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11.
Tomasz Goslinski Zbigniew Dutkiewicz Michal Kryjewski Ewa Tykarska Lukasz Sobotta Wojciech Szczolko Maria Gdaniec Jadwiga Mielcarek 《Monatshefte für Chemie / Chemical Monthly》2011,13(1):599-608
Abstract
An earlier developed alkylating path leading to tetraalkylated diaminomaleonitrile derivatives was explored. Attempts to explain the reactivity of the representative dialkylated diaminomaleonitrile 2,3-bis[(3-pyridylmethyl)amino]-2(Z)-butene-1,4-dinitrile during the alkylation reaction were performed using X-ray and density functional theory (DFT) studies. The condensed Fukui functions accompanied by softness indices were found to be useful in explaining its reactivity observed during the reaction. The values of the Fukui functions and condensed softness for electrophilic attack calculated from Mulliken, L?wdin, and natural population analyses closely corresponded to the experimental observations. When 2,3-bis[(3-pyridylmethyl)amino]-2(Z)-butene-1,4-dinitrile disodium salt was treated with dimethyl sulfate at lower temperatures the alkylation reaction prevailed, whereas at higher temperatures the alkylating agent acted as a hydride anion acceptor, which favored the elimination reaction. The tetraalkylated dinitrile 2,3-bis[methyl(3-pyridylmethyl)amino]-2(Z)-butene-1,4-dinitrile was used in the synthesis of tribenzoporphyrazine bearing methyl(3-pyridylmethyl)amino groups, which was subsequently subjected to solvatochromic and metallation studies. The changes observed during metallation seem to result from the coordination of the 3-pyridyl group by a palladium ion. This could influence the configuration of the methyl(3-pyridylmethyl)amino moiety, causing more effective donation of a lone pair of electrons from peripheral nitrogen to the macrocyclic ring. 相似文献12.
Benjamin Waldher Jadwiga Kuta Samuel Chen Neil Henson Aurora E. Clark 《Journal of computational chemistry》2010,31(12):2307-2316
The ForceFit program package has been developed for fitting classical force field parameters based upon a force matching algorithm to quantum mechanical gradients of configurations that span the potential energy surface of the system. The program, which runs under UNIX and is written in C++, is an easy‐to‐use, nonproprietary platform that enables gradient fitting of a wide variety of functional force field forms to quantum mechanical information obtained from an array of common electronic structure codes. All aspects of the fitting process are run from a graphical user interface, from the parsing of quantum mechanical data, assembling of a potential energy surface database, setting the force field, and variables to be optimized, choosing a molecular mechanics code for comparison to the reference data, and finally, the initiation of a least squares minimization algorithm. Furthermore, the code is based on a modular templated code design that enables the facile addition of new functionality to the program. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
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Waldemar Tomaszewski Vladimir M. Gun’ko Roman Leboda Jadwiga Skubiszewska-Zięba 《Central European Journal of Chemistry》2010,8(4):750-757
Solid phase extraction (SPE) of methoxy- and methylenedioxyamphetamines from diluted aqueous solutions was investigated on
carbon and polymeric adsorbents of different textures and chemical compositions. Those adsorbents were applied cartridges
packed with three chemically modified carbons prepared from plum stones (initial A2PS, oxidized A2PS-O, and reduced A2PS-H)
and commercially available adsorbents (polymeric LiChrolut EN, graphitized Hypercarb and Carboprep). Several factors influence
the recovery rates of amphetamine derivatives such as the polarity of adsorbates (free energy of salvation), the specific
surface area and surface composition of adsorbents, and the solvent characteristics. Different combinations of these factors
affect the recovery rate (R1) for high- and low-surface area adsorbents. The minimal R1 values are observed for an amphetamine
derivative at a maximal solvation effect and for a set of amphetamines adsorbed on graphitized carbons.
相似文献
16.
Tomasz Gubica Jadwiga Stroka Andrzej Temeriusz Marianna Kańska 《Journal of Physical Organic Chemistry》2011,24(12):1229-1234
Ten nitrophenyl N‐glycosides have been studied electrochemically in neutral (at pH 7) water–organic solutions by cyclic voltammetry using static mercury drop electrode. For all compounds under investigation the two electrochemical processes have been observed: the four‐electron irreversible reduction of their nitro groups to the corresponding phenylhydroxylamine derivatives, as well as the two‐electron quasi‐reversible process between phenylhydroxylamine and nitroso derivatives. For three compounds the additional electrochemical processes have been also observed, which can be connected with the formation of azoxybenzene derivatives. The potentials of both redox processes: a two‐electron quasi‐reversible R? NHOH/R? NO (Ef) and four‐electron irreversible R? NO2/R? NHOH (Epc(I)) systems have been determined and discussed according to crystal structures of selected compounds. Ef and Epc(I) depended strongly on the positive mesomeric effect (caused by glycosidic nitrogen atom), as well as on the intramolecular hydrogen bond between electroactive nitro group and the hydrogen atom at the glycosidic atom observed in N‐o‐nitrophenyl‐2,3,4,6‐tetra‐O‐acetyl‐β‐D ‐glucopyranosylamine. Moreover, the chirality of selected reactants has had the pronounced effect on the Epc(I). Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
17.
