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V. G. Dubrovskii V. M. Ustinov A. A. Tonkikh V. A. Egorov G. E. Cirlin P. Werner 《Technical Physics Letters》2003,29(9):721-724
The morphological characteristics of hut-cluster ensembles formed in a Ge/Si(100) heteroepitaxial system have been studied as functions of the substrate surface temperature by theoretical methods and by atomic force microscopy. As the temperature increases from 420 to 500°C, the lateral size of nanoclusters with a square base (grown at the same rate of 0.0345 ML/s to a total coverage of 6.2 ML) grows from 12 to 20 nm, while their number density on the substrate surface drops from 5.6×1010 to 1.5×1010 cm−2. Predictions of a kinetic model are in sufficiently good agreement with the experimental data. 相似文献
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By comparing the experimental data of the Sauter-mean-diameter d 32 and the hold up ? with models from literature, there are presented equations for d 32 and ? for the used conical turbine in gas-liquid systems. The necessary adjustment of the proportionality constants of the literature equations will be explained on the basis of fluiddynamical phenomena. It can be established by fluid-dynamical results of a former study carried out with laser-doppler-anemometry. Coalescence phenomena are taken into account in the model using an analogy to bubble columns. The analogy to bubble columns turns out to be suitable. Arguments for the necessity of considering the local fluiddynamics in the modelling of dispersions are presented. 相似文献
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Maurus Biedermann Konrad Grob Dieter Fr?hlich Werner Meier 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1992,195(5):409-416
Summary On-line coupled liquid chromatography-gas chromatography-flame ionisation detection (LC-GC-FID) enables efficient and unambiguous determination of irradiation for some fat-containing foods (e.g. meat). Other products, however, contain interfering components or are contaminated, e.g., with mineral oil. Since more selective detection by mass spectrometry has limited success, the determination was improved by a more selective isolation of some key components among the fat degradation products, e.g. the dienes or trienes, by LC-LC-GC-FID. Applications are shown for soup mixes, some spices, fish, and shrimps.
Nachweis der Bestrahlung fetthaltiger Lebensmittel durch direkt gekoppelte LC-GC und LC-LC-GC
Zusammenfassung Die Bestrahlung einiger fetthaltiger Lebensmittel, z. B. Fleisch, kann mit direkt gekoppelter LC-GC-FID rationell und eindeutig nachgewiesen werden. In anderen Proben wird die Analyse aber durch Inhaltsstoffe des Produktes oder durch Verunreinigungen (z. B. mit Mineralöl) gestört. Da selektivere Detektion durch Massenspektrqmetrie wenig verspricht, wurde der Nachweis durch selektivere Isolierung von Schlüsselkomponenten unter den Bestrahlungsprodukten, z. B. der Diene oder Triene, mittels LC-LC-GC yerbessert. Anwendungen werden gezeigt für Suppenpulver, einige Gewürze, Fisch und Garnelen.相似文献
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In this paper nucleation of superconductivity in films in investigated numerically for all temperatures. Recent predictions of magnetically enhanced superconductivity, even above the critical temperature, are not confirmed. In a limiting case also the surface critical fieldH
c3 was obtained for all temperatures.Dedicated to Professor L. Tewordt on the occasion of his 65th birthday. 相似文献
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Lilli Heinrich und Werner Baltes 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1987,185(5):362-365
Zusammenfassung In zwei unterschiedlich gerösteten Robustakaffees und vier handelsüblichen Röstkaffees wurden die Phenole in bezug auf Struktur und Quantität untersucht. Nach speziellen Extraktions- und Reinigungsverfahren erfolgte die Identifizierung und Quantifizierung nach gaschromatographischer Trennung der Trimethylsilylether mit Hilfe der GC-MS-Kopplung. Die Gehalte der 35 identifizierten Phenole lagen in einem Bereich von unter 0,1 bis über 1000 mg/kg. 16 Phenole wurden erstmals im Kaffee nachgewiesen.
Herrn Dr. H. Lange zum 60. Geburtstag gewidmet 相似文献
Determination of phenols in coffee
Summary The structure and quantity of phenols, occurring in two different roastedRobusta coffees and in four samples of roast coffee, were investigated. Identification and quantification were carried out after special extraction procedures and clean-up methods by gas chromatography/mass spectrometry. The quantities of 35 phenols investigated ranged from below 0.1 mg/kg to more than 1000 mg/kg. Sixteen phenols were identified in coffee for the first time.
Herrn Dr. H. Lange zum 60. Geburtstag gewidmet 相似文献
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This paper is the second of a series concerned with the penetration and perforation phenomena in two types of propellant and explosive simulant, named Propergol, due to the impact at normal incidence of both blunt and conically-tipped steel strikers. The collision results in fragmentation, plug formation and generation of a cloud of debris that includes particles of measurable dimensions traveling with significant velocities. Both the fragment size and area as well as the ejecta mass are determined experimentally as a function of Propergol specimen thickness and impact velocity or energy. The cumulative number of fragments as a function of size for the Propergol is uniformly found to be a bi-linear semi-logarithmic relationship with the bifurcation occurring at the mean crystal radius. Individual crystals and the crater generated are examined by means of a scanning electron microscope.
A phenomenological model of the fragmentation process is constructed, based on an assumed spherical shape of the fragments and the bi-linear fragment distribution, using energy methods. This is combined with a perforation analysis that considers the process to be sequentially composed of initial indentation, fragmentation, and sliding and deflection of the Propergol disks. An evaluation of this model providing fragment volumes as a function of impact velocity is compared with experimental results and found to be in good agreement. 相似文献