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161.
Lukáš Smolko Juraj Černák Juraj Kuchár Danica Sabolová Roman Boča 《Chemical Papers》2018,72(4):877-882
Interaction of two mononuclear tetracoordinate complexes [Co(dmphen)Br2] and [Co(dmphen)I2] (dmphen = 2,9-dimethyl-1,10-phenanthroline), which have been recently reported to behave as single-molecule magnets (SMMs) in an applied external field, with calf thymus (CT) DNA in solution was studied by spectral methods (UV–Vis, fluorescence, and circular dichroism). Results indicate that both complexes along with their chlorido analogue [Co(dmphen)Cl2] are able to bind with the CT DNA via intercalation, with the values of Stern–Volmer constants obtained from the linear quenching plot in range of 1.86 × 104–2.11 × 104 M?1. Furthermore, Topoisomerase I inhibition studies suggest that all three complexes exhibit inhibition activity at concentrations of 45 μM. 相似文献
162.
163.
Marcel Ehn Nikolay Georgiev Vassilev Peter Kasák Branislav Horváth Juraj Filo Kurt Mereiter Erik Rakovský Martin Putala 《Tetrahedron: Asymmetry》2013,24(20):1303-1311
A series of ortho-substituted 2,2′-aryl-1,1′-binaphthalenes were prepared via Negishi arylation of 2,2′-diiodo-1,1′-binaphthalene in good to high yields (65–95%) as an equilibrium mixtures of up to three atropisomers (unlike,unlike, like,unlike, and like,like). Thermodynamic stability parameters of the atropisomers were evaluated from VT NMR spectra by regression analysis. The DFT parameters calculated using CAM-B3LYP functional comprising solvent permittivity were, apart from the toluene solution, which was expected to interact with the aromatic solute, in qualitative agreement with the experimental values. In the case of the ditolyl derivative, the population of the atropisomers was confirmed by CD spectroscopy via comparison with the population-weighted averaged spectrum computed using the M06 functional. X-ray structure analyses of particular atropisomers of the dianisyl, dianilinyl, and dinaphthyl derivatives are also presented and discussed. 相似文献
164.
Bernard Mravec Anna Marini Prof. Matteo Tommasini Dr. Juraj Filo Dr. Marek Cigáň Mariachiara Mantero Dr. Silvano Tosi Prof. Maurizio Canepa Dr. Andrea Bianco 《Chemphyschem》2021,22(6):533-541
Photochromic hydrazones are attracting the attention in the field of photochromic systems especially due to their P-type character. To understand the structural features and their correlation with the spectroscopic data, UV-Vis, vibrational and ellipsometry spectroscopic techniques are employed with the support of density functional theory (DFT) calculations to three hydrazone derivatives based on benzoylpyridine. Interestingly, analysis of the structure shows the presence of two distinct rotamers around the pyridine ring with different energy and the well-defined conjugation path that changes due to E to Z isomerization especially in the hydrazone −C=N−NH part of the skeleton. IR and Raman spectra are analyzed, showing a higher selectivity in the Z form; moreover, the comparison with the normal modes proves the effect of the reaction on the backbone structure. The experimental results are in good agreement with the theoretical predictions, especially in the case of the Raman spectrum. The molecular polarization also changes from E to Z forms as predicted by DFT calculations. Spectroscopic ellipsometry on thin films of TOPAS doped with 10 %wt of the dimethylamino hydrazone derivative is used to prove such change at the molecular level. A modulation of the refractive index is observed, and it is correlated with the concentration of the active moiety and the calculated electronic polarizabilities. 相似文献
165.
166.
The paper presents a simple synthesis of substituted propargyl vinyl ethers and their subsequent thermally-initiated Claisen rearrangement leading to various 3-substituted homoallenyl aldehydes. Several methods, including Sonogashira coupling, base-promoted substitution on the triple bond by sodium amide or butyllithium, and the preparation of substituted propargyl alcohols, were used in the initial step. Phosphate-protected homoallenyl aldehyde hydrazone derivatives were synthesised and fully characterised. The stereochemistry of 9-anthracene carbaldehyde hydrazone, which, surprisingly, afforded both cis and trans isomers, was established using X-ray analysis. 相似文献
167.
