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151.
We demonstrate the use of membrane preconcentration capillary electrophoresis tandem mass spectrometry (mPC-CE-MS/MS) for sequencing peptides at the sub-100 femtomole level. In particular by loading the mPC-CE cartridge off-line with a pressurized bomb apparatus, 100 mul solutions can be loaded in <5 min. Furthermore, mPC-CE-MS in conjunction with on-line transient isotachophoresis carried out in 25 mum i.d. capillaries results in enhanced resolution and theoretical plate values as compared to convention 50-75 mum i.d. capillaries. We show that this is a powerful new approach in the sequencing of biologically derived compounds from complex mixtures such as MHC class I peptides. 相似文献
152.
A new technique for the identification of nonlinearity in multi-degree of freedom systems is presented. The technique is based on the joint application of the Gabor and the Hilbert transforms to the transient response of a system. The Gabor transform is used first to identify a time-variant matrix representing the spatial behaviour of the system. This matrix is then used to decouple the transient response into a set of uncoupled quasi-harmonic components. Finally the Hilbert transform is applied to identify the dissipative and restoring forces associated with each component which is equivalent to a single degree of freedom system. Numerical examples are supplied to help clarify the main advantages and the possible limitations of the method in the presence of strong nonlinearities and closely spaced frequencies. 相似文献
153.
An improved nonlinear model for an automotive shock absorber 总被引:7,自引:0,他引:7
A new physical model for a shock absorber is presented which provides a more realistic representation of the stiffness characteristics than previous simple models. The new model is validated on experimental data. 相似文献
154.
M. A. Slifkin A. Al-Rahmani M. Imanieh R. D. Tomlinson H. Neumann 《Crystal Research and Technology》1991,26(1):109-119
Photoconductivity spectra of n-type CuInSe2 single crystals are measured in the photon energy range hv = 0.75 – 3.1 eV and as a function of temperature in the range T = 80 – 320 K. It is found that the photoconductivity of as-grown crystals is a nearly pure surface effect, while sensitization of the crystal volume is observed only after sufficiently long annealing in the presence of powdered material. To explain the temperature dependence of the photoconductivity carrier trapping processes must be taken into account. 相似文献
155.
The lattice damage of p-type CuInSe2 single crystals implanted with 10 keV protons in the fluence range from 2.5 · 1014 to 8 · 1015 cm−2 was investigated using the Rutherford backscattering/channeling technique. At proton fluences up to about 2 · 1015 cm−2 radiation annealing of the defects is observed which is ascribed to very high defect concentrations in the unimplanted samples. At higher fluences radiation damage occurs but the concentration of radiation induced defects ramains low. There are indications that selenium interstitials or defect complexes with selenium interstitials involved are stable defects at room temperature. 相似文献
156.
H. Neumann W. Hrig P. A. Jones G. Lippold H. Sobotta R. D. Tomlinson M. V. Yakushev 《Crystal Research and Technology》1994,29(5):719-726
Optical absorption spectra in the photon energy range from 0.4 to 1.2 eV and photoreflectance spectra in the range of the fundamental edge are measured on n-type CuInSe2 single crystals. Photoreflectance spectroscopy yields the true gap energy while the near-edge absorption spectra are dominated by acceptor–to–conduction band transitions, the acceptor ionisation energy being about 80 meV. Based on intrinsic defect chemistry considerations this acceptor is ascribed to copper vacencies. 相似文献
157.
Both p-type and n-type CuInSe2 single crystals were implanted with 40 keV 130Xe+ ions up to doses of 5 · 1016 cm−2. Implanted layers on p-type substrates showed an initial increase of the resistivity followed by a continuous decrease of the resistivity at higher doses. Implanted layers on n-type substrates gave also an increase of the resistivity at lower doses, but at higher doses a conductivity type conversion from n-type to p-type took place, followed by a decrease of the resistivity. To explain the experimental results it is supposed that the increase of the resistivity is mainly due to charge carrier scattering at extended defects while the decrease of the resistivity at high doses is due to the predominant creation of intrinsic acceptor states during implantation. 相似文献
158.
159.
H. Laalej Z. Q. Lang S. Daley I. Zazas S. A. Billings G. R. Tomlinson 《Nonlinear dynamics》2012,69(1-2):409-421
In a previous study, the authors have proved that in theory the introduction of a cubic non-linear damping can produce ideal vibration isolation such that the system force transmissibility over the resonant frequency region is modified, but the transmissibility over the non-resonant regions remain unaffected. The present study is concerned with both an experimental verification of this theoretical finding and the selection of the cubic damping characteristic parameter required to achieve a desired performance for a single degree of freedom vibration isolation system. These results provide an important basis for the design and practical application of non-linearly damped vibration isolation systems in engineering practice. 相似文献
160.
Nigel J. Clarke Andy J. Tomlinson Stephen Naylor 《Journal of the American Society for Mass Spectrometry》1997,8(7):743-748
Capillary isoelectric focusing (cIEF) coupled to mass spectrometry (cIEF-MS) offers a potentially very powerful analytical tool for the investigation of physiological samples. The high resolving capabilities of cIEF in combination with the high sensitivity and enhanced structural information provided by MS is highly desirable for the analysis of complex samples. However a major limitation of the technique has always been the requirement to desalt samples prior to cIEF analysis. Such desalting normally occurs off-line and therefore adds complexity and the possibility of sample loss or contamination. In this study we demonstrate the use of a modified cIEF protocol which enables samples containing physiological levels of salts to be desalted on-line, within the cIEF capillary. This new technique is very fast and efficient, allowing the direct analysis of a physiologically derived fluid that contains a complex mix of proteins, such as human cerebrospinal fluid by cIEF-MS in a single step experiment. 相似文献