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排序方式: 共有145条查询结果,搜索用时 62 毫秒
1.
Ksenia Pumpor Elisabeth Windeisen Klaus Burger 《Journal of heterocyclic chemistry》2003,40(3):435-442
The synthesis of heterocyclic α‐mercapto acids starting from (RS)‐thiomalic acid using hexafluoroacetone as protecting and activating agent is described. The new compounds are useful building blocks for peptide and depsipeptide modification as well as for drug design. 相似文献
2.
L. A. Reznikova E. E. Morgunova A. D. Davydov 《Russian Journal of Electrochemistry》2002,38(6):659-662
The instability of the limiting current of the cathodic reaction is studied in the I–
3–I–/Pt system with excess of potassium iodide at the electrode situated at the bottom of a vertical cylindrical channel. Dependence of parameters of the oscillation process on the concentration of electroactive and supporting ions and solution viscosity is analyzed. The deceleration of the transport processes in solutions containing glycerol is shown to be due to a considerable decrease in the triiodide ion diffusion coefficient. 相似文献
3.
Ksenia Shilyaeva Nils Elander Evgeny Yarevsky 《International journal of quantum chemistry》2007,107(6):1301-1315
Peaks in collision cross sections are often interpreted as resonances. The complex dilation method, as well as other methods relying on analytic continuation of the scattering formalism, can be used to clarify whether these structures are true resonances in the sense that they are poles of the S‐matrix and the associated Green function. The performance of the Mittag–Leffler expansion and T‐matrix Green function expansion methods are formally and computationally compared. The two methods are applied to two model potentials. Eigenenergies, s‐wave residues, and cross sections are computed with both methods. The resonance contributions to the cross sections are further analyzed by removing the residue contributions from the Mittag–Leffler and Green function expansion sums, respectively. It is suggested that the contribution of a resonance to a cross section should be defined through its S‐matrix residue. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
4.
Electron ionization (EI) mass spectra of 46 compounds from several different compound classes were measured. Their molecular ion abundances were compared as obtained with 70‐eV EI, with low eV EI (such as 14 eV), and with EI mass spectra of vibrationally cold molecules in supersonic molecular beams (Cold EI). We further compared these mass spectra in their National Institute of Standards and Technology (NIST) library identification probabilities. We found that
- Low eV EI is not a soft ionization method, and it has little or no influence on the molecular ion relative abundances for large molecules and those with weak or no molecular ions.
- Low eV EI for compounds with abundant or dominant molecular ions in their 70 eV mass spectra results in the reduction of low mass fragment ions abundances thereby reducing their NIST library identification probabilities thus rarely justifies its use in real‐world applications.
- Cold EI significantly enhances the relative abundance of the molecular ions particularly for large compounds; yet, it retains the low mass fragment ions; hence, Cold EI mass spectra can be effectively identified by the NIST library.
- Different standard EI ion sources provide different 70 eV EI mass spectra. Among the Agilent technologies ion sources, the “Extractor” exhibits relatively abundant molecular ions compared with the “Inert” ion source, while the “High efficiency source” (HES) provides mass spectra with depleted molecular ions compared with the “Inert” ion source or NIST library mass spectra.
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7.
Eremina Julia A. Smirnova Ksenia S. Lider Elizaveta V. Klyushova Lyubov’ S. Sheven’ Dmitriy G. Potkin Vladimir I. 《Transition Metal Chemistry》2022,47(1):19-30
Transition Metal Chemistry - In this study, Ni(II) and Co(II) complexes [Co(H2O)2L2] (1), [Ni(H2O)2L2] (2), [Co(phen)L2] (3), [Ni(phen)L2]·2H2O·EtOH (4·2H2O), and... 相似文献
8.
We demonstrate the controlled preparation of Er‐ and Eu‐doped GaP‐oxide porous composites. The fabrication procedure entails the use of porous semiconductor templates and the impregnation of rare earth ions from a rare earth salt solution in alcohol and thermal treatment. The composites exhibit strong green and red emission that comes from finely dispersed ErPO4 and EuPO4 oxide submicron phases in the composite. These materials may prove useful in future generations of optoelectronic and photonic devices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
9.
Structure and properties of materials based on thiokol oligomer-containing photopolymer compositions
I. A. Novakov A. V. Nistratov V. I. Frolova V. A. Lukasik O. A. Reznikova E. N. Titova 《Polymer Science Series D》2009,2(4):199-203
The demonstrated perspectives of thiokols application for the creating photo-solidifying compositions. The chemical interaction
of a polymerizing component with polysulfide oligomer was found to be responsible for the substantial increase in viscosity
that made the shelf period rather short. A content of oligo thiol of up to 25 wt % significantly increased the degree of cross
linking for materials. Furthermore, the use of thiokol in photo-solidifying compositions allowed increasing of elasticity
and strength parameters of composites. 相似文献
10.
Denis A. Knyazkov Artëm M. Dmitriev Oleg P. Korobeinichev Ksenia N. Osipova Gianmaria Pio Andrey G. Shmakov Ernesto Salzano 《Proceedings of the Combustion Institute》2021,38(2):2467-2475
The knowledge of the combustion chemistry of oxygenated fuels is essential for the development of detailed kinetic mechanisms suitable for the combustion processes involving biofuels. Moreover, epoxidized olefins, are increasingly used as chemical intermediates or as bulk chemicals. Nevertheless, a dearth of data for their reactivity in the oxidative environment can be observed in the current literature. This study reports the experimental and the model characterization of the flame structure of propylene oxide at stoichiometric and fuel-rich conditions at atmospheric pressure. To this aim, the species mole fractions in three premixed flames stabilized on a flat-flame burner have been quantitatively measured by using the flame sampling molecular beam mass spectrometry. Three chemical kinetic mechanisms retrieved from the current literature involving propylene oxide chemistry have been validated against the novel experimental data. In general, the predictions appeared to be in satisfactory agreement with measurements except for acetaldehyde and ketene. The rate of production analysis in the flame has shown that the discrepancies observed for these species are related basically to the incorrect ratio between the rates of primary reaction pathways of propylene oxide destruction. 相似文献