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61.
Lubineau A Lortat-Jacob H Gavard O Sarrazin S Bonnaffé D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(17):4265-4282
We have recently described the preparation of three building blocks for the combinatorial synthesis of heparan sulfate (HS) fragments. Herein we show that one of these building blocks (disaccharide 4) allows the preparation, in high yields and with total alpha stereoselectivity, of tetra-, hexa- and octasaccharides from the heparin (HP) regular region, by using 2+2, 2+4 and 4+4 glycosylation strategies, respectively. These oligosaccharides were processed into sulfated derivatives bearing an allyl moiety in the anomeric position. The UV-promoted conjugation of these compounds with alpha,omega-bis(thio)poly(ethylene glycol) spacers of three different lengths allowed us to prepare nine benzylated glycoconjugates. After final deprotection, the glycoconjugates 1 a-c, 2 a-c and 3 a-c were obtained and their ability to inhibit the interaction between IFN-gamma and HP was tested by using surface plasmon resonance detection. Compound 3 b, containing two HP octasaccharides linked by a 50-A linker was able to inhibit the IFN-gamma/HP interaction with an IC(50) value of approximately 35 nM. In addition, the nine glycoconjugates were perfect tools in the study to ascertain the topology of the IFN-gamma binding site on HS. Compounds 1 a-c, 2 a-c and 3 a-c, by mimicking the alternating sulfated and nonsulfated regions found in HS, thus comprise the first example of a library of synthetic HS mimetics giving access to the "second level of molecular diversity" found in HS. 相似文献
62.
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64.
Jean Roncali Christine Thobie-gautier Hugues Brisset 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):513-514
Abstract A new synthetic approach for the reduction of the bandgap of molecular and polymeric conjugated systems is presented. 相似文献
65.
Ming Li Maoyu Shang Hugues F. Duval W. Robert Scheidt 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):1206-1207
The precise structure of the title compound, [Fe2O(C44H24Br4N4)2]·2CH2Cl2, is reported. The Fe—N distances are non‐equivalent in pairs because of the asymmetric peripheral substitution; the values are 2.098 Å to the brominated rings and 2.041 Å to the other two rings. The Fe—O bond distance is 1.7583 (4) Å. The molecule has required twofold symmetry so that there is one unique porphyrin macrocycle and one Fe—O bond length in contrast to a previous report on the same species. 相似文献
66.
Jean-Louis Santailler Claire Audoin Guy Chichignoud Rémy Obrecht Belkhiri Kaouache Pascal Marotel Denis Pelenc Stéphane Brochen Jérémy Merlin Isabelle Bisotto Carole Granier Guy Feuillet François Levy 《Journal of Crystal Growth》2010,312(23):3417-3424
A chemically assisted vapour phase transport (CVT) method is proposed for the growth of bulk ZnO crystals. Thermodynamic computations have confirmed the possibility of using CO as a sublimation activator for enhancing the sublimation rate of the feed material in a large range of pressures (10−3 to 1 atm) and temperatures (800–1200 °C). Growth runs in a specific and patented design yielded single ZnO crystals up to 46 mm in diameter and 8 mm in thickness, with growth rates up to 400 μm/h. These values are compatible with an industrial production rate. N type ZnO crystals (μ=182 cm2/(V s) and n=7 1015 cm−3) obtained by this CVT method (Chemical Vapour Transport) present a high level of purity (10–30 times better than hydrothermal ZnO crystals), which may be an advantage for obtaining p-type doped layers ([Li] and [Al] <10+15 cm−3). Structural (HR-XRD), defect density (EPD), electrical (Hall measurements) and optical (photoluminescence) properties are presented. 相似文献
67.
Normal-phase HPLC and hydrophilic interaction HPLC (HILIC) were investigated for the separation of selenometabolites in a water extract of Se-rich yeast prior to their detection by ICP-MS and identification by electrospray MS/MS. The targeted fraction was a low-abundant fraction co-eluting with salt and sulfur analogues in size-exclusion chromatography which has so far been inaccessible to Se speciation studies. The optimization of the separation conditions resulted in the highest separation efficiency when HILIC was used and elution was carried out isocratically with a low concentration ammonium acetate buffer (1 mM ammonium acetate/10 mM acetic acid) in 80% acetonitrile. Out of 15 peaks observed with the Se-specific ICP-MS detection 12 was identified by electrospray Q-TOF MS/MS (2,3-dihydroxypropionyl (DHP)-Se-methylselenocysteine [M+H]+: 272, Se-methyl-γ-glutamyl-selenocysteinylglycine dioxide [M+H]+: 402, γ-glutamyl-Se-methylselenocysteine [M+H]+: 313; isomers of γ-glutamylselenocystathionine [M+H]+: 400; Se-methyl-selenoglutathione [M+H]+: 370, isomers of N-acetylselenocystathionine [M+H]+: 313, 2,3-DHP-selenohomolanthionine [M+H]+: 373, isomers of 2,3-DHP-selenocystathionine [M+H]+: 359, 2,3-DHP-selenolanthionine [M+H]+: 345 and selenohomolanthionine [M+H]+: 285). 相似文献
68.