J. Szydlowska K. Trzcinska P. Bilkova J. Mieczkowski D. Pociecha E. Gorecka 《Liquid crystals》2006,33(3):335-339
Doping a photoconductive mesogenic material with a small amount of functionalized fullerene significantly increases the photocurrent. LESR studies show the appearance of a long-lived charge-separated state under light illumination, with a negative charge on the fullerene moiety. This confirms that in the system studied the fullerene unit acts as an electron trap. In the lamellar structure of the liquid crystalline phase the fullerene units and mesogenic cores are separated, which ensures better space separation between negative and positive charges. As a result the charge recombination is slowed and the photocurrent is amplified. 相似文献
18.
Tomasz GoslinskiTomasz Osmalek Krystyna KonopkaMarcin Wierzchowski Piotr Fita Jadwiga Mielcarek 《Polyhedron》2011,30(9):1538-1546
Two novel zinc(II) phthalocyanines bearing non-peripheral ester-alkyloxy substituents (Pc-4 and Pc-5) were synthesized, by a two-step procedure starting from 2,3-dicyanohydroquinone. Both sensitizers show promising photophysical properties, including solvatochromic study, qualitative evaluation of emission, aggregation behavior and singlet oxygen generation. It was proven that the photodynamic activity of the compounds studied depends on the molecular oxygen level. Comparison of the quantum yields of singlet oxygen generation as well as the oxidation rate constants using 1,3-diphenylisobenzofurane before and after deaeration proved the photodynamic effect of Pc-4 and Pc-5 to be governed by the photosensitization mechanism II. Changes in the quantities of the compounds exposed to irradiation were also estimated. Upon their exposure to light the changes in intensity of the Q band were monitored. The photodecomposition of Pc-4 and Pc-5 in DMSO or DMF solutions was found to proceed according to the first order kinetic reaction in two stages.The photosensitizing effect of Pc-4 in HSC-3 cells was significantly lower than that of ZnPc. Pc-4 was ineffective at 0.1 μM, while a low, approx. 15% photocytotoxicity was observed at 5 μM, at a distance of 5 and 10 cm. The efficacy of Pc-4 in photokilling of cultured cells is affected by hydrophobicity and the aggregation status of the photosensitizer. 相似文献
19.
Woźnica M Butkiewicz A Grzywacz A Kowalska P Masnyk M Michalak K Luboradzki R Furche F Kruse H Grimme S Frelek J 《The Journal of organic chemistry》2011,76(9):3306-3319
In the present work, the validity of the helicity rule relating the absolute configuration of the bridgehead carbon atom in bicyclic β-lactams to the sign of the 220 nm band observed in their electronic circular dichroism (ECD) spectra is examined for ring-expanded cephalosporin analogues. To this end, a series of model compounds with a seven-membered ring condensed with the β-lactam unit was synthesized. A key step of their synthesis was either the ring-closing metathesis (RCM) or the free radical cyclization leading to the seven-membered ring with an S, O, or C atom at the 6 position in the bicyclic skeleton. To investigate the scope and limitations of the simple, empirically established helicity rule, a combination of ECD spectroscopy, variable-temperature ECD measurements, X-ray analysis, and time-dependent density functional theory (TD-DFT) calculations was used. A comparison of the experimental ECD spectra with the spectra simulated by TD-DFT calculations gives a reasonable interpretation of the Cotton effects observed in the 240-215 nm spectral range. The results suggest that the helicity rule does not apply to the investigated compounds because of the planarity of their amide chromophore. Thus, these compounds do not constitute an exception to the rule that was established for bi- and polycyclic β-lactams with the nonplanar amide chromophore only. 相似文献
20.
Jadwiga Mielcarek Magdalena Kula Róa Zych Pawe Grobelny 《Reaction Kinetics and Catalysis Letters》2005,86(1):119-126
Summary The effect of solvent on the photodegradation kinetics of fluvastatin was evaluated. The degradation rate of fluvastatin was estimated on the basis of the quantum yields and kinetic parameters determination. The photodegradation appeared to follow first-order kinetics. In order to establish the light intensity absorbed by a system, Reinecke’s salt was used as a chemical actinometer. 相似文献