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31.
The building recession in many western industrialised countries has obliged their construction industries to look abroad for new markets. A Swedish view of this situation and the scope for consultancy work overseas is given here by a partner in civil engineering consultants Kjessler and Mannerstråle, AB, of Stockholm. Most recent estimates, incidentally, put the annual value of such Swedish construction consultancy work abroad as £50-£60 million, about 60 per cent of it in the Middle East. 相似文献
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In one of several pilot projects financed through the Swedish Council of Building Research, the Department of Building Technology at the Royal Institute of Technology, Stockholm, showed how energy consumption could be reduced by more than 50 per cent in a typical three-storey block of flats built around 1940. Thermal insulation levels of the building were low by Swedish standards — walls and roofs having U-values of 1.2 W/m2. °C — and oil consumption was as high as 60 litres per m2 of net dwelling area. 相似文献
35.
Végvári A Larsson AK Hjertén S Mannervik B 《Chembiochem : a European journal of chemical biology》2002,3(11):1117-1125
The tripeptide glutathione is a prominent intracellular constituent that provides protection against genotoxic and carcinogenic electrophiles and is also a component of several biological signal substances. Glutathione conjugates, free glutathione, and glutathione disulfide contain charged amino acid residues, which contribute to solubility in aqueous media. However, the amphipathic nature of glutathione conjugates and the small differences that may distinguish the S substituents, pose analytical problems in their resolution. The present study demonstrates how homologous S-alkyl and S-benzyl conjugates of high structural similarity can be efficiently resolved by capillary electrophoresis. Inclusion of beta-cyclodextrins in the buffer or in a polyacrylamide gel affords baseline separation of the analytes. The separation methods described are applicable to enzyme assays in vitro and to the identification and quantification of glutathione conjugates of importance in toxicology and physiology. The contribution of beta-cyclodextrin to the separation is primarily based on interactions between its hydrophobic cavity and the S-alkyl and S-benzyl groups of the analytes. 相似文献
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Bengt Källbäck 《Solid-state electronics》1975,18(3):257-262
In this paper effects of importance for the stabilization of supercritical n+nn+ GaAs transferred electron devices are considered. By small-signal impedance calculations and measurements it is shown that doping- as well as temperature gradients of correct polarity reduce the device negative resistance and enhance stability. It is also found that an increasing doping density reduces the negative resistance. Finally it is demonstrated that relaxation effects have a profound influence on the impedance, and that such effects have to be included in a small-signal analysis in order to give reasonable agreement with measurements. 相似文献
38.
Bengt Sundström 《Engineering Fracture Mechanics》1974,6(3):483-492
Fracture mechanics is applied to the problem of microcrack initiation on cylindrical (spherical) particles in a matrix. The numerical calculations have been performed by the finite element method.A stress criterion for the initiation of interfacial, cap shaped, microcracks is derived as function of inclusion size and bonding strength. It is found that the cracks are unstable below a minimum “cap angle”. Comparison with experiments shows reasonable quantitative agreement. 相似文献
39.
Bengt . kesson 《International journal for numerical methods in engineering》1976,10(6):1221-1231
The described program PFVIBAT uses the exact displacement method to perform free and forced vibration analysis entirely within the differential equation theory of beams thus avoiding assumed modes and lumped masses. The frame may contain rigid bodies. Clamped, hinged, guided and rolling connections are allowed for. Consideration of rotatory inertia, shear deformation and second-order bending moments and shear forces as caused by static axial load is optional. Eigenfrequencies and modal masses are calculated with an accuracy that may be specified. Displacement and moment modes are plotted. Transient vibrations are studied. 相似文献
40.
Accuracy in multiangle light scattering measurements for molar mass and radius estimations. Model calculations and experiments 总被引:1,自引:0,他引:1
Multiangle light scattering (MALS) is a well-established technique used to determine the size of macromolecules and particles. In this study, different extrapolation procedures used in MALS were investigated with regard to accuracy and robustness in the obtained molar mass and rms radius. Three different mathematical transformations of the light scattering function referred to as the Debye, Zimm, and Berry methods for constructing the Debye plot were investigated for two idealized polymer shapes, homogeneous spheres and random coils, with radii from 25 to 250 nm. The effect of the angular interval used for the extrapolation was investigated, as was the robustness of the different transformations toward errors in the measured light scattering intensity at low angles. For an rms radius less than 50 nm, the relative error in molar mass due to extrapolation was less than 1% independent of the method used. For larger radii, the error increased and the extrapolation procedure became more critical. For random coil polymers, the Berry method was superior in terms of accuracy and robustness. For spheres, the Debye method was superior. The Zimm method was inferior to the others. The different extrapolation methods were evaluated and compared on experimental data from a size exclusion chromatography-MALS analysis of an ultrahigh molar mass poly(ethylene oxide) (PEO). The PEO data qualitatively verified the calculations and stressed the importance of optimizing the extrapolation procedure after careful evaluation of the experimental data. A discussion of how to detect erroneous data in an experimental Debye plot is given. 相似文献