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41.
J. Mika 《Fresenius' Journal of Analytical Chemistry》1929,78(7-8):268-297
Ohne Zusammenfassung 相似文献
42.
Anne Vuorema Mika Sillanpää Liza Rassaei Matthew J. Wasbrough Karen J. Edler Wim Thielemans Sara E. C. Dale Simon Bending Daniel Wolverson Frank Marken 《Electroanalysis》2010,22(6):619-624
A novel way to produce ultrathin transparent carbon layers on tin‐doped indium oxide (ITO) substrates is developed. The ITO surface is coated with cellulose nanofibrils (from sisal) via layer‐by‐layer electrostatic binding with poly(diallyldimethylammonium chloride) or PDDAC acting as the binder. The cellulose nanofibril‐PDDAC composite film is then vacuum‐carbonised at 500 °C. The resulting carbon films are characterised by atomic force microscopy (AFM), small angle X‐ray scattering (SAXS), wide‐angle X‐ray scattering (WAXS), and Raman methods. Smooth carbon films with good adhesion to the ITO substrate are formed. The electrochemical characterisation of the carbon films is based on the oxidation of hydroquinone and the reduction of benzoquinone in aqueous phosphate buffer media. A modest effect of the cellulose nanofibril‐PDDAC film on the rate of electron transfer is observed. The effect of the film on the rate of electron transfer after carbonisation is more dramatic. For a 40‐layer cellulose nanofibril‐PDDAC film after carbonisation a two‐order of magnitude change in the rate of electron transfer occurs presumably due to a better interaction of the hydroquinone/benzoquinone system with the electrode surface. 相似文献
43.
Mika Mahosenaho Felice Caprio Laura Micheli Adama M. Sesay Giuseppe Palleschi Vesa Virtanen 《Mikrochimica acta》2010,170(3-4):243-249
A disposable tri-enzymatic biosensor is presented for the determination of α-amylase in human saliva. It is based on the quantity of maltose generated by hydrolysis of maltopentose in the presence of salivary α-amylase. The biosensor is fabricated by co-immobilization of the enzymes α-glucosidase, glucose oxidase, and mutarotase on screen-printed electrodes modified with Prussian Blue. The assay can be performed with a “drop” of sample, this allowing for ease and simplicity. A linear relationship is found for the range from 5 to 250 units per mL, with an LOD of 5 units per mL. The biosensor is stable for at least one month and over this time retains 80% of its original activity. The system was then evaluated for matrix effects of human saliva and compared to a spectrometric method using a commercially available kit. 相似文献
44.
Leo Syrjänen Martti Tolvanen Mika Hilvo Ayodeji Olatubosun Alessio Innocenti Andrea Scozzafava Jenni Leppiniemi Barbara Niederhauser Vesa P Hytönen Thomas A Gorr Seppo Parkkila Claudiu T Supuran 《BMC biochemistry》2010,11(1):1-13
Background
The β-carbonic anhydrase (CA, EC 4.2.1.1) enzymes have been reported in a variety of organisms, but their existence in animals has been unclear. The purpose of the present study was to perform extensive sequence analysis to show that the β-CAs are present in invertebrates and to clone and characterize a member of this enzyme family from a representative model organism of the animal kingdom, e.g., Drosophila melanogaster.Results
The novel β-CA gene, here named DmBCA, was identified from FlyBase, and its orthologs were searched and reconstructed from sequence databases, confirming the presence of β-CA sequences in 55 metazoan species. The corresponding recombinant enzyme was produced in Sf9 insect cells, purified, kinetically characterized, and its inhibition was investigated with a series of simple, inorganic anions. Holoenzyme molecular mass was defined by dynamic light scattering analysis and gel filtration, and the results suggested that the holoenzyme is a dimer. Double immunostaining confirmed predictions based on sequence analysis and localized DmBCA protein to mitochondria. The enzyme showed high CO2 hydratase activity, with a kcat of 9.5 × 105 s-1 and a kcat/KM of 1.1 × 108 M- 1s- 1. DmBCA was appreciably inhibited by the clinically-used sulfonamide acetazolamide, with an inhibition constant of 49 nM. It was moderately inhibited by halides, pseudohalides, hydrogen sulfide, bisulfite and sulfate (KI values of 0.67 - 1.36 mM) and more potently by sulfamide (KI of 0.15 mM). Bicarbonate, nitrate, nitrite and phenylarsonic/boronic acids were much weaker inhibitors (KIs of 26.9 - 43.7 mM).Conclusions
The Drosophila β-CA represents a highly active mitochondrial enzyme that is a potential model enzyme for anti-parasitic drug development. 相似文献45.
