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41.
Wortberg M Ziemer W Kugel M Müller H Neu HJ 《Analytical and bioanalytical chemistry》2006,384(5):1113-1122
An online GC–MS-system for automated monitoring of crude wastewater at a complex chemical production site is presented. The
modular system is, in principal, based on commercial equipment, but utilizes a special, two-stage injector, which consists
of a splitless vaporization chamber on top of a PTV injector filled with Tenax. This set-up enables direct injection of wastewater.
Almost 140 volatile and semi-volatile compounds are calibrated down to 1 mg L−1, which is sufficient for analysis of the influent of the wastewater-treatment plant. Two instruments analyze alternately,
every 20 min, and the instrument cycle time is 40 min. The quantitative results are transferred to a database which is connected
to a process-control system. Depending on the nature and concentration of a compound, an alarm can be generated and the wastewater
stream can be diverted into an “off spec tank” if necessary. The GC–MS-system operates quasi-continuously with a system availability
>98%. Data quality is automatically controlled in each run and by daily analysis of a quality-control sample. The development
of a novel stacked PTV–PTV injector design to expand the range of analytes to selected basic compounds is described. 相似文献
42.
A. Teigelh?fer P. Bricault O. Chachkova M. Gillner J. Lassen J. P. Lavoie R. Li J. Mei?ner W. Neu K. D. A. Wendt 《Hyperfine Interactions》2010,196(1-3):161-168
Due to the large absorption cross section for optical transitions into Rydberg and autoionizing states compared to non-resonant ionization, these states are of particular interest for use in efficient laser resonance ionization excitation schemes as used in Resonant Ionization Laser Ion Sources (RILIS). In order to identify these atomic states extensive laser spectroscopy has to be performed. The lasers employed at TRIUMF’s laser ion source are birefringent filter tuned titanium:sapphire (Ti:Sa) lasers which are designed for long term frequency stability rather than continuous tuning. The design and characteristics of a grating tuned, high repetition rate, pulsed Ti:Sa laser for spectroscopy applications are presented. This laser allows fast scans of up to 40 THz with a laser linewidth of approximately 6 GHz. First tests were performed by scanning across the Rydberg series of gallium. 相似文献
43.
T. Shapoval V. Metlushko M. Wolf V. Neu B. Holzapfel L. Schultz 《Physica C: Superconductivity and its Applications》2010,470(19):867-870
Low-temperature magnetic force microscopy (LT-MFM) was used to study the distribution of superconducting vortices in Nb above a square array of 1 μm-sized circular ferromagnetic dots in a magnetic-vortex state. The force that the MFM tip exerts on the individual vortex in the depinning process was used to estimate the spatial modulation of the pinning potential. It was found, that the superconducting vortices which are preferably located on top of the Py dots experience a pinning force, about 15 times stronger as compared to the pinning force in the pure Nb film. This strong pinning exceeds the repulsive interaction between the superconducting vortices and allows vortex clusters to be located above the dots. 相似文献
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Shock wave emission induced by intense laser pulses is investigated experimentally. The present work focuses on the conditions of shock wave emission in glycerine and distilled water during the first bubble collapse. Experimental investigations are carried out in liquids as a function of temperature and viscosity. Comparison is made with the theoretical work of Poritsky (Proc 1st US Natl Congress Appl Mech 813–821, 1952) and Brennen (Cavitation and bubble dynamics, Oxford University Press 1995). To the best knowledge of the authors, this is the first experimental verification of those theories. 相似文献
48.
S. Koch W. Garen M. Müller W. Neu 《Applied Physics A: Materials Science & Processing》2004,79(4-6):1071-1073
Environmental concerns about the amount of dissolved heavy metals in coastal tidal waters have led to investigations into possible ways to detect chromium dissolved in water. A method using fluorescence spectroscopy in solution has been proposed. However, such optical emission spectroscopic methods tend to suffer from a lack of sensitivity caused by the strong quenching processes in liquids. In this investigation, Nd:YAG Q-switched laser pulses were utilised to generate a plasma filled bubble in a chromium solution. Fluorescence in the plasma was detected using an optical fibre tip placed adjacent to the bubble. Light wavelengths characteristic of chromium were detected and spectral images recorded using an optical multi-channel analyzer. PACS 39.30.+w; 42.62 Fi; 52.38 Mf; 92.20 Ny 相似文献
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