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951.
Tom Otieno Jaime R. Blanton M. Jason Hatfield Sherry L. Asher Sean Parkin 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(3):m182-m185
The reaction of Cu(ClO4)2·6H2O, NaAsF6 and excess pyrazole yields hexakis(pyrazole‐κN2)copper(II) bis(hexafluoroarsenate), [Cu(C3H4N2)6](AsF6)2 or [Cu(pzH)6](AsF6)2 (pzH is pyrazole), (I). The analogous hexakis(pyrazole‐κN2)copper(II) hexafluorophosphate perchlorate complex, [Cu(C3H4N2)6](PF6)1.29(ClO4)0.71 or [Cu(pzH)6](PF6)1.29(ClO4)0.71, (II), is obtained in a similar fashion, using KPF6 in place of NaAsF6. Both compounds contain the hitherto unknown [Cu(pzH)6]2+ complex cation, in which the copper(II) ion lies at the center of a regular octahedron of coordinated N atoms. The cation has crystallographically imposed symmetry. The X‐ray data indicate that the lack of the expected distortion can be accounted for by the presence of either static Jahn–Teller disorder or dynamic Jahn–Teller distortion. 相似文献
952.
Summary Phenosafranine (Ph) and Neutral Red (NR) in the presence of iron(III) are decolorized by illumination with light of wavelength shorter than 360 nm. The decolorization mechanism involves ·OH radicals, formed during the photo-excitation of hydrolysed iron(III) species. In the presence of oxygen, iron(III) acts as a catalyst in the photochemical process. The photo-oxidation of Ph and NR is followed by measuring the decrease in absorbance of the dyes, and linear calibration graphs in the range 1–11 ppm of iron are obtained. The decrease in the fluorescence of phenosafranine has also been used to measure the photo-oxidation of this dye, and is linearly related to iron concentration in the range 0.1–1.1 ppm. Phosphate strongly inhibits the iron(III)-catalysed photodecolorization and this can be made the basis of a method for its determination (concentration limit 1×10–5
M).
Photooxydation von Phenosafranin und Neutralrot in Gegenwart von Eisen(III): Bestimmung von Spuren Eisen und Phosphat
Zusammenfassung Phenosafranin (Ph) und Neutralrot (NR) werden in Gegenwart von Fe(III) durch Belichtung unter 360 nm entfärbt. Der Mechanismus dieses Vorgangs erfordert die Gegenwart von OH-Radikalen, die sich bei Belichtung von hydrolysierten Fe(III)-Verbindungen bilden. In Gegenwart von Sauerstoff wirkt Fe(III) als Katalysator der photochemischen Reaktion. Die Photooxydation von Ph und NR läßt sich durch Abnahme der Absorbanz der beiden Farbstoffe verfolgen. Dabei ergeben sich lineare Eichkurven für 1–11 ppm Fe. Die Abnahme der Fluoreszenz von Ph dient ebenfalls zur Messung der Photooxydation dieses Farbstoffes und verläuft für 0,1–1,1 ppm Fe linear. Phosphat hindert die Fe(III)-katalysierte Photoentfärbung, was als Grundlage für die Phosphatbestimmung bis zu 1×10–5 M dienen kann.相似文献
953.
954.
Thanh N. Truong Tom Cook Manohar Nayak Chaiwoot Boonyasiriwat Le-Thuy T. Tran Shaowen Zhang 《Molecular physics》2013,111(4):353-360
We present a development of an integrated extendable web-based environment called Computational Science and Engineering On-line (CSEO) to include different fields of computational science. Our initial efforts are focusing on an integrated environment for multi-scale modelling of complex reacting systems from fundamental quantum chemistry with different entry points. CSEO provides an information management system that allows data flow from one application to another in a transparent manner. In addition, it provides a set of web-based graphic-user interfaces (GUIs) to different scientific applications. Current available GUIs are for quantum chemistry, thermodynamics and kinetics. Work is in progress to allow CSEO accessing resources from the computing grids using the Globus technology. CSEO can be accessed at http://cseo.net. It can also be hosted at different mirror sites. 相似文献
955.
Stefan Schernich Dr. Mathias Laurin Dr. Yaroslava Lykhach Dr. Nataliya Tsud Dr. Marek Sobota Dr. Tomáš Skála Dr. Kevin C. Prince Dr. Nicola Taccardi Valentin Wagner Prof. Dr. Hans-Peter Steinrück Prof. Dr. Vladimír Matolín Prof. Dr. Peter Wasserscheid Prof. Dr. Jörg Libuda 《Chemphyschem》2013,14(16):3673-3677
956.
957.
958.
Tom Desmet Marc Claeyssens Kathleen Piens Wim Nerinckx 《Journal of carbohydrate chemistry》2013,32(4):164-180
The cellulase mixture of Hypocrea jecorina (formerly Trichoderma reesei) contains a variety of exo- and endoglucanases that belong to different structural families. As such, these enzymes form an interesting model system to study the enzyme-ligand interactions in glycoside hydrolases. The nucleophilic carboxylate of retaining β-glycosidases is believed to form a hydrogen bond with the 2-hydroxyl group of their substrate. Consequently, replacing this hydroxyl group with an amino group should result in a stronger electrostatic interaction and thus an increased affinity for the ligand. In this study, several modified cellobiosides were synthesized and evaluated as cellulase inhibitors. The introduction of an amino group was found to have an unpredictable effect on the inhibitory power of the ligands. However, the enzymes display a very high affinity for the corresponding 2-azido compounds, precursors in the synthetic route. The new ligand m-iodobenzyl 2-deoxy-2-azido-β-cellobioside even is the strongest inhibitor of cellobiohydrolase I known to date (KI = 1 μM). 相似文献
959.
Zhengjie He Susan Laurens Xavier M. Mbianda Agnes M. Modro Tom A. Modro 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1689-1692
This work summarizes studies on the preparation, structure, and reactivity of a new heterocyclic system containing phosphorus and nitrogen: 2,8-disubstituted-2,5,8-triaza-1 u 5 -phosphabicyclo[3.3.0]octane 1-oxide (and 1-sulfide). 相似文献
960.
Receptors ferrocene–triazole–pyridine triads assembled with Zn(II) or Cd(II) metal cations behave as chemosensor molecules for HSO4 ? anions through electrochemical and optical channels: the redox peak of the ferrocene/ferrocenium redox couple is shifted cathodically by 72–53 mV, and a new absorption band appeared in the UV–vis spectrum upon complexation with the HSO4 ? anion. Association constants, detection limits and stoichiometries of the recognition processes have been determined, whereas 1H NMR experiments and density functional theory calculations are used to suggest the plausible binding mode taking place in the new supramolecular assembly formed. 相似文献