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91.
Ryan M. Rich Mark Mummert Zygmunt Gryczynski Julian Borejdo Thomas Just Sørensen Bo W. Laursen Zeno Foldes-Papp Ignacy Gryczynski Rafal Fudala 《Analytical and bioanalytical chemistry》2013,405(14):4887-4894
Fluorescence correlation spectroscopy (FCS) is a frequently applied technique that allows for the precise and sensitive analysis of molecular diffusion and interactions. However, the potential of FCS for in vitro or ex vivo studies has not been fully realized due in part to artifacts originating from autofluorescence (fluorescence of inherent components and fixative-induced fluorescence). Here, we propose the azadioxatriangulenium (ADOTA) dye as a solution to this problem. The lifetime of the ADOTA probe, about 19.4 ns, is much longer than most components of autofluorescence. Thus, it can be easily separated by time-correlated single-photon counting methods. Here, we demonstrate the suppression of autofluorescence in FCS using ADOTA-labeled hyaluronan macromolecules (HAs) with Rhodamine 123 added to simulate diffusing fluorescent background components. The emission spectrum and decay rate of Rhodamine 123 overlap with the usual sources of autofluorescence, and its diffusion behavior is well known. We show that the contributions from Rhodamine 123 can be eliminated by time gating or by fluorescence lifetime correlation spectroscopy (FLCS). While the pairing of ADOTA and time gating is an effective strategy for the removal of autofluorescence from fluorescence imaging, the loss of photons leads to erroneous concentration values with FCS. On the other hand, FLCS eliminates autofluorescence without such errors. We then show that both time gating and FLCS may be used successfully with ADOTA-labeled HA to detect the presence of hyaluronidase, the overexpression of which has been observed in many types of cancer. 相似文献
92.
Dawei Jiang Yang He Simone Budow Zygmunt Kazimierczuk Henning Eickmeier Hans Reuter Frank Seela 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(11):o561-o564
The title compound, C9H12N6O3, shows a syn‐glycosylic bond orientation [χ = 64.17 (16)°]. The 2′‐deoxyfuranosyl moiety exhibits an unusual C1′‐exo–O4′‐endo (1T0; S‐type) sugar pucker, with P = 111.5 (1)° and τm = 40.3 (1)°. The conformation at the exocyclic C4′—C5′ bond is +sc (gauche), with γ = 64.4 (1)°. The two‐dimensional hydrogen‐bonded network is built from intermolecular N—H...O and O—H...N hydrogen bonds. An intramolecular bifurcated hydrogen bond, with an amino N—H group as hydrogen‐bond donor and the ring and hydroxymethyl O atoms of the sugar moiety as acceptors, constrains the overall conformation of the nucleoside. 相似文献
93.
St. Chibowski A. Komosa M. Reszka J. Solecki J. Zygmunt 《Journal of Radioanalytical and Nuclear Chemistry》2000,246(1):199-206
A horizontal transport of radionuclides was studied by the analysis of the radioactivity of the surface soil samples from valleys of Wieprz river and its bottom sediments. Natural gamma-isotopes (40K, 238U and 232Th series) antropogenic (134Cs and 137Cs) and alpha-isotopes 238Pu and 239,240Pu were measured. The different kind of bed rock and terrain configuration, influenced the radionuclide transportation from the soil to river bottom sediments. Radioactivity of the sediment samples is definitely lower than the soils. Very strong adsorption of isotopes in soil hinders their horizontal migration. Calculated 238Pu/239,240Pu ratio is characteristic for global fallout and about 90% of the 137Cs comes from Chernobyl. 相似文献
94.
Ji Li Zhuying Wang Ignacy Gryczynski Wlodek Mandecki 《Analytical and bioanalytical chemistry》2010,398(5):1993-2001
The aim of this study is to improve assay sensitivity in common solid-phase bioassay configurations as the result of using
silver nanoparticles. The solid phase was provided by numerically indexed, silicon-based electronic chips, microtransponders
(p-Chips) that have previously been used in multiplexed assays. Assay configurations investigated included an ELISA-type immunoassay
and a DNA hybridization assay. The surface of p-Chips was derivatized with the silver island film (SIF) and a polymer, and
then characterized with AFM and SEM. Silver nanoparticle sizes were in the range of 100 to 200 nm. Four fluorophores were
tested for fluorescence enhancement; namely, green fluorescent protein, phycoerythrin, Cy3 and Alexa Fluor 555. We consistently
observed significant fluorescence enhancement and sensitivity improvement in the p-Chip-based assays: the sensitivity in the
cytokine IL-6 immunoassay was 4.3 pg/ml, which represented a 25-fold increase over the method not involving a SIF; and 50 pM
in the hybridization assay, a 38-fold increase. The greatest enhancement was obtained for p-Chip surfaces derivatized first
with the polymer and then coated with SIF. In conclusion, we show that the SIF-p-Chip-based platform is a highly sensitive
method to quantify low-abundance biomolecules in nucleic acid-based assays and immunoassays. 相似文献
95.