Combined DFT calculations and UV-vis-NIR, ESR, and SQUID measurements revealed that the ground-state electronic structure of a linear π-conjugated oligomer dication composed of two pyrrole and six or seven thiophene rings and methylthio end-capping units is dominated by a singlet biradical character. 相似文献
46.
47.
Noriko Hata Shiho Hieda Mika Yamada Rie Yasui Hideki Kuramitz Shigeru Taguchi 《Analytical sciences》2008,24(7):925-928
The formation of a liquid organic ion associate in an aqueous sample was applied to the concentration and determination of cadmium in environmental water samples. Cadmium was converted into a complex with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol (5-Br-PAPS) in a 40-mL sample solution, and was extracted into a liquid ion associate of phenolsulfonate and benzethonium during phase formation. More than 400-fold enrichment was easily attained by this technique, because the volume of the liquid organic phase formed was very small, ca. 2 microL. After dilution of the organic phase with a small volume of 2-methoxyethanol, the cadmium in the solution was determined by GF-AAS. The detection limit was 0.09 ng/L (3sigma(b)). This method was applied to the determination of cadmium in river water and seawater. 相似文献
48.
Mika Seppälä 《Discrete and Computational Geometry》1994,11(1):65-81
In this paper we derive a numerical method which allows us to compute periods of differentials on areal algebraic curve with real points. This leads to an algorithm which can be implemented on a computer and can be used to study the Torelli mapping numerically.
Dedicated to the memory of Mario Raimondo
This work was supported by the EC Science Plan Contract No. SC1*-CT91-0716 and the Academy of Finland. 相似文献
49.
Sur les immeubles triangulaires et leurs automorphismes 总被引:1,自引:0,他引:1
Résumé Les travaux de J. Tits ont conduit à la classification complète des immeubles euclidiens de dimension supérieure ou égale
à 3. L’ensemble de ces immeubles à isomorphisme près est dénombrable et paramétré par les corps locaux qui leur correspondent.
Dans cet article nous nous intéressons aux immeubles triangulaires, qui sont euclidiens de dimension 2 et pour lesquelles
une paramétrisation analogue est impossible. Nous construisons une lamination Λ sur un espace topologique localement compact
séparé, dont l’espace des feuilles est l’ensemble des immeubles triangulaires à isomorphisme près. On considère ainsi les
immeubles triangulaires comme points d’un espace dont Λ est une désingularisation naturelle. Nous établissons des résultats
de chirurgie sur les immeubles triangulaires à données locales fixées. Ils entra?nent par exemple que Λ est topologiquement
transitive. Nous montrons qu’un immeuble triangulaire générique au sens de Baire a un groupe d’automorphismes trivial et qu’il
contient toutes les géométries locales possibles. L’espace des immeubles triangulaires à isomorphisme près est un nouvel exemple
d’espace non commutatif.
Le second auteur a été en partie financé par JSPS. 相似文献
50.
Noora Ristolainen Ulla Vainio Santeri Paavola Mika Torkkeli Ritva Serimaa Jukka Seppl 《Journal of Polymer Science.Polymer Physics》2005,43(14):1892-1903
The properties of polypropylene composites can be tailored through the use of nanoclay fillers. The effectiveness of a metallocene‐catalyzed hydroxyl‐functional polypropylene in the compatibilization of polypropylene layered nanosilicate composites was studied, and the results were compared with those for a commercial maleic anhydride functionalized polypropylene. Polypropylene/organoclay nanocomposites were prepared by melt blending, and two polypropylene/compatibilizer/organoclay ratios, 90/5/5 and 70/20/10, were characterized. The organomodification of the clay was carried out with octadecylamine and N‐methylundecenylamine. The structure of the layered silicate was studied by transmission electron microscopy, wide‐angle X‐ray scattering, and small‐angle X‐ray scattering. The fracture surfaces of the composites and thus the efficiency of the compatibilizers to penetrate the galleries of the organoclays were characterized by scanning electron microscopy, and the melt viscosity was studied by stress‐controlled rotational rheometry. The nanostructure was observed with both alkyl amines used for intercalation. The fillers facilitated the processability of all the composites, consisting of equal amounts of compatibilizer and organoclay filler and, in some of the composites, containing twice as much compatibilizer as organoclay filler. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1892–1903, 2005 相似文献