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31.
Bionanocomposites based on the association between biological polymers and inorganic colloids are an emerging class of materials, with main applications in biotechnology and biomedicine. They combine the chemical diversity, hierarchical structure, and biocompatibility of natural biomacromolecules with the robustness and functionality of mineral phases. In particular, biopolymer hydrogels can act as templates and/or host matrices for nanoparticles to design bionanocomposites with tailored optical, conductive, magnetic, mechanical, and bioactive properties. This review presents the key concepts on which such materials are currently designed, in terms of chemistry and physics. Specific examples are provided to illustrate the importance of the bio‐organic/inorganic interface on the final properties of the composite structures. It is finally suggested that bionanocomposites have a major role to play for the development of green materials and bio‐responsive devices. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
32.
Emmanuelle Lipka Sa?d Yous Christophe Furman Pascal Carato Carole Deghaye Jean-Paul Bonte Claude Vaccher 《Chromatographia》2012,75(7-8):337-345
In the present study, baseline separation of the enantiomers of 16 β-carboline derivatives was successfully achieved using both capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) techniques in short run times (<15?min) and thus permit the determination of enantiomeric excess. In HPLC methodology, cellulose chiral stationary phase (Chiralcel OD-H) was used with a binary mobile phase constituted of n-hexane/ethanol 85/15 leading to a resolution factor of 12.6 in 15?min. Preparative HPLC allowed to obtain pure enantiomers of two compounds. In CE, chiral selectivity was developed with an in-capillary stacking strategy using anionic (highly sulfated-γ) cyclodextrins 5% (w/v) as chiral selectors and a 60?mM phosphate buffer (pH 2.5) resulting in a resolution of 10.26 in 14?min of analysis. The analytical characteristics of the two developed methods were studied in terms of repeatability, limits of detection and limits of quantification showing their suitability to be extended to all the other molecules. 相似文献
33.
Allen CM Langlois R Sharman WM La Madeleine C Van Lier JE 《Photochemistry and photobiology》2002,76(2):208-216
Photodynamic therapy (PDT) is a promising treatment modality that has recently been accepted in clinics as a curative or palliative therapy for cancer and other nonmalignant conditions. Phthalocyanines (Pc) are attractive photosensitizers for PDT because of their enhanced photophysical and photochemical properties. The overall charge and solubility of Pc play a major role in their potential usefulness for PDT. A series of amphiphilic derivatives of tetrasulfonated aluminum Pc (AlPcS4) was prepared by substituting one of the four sulfonate groups with aliphatic side chains of 4, 8, 12 and 16 carbon atoms. The photodynamic properties of the derivatives were compared with those of AlPcS4 and the adjacent disulfonated aluminum Pc. Parameters studied included reversed-phase high-performance liquid chromatography (HPLC) retention times, capacity to generate singlet oxygen (1O2), in vitro cell uptake and phototoxicity, as well as PDT response of transplantable EMT-6 tumors in mice. The monomerized AlPcS4 derivatives showed similar or higher capacities to generate 1O2 as compared with the parent AlPcS4 as measured from relative L-tryptophan photooxidation yields. A549 cell uptake of the AlPcS4 derivatives decreased in the following order: AlPcS4(C16) > AlPcS4(C12) > AlPcS4(C8) > AlPcS4(C4). Human low-density lipoprotein at high concentrations (40 micrograms/mL) completely prevented uptake, whereas at 4 micrograms/mL uptake was decreased for the more lipophilic compounds and yet remained unaffected for the more hydrophilic dyes. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, A549 cell survival was assessed; it showed that photocytotoxic activity varied directly with the HPLC retention times, i.e. more hydrophilic compounds were less phototoxic. As 1O2 yields were similar for the four substituted AlPcS4 derivatives, it was postulated that the increased cytotoxic activity was caused by enhanced subcellular localization as a result of the long aliphatic side chains. These amphiphilic compounds proved to be photodynamically potent against the EMT-6 mouse mammary tumor model implanted in Balb/c mice. At dye doses of 0.2 mumol/kg and a fluence of 400 J/cm2 complete tumor regression was observed with no morbidity. The substitution of AlPcS4 with long aliphatic chains on the macrocycle greatly enhances its photodynamic efficacy both in vitro and in vivo. 相似文献
34.
