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981.
Enzymes may be used to develop an environmentally friendly alternative to the conventional polluting technologies in textile
finishing. The action of the unlabeled and fluorescent labeled proteolytic enzymes subtilisin and trypsin on wool was examined.
Scanning electron micrographs and a diffusion study, based on fluorescence microscopy, localized the enzymatic attack on the
fiber. A kinetic study was carried out by monitoring the amino acid content of the treatment liquor.
Enzymatic action is not confined to the fiber surface. To limit attack to the surface and reduce wool damage new treatment
methods such as enzyme immobilization onto a solid carrier must be investigated. 相似文献
982.
Magdalena Kloskowska Antoni Konitz Wiesaw Wojnowski Barbara Becker 《无机化学与普通化学杂志》2006,632(15):2424-2428
The title compound, [Sn(μ–S){SSi(OtBu)3}2]2 ( 1 ), containing four–coordinated tin(IV), crystallizes in two polymorphic modifications. The orthorhombic 1a –form has been obtained in the reaction of (tBuO)3SiSH and Et3N with SnCl2, whereas the triclinic 1b –form in the reaction with SnCl4 as substrate. The crystal and molecular structures of both polymorphs ( 1a as a redetermination) have been determined by a single–crystal X–ray diffraction study at room temperature. The title compound was shown to react with ammonia and ammonia complexes of some d–block metal cations giving products of Sn–S bond cleavage. 相似文献
983.
Silica particles containing immobilised peptidic templates have been used for the generation of hierarchically imprinted polymers. The pores of the silica mould were filled with a mixture of monomers/initiator and polymerised, followed by dissolution of the silica template. This method leaves behind imprinted polymers with binding sites located at the surface, which are capable of recognising larger molecules with the same immobilised epitope. All the products resulting from solid-phase synthesis of peptides were characterised by elemental analysis, FT-IR spectroscopy and fluorescence microscopy. The hierarchically imprinted polymers generated from these products were characterised by elemental analysis, FT-IR spectroscopy, fluorescence microscopy, scanning electron microscopy (SEM) and nitrogen adsorption, providing evidence concerning the reproducibility of each step. The chromatographic properties of the materials have been investigated and the advantages of the immobilisation method have been proven. The materials exhibit selectivity for their templates and other structurally related dipeptides. Furthermore, the polymers proved to be capable of recognising larger peptides containing the immobilised sequence. 相似文献
984.
Magdalena Maj-Żurawska Werner Buchser Daniel Ammann Dieter H. Welti Brnö Pretsch Walter Keller-Schierlein Wilhelm Simon 《Mikrochimica acta》1987,92(1-3):1-10
Lipophilic bis--diketones have been prepared by covalently linking two-diketone subunits. Potentiometric studies on liquid membrane electrode cell assemblies showed no improvement of the ion selectivities induced by the bridged systems in comparison to unbridged-diketones. The dissociation constants of the enol functions in the bis--diketones indicate that under the conditions of the EMF measurement probably only one-diketone unit is deprotonated in the liquid membrane phase. The complexation of these-diketones with Mg2+ and Ca2+ was studied by13C NMR-monitored titrations in a homogeneous organic phase.On leave from the Chemistry Department, University of Warsaw, Warsaw, Poland 相似文献
985.
Grażyna Janowska Teresa Mikołajczyk Magdalena Olejnik 《Journal of Thermal Analysis and Calorimetry》2007,88(3):843-849
The effects of basic fibre-forming parameters on the thermal properties and flammability of fibres from polyimidoamide (PIA)
nanocomposite have examined. The comparative analysis of the properties of fibres from modified PIA and PIA nanocomposite
has been conducted.
The multi-functional fibres prepared from PIA nanocomposite show increased porosity and sorption properties as well as a high
thermal stability and reduced flammability in comparison with fibres without MMT. 相似文献
986.
Nitric oxide (.NO) has a multitude of physiological roles, including the ability to protect cells against oxidant-induced killing, e.g. by inhibiting caspase-mediated apoptosis or by intercepting damaging free radicals derived from membrane lipids. The purpose of this study was to test the hypothesis that low flux .NO acting in the latter fashion can enhance tumor-cell resistance to photodynamic killing, specifically that sensitized by 5-aminolevulinic acid (ALA)-derived protoporphyrin IX (PpIX). Preliminary model experiments with iron-ascorbate-treated, PpIX-sensitized liposomes showed that spermine NONOate (SPER/NO)-derived .NO had no effect on photoinduced accumulation of primary singlet oxygen adducts, e.g. the cholesterol hydroperoxide 5 alpha-OOH, but dose-dependently inhibited the buildup of free radical-generated oxidation products arising from one-electron turnover of primary peroxides. In subsequent studies, breast tumor COH-BR1 cells in serum-free medium were treated with 1 mM ALA for 15 min and then without ALA for 3.75 h, allowing biogenerated PpIX to diffuse to extramitochondrial sites, including plasma membrane. Cells were irradiated in the absence or presence of SPER/NO and compared for peroxidative damage and Hoechst-assessed viability after 5 h in the dark. Iron-stimulated necrotic photo-killing and accumulation of chain lipid peroxidation products were observed, and this was inhibited strongly by SPER/NO, but not by decomposed SPER/NO, confirming that .NO was the active agent. When introduced after irradiation, .NO became progressively less inhibitory, consistent with ongoing but waning free-radical activity. These findings provide new insights into the possible role of .NO in tumor resistance to ALA-photodynamic therapy and other photo-dynamic treatments. 相似文献
987.
