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101.
Jaworska Alicja 《Central European Journal of Mathematics》2007,5(4):665-685
Trivial extensions of a certain subclass of minimal 2-fundamental algebras are examined. For such algebras the characterization
of components of the Auslander-Reiten quiver which contain indecomposable projective modules is given.
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102.
Krystyna Czaja Marzena Biaek Alicja Utrata 《Journal of polymer science. Part A, Polymer chemistry》2004,42(10):2512-2519
The study of ethylene/1‐hexene copolymerization with the zirconocene catalyst, bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2)/methylaluminoxane (MAO), anchored on a MgCl2(THF)2 support was carried out. The influence of 1‐hexene concentration in the feed on catalyst productivity and comonomer reactivity as well as other properties was investigated. Additionally, the effect of support modification by the organoaluminum compounds [(MAO, trimethlaluminum (AlMe3), or diethylaluminum chloride (Et2AlCl)] on the behavior of the MgCl2(THF)2/Cp2ZrCl2/MAO catalyst in the copolymerization process and on the properties of the copolymers was explored. Immobilization of the Cp2ZrCl2 compound on the complex magnesium support MgCl2(THF)2 resulted in an effective system for the copolymerization of ethylene with 1‐hexene. The modification of the support as well as the kind of organoaluminum compound used as a modifier influenced the activity of the examined catalyst system. Additionally, the profitable influence of immobilization of the homogeneous catalyst as well as modification of the support applied on the molecular weight and molecular weight distribution of the copolymers was established. Finally, with the successive self‐nucleation/annealing procedure, the copolymers obtained over both homogeneous and heterogeneous metallocene catalysts were heterogeneous with respect to their chemical composition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2512–2519, 2004 相似文献
103.
104.
Hydrogen‐deuterium exchange of α‐carbon protons and fragmentation pathways in N‐methylated glycine and alanine‐containing peptides derivatized by quaternary ammonium salts
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Remigiusz Bąchor Magdalena Rudowska Alicja Kluczyk Piotr Stefanowicz Zbigniew Szewczuk 《Journal of mass spectrometry : JMS》2014,49(6):529-536
Recently, we developed a selective and efficient method of hydrogen‐deuterium exchange (HDX) at the α‐carbon (α‐C) of sarcosine residue (N‐methylglycine) in model peptides [B?chor et al. J. Mass Spectrom. 2014, 49, 43]. Here, we report the influence of quaternary ammonium (QA) group on HDX at the α‐C of sarcosine and N‐methylalanine in peptides. The obtained results suggest a significant acceleration of the HDX in sarcosine residue caused by the presence of QA. The effect depends on the distance between the sarcosine residue and QA moiety. The deuterons, introduced at α‐C, are resistant to the back‐exchange in acidic aqueous solution. The collision induced dissociation of the deuterium‐labeled analogs of QA‐tagged oligosarcosine peptides without mobile hydrogen revealed the mobilization of the hydrogens localized at α‐C of sarcosine residue. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
105.
Piotr Garbacki Artur Teżyk Przemysław Zalewski Anna Jelińska Magdalena Paczkowska Alicja Talczyńska Irena Oszczapowicz Judyta Cielecka-Piontek 《Chromatographia》2014,77(21-22):1489-1495
A sensitive UHPLC-DAD method was developed for determination of diastereoisomers of cefuroxime axetil in bulk substance in amorphous and crystalline forms as well as in pharmaceutical preparations. Chromatographic separation was achieved on Kinetex C-18 (100 mm × 2.1 mm, 1.7 µm) column with mobile phase consisting of 0.1 % formic acid:methanol (88:12, v/v), at the flow rate of 0.7 mL min?1 and total run time of 3 min. The wavelength of the DAD detector was set at 278 nm. Inter-day precision (RSD) was less than 3 % and accuracy level ranged between 98.31 and 104.99 %. Degradation products of cefuroxime axetil in aqueous solutions and in the solid state were identified with a EIS-Q-MS mass spectrometer. The solubility of above-mentioned polymorphic forms of cefuroxime axetil in suitable solvents is a crucial factor during preparation of samples and is essential for chromatographic separation of its diastereoisomers. 相似文献
106.