Jašíková L Hanikýřová E Škríba A Jašík J Roithová J 《The Journal of organic chemistry》2012,77(6):2829-2836
A new reaction mechanism for the Lossen rearrangement of hydroxamic acids catalyzed by basic salts is presented. It is shown that the rearrangement proceeds in metal complexes of deprotonated hydroxamic acids. The deprotonation can occur either at the oxygen atom (observed for the zinc complexes) or at the nitrogen atom (observed for the potassium complexes). Both anionic forms are characterized by infrared multiphoton dissociation spectroscopy. The rearrangements proceed from the reactive N-deprotonated metal hydroxamates and lead to metal carbamates. The mechanism is elucidated by computational chemistry, mass-spectrometric studies, and preparative experiments. 相似文献
168.
Adriana Czímerová Alexander Čeklovský Juraj Bujdák 《Central European Journal of Chemistry》2009,7(3):343-353
Layer charge is one of the key parameters used for the characterisation of expandable clay minerals, smectites. It determines
most significant properties of the material which are important from the industrial application point of view. This work is
related to a novel method introduced to characterize the layer charge of smectites, based on using cationic organic dyes as
molecular sensors. One xanthene and four phenothiazine cationic dyes were tested using reduced charge montmorillonites (RCMs)
and compared with methylene blue, which has been used most frequently. The characterization of the charge was based on the
formation of molecular assemblies (H- and J-aggregates) composed by dye cations, which were easily detectable using absorption spectroscopy in the UV/VIS spectrum. More
detailed characterization of the spectra required calculations of second-derivative curves. For all of the reaction systems
tested in this work, the molecular aggregation increased with the layer charge of RCMs. Slight to moderate differences in
the formation of dye assemblies related to the differences in the molecular structures of the individual dye cations. For
example, the molecular asymmetry of azure A brought about the formation of coexistent species of similar structures. The structure
of the heteroaromatic skeleton affected the extent of the aggregation and spectral changes with time. The presence of reactive,
non-substituted amino groups in thionine cations probably partially decomposed in the clay mineral colloids based on high-charge
RCMs. Any of the tested dyes could be used as molecular sensors for empirical characterization of the layer charge of clays
taking into account the differences mentioned above.
相似文献
169.
Juraj ernk Anna Pavlov Michal Duek Karla Fejfarov 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(7):m260-m262
<!?tpct=26.8pt>In the ionic title compound, [Ni(NO3)(C10H9N3)2]NO3, the central NiII atom exhibits cis‐NiN4O2 octahedral coordination with three chelating ligands, viz. one nitrate anion and two di‐2‐pyridylamine (dpya) molecules. A second nitrate group acts as a counter‐ion. The complex cations and the nitrate anions are also linked by N—H...O hydrogen bonds. The compound was prepared in two different reproducible ways: direct synthesis from Ni(NO3)2 and dpya yielded systematically twinned crystals (the twinning law is discussed), while single crystals were obtained unexpectedly from the Ni(NO3)2/dpya/maleic acid/NaOH system. 相似文献
170.
Poly(ether amide)s containing naphthalene unit were prepared either by the polyaddition reaction of aromatic bis(2‐oxazoline)s with the different dihydroxynaphthalenes or by the homopolyaddition of a monomer containing an oxazoline, a hydroxy, and naphthalene moieties. First, polymerization method represents AA + BB mode where 1,4‐phenylene‐2,2′‐bis(2‐oxazoline) (A) and 1,3‐phenylene‐2,2′‐bis(2‐oxazoline) (B) were used as AA monomers and four different dihydroxynaphthalenes 1–4 were used as BB monomers. In the second case, 2‐(6‐hydroxynaphthalene‐2‐yl)‐2‐oxazoline (5) was used as AB‐type monomer in thermally induced polymerizations. The time dependences of polyadditions in bulk as well as in the solution were examined. The reduction of molar mass was observed after the initial fast increase of molar mass. This can be explained by the presence of side and degradation reactions. In both cases, polyadditions resulted in the linear poly(ether amide)s, which were characterized by 1H and 13C NMR spectroscopy. Thermal properties of the prepared polymers were studied by differential scanning calorimetry (DSC) measurements. Comparison of the temperatures of glass transition for polymers prepared in AA + BB mode shows the strong dependence of thermal properties on the structure of the polymers. The values were in the range of 136–171°C. The glass‐transition temperature (Tg) of poly[2‐(6‐hydroxynaphthalene‐2‐yl)‐2‐oxazoline] prepared by AB‐type polyaddition is 183°C, which corresponds to the higher contents of hard aromatic segments in the latter type of polymers compared to the polymers prepared in the AA + BB‐type polyadditions. The described polymers represent novel naphthalene unit‐containing poly(ether amide)s for different applications in material science. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献