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1.
We obtain a solution of the DGLAP equation for the gluon at low x first by expanding the gluon in a Taylor series and then using the method of characteristics. We test its validity by comparing
it with that of Glück, Reya and Vogt. The convergence criteria of the approximation used are also discussed. We also calculate
εF
2(x,Q)2/ε In Q
2 using its approximate relations with the gluon distribution at low x. The predictions are then compared with the HERA data. 相似文献
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Summary A diffusive sampler for the large scale routine determination of airborne formaldehyde was developed. Formaldehyde is sampled in a badge-type passive sampler containing a 2,4-dinitrophenylhydrazine-coated filter paper as sampling layer. Formaldehyde is immediately converted to the corresponding hydrazone, which, after desorption with acetonitrile, is separated and quantified by gradient HPLC using UV detection at 345 nm. Calibration was done via an active sampling method and showed an excellent, time- and concentration-independent linear performance of the diffusive samplers. A detection limit of about 0.05 ml/m3·h (ppm·h) and a relative standard deviation of about 10% ensured a good analytical reliability. By testing the influence of air movements at the sampler surface, a minimum air velocity of 10 cm/s was found necessary to ensure representative sampling. 相似文献
6.
H. U. Burger Dipl.-Math. Professor Dr. U. Müller-Funk Professor Dr. H. Witting 《Mathematical Methods of Operations Research》1992,36(2):163-184
Summary There is an abundancy of problems in which no parametric model realistically describes the situation and in which, accordingly, we have to resort to nonparametric methods. As the numerical problems connected with nonparametric tests are becoming less and less important, rank tests, permutation tests and the like are becoming more and more part of the standard armatory of applied statisticians. The lack of tabulated critical values, for instance, should no longer be a serious objection against the use of permutation tests in practice; cf. Edgington (1987).The rationale underlying permutation and rank tests has been outlined in quite a number of text books and papers; cf. Fraser (1957), Lehmann (1959), Hájek-Sidák (1967) or Witting (1970). Roughly speaking, permutation tests are constructibel if the data can be condensed by means of a sufficient and complete statistic allowing for the proper kind of conditioning. Rank tests arise if the underlying problem is invariant with respect to (w.r.t.) a large group of transformations which leads to a maximal invariant statistic consisting of (signed) ranks.Most practical nonparametric problems, however, are too complex to be tractable by just one of those approaches. Many of them, however, can be handled by a combination of both techniques. In this paper we outline the logic underlying that combined reduction method and apply it to construct locally most powerful tests. Moreover, we discuss what we label Hoeffding's transfer problem, i.e. the uniformity aspect of locally most powerful tests with respect to the starting point at the boundary. We are concentrating on the discussion of the nonparametric two-sample location and scale problem. Further important problems are mentioned in Section III.This is a written account of an invited lecture delivered by the third author on occasion of the 14th Symposium über Operations Research, Ulm, September 6–8, 1989. 相似文献
7.
Background
Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH. 相似文献8.
Overtone spectrum of o, m and p-nitrobenzaldehydes and p-chlorobenzaldehyde has been studied in 2000–12000 cm−1 region. Vibrational frequencies and anharmonicity constants for aryl as well as alkyl CH stretch vibrations have been determined.
We have also determined the internuclear distances for the aryl CH bond in the different molecules. The small variation observed
in these distances is an indication of the substitution effect.
It is observed that in the case of p-disubstituted benzens, the shift in aryl CH bond is proportional to sum of the Hammet σ of the substituents. However in the
case of o-disubstituted benzenes it is only 80% of the para-substituted shift. 相似文献
9.
Background
Organic light emitting devices (OLED) are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato)-aluminium(III), known as Alq3, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq3 in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR) is a useful tool for this which can also complement the information obtained with X-ray diffraction studies. 相似文献10.
Zusammenfassung Zur Dimensionierung von Lagerhallen wird ein Irrwanderungs-modell angegeben und ein Verfahren zur vereinfachten Berechnung der zugrunde liegenden Limesverteilung diskutiert.
Summary A stochastic model for planning store-houses is mentioned. A method for the simplified calculation of the corresponding limit distribution is considered.相似文献