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1.
In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple approach to study the full 3D morphology of phase‐separated blends, taking advantage of the possibility to selectively dissolve the different components is introduced. This method is applied in combination with AFM to investigate a blend of a semiconducting and ferroelectric polymer typically used as active layer in organic ferroelectric resistive switches. It is found that the blend consists of a ferroelectric matrix with three types of embedded semiconductor domains and a thin wetting layer at the bottom electrode. Statistical analysis of the obtained images excludes the presence of a fourth type of domains. The criteria for the applicability of the presented technique are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1231–1237  相似文献   
2.
    
Zusammenfassung Es wird über die Störung der emissionsspektrometrischen Analyse von mineralischen Stoffen durch die Kombination einer Bezugs- und Analysenlinie mit unterschiedlichen Konzentrationsempfindlichkeiten berichtet. Die Störung kann beseitigt werden, wenn die Summe der Atomkonzentrationen der metallischen Komponenten im Aufschluß konstant gehalten wird. Das führt zu einer Variation der Verhältnisse Probe-/Puffermenge, durch die flüchtige Bestandteile und die Summen der Atomkonzentrationen der Proben berücksichtigt werden.
Summary When mineral samples are being analysed by an optical emission method different concentration sensitivities of the element and internal standard lines give rise to a systematic error. To eliminate this error it is necessary to maintain the sum of atomic concentrations of the metallic constituents in the fuse constant by varying the ratio sample size/fluxing agent according to volatile components and the sums of atomic concentrations of the samples.


Herrn Dr. O. G. Koch danken wir für freundliche Diskussionen, Herrn L. Krämer für die sorgfältige Ausführung der Versuche.  相似文献   
3.
Summary The relationships between Quality, Quality Assurance and Third Party Approval by accreditation based on formal application of EN 29002, EN 45001 and ISO Guide 25 are briefly outlined for analytical chemical laboratories working in the non-regulated area. The roles of human beings in laboratories and accreditation bodies are discussed and recommendations are made on how to minimize friction during accreditation processes. The structures of the European Accreditation Systems are reviewed and the efforts towards mutual recognition of the national accreditation bodies are described and critically assessed. The lack of competition based on free market conditions in the framework of company law is deplored. The assessment of laboratory systems, rather than assessing the activity of laboratories against technical standards, is recommended (unless it is otherwise requested). The beneficial effects of the process of accreditation on competence and quality of the activity of the laboratory are emphasized.  相似文献   
4.
    
Zusammenfassung Zur Vorbereitung von Proben von Ferrolegierungen für die Röntgenfluorescenzspektrometrie werden diese mittels nasser oder trockener chemischer Aufschlüsse im Platintiegel isoformiert. Danach wird mit Natriumtetraborat aufgeschlossen. Die Schmelze wird auf vorerhitzte Nickelscheiben gegossen. Sie verteilt sich in dünner Schicht über die Oberfläche der Metallscheiben und bildet eine ebene Fläche, die für die Analyse benutzt wird.Die mit dem Verfahren erzielbare Genauigkeit (rel. Standardabweichung) liegt für Gehalte von 50–85% zwischen 0,10 und 0,15%.
On the preparation of samples of ferro alloys for X-ray fluorescence analysis
The samples are submitted to a dry or wet chemical treatment in a platinum crucible for homogenisation and are fused with sodium tetraborate. The melt is poured on preheated nickel disks where it spreads in a thin layer forming an even surface which is used for analysis. The relative standard deviation obtained by this method is 0.10 to 0.15% for contents of 50 to 85%.


