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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
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Eugen Jóna Marian Koman Anton Sirota 《Journal of inclusion phenomena and macrocyclic chemistry》1998,30(1):1-12
The stoichiometry and spectral properties of [Ni(4-Etpy)4(NCS)2]nG clathrates have been studied where n = 2 for G = 1-BrN (N = naphthalene), n = 1 or 2 for G = 1-MeN, and n = 0.5 for 2-MeN and 2-BrN. The complexes under study show electronic absorption spectra typical of an octahedral environment of the Ni(II) central atom. The differences found in IR spectra for the (CN) and (Ni–-NNCS) vibrations are discussed. The crystal structure of [Ni(4-Etpy)4(NCS)2]1-MeN was determined by X-ray diffraction and refined to R = 0.0586. Discrete non-centrosymmetric [Ni(4-Etpy)4(NCS)2] molecules form layers of a host structure and the space between the layers is occupied by 1-MeN. The relationship between interatomic distances in the host complex of similar clathrates are discussed. 相似文献
4.
Jóna E. Kubranová M. Sirota A. Šimon P. 《Journal of Thermal Analysis and Calorimetry》1998,52(2):373-382
The stoichiometry of thermal decomposition and enthalpy and structural changes were studied for the compounds formed by penetration
of [Ni(4-Etpy)4(NCS)2] (I) into Ca-montmorillonite (II) or Cr-, Zr- and Al-pillared analogues (III, IV and V, respectively).
The mass fractions of complex I in II, III, IV or V are different. It was found for all studied compounds that the release
of L (L=4-Etpy) is a three-step process (-2L, -1L, -1L), and differences occurred in enthalpy changes (δH in kJ per mole of
I) corresponding to the individual processes. These differences and the changes in diffraction and spectral properties of
the species formed after intercalation are assumed to have their roots in different intramolecular guest-host interactions
in the studied compounds.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
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
6.
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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D. P. Singh B. Sirota S. Talpatra P. Kohli C. Rebholz S. M. Aouadi 《Journal of nanoparticle research》2012,14(4):781
Silver molybdate microrods are self-assembled into micron sized, broom-like and flower-like structures. Our investigations
indicate that through a simple hydrothermal process, large scale production of such structure is possible. Using ammonium
molybdate and silver nitrate solutions as precursors, we were able to show that the self assembled architectures were dependent
on the pH of the starting precursor material. To understand the formation and destructions of the flower-like morphology,
a systematic broad range (from acidic to basic) of pH-controlled experiments were performed and its influence on the structure/microstructure
of synthesized materials was investigated. Scanning electron microscopy studies revealed that the morphology and microstructure
of the products varied significantly by changing pH values from 3 to 8 during mixing of the reactants. pH = 3 and 4 resulted
in the self assembly of monoclinic Ag2(Mo2O7) microrods into broom-like structures, whereas pH = 5 resulted into the flower-like morphology of mixed phase of monoclinic
and triclinic Ag2Mo2O7. We also found that increasing the pH after a certain threshold value (for example pH > 6) resulted in total collapse of
the flower-like morphology. Further increase of the pH to 7 and 8 resulted, the formation of microparticles of Ag2MoO4. A tentative scheme based on the pH-driven evolution of the self-assembly has been given to explain the formation of the
observed heterostructures. Preliminary electrical characterization of thin films of the flower-like structures rendered non-linear
current–voltage (I–V) responses. We also observed a strong hysteresis in the I–V responses of the flower-like structures developed
under high bias conditions. 相似文献
10.
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