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161.
Bonifazi D Nacci C Marega R Campidelli S Ceballos G Modesti S Meneghetti M Prato M 《Nano letters》2006,6(7):1408-1414
Understanding and controlling the chemical reactivity of carbon nanotubes (CNTs) is a fundamental requisite to prepare novel nanoscopic structures with practical uses in materials applications. Here, we present a comprehensive microscopic and spectroscopic characterization of carbon nanotubes which have been chemically modified. Specifically, scanning tunneling microscopy (STM) investigations of short-oxidized single-walled carbon nanotubes (SWNTs) functionalized with aliphatic chains via amide reaction reveal the presence of bright lumps both on the sidewalls and at the tips. The functionalization pattern is consistent with the oxidation reaction which mainly occurs at the nanotube tips. Thermogravimetric analysis (TGA), steady-state electronic absorption (UV-vis-NIR), and Raman spectroscopic studies confirm the STM observations. 相似文献
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A phosphorus (P) donor has been extensively studied in bulk Si to realize the concept of Kane quantum computers. In most cases the quantum bit was realized as an entanglement between the donor electron spin and the nonzero nuclei spin of the donor impurity mediated by the hyperfine coupling between them. The donor ionization energies and the spin-lattice relaxation time limited the temperatures to a few kelvin in these experiments. Here, we demonstrate by means of ab initio density functional theory calculations that quantum confinement in thin Si nanowires (SiNWs) results in (i) larger excitation energies of donor impurity and (ii) a sensitive manipulation of the hyperfine coupling by external electric field. We propose that these features may allow to realize the quantum bit (qubit) experiments at elevated temperatures with a strength of electric fields applicable in current field-effect transistor technology. We also show that the strength of quantum confinement and the presence of strain induced by the surface termination may significantly affect the ground and excited states of the donors in thin SiNWs, possibly allowing an optical read-out of the electron spin. 相似文献
165.
Mader A Gruber K Castelli R Hermann BA Seeberger PH Rädler JO Leisner M 《Nano letters》2012,12(1):420-423
Carbohydrate-based sensors, that specifically detect sugar binding molecules or cells, are increasingly important in medical diagnostic and drug screening. Here we demonstrate that cantilever arrays functionalized with different mannosides allow the real-time detection of several Escherichia coli strains in solution. Cantilever deflection is thereby dependent on the bacterial strain studied and the glycan used as the sensing molecule. The cantilevers exhibit specific and reproducible deflection with a sensitivity range over four orders of magnitude. 相似文献
166.
Barbani N Guerra GD Cristallini C Urciuoli P Avvisati R Sala A Rosellini E 《Journal of materials science. Materials in medicine》2012,23(1):51-61
The aim of this work was the morphological, physicochemical, mechanical and biological characterization of a new composite
system, based on gelatin, gellan and hydroxyapatite, and mimicking the composition of natural bone. Porous scaffolds were
prepared by freeze–drying technique, under three different conditions of freezing. The morphological analysis showed a homogeneous
porosity, with well interconnected pores, for the sample which underwent a more rapid freezing. The elastic modulus of the
same sample was close to that of the natural bone. The presence of interactions among the components was demonstrated through
the physicochemical investigation. In addition, the infrared chemical imaging analysis pointed out the similarity among the
composite scaffold and the natural bone, in terms of chemical composition, homogeneity, molecular interactions and structural
conformation. Preliminary biological characterization showed a good adhesion and proliferation of human mesenchymal stem cells. 相似文献
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At JET new plasma-facing components for the main chamber wall and the divertor are being designed and built to mimic the expected ITER plasma wall conditions in the deuterium-tritium operation phase. The main wall elements at JET will be made of beryllium and the divertor plasma-facing surface will be made of tungsten. Most of the divertor tiles will consist of tungsten-coated Carbon Fibre Composite (CFC) material. However one toroidal row in the outer divertor will be made of solid, inertially cooled tungsten. The geometry of these solid tungsten divertor components is optimized within the boundary conditions of the interfaces and the constraints given by the electrodynamical forces. Shadowing calculations as well as rough field line penetration analysis is used to define the geometry of the tungsten lamella stacks. These calculations are based on a set of magnetic equilibria reflecting the operation domain of current JET plasma scenarios. All edges in poloidal and toroidal direction are shadowed to exclude near perpendicular field line impact. In addition, the geometry of the divertor structure is being optimized so that the fraction of the plasma wetted surface is maximised. On the basis of the optimized divertor geometry, performance calculations are done with the help of ANSYS to assess the maximum power exhaust possible with this inertially cooled divertor row. 相似文献
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Key hurdles in the Mediterranean‐style dry fermented sausage “Salsiccia Sarda” as influenced by different ingredients related to product safety
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Riccardo Consigliere Domenico Meloni Rina Mazzette 《Journal of Food Processing and Preservation》2018,42(1)
According to EC Reg. 2073/2005, Food Business Operators must demonstrate the safety of fermented sausages by using different approaches based on physico‐chemical analyses, predictive microbiology and Microbial Challenge Test. The aim of the present study was to investigate the application of different ingredients related to product safety on the development of key hurdles in Mediterranean‐style dry fermented sausages as “Salsiccia Sarda”. Weight loss, pH and aw were evaluated as ripening monitoring tool. Predictive mathematical models to evaluate the survival of Listeria monocytogenes complemented the present study. The evolution of aw and weight loss to values capable to support product's safety was shown to be closely related and was validated as a simple and effective monitoring tool of the Critical Control Point ripening. Based on the fermented sausage characteristics, “Salsiccia Sarda” at the end of ripening is unable to support the growth of the pathogen.