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21.
Nowicka AM Zabost E Donten M Mazerska Z Stojek Z 《Analytical and bioanalytical chemistry》2007,389(6):1931-1940
A method is presented for the electroanalytical characterization of interactions of dsDNA with a drug, under conditions that
both agents are dissolved in the phosphate buffer solution and both are electroactive. Normal pulse, square wave, differential
pulse, and cyclic voltammetries were employed in the measurements of the drug and dsDNA oxidation signals at carbon electrodes.
UV–Vis spectroscopy was used as a non-electrochemical method to support the electroanalytical data. An anticancer drug, C-1311
(5-diethylaminoethyl-amino-8-hydroxyimidazoacridinone), has been selected for the examination. Normal pulse voltammetry was
particularly useful in showing that under the conditions employed neither dsDNA nor the drug were adsorbed at the electrode
surface. Necessary conditions for the appearance of the well-defined dsDNA voltammetric signal (guanine peak) are: rigorous
chemical and biological purity in the cell and appropriate purity of DNA. An analysis of the obtained results confirmed that
there were two modes of interaction between C-1311 and dsDNA: by intercalation and electrostatically. In the presence of excess
NaCl the electrostatic interactions deteriorate. The binding constants (K
1 and K
2, respectively) and the number (n) of nucleic base pairs (bp) and the number (m) of phosphate groups (pg) interacting with one molecule of drug have been determined. For strong interactions (intercalation)
the values of the binding constant, K
1, and the binding-site size, n, equal 3.7 × 104 M−1 and 2.1, respectively. For the weak electrostatic interactions the K
2 and m parameters equal 0.28 × 104 M−1 and 4.7. The intercalation process is rather slow and its rate (the conditions of pseudo-first-order reaction) was estimated
to equal 7 × 10−4 s−1. The possibility of independent determination of both interacting agents was very useful in the study.
Figure Intercalation of C-1311 into a dsDNA fragment 相似文献
22.
Zofia Stepien/snm> 《Geometriae Dedicata》2002,93(1):37-45
We prove the formality property of any homogeneous space G/G
generated by an automorphism of finite order of a compact simple Lie group G. 相似文献
23.
The aim of the paper is to point out some imprecision in Srivastava and Hui’s tests for multivariate normality. A correction for their tests is proposed. 相似文献
24.
Joanna Wiśniewska Hasan Marai Andrzej Karocki Konrad Szaciłowski Ewa Kita Zofia Stasicka 《Journal of photochemistry and photobiology. A, Chemistry》2010,209(2-3):121-127
Irradiation of chromium(III) complexes with oxalate and pyridinedicarboxylate ligands (pda = 2,3-, 2,4-, or 2,5-dicarboxylate) leads to diverse behaviors, dictated by light energy, presence of oxygen and the ligand nature. Irradiation within the MC bands is unaffected by O2 and results in ligand substitution. The LMCT excitation is effective only when oxalate is coordinated to Cr(III); then electron transfer from oxalate to central ion generates an intermediate, consisted of a Cr(II)species and the C2O4? radicals. The species undergo fast redox reactions dependent on the presence of O2 and the pda ligand.(1) In anoxic medium the fast outersphere electron transfer from Cr(II) to solvent, generates hydrated electrons and re-oxidizes the chromium centre to CrIII. Then geminate recombination regenerates substrate, whereas competitive release of the C2O4? radical leads to substitution of one oxalate ligand by two water molecules (aquation induced by the LMCT excitation). In the presence of the pda ligand the outersphere electron transfer is accompanied by the innersphere CT, generating Cr(III) coordinated to two radical ligands: C2O4? and pda3?; the intermediate releases also eaq?, but this reaction is slower than that of the homoleptic oxalate complex. Hydrated electrons are scavenged also by the released radicals. All these processes are completed within microseconds and in consequence, the Cr(III) complexes irradiated in deoxygenated solutions are insensitive to subsequent oxygenation.(2) When UV-irradiation is carried out in oxygenated medium reaction of Cr(II) species with molecular oxygen competes with the outer- or inner electron transfer observed in anoxic medium. Both these pathways result in generation of chromate(VI). Quantum yield of the Cr(VI) production is sensitive to the presence and structure of pda ligand, decreasing within the series 2,3-pda > 2,4-pda > 2,5-pda. 相似文献
25.
Zofia?Krystyna?DrzazgaEmail author Karina?Maciejewska Katarzyna?Michalik Micha??Kaszuba Barbara?Nowińska 《Journal of fluorescence》2011,21(3):883-886
The influence of antiretroviral drug zidovudine treatment during pregnancy on mandible development in newborn rats was studied. The fluorescence of mandibles from 7-, 14-
and 28-days old individuals was measured by means of fiber-optical fluorescence analyzer with 407 nm laser excitation. Obtained
results revealed disturbing effect of maternal zidovudine administration on mandible fluorescence intensity which should decrease with bone development. Small changes in fluorescence
of porphyrin forms are maintaining in the first month of newborns life while the changes observed in 440–585 nm range disappear. 相似文献
26.
Maria Chrzanowska Agnieszka Grajewska Zofia Meissner Maria Rozwadowska Iwona Wiatrowska 《Tetrahedron》2012,68(14):3092-3097
A sequence of two reactions: the Petasis reaction, in which an aminoacetaldehyde acetal was used as the amine component, followed by Pomeranz–Fritsch–Bobbitt cyclization, has been shown to be a convenient and simple method for the synthesis of tetrahydroisoquinoline-1-carboxylic acids. Using this method several acids have been prepared in good to excellent yields and characterized as hydrochloride salts. 相似文献
27.
