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31.
Yang Zhong-zhi Branka Kova
Edgar Heilbronner Sayed Eltamany Henning Hopf 《Helvetica chimica acta》1981,64(7):1991-2001
The photoelectron (PE.) spectra of thirteen methyl-substituted [2.2]paracyclophanes have been recorded and analyzed, to assess the influence of methyl-substitution on their ionization energies. It is shown that this influence is qualitatively and quantitatively the same as for benzenes and other π-systems. Comparison with the previous results obtained for the [2r]cyclophanes (r=2 to 6) strongly suggests that the hyperconjugative model for alkyl-group/π-system interactions is more appropriate than the inductive one. 相似文献
32.
Novak I Kovac B 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,61(11-12):2771-2774
HeI and HeII photoelectron spectra of 6-chloro-1,3-dimethyluracil have been measured. The assignment of the spectrum was made by comparison with photoelectron spectra of related compounds and by high-level OVGF calculations. The electronic structure changes in substituted nucleobases are discussed on the basis of photoelectron spectroscopic data. The electronic structure data are compared with structure-activity relationships regarding enzyme inhibition and complex formation. The electronic structure data give some insight into the nature of binding between nucleobases' derivatives and different enzymes whose activity they inhibit. 相似文献
33.
J. Klein A. Léger S. De Cheveigné C. Guinet M. Belin D. Defourneau 《Surface science》1979,82(1):L288-L292
Inelastic Electron Tunneling Spectroscopy of CO adsorbed on alumina supported Rh allows the observation of the low frequency metal-carbon vibrational modes (~1000 cm?1) that cannot be seen by Infrared Spectroscopy. We present a preliminary attempt to assign the modes observed, using istopic shifts . 相似文献
34.
The electronic structures of several halogen substituted bezoquinones and benzoquinoneimines have been studied by HeI/HeII photoelectron spectroscopy and Green's function calculations. The information on the electronic structure is discussed in the context of their electron-transfer properties and biological activity. 相似文献
35.
Covalent assembly between gold-thiolate nanoparticles (AuNPs) and the cluster [Fe(eta(5)-C(5)H(5))(mu(3)-CO)](4), 1, can be achieved either by direct Brust-Schriffin-type synthesis using a mixture of undecanethiol and a thiol functionalized with , or by substitution of undecanethiolate ligands in AuNPs by thiolate ligands functionalized with ; cyclic voltammetry of these AuNPs functionalized with allows us to recognize and titrate the oxo-anions H(2)PO(4)(-) and ATP(2-). 相似文献
36.
The present study reports the investigation of capillary electrophoresis (CE) for the separation of the photosynthetic pigments (chlorophyll derivatives as well as carotenoids) together. Various CE methods, such as micellar electrokinetic chromatography, capillary electrokinetic chromatography, and nonaqueous capillary electrophoresis (NACE) are tested, with coated and uncoated capillary columns to evaluate optimal separation conditions using diode array detection. The effect of different type and composition of organic solvents and surfactants on the separation is discussed. Detection limits are found in the range of 1.14-2.45 ppm. According to the system suitability results, the most effective separation is observed using NACE with Aliquat 336 as cationic surfactant in coated capillary and mixture of MeOH-ACN-THF (5:4:1, v/v/v) as solvent. Quantitative evolution is investigated, and recovery percentage values are found to be 96.7-102%. 相似文献
37.
Pavić Kristina Rajić Zrinka Michnová Hana Jampílek Josef Perković Ivana Zorc Branka 《Molecular diversity》2019,23(3):657-667
Molecular Diversity - Here, we describe design and synthesis of twelve novel compounds bearing primaquine motif and hydroxy- or halogenamine linked by an urea or bis-urea spacer. Preparation of... 相似文献
38.
Claude Belin Monique Tillard Laurent Spina Yong Zhong Jia 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(5):i51-i53
Aluminium germanium lithium, AlGeLi, crystallizes in two cubic dimorphs. The structure of the F3m form, already inferred from powder data, has been confirmed by both powder and single‐crystal X‐ray diffraction studies. The second dimorph, not previously identified, adopts a disordered centrosymmetric structure with space group Fmm. 相似文献
39.
Branka Dra?i? Sanja Grguri?-?ipka Ivanka Ivanovi? ?ivoslav Lj. Te?i? Gordana Popovi? 《Journal of the Iranian Chemical Society》2012,9(1):7-12
Acid?Cbase equilibria of the aqua adducts of Ru(II) arene complexes, general formulae [(??6-p-cymene)Ru (L1?3)Cl2] where L1?=?3-acetylpyridine (1), L2?=?4-acetylpyridine (2) and L3?=?2-amino-5-chloropyridine (3), then [(??6-p-cymene)Ru(HL4)Cl2] with HL4?=?isonicotinic acid (4); [(??6-p-cymene)Ru(HL5?8)Cl] where H2L5?=?2,3-pyridine dicarboxylic acid (5), H2L6?=?2,4-pyridine dicarboxylic acid (6), H2L7?=?2,5-pyridine dicarboxylic acid (7) and H2L8?=?2,6-pyridine dicarboxylic acid (8) have been studied. pK a values were determined by potentiometry at 25?°C and constant ionic strength of 0.1?M NaNO3. The assumed equilibria were confirmed by UV and 1H-NMR spectroscopy. 相似文献
40.
Brunker TJ Kovač B Kowalski K Polit W Winter RF Rheingold AL Novak I 《Dalton transactions (Cambridge, England : 2003)》2012,41(13):3675-3683
The preparation and crystal structure of a new 2,5-dimethylazaferrocene (DMAF) adduct of borane (DMAF-BH(3)) are reported. The electronic structures of 1,2,3,4,5-pentamethylazaferrocene (PMAF), its borane adduct 1,2,3,4,5-pentamethylazaferrocene-BH(3) (PMAF-BH(3)) and of DMAF-BH(3) have been studied by HeI-HeII UV photoelectron spectroscopy (UPS) and high-level DFT methods. UPS data reveal the influence of borane and methyl substitution on the electronic structures of azaferrocenes, which have been rationalized by inductive and hyperconjugative effects. UPS data also allow for the estimation of azaferrocene lone-pair stabilization upon coordination to borane, and suggest that pyridine is a slightly stronger sigma donor toward BH(3) than either azaferrocene studied. UV-Vis spectroscopic data for the radical cation of PMAF were also obtained and compared with the UPS data. 相似文献