the charge-reduced ions indicated that the unpaired electron was delocalized between the diazirine and amide π* electronic systems in the low electronic states of the cation-radicals. The diazirine moiety in GL*GGK-NH2was calculated to have an intrinsic electron affinity of 1.5 eV, which was further increased by the Coulomb effect of the peptide positive charge. Mechanisms are proposed for the unusual elimination of hydrazine from the photo-labeled peptide ions. Figure
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303.
304.
Praus P Kozák O Kočí K Panáček A Dvorský R 《Journal of colloid and interface science》2011,360(2):574-579
CdS nanoparticles were precipitated by the reaction of cadmium acetate with sodium sulphide in the presence of cetyltrimethylammonium (CTA) and deposited on montmorillonite (MMT). The resulting CdS-MMT nanocomposite contained 6 wt.% of CdS and 30 wt.% of CTA. Band-gap energy of CdS was estimated at 2.63±0.09 eV using the Tauc plot. The size of CdS nanoparticles was calculated from the band-gap energy at 5 nm and from the micrographs of transmission electron microscopy (TEM) at 5 nm. Selected area electron diffraction (SAED) recognized the cubic structure of CdS (Hawleite). The dynamic light scattering (DLS) method confirmed that CdS nanoparticles were anchored on the surface of MMT particles. CTA was found to be intercalated into MMT and adsorbed on its external surface. CdS-MMT was used for the photoreduction of carbon dioxide dissolved in NaOH solutions. The yields of originating gas products can be arranged in the order: H(2) ? CH(4) > CO. Amounts of these products were 4-8 folds higher then those obtained with TiO(2) Evonic P25. Hydrogen reduced CO(2) to CO and CH(4). 相似文献
305.
Mohan T Kargl R Doliška A Vesel A Köstler S Ribitsch V Stana-Kleinschek K 《Journal of colloid and interface science》2011,358(2):604-610
The wettability and surface free energy (SFE) of partly and fully regenerated cellulose model surfaces from spin coated trimethylsilyl cellulose were determined by static contact angle (SCA) measurements. In order to gain detailed insight into the desilylation reaction of the surfaces the results from SCA measurements were compared with data from other surface analytical methods, namely thickness measurements, X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance infrared spectroscopy (ATR-IR). Additionally, the influence of ultra high vacuum treatment (UHV) during XPS measurements on the water wettability and surface morphology of regenerated cellulose thin films was investigated. The wetting of polar and non-polar liquids increased with prolonged regeneration time, which is reflected in the higher SFE values and polarities of the films. After UHV treatment the water SCA of partly regenerated films decreases, whereas fully regenerated cellulose shows a higher water SCA. Therefore it is assumed that volatile desilylation products tend to adsorb on partly regenerated films, which strongly influences their wettability. 相似文献
306.
Marija Alešković Nikola Basarić Kata Mlinarić‐Majerski 《Journal of heterocyclic chemistry》2011,48(6):1329-1335
A facile three‐step synthesis of 2‐(2‐aminophenyl)pyrrole ( 1 ) and 2‐[(2‐aminomethyl)phenyl]pyrrole ( 2 ) is reported by use of Suzuki coupling of N‐Boc‐pyrrol‐2‐yl boronic acid ( 3 ) and o‐substituted aryl halogenides, followed by hydrogenation. The Pd‐catalyzed cross‐coupling reaction is optimized to be applicable to a wide range of substitued aryl halogenides, with electron‐donating and electron‐withdrawing substituents, 5a , 5b , 5c , 5d , 5e , 5f , 5g . Moreover, Pd‐catalyzed coupling of o‐bromoaniline and 3 could be applied for the one‐step preparation of pyrrolo[1,2‐c]quinazolin‐5(6H)‐one ( 8 ). J. Heterocyclic Chem., (2011). 相似文献
307.
308.
Ilya Kuselman Ilana Schumacher Francesca Pennecchi Cathy Burns Aleš Fajgelj Paolo de Zorzi 《Accreditation and quality assurance》2011,16(12):615-622
A metrological approach for investigating out-of-specification (OOS) test results in long-term stability study of drug products
was used. It is shown that OOS test results can indicate an actual change in a measured property of a product or be metrologically
related with a certain confidence probability, i.e., be caused by the measurement problems, while the product still meets
the quality requirements at the time of testing. As examples, results of testing sodium chloride injections in 500-mL plastic
containers and of epinephrine (l-adrenaline) injections in 1-mL ampoules were discussed. Regression analysis of the data was performed, as well as warning
and action lines for shelf life of the products calculated for relevant measurement uncertainties and confidence probabilities.
Producer’s and consumer’s risks of the established shelf life values were also estimated. 相似文献
309.
Photoabsorption spectra of clusters, N=5–9, have been calculated using a diatomics-in-molecules like electronic structure model and a path-integral Monte Carlo sampling method. A qualitative change in the calculated spectra has been observed at N=9, which has been interpreted in terms of a structural transformation in the clusters consisting in a transition from trimer-like ionic cores observed for N≤7 to dimer-like ionic cores prevailing in through an intermediate state (comparable abundances of both types of ionic cores) observed in . The calculated spectra have been thoroughly compared with an earlier calculation on , , and reported from our group and data available for the same cluster sizes from an experiment. 相似文献