Makowska-Grzyska MM Jeppson PC Allred RA Arif AM Berreau LM 《Inorganic chemistry》2002,41(19):4872-4887
Using a mixed nitrogen/sulfur ligand possessing a single internal hydrogen bond donor (N,N-bis-2-(methylthio)ethyl-N-(6-amino-2-pyridylmethyl)amine (bmapa)), we prepared and structurally and spectroscopically characterized a series of zinc complexes possessing a single alcohol ([(bmapa)Zn(MeOH)](ClO(4))(2) (1)), formamide ([(bmapa)Zn(DMF)](ClO(4))(2) (3), [(bmapa)Zn(NMF)](ClO(4))(2) (4)), or sulfoxide ([(bmapa)Zn(DMSO)](ClO(4))(2) (7), [(bmapa)Zn(TMSO)](ClO(4))(2) (8)) ligand. X-ray crystallographic characterization was obtained for 1.MeOH, 3, 4, 7.DMSO, and 8. To enable studies of the influence of the single hydrogen bond donor amino group of the bmapa ligand on the chemistry of zinc/neutral oxygen donor binding interactions, analogous alcohol ([(bmpa)Zn(MeOH)](ClO(4))(2) (2)), formamide ([(bmpa)Zn(DMF)](ClO(4))(2) (5), [(bmpa)Zn(NMF)](ClO(4))(2) (6)), and sulfoxide ([(bmpa)Zn(DMSO)](ClO(4))(2) (9), [(bmpa)Zn(TMSO)](ClO(4))(2) (10)) complexes of the bmpa (N,N-bis-2-(methylthio)ethyl-N-(2-pyridylmethyl)amine) ligand system were generated and characterized. Of these, 2, 5, 6, and 9.2DMSO were characterized by X-ray crystallography. Solution spectroscopic methods ((1)H and (13)C NMR, FTIR) were utilized to examine the formamide binding properties of 3-6 in CH(3)CN and CH(3)NO(2) solutions. Conclusions derived from this work include the following: (1) the increased donicity of formamide and sulfoxide donors (versus alcohols) makes these competitive ligands for a cationic N/S-ligated zinc center, even in alcohol solution, (2) the inclusion of a single internal hydrogen bond donor, characterized by a heteroatom distance of approximately 2.80-2.95 A, produces subtle structural perturbations in N/S-ligated zinc alcohol, formamide, or sulfoxide complexes, (3) the heteroatom distance of a secondary hydrogen-bonding interaction involving the oxygen atom of a zinc-coordinated alcohol, formamide, and sulfoxide ligand is reduced with increasing donicity of the exogenous ligand, and (4) formamide displacement on a N/S-ligated zinc center is rapid, regardless of the presence of an internal hydrogen bond donor. These results provide initial insight into the chemical factors governing the binding of a neutral oxygen donor to a N/S-ligated zinc center. 相似文献
988.
[chemical reaction: see text]. A stereoselective total synthesis of the visual pigment A2E has been achieved with use of palladium-catalyzed cross-coupling reactions in all key steps: a regioselective Suzuki or Negishi coupling of 2,4-dibromopyridine, a Sonogashira reaction, and a double Stille cross-coupling to complete the bispolyenyl skeleton. 相似文献
989.
Agnieszka J. Rybarczyk‐Pirek Magdalena Maecka Sawomir J. Grabowski Jolanta Nawrot‐Modranka 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):o405-o406
In (E)‐3‐{[(diphenoxyphosphoryl)methylhydrazono]methyl}‐4H‐1‐benzopyran‐4‐one, C23H19N2O5P, the benzopyran–methylhydrazone moiety is planar and the two phenoxy phenyl rings are inclined at angles of 21.29 (6) and 89.33 (5)°. Weak C—H?O and C—H?N intramolecular interactions exert some influence on the planarity and orientation of that moiety. 相似文献
990.
Stanislaw Boryczka Magdalena Rudnik Andrzej Malankiewicz 《Journal of heterocyclic chemistry》1996,33(1):145-149
Starting from the reaction of thioquinanthrene 1 with sodium methoxide followed by the reaction with α,ω-dihalogenoalkanes, title bis-methoxy oligomers 4a-c with four 3,4-quinolinediyl units were prepared (40–91%). Acid catalysed hydrolysis of methoxy groups in 4a-c gave tetramers 5a-c (46–94%) with two 4(1H)-quinolinone functions. The reactions of bis-quinolinones 5a-c with phosphoryl chloride in DMF run as deoxo-chlorination and afforded tide dichlorotetramers 6a-c (51–66%) with 4-chloroquinolinyl groups. The treatment of bis-methoxy tetramers 4a -c with boiling phosphoryl chloride led to title α,ω-bis(4-chloro-3-quinolinylthio)alkanes 7a-c (52–56%) and thioquinanthrene (65–70%). 相似文献