Cirtiu CM Hassani HO Bouchard NA Rowntree PA Ménard H 《Langmuir : the ACS journal of surfaces and colloids》2006,22(14):6414-6421
The electrocatalytic hydrogenation (ECH) of phenol has been studied using palladium supported on gamma-alumina (10% Pd-Al2O3) catalysts. The catalyst powders were suspended in aqueous supporting electrolyte solutions containing methanol and short-chain aliphatic acids (acetic acid, propionic acid, or butyric acid) and were dynamically circulated through a reticulated vitreous carbon cathode. The efficiency of the hydrogenation process was measured as a function of the total electrolytic charge and was compared for different types of supporting electrolyte and for various solvent compositions. Our results show that these experimental parameters strongly affect the overall ECH efficiency of phenol. The ECH efficiency and yields vary inversely with the quantity of methanol present in the electrolytic solutions, whereas the presence of aliphatic carboxylic acids increased the ECH efficiency in proportion to the chain length of the specific acids employed. In all cases, ECH efficiency was directly correlated with the adsorption properties of phenol onto the Pd-alumina catalyst in the studied electrolyte solution, as measured independently using dynamic adsorption isotherms. It is shown that the alumina surface binds the aliphatic acids via the carboxylate terminations and transforms the catalyst into an organically functionalized material. Temperature-programmed mass spectrometry analysis and diffuse-reflectance infrared spectroscopy measurements confirm that the organic acids are stably bound to the alumina surface below 200 degrees C, with coverages that are independent of the acid chain length. These reproducibly functionalized alumina surfaces control the adsorption/desorption equilibrium of the target phenol molecules and allow us to prepare new electrocatalytic materials to enhance the efficiency of the ECH process. The in situ grafting of specific aliphatic acids on general purpose Pd-alumina catalysts offers a new and flexible mechanism to control the ECH process to enhance the selectivity, efficiency, and yields according to the properties of the specific target molecule. 相似文献
69.
Fibronectin (Fn), a high molecular weight glycoprotein, is a central element of extracellular matrix architecture that is involved in several fundamental cell processes. In the context of bone biology, little is known about the influence of the mineral surface on fibronectin supramolecular assembly. We investigate fibronectin morphological properties induced by its adsorption onto a model mineral matrix of hydroxyapatite (HA). Fibronectin adsorption onto HA spontaneously induces its aggregation and fibrillation. In some cases, fibronectin fibrils are even found connected into a dense network that is close to the matrix synthesized by cultured cells. Fibronectin adsorption-induced self-assembly is a time-dependant process that is sensitive to bulk concentration. The N-terminal domain of the protein, known to be implicated in its self-association, does not significantly inhibit the protein self-assembly while increasing ionic strength in the bulk alters both aggregation and fibrillation. The addition of a non-ionic surfactant during adsorption tends to promote aggregation with respect to fibrillation. Ultimately, fibronectin fibrils appear to be partially structured like amyloid fibrils as shown by thioflavine T staining. Taken together, our results suggest that there might be more than one single organization route involved in fibronectin self-assembly onto hydroxyapatite. The underlying mechanisms are discussed with respect to Fn conformation, Fn/surface and Fn/Fn interactions, and a model of fibronectin fibrillogenesis onto hydroxyapatite is proposed. 相似文献
70.
Binet C Bourrier D Dilhan M Estève D Ferrère S Garrigue JC Granier H Lattes A Gué AM Mauzac M Mingotaud AF 《Talanta》2006,69(3):757-762
Liquid crystalline thin films elastomers that are able to bind pesticides have been developed. The synthesis involves grafting mesogen and crosslinkable groups on a polysiloxane chain in the presence of a template molecule. The molecular imprinted material is obtained after thin film deposition, UV crosslinking and washing. Experiments of readsorption of pesticide are presented. Development of a multisensor platform based on thermal and capacitive sensors is described and tests of deposition of the polymer film are presented. 相似文献