Dirk Pfefferkorn Sven Sonntag Samuel O. Kyeremateng Zofia Funke Hans‐Werner Kammer Jörg Kressler 《Journal of Polymer Science.Polymer Physics》2010,48(17):1893-1900
The pressure–volume–temperature behavior of miscible blends of poly(ethylene oxide) (PEO) and poly(methyl acrylate) (PMA) was studied over extended ranges of temperature and pressure. From pressure–volume–temperature data, the reduction parameters for the Flory‐Orwoll‐Vrij equation‐of‐state were determined. It was found that reduction parameters as well as density, thermal expansion coefficient, and isothermal compressibility vary with composition in a nonlinear manner. The surface tension of the blends in the molten state was measured over the whole composition range using the sessile drop method. The surface tension was found to display negative deviation from additivity pointing toward a remarkable surface excess of PMA. Moreover, surface tension displays a minimum in the range of low PEO content at weight fraction of ~0.19. In addition, the temperature coefficient of surface tension shows negative deviation from linearity. It stays constant when PMA is in excess. Results are discussed in terms of equation‐of‐state thermodynamics. The minimum of surface tension can be well explained by weak self‐association of PEO in the bulk. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1893–1900, 2010 相似文献
28.
Sylwia Basąg František Kovanda Zofia Piwowarska Andrzej Kowalczyk Katarzyna Pamin Lucjan Chmielarz 《Journal of Thermal Analysis and Calorimetry》2017,129(3):1301-1311
The Co–Mg–Al mixed metal oxides were prepared by calcination of co-precipitated hydrotalcite-like precursors at various temperatures (600–800 °C), characterised with respect to chemical (AAS) and phase (XRD) composition, textural parameters (BET), form and aggregation of cobalt species (UV–vis-DRS) and their redox properties (H2-TPR, cyclic voltammetry). Moreover, the process of thermal decomposition of hydrotalcite-like materials to mixed metal oxide systems was studied by thermogravimetric method combined with the analysis of gaseous decomposition products by mass spectrometry. Calcined hydrotalcite-like materials were tested as catalysts for methanol incineration. Catalytic performance of the oxides depended on cobalt content, Mg/Al ratio and calcination temperature. The catalysts with lower cobalt content, higher Mg/Al ratio and calcined at lower temperatures (600 or 700 °C) were less effective in the process of methanol incineration. In a series of the studied catalysts, the best results, with respect to high catalytic activity and selectivity to CO2, were obtained for the mixed oxide with Co:Mg:Al molar ratio of 10:57:33 calcined at 800 °C. High activity of this catalyst was likely connected with the presence of a Co–Mg–Al spinel-type phases, containing easy reducible Co3+ cations, formed during high-temperature treatment of the hydrotalcite-like precursor. 相似文献
29.
Zofia M. Wosinska Faye L. Stump Rajeev Ranjan Edward D. Lorance GeNita N. Finley Priya P. Patel Muzamil A. Khawaja Katie L. Odom Wolfgang H. Kramer Ian R. Gould 《Photochemistry and photobiology》2014,90(2):313-328
Irreversible photooxidation based on N–O bond fragmentation is demonstrated for N‐methoxyheterocycles in both the singlet and triplet excited state manifolds. The energetic requirements for bond fragmentation are studied in detail. Bond fragmentation in the excited singlet manifold is possible for ππ* singlet states with energies significantly larger than the N–O bond dissociation energy of ca 55 kcal mol?1. For the nπ* triplet states, N–O bond fragmentation does not occur in the excited state for orbital overlap and energetic reasons. Irreversible photooxidation occurs in the singlet states by bond fragmentation followed by electron transfer. Irreversible photooxidation occurs in the triplet states via bimolecular electron transfer to the donor followed by bond fragmentation. Using these two sensitization schemes, donors can be irreversibly oxidized with oxidation potentials ranging from ca 1.6–2.2 V vs SCE. The corresponding N‐ethylheterocycles are characterized as conventional reversible photooxidants in their triplet states. The utility of these sensitizers is demonstrated by irreversibly generating the guanosine radical cation in buffered aqueous solution. 相似文献
30.
Renata ?yszczek Zofia Rz?czyńskaAlina Kula Agnieszka G?adysz-P?aska 《Journal of Analytical and Applied Pyrolysis》2011,92(2):347-354
The lanthanide 2,6-naphthalenedicarboxylates series of the formulas Ln2(ndc)3·nH2O, where Ln = lanthanides from La(III) to Lu(III); ndc - C10H6(COO)22−; n = 4, 4.5 or 5 have been prepared by the precipitation method. All obtained products were examined and characterized by elemental analysis, FTIR spectroscopy, simultaneous thermal analyses TG-DSC and TG-FTIR, X-Ray diffraction patterns as well as luminescence measurements. The crystalline compounds form three isostructural groups: Ce-Sm; La and Eu-Dy; Ho-Lu. In all complexes, the ndc2− ligand appears in the deprotonated form. Heating of the complexes resulted in the multi-steps decomposition process. The dehydration process leads to the formation of stable crystalline Ln2ndc3 compounds which further decompose to the corresponding lanthanide oxides (air atmosphere). In argon atmosphere they decompose with releasing of water, carbon oxides and naphthalene molecules. The luminescence properties of Eu(III), Nd(III), Tb(III) and Er(III) complexes were investigated. The complexes of Eu(III) and Tb(III) emitted red and green light when excited by ultraviolet light whereas Nd(III) and Er(III) display emissions in the NIR region. 相似文献