Baffert C Collomb MN Deronzier A Pécaut J Limburg J Crabtree RH Brudvig GW 《Inorganic chemistry》2002,41(6):1404-1411
Two new terpyridine dimanganese oxo complexes [Mn(2)(III,IV)(mu-O)(2)(terpy)(2)(CF(3)CO(2))(2)](+) (3) and [Mn(2)(III,III)(mu-O)(terpy)(2)(CF(3)CO(2))(4)] (4) (terpy = 2,2':6,2' '-terpyridine) have been synthesized and their X-ray structures determined. In contrast to the corresponding mixed-valent aqua complex [Mn(2)(III,IV)(mu-O)(2)(terpy)(2)(H(2)O)(2)](3+) (1), the two Mn atoms in 3 are not crystallographically equivalent. The neutral binuclear monooxo manganese(III,III) complex 4 exhibits two crystallographic forms having cis and trans configurations. In the cis complex, the two CF(3)CO(2)(-) ligands on each manganese adopt a cis geometry to each other; one CF(3)CO(2)(-) is trans to the oxygen of the oxo bridge while the second is cis. In the trans complex, the two coordinated CF(3)CO(2)(-) have a trans geometry to each other and are cis to the oxo bridge. The electrochemical behavior of 3 in organic medium (CH(3)CN) shows that this complex could be oxidized into its corresponding stable manganese(IV,IV) species while its reduced form manganese(III,III) is very unstable and leads by a disproportionation process to Mn(II) and Mn(IV) complexes. Complex 4 is only stable in the solid state, and it disproportionates spontaneously in CH(3)CN solution into the mixed-valent complex 3 and the mononuclear complex [Mn(II)(terpy)(2)](2+) (2), thereby preventing the observation of its electrochemical behavior. 相似文献
35.
Nanoscale energetic materials 总被引:1,自引:0,他引:1
Carole Rossi 《Journal of Physics and Chemistry of Solids》2010,71(2):57-7447
36.
37.
Mycothiol is a low-molecular weight thiol produced by actinomycetes that serves to protect these organisms from oxidative stress and alkylating agents. We report the total synthesis of mycothiol bimane (1) which is a commonly isolated derivative of mycothiol. The synthesis confirms the original structure assignment and unambiguously establishes the absolute stereochemistry of mycothiol to be 1-d-myo-inosityl 2-deoxy-2-(N-acetamido-l-cysteinamido)-alpha-d-glucopyranoside. 相似文献
38.
A simple and robust method for determining the relative orientations of covalently linked protein domains using conjoined rigid body/torsion angle dynamics simulated annealing on the basis of residual dipolar couplings is presented. In this approach each domain is treated as a rigid body and the relevant degrees of conformational freedom are restricted to the backbone torsion angles (phi, psi) of the linker between the domains. By this means translational information afforded by the presence of an intact linker is preserved. We illustrate this approach using the domain-swapped dimer of the HIV-inactivating protein cyanovirin-N as an example. 相似文献
39.
[reaction: see text] The addition of nucleophiles to 3-substituted pyridinium salts prepared from N-methylbenzamide and various pyridines has been investigated. Good to excellent regioselectivities favoring the 2,3-disubstituted 1,2-dihydropyridines were observed. The resulting 1,2-dihydropyridines led to the corresponding 2,3-disubstituted pyridines upon treatment with Mn(OAc)3/NaIO4. This methodology was also successfully applied to the enantioselective syntheses of (-)-L-733,061 and (-)-CP-99,994, two members of a new class of highly potent, nonpeptide, Substance P antagonists. 相似文献
40.
Plane-wave density functional theory has been applied to determine the strengths of hydrogen bonds in the phase I crystal structures of ammonia and urea. For ammonia, each component of the trifurcated hydrogen bond has been found to be almost as strong as a standard N-H.N interaction, and for urea the strengths of the two different N-H.O interactions have been determined by a quantum mechanical technique for the first time. 相似文献