Mechanistic Insight into Peroxo‐Shunt Formation of Biomimetic Models for Compound II,Their Reactivity toward Organic Substrates,and the Influence of N‐Methylimidazole Axial Ligation
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Maria Oszajca Agnieszka Drzewiecka‐Matuszek Dr. Alicja Franke Dr. Dorota Rutkowska‐Zbik Dr. Małgorzata Brindell Prof. Małgorzata Witko Prof. Grażyna Stochel Prof. Rudi van Eldik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2328-2343
High‐valent iron‐oxo species have been invoked as reactive intermediates in catalytic cycles of heme and nonheme enzymes. The studies presented herein are devoted to the formation of compound II model complexes, with the application of a water soluble (TMPS)FeIII(OH) porphyrin ([meso‐tetrakis(2,4,6‐trimethyl‐3‐sulfonatophenyl)porphinato]iron(III) hydroxide) and hydrogen peroxide as oxidant, and their reactivity toward selected organic substrates. The kinetics of the reaction of H2O2 with (TMPS)FeIII(OH) was studied as a function of temperature and pressure. The negative values of the activation entropy and activation volume for the formation of (TMPS)FeIV?O(OH) point to the overall associative nature of the process. A pH‐dependence study on the formation of (TMPS)FeIV?O(OH) revealed a very high reactivity of OOH? toward (TMPS)FeIII(OH) in comparison to H2O2. The influence of N‐methylimidazole (N‐MeIm) ligation on both the formation of iron(IV)‐oxo species and their oxidising properties in the reactions with 4‐methoxybenzyl alcohol or 4‐methoxybenzaldehyde, was investigated in detail. Combined experimental and theoretical studies revealed that among the studied complexes, (TMPS)FeIII(H2O)(N‐MeIm) is highly reactive toward H2O2 to form the iron(IV)‐oxo species, (TMPS)FeIV?O(N‐MeIm). The latter species can also be formed in the reaction of (TMPS)FeIII(N‐MeIm)2 with H2O2 or in the direct reaction of (TMPS)FeIV?O(OH) with N‐MeIm. Interestingly, the kinetic studies involving substrate oxidation by (TMPS)FeIV?O(OH) and (TMPS)FeIV?O(N‐MeIm) do not display a pronounced effect of the N‐MeIm axial ligand on the reactivity of the compound II mimic in comparison to the OH? substituted analogue. Similarly, DFT computations revealed that the presence of an axial ligand (OH? or N‐MeIm) in the trans position to the oxo group in the iron(IV)‐oxo species does not significantly affect the activation barriers calculated for C?H dehydrogenation of the selected organic substrates. 相似文献
107.
108.
The first synthesis of the bis(2-hydroxybenzoyl)dinaphthotetraaza[14]annulene ligand and its O,O-bis-alkylated derivatives containing a decanedioxy bridging moiety, pendant bis-alkoxy groups as well as dicationic butoxypyridinium substituents is reported. The synthetic procedures, full analytical and spectroscopic characterisation (NMR, MS and IR) and crystal structures of the new products are described. The crystal structures show that naphthylene moieties incorporated into the investigated derivatives provide additional opportunities for non-covalent interactions between the molecules. 相似文献
109.
Agnieszka Adamczyk-Wo?niak Raluca M. FratilaIzabela D. Madura Alicja Pawe?koAndrzej Sporzyński Marta TumanowiczAldrik H. Velders Jacek ?y?a 《Tetrahedron letters》2011,52(49):6639-6642
The synthesis of 2-(arylaminomethyl)phenylboronic acid via an amination-reduction reaction has been investigated within a model system comprising 2-formylphenylboronic acid and N-ethylaniline. Adoption of the appropriate reaction conditions influences the reactivity of 2-formylphenylboronic acid, enabling efficient synthesis of so-far unobtainable 2-(arylaminomethyl)phenylboronic compounds. The first crystal structure of the aromatic amine derivative has been determined and described. 相似文献
110.
Alicja Jaworska 《代数通讯》2013,41(11):3935-3947
There are considered trivial extensions of minimal 2-fundamental algebras. It is shown that if the Auslander–Reiten quiver Γ A of a minimal 2-fundamental algebra A contains a starting component or an ending component which is not generalized standard, then the Auslander–Reiten quiver Γ T(A) of the trivial extension T(A) of A contains also a component that is not a generalized standard. 相似文献