Dariusz Wyrzykowski Rafa Kruszyski Urszula Kucharska Zygmunt Warnke 《无机化学与普通化学杂志》2006,632(4):624-628
A series of tetrahalogenoferrates(III), [FeBr4?nCln]? (n=0‐4) stabilized with the tetrabutylammonium cation, of general formula [(C4H9)4N][FeBr4?nCln], has been synthesized. The crystal and molecular structure of [(C4H9)4N][FeCl4] was determined. The iron cation adopts slightly distorted tetrahedral coordination with two opposite angles smaller than tetrahedral one, two equal to tetrahedral and two larger than tetrahedral. The bond valences were computed. The total valence of iron atom is equal to 3.08. In the structure can be found only one hydrogen bond C(1)–H···Cl. Except mentioned there are no unusually intermolecular short contacts between ions existing in the structure. All [(C4H9)4N][FeBr4?nCln] (n=0‐4) compounds are isostructural in solid state. On the basis of conductometric measurements, relative stabilities of the anions have been estimated in methanol (MeOH), dimethyl sulfoxide (DMSO), acetone (AC), acetonitrile (AN) and dichloromethane (CH2Cl2) representing both polar (including amphiprotic and aprotic) as well as non‐polar solvents. Further, the dissociation constants of the compounds were calculated from the expanded Pitt's conductivity equation. The results of the conductometric measurements were supported by electronic spectra. 相似文献
96.
Sabato D'Auria Paolo Bazzicalupo Mosé Rossi Ignacy Gryczynski Joseph R. Lakowicz 《Journal of fluorescence》2000,10(1):27-34
ASCUT-1 is a protein found in cuticlin, the insoluble residue of the cuticles of the nematode Ascaris lumbricoides. It contains the CUT-1-like domain which is shared by members of a novel family of components of extracellular matrices. The monomeric form of ASCUT-1 contains a single tryptophan residue. An understanding of the structure-function relationship of the protein under different chemical-physical conditions is of fundamental importance for an understanding of its structure and function in cuticles. In this paper we report the effect of the temperature and sodium dodecyl sulfate on the structural stability of this protein. The structure of the protein was studied in the temperature range 25–85°C in the absence and in the presence of sodium dodecyl sulfate by frequency-domain measurements of the intrinsic fluorescence intensity and anisotropy decays. The time-resolved fluorescence data in the absence of SDS indicated that the tryptophanyl emission decays were well described by a bimodal lifetime distribution, and that the temperature increases resulted in the sharpening and in the shortening of the tryptophanyl lifetime distribution. In the presence of SDS an unimodal fluorescence lifetime distribution as well as a marked decrease in the anisotropy decay values were observed. 相似文献
97.
Zygmunt Zolnierek 《Journal of Physics and Chemistry of Solids》1984,45(5):523-528
A modification of the point charge model is proposed, taking into account the electronegatives of the metal and ligand atoms. On this basis empirical formulas for the effective ligand (L) charge and its distance with respect to the metal (M) origin have been set up. For a VM valent metal atom, surrounded by NL-nearest ligands at distance R0, the respective relations qeff = vM(?L/?M ? 1)/NR0?L/(?L+ ?M) are obtained. When applied to almost forty lanthanide and actinide non-metallic compounds the model shows reasonable agreement with the experimental data available. 相似文献
98.
Summary Presented data give some informations of analytical importance as a result of pulse polarographic investigations of Ge(IV) in KCl solutions within pH range 3–12 at Ge concentration from 1×10–4 to 2.5×10–6 M. It was shown that Ge(IV) can be polarographically active in acidic solution but its reduction interferes with hydrogen gas development. The addition ofp-quinone enables the determination of Ge(IV) without this interfering effect.Suggested explanation of the observed changes in polarographic curves dependent on pH and Ge concentration based on the existence of several polarographically active forms.
Elektroanalytische Bemerkungen zur pulspolarographischen Bestimmung von Ge(IV)
Zusammenfassung Unsere Ergebnisse bieten einige Informationen über die pulspolarographische Bestimmung von Ge(IV) in KCl-Lösungen innerhalb pH 3–12 und bei Ge-Konzentrationen zwischen 10–4 und 2,5×10–6 M. Es wurde gezeigt, daß Ge(IV) in saurer Lösung polarographisch aktiv ist, seine Reduktion aber durch Wasserstoff-Entwicklung gestört wird. Der Zusatz vonp-Chinon beseitigt diese Störung. Die Änderung der polarographischen Kurven je nach Ge-Konzentration und pH beruht vermutlich auf der Existenz verschiedener polarographisch aktiver Formen.相似文献
99.
100.