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1.
Rats given medial frontal lesions on Postnatal Day 1 or Day 10 were trained on the Morris water task on Days 19–21 or Days 56–58. The operated groups were equally impaired at the water task on Days 19–21, but the Day 10 rats had recovered by 56 days. Dendritic arborization and spine density were analyzed in parietal layer II–III pyramidal cells. At Day 60, but not at Day 22, the Day 10 animals had more dendritic spines per unit dendritic length than did the controls or Day 1 rats. Thus, there was functional recovery rather than sparing after frontal lesions at 10 days, and the recovery was correlated with an increase in dendritic spines. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
Osemwengie Iyoha Bret Howard Bryan Morreale Richard Killmeyer Robert Enick 《Topics in Catalysis》2008,49(1-2):97-107
The hydrogen permeance of 1 mm-thick Pd80wt%Cu foils was measured in the presence of equimolar mixtures of H2 with CO, CO2 or H2O over the temperature and total pressure ranges of 623–1,173 K and 0.62–2.86 MPa, respectively. In all cases, permeance losses at 623 and 738 K were very modest. At higher temperatures, more significant decreases in membrane permeance were observed with the highest reduction of about 50% occurring when macroscopic carbon deposition occurred on the membrane surface during H2–CO exposure at 908 K. The more worrisome effects of exposure to these gases, however, were the micron-scale surface defects observed at 908 and 1,038 K. Although the 1 mm thick disk membranes retained their mechanical integrity, such defects could cause catastrophic failure of ultra-thin, Pd–Cu membranes (1–5 μm thick) deposited on porous substrates. 相似文献
3.
Jon Bryan Burley 《Landscape Research》1992,17(2):74-78
This paper describes the configuration and cultural context of the oldest known designed space in central America, Gheo-Shih, dating from 5,000 - 4,000 BC. This site may have been a ceremonial space, being employed in a similar fashion to ceremonial spaces of Native American cultures from the North American Great Basin. It contains physical features that set precedents and are similar to the geomantic features of later nearby Mesoamerican cultures. 相似文献
4.
Bryan Poulson 《Corrosion Science》2004,46(3):729-753
A simple stress-corrosion cracking (SCC) specimen, suitable for slow strain rate testing and incorporating heat transfer, with an artificial crevice or deposits has been designed and tested. It appears that when the solute level is above a certain value it can concentrate. The kinetics of solute accumulation and the concentration that can be induced in the specimen have been determined. Build up of solute from the ppm level in the bulk environment to the level required to cause cracking can take hours, not days or years. The limiting concentration reached is controlled by thermodynamics, specifically the available superheat. A brief review of relevant literature suggests that this experimental approach to predicting SCC has significant advantages over a modelling or measurement approach. The specimen also lends itself to a monitoring role--a modern version of the Schroeder embrittlement detector. 相似文献
5.
L. Pamela Cook Emeka Nwankwo Gilberto Schleiniger Bryan Wood 《Journal of Engineering Mathematics》2003,45(3-4):269-282
A general formulation for capillary flow of two miscible fluids – one a dilute plug of polymer fluid inserted into a fully developed Poiseuille flow of the other, a Newtonian stream – is examined for its long time behavior. Phenomenologically, the system evolves from an initial state, that of a plug within the boundaries of sharp, well defined fronts inside a Newtonian stream, to a more homogenized state in the very long time scale. This problem was addressed by G.I. Taylor but with regard to a system of two Newtonian fluids, leading to the well-known results commonly described as `Taylor axial dispersion'. In this paper, a general and systematic perturbation analysis is presented from which Taylor's result is recovered as a special case of a more general solution which applies to fluids incorporating elastic properties. In particular, the influence of viscoelasticity and (polymer) diffusivity on the observed pressure profile in the capillary conduit is examined. This effect is clearly separated out for small Peclet number flows using asymptotic and numerical analysis. The results identify the influence of fluid viscosity, elasticity, and diffusivity on the observed pressure profile and form the basis for the improved characterization of polymeric elasticity using capillaries – a finding that is of significant scientific and commercial interest. These results were obtained by the authors as a class of observations resulting from the perturbation analysis of forced-flow capillary devices in viscoelastic fluid property investigation. 相似文献
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Hebb's principal theoretical propositions, the cell assembly and the nature of synaptic change, were generated at a time when the focus of work in behavioural neuroscience was directed at understanding issues such as the principles governing the behaviour of animals in neuropsychological studies of learning and memory and the role of drives in the control of behaviours like sex and feeding and drinking. It was not until attention shifted to understanding the neural underpinnings of learning and memory that Hebb's propositions had an impact on behavioural neuroscience as they provided a simple, and testable, mechanism for synaptic plasticity observed both in learning and in other forms of experience-dependent neural change. But much of the field remains interested in other issues such as sensation and perception, motivation, attention, and so on, and to date, Hebb's propositions have had little impact. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
This paper deals with the issues of development and implementation of a real-time NURBS interpolator for a six-axis robot. Using an open-architecture controller system as a testbed, a real-time NURBS curve interpolator was developed, implemented and tested. Sample runs were conducted with the resulting trajectories measured in real-time during robot motion. The resulting trajectories are analyzed, discussed and compared with those from a commonly used point-to-point approximation technique. The real-time NURBS curve interpolator's feasibility, advantages and related issues are also discussed. 相似文献
10.
R. Murray C. Bryan H. Yu S. Lycett 《Journal of Materials Science: Materials in Electronics》1996,7(5):341-345
The potential associated with quantum well (QW) structures is usually assumed to be a step function; this implies a compositional abruptness at each interface. But abrupt interfaces do not occur in practice, especially if one of the atoms segregates during growth. This leads to asymmetries in the QW potentials which could radically affect device performance. 相似文献