Herrn R. Klein danke ich für sorgfältige Ausführung der langwierigen experimentellen Arbeiten.  相似文献   
5.
Based on the accepted definition of accuracy in analytical chemistry the distinction between accuracy and trueness is discussed and the superiority of trueness to accuracy in the hierarchy of terms is stressed.An updated model describing trueness of an analytical result is proposed and the process of analytical recognition is also considered. This model allows for determination of trueness from the repeatability of the method when applied under well defined working conditions, and thereby complies with the legal criteria of quality assurance. A strict division of analytical working methods is made:
–  the generation of a true value by primary calibration applying complete synthesis or reconstitution of the sample portion and then establishing secondary reference samples, deliberately adapted to the analytical problem. This is distinguished from
–  the formalised application of these reference samples, in order to transfer the trueness from the reference to the analytical sample.
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6.
We have quantum chemically analyzed element−element bonds of archetypal HnX−YHn molecules (X, Y=C, N, O, F, Si, P, S, Cl, Br, I), using density functional theory. One purpose is to obtain a set of consistent homolytic bond dissociation energies (BDE) for establishing accurate trends across the periodic table. The main objective is to elucidate the underlying physical factors behind these chemical bonding trends. On one hand, we confirm that, along a period (e. g., from C−C to C−F), bonds strengthen because the electronegativity difference across the bond increases. But, down a period, our findings constitute a paradigm shift. From C−F to C−I, for example, bonds do become weaker, however, not because of the decreasing electronegativity difference. Instead, we show that the effective atom size (via steric Pauli repulsion) is the causal factor behind bond weakening in this series, and behind the weakening in orbital interactions at the equilibrium distance. We discuss the actual bonding mechanism and the importance of analyzing this mechanism as a function of the bond distance.  相似文献   
7.
Introducing solubilizing α-branched alkyl chains on a poly(diketopyrrolopyrrole-alt-terthiophene) results in a dramatic change of the structural, optical, and electronic properties compared to the isomeric polymer carrying β-branched alkyl side chains. When branched at the α-position the alkyl substituent creates a steric hindrance that reduces the tendency of the polymer to π–π stack and endows the material with a much higher solubility in common organic solvents. The wider π–π stacking and reduced tendency to crystallize, evidenced from grazing-incidence wide-angle X-ray scattering, result in a wider optical band gap in the solid state. In solar cells with a fullerene acceptor, the α-branched isomer affords a higher open-circuit voltage, but an overall lower power conversion efficiency as a result of a too well-mixed nanomorphology. Due its reduced π–π stacking, the α-branched isomer fluoresces and affords near-infrared light-emitting diodes emitting at 820 nm.  相似文献   
8.
It remains a challenge to precisely tailor the morphology of polymer monolayers to control charge transport. Herein, the effect of the dissolution temperature (Tdis) is investigated as a powerful strategy for morphology control. Low Tdis values cause extended polymer aggregation in solution and induce larger nanofibrils in a monolayer network with more pronounced π–π stacking. The field‐effect mobility of the corresponding monolayer transistors is significantly enhanced by a factor of four compared to devices obtained from high Tdis with a value approaching 1 cm2 V?1 s?1. Besides that, the solution kinetics reveal a higher growth rate of aggregates at low Tdis, and filtration experiments further confirm that the dependence of the fibril width in monolayers on Tdis is consistent with the aggregate size in solution. The generalizability of the Tdis effect on polymer aggregation is demonstrated using three other conjugated polymer systems. These results open new avenues for the precise control of polymer aggregation for high‐mobility monolayer transistors.  相似文献   
9.
We introduce monosaccharides as versatile water‐soluble units to compatibilise supramolecular polymers based on the benzene‐1,3,5‐tricarboxamide (BTA) moiety with water. A library of monosaccharide‐based BTAs is evaluated, varying the length of the alkyl chain (hexyl, octyl, decyl and dodecyl) separating the BTA and saccharide units, as well as the saccharide units (α‐glucose, β‐glucose, α‐mannose and α‐galactose). In all cases, the monosaccharides impart excellent water compatibility. The length of the alkyl chain is the determining factor to obtain either long, one‐dimensional supramolecular polymers (dodecyl spacer), small aggregates (decyl spacer) or molecularly dissolved (octyl and hexyl) BTAs in water. For the BTAs comprising a dodecyl spacer, our results suggest that a cooperative self‐assembly process is operative and that the introduction of different monosaccharides does not significantly change the self‐ assembly behaviour. Finally, we investigate the potential of post‐assembly functionalisation of the formed supramolecular polymers by taking advantage of dynamic covalent bond formation between the monosaccharides and benzoxaboroles. We observe that the supramolecular polymers readily react with a fluorescent benzoxaborole derivative permitting imaging of these dynamic complexes by confocal fluorescence microscopy.  相似文献   
10.
Zusammenfassung Zur Bestimmung von Niob unter 0,06% und Zirkonium unter 0,1% in unlegiertem Stahl wird die Hauptmenge Eisen mit Methylisobutylketon aus 7 N HCl-Lösung abgetrennt. Niob wird bei pH 5,8 durch Komplexbildung mit 4-(2-Pyridylazo)-resorcin und Zirkonium bei pH 5,2 mit Brenzcatechinviolett bestimmt. Die Störungen durch andere Ionen werden durch Zugabe von ÄDTE verhindert und bei der Zirkoniumbestimmung teilweise durch Entfärben des gebildeten Komplexes mit Fluorwasserstoffsäure umgangen. Die erzielte Genauigkeit und der erforderliche Zeitbedarf sind in den Tabellen angegeben.
Summary For the determination of niobium below 0.06% and of zirconium below 0.1% in plain carbon steels most of the iron is extracted by means of MIBK from 7 N HCl solution. Niobium is determined at pH 5.8 with 4-(2-pyridylazo)-resorcinol and zirkonium at pH 5.2 with pyrocatechol violet by the formation of complexes. Interferences from other ions are prevented by the addition of EDTA and in the case of zirconium farther avoided by bleaching the complex with hydrofluoric acid. The accuracy obtained and the time required are reported in the tables.
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