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排序方式: 共有630条查询结果,搜索用时 31 毫秒
1.
Applied Composite Materials - Determining the impact behavior of adhesive joints allows the designing of high-strength joints. Therefore, the dynamic behavior of adhesive joints has recently become... 相似文献
2.
F Ildan S Polat AI G?cer A Oner T Isbir UO Mete M Kaya A Karadayi 《Canadian Metallurgical Quarterly》1996,138(3):338-345
The sodium-potassium activated and magnesium dependent adenosine-5'-triphosphatase (Na(+)-K(+)/Mg(+2) ATPase EC.3.6.1.3.) activity and lipid peroxidation and early ultrastructural findings were determined in rat brain at the acute stage of ischaemia produced by permanent unilateral occlusion of the middle cerebral artery (MCA). The effects of the pretreatment with intravenous high-dose methylprednisolone (MP) on these biochemical indices and ultrastructural findings were also evaluated in the same model. The rats were divided into four groups. In group I, 10 rats were used to determine Na(+)-K(+)/Mg(+2) ATPase activity and the extent of lipid peroxidation by measuring the malondialdehyde (MDA) content and normal ultrastructural findings. In group II on 20 rats, only subtemporal craniectomy was done in order to determine the effects of the surgical procedure on these indices and findings. This group was treated intravenously with saline solution before occlusion. In group III with MCA occlusion, saline solution was administered intravenously to 20 rats in the same amount of methylprednisolone used in group IV, ten minutes before the occlusion. In Group IV, a single high-dose (30 mg/kg) of methylprednisolone was administered intravenously, ten minutes before occlusion in 20 rats. After occlusion of the middle cerebral artery, Na(+)-K(+)/Mg(+2) ATPase activity was decreased promptly in the first ten minutes in the ischaemic hemisphere and remained at a lower level than the contralateral hemispheres in the same group and the normal levels in group I, during 120 minutes of ischaemia. A single dose methylprednisolone pretreatment prohibited the inactivation of Na(+)-K(+)/Mg(+2) ATPase. On the other hand, there was significant difference in malondialdehyde content between group I and group III. Malondialdehyde levels were significantly increased following ischaemia and a non-significant increase was observed in the contralateral hemisphere. Methylprednisolone treatment significantly decreased malondialdehyde content on the side of the ischaemic hemisphere. We conclude that there is a positive relationship between membrane-bound enzyme Na(+)-K(+)/Mg(+2) ATPase activity, malondialdehyde content and early ultrastructural changes in the treated group with MP. These data suggest that the pretreatment injection of high doses (30 mg/kg) methylprednisolone contribute to the protection of the brain from ischaemia with stabilization of the cell membrane by effecting the lipid peroxidation and the activation of Na(+)-K(+)/Mg(+2) ATPase. 相似文献
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4.
Amblyopia is a neuronal abnormality of vision that is often considered irreversible in adults. We found strong and significant improvement of Vernier acuity in human adults with naturally occurring amblyopia following practice. Learning was strongest at the trained orientation and did not transfer to an untrained task (detection), but it did transfer partially to the untrained eye (primarily at the trained orientation). We conclude that this perceptual learning reflects alterations in early neural processes that are localized beyond the site of convergence of the two eyes. Our results suggest a significant degree of plasticity in the visual system of adults with amblyopia. 相似文献
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6.
Ergin Murat Altuner Hami Alpas Yasar Kemal Erdem Faruk Bozoglu 《European Food Research and Technology》2006,222(3-4):392-396
Interest in high hydrostatic pressure (HHP) applications on milk and dairy products has recently increased as HHP offers a
new technology for food preservation to the food industry. Although HHP-induced microbial destruction, rennet or acid coagulation
of milk and increase in cheese yield has been reported, the actual effect of HHP application on milk constituents still remains
to be unexplained. Therefore, we have analyzed the effect of HHP on physicochemical and biochemical properties such as turbidity,
pH and especially protein micelle surface hydrophobicity of milk proteins. To serve for this purpose, milk samples with different
fat contents were pressurized from 110 to 440 MPa at 25 °C for 10 and 20 min. Turbidity decreased with pressure increase and
there was a slight change in pH. In order to measure the extent of exposure of hydrophobic groups of proteins to HHP, the
method described by Bonomi et al. [1], based on use of a fluorescent probe, was utilized. In the light of the results obtained, it can be concluded that HHP has
an effect on non-covalent interactions and especially hydrophobic bonds in milk. As the pressure is increased from 110 to
440 MPa, the micelles possibly decompose into sub-micelles and the embedded hydrophobic areas inside these micelles re-position
in such a way that they can readily interfere with the fluorescent marker, ANS. These results may lead to practical applications
of HHP treatment in the dairy industry to produce microbiologically safe, minimally processed products with high nutritional
and sensory quality and novel texture. 相似文献
7.
Real-Time Edge Follow: A Real-Time Path Search Approach 总被引:1,自引:0,他引:1
Undeger C. Polat F. 《IEEE transactions on systems, man and cybernetics. Part C, Applications and reviews》2007,37(5):860-872
Real-time path search is the problem of searching a path from a starting point to a goal point in real-time. In dynamic and partially observable environments, agents need to observe the environment to track changes, explore to learn unknowns, and search suitable routes to reach the goal rapidly. These tasks frequently require real-time search. In this paper, we address the problem of real-time path search for grid-type environments; we propose an effective heuristic method, namely a real-time edge follow alternative reduction method (RTEF-ARM), which makes use of perceptual information in a real-time search. We developed several heuristics powered by the proposed method. Finally, we generated various grids (random-, maze-, and U-type), and compared our proposal with real-time A*, and its extended version real-time A* with n-look-ahead depth; we obtained very significant improvements in the solution quality. 相似文献
8.
Engineering with Computers - A novel Harris hawks optimization algorithm is applied to microchannel heat sinks for the minimization of entropy generation. In the formulation of the heat transfer... 相似文献
9.
Novel hybrid DNN approaches for speaker verification in emotional and stressful talking environments
Shahin Ismail Nassif Ali Bou Nemmour Nawel Elnagar Ashraf Alhudhaif Adi Polat Kemal 《Neural computing & applications》2021,33(23):16033-16055
Neural Computing and Applications - In this work, we conducted an empirical comparative study of the performance of text-independent speaker verification in emotional and stressful environments.... 相似文献
10.
Copper containing 6000-series aluminium alloys may become susceptible to intergranular corrosion (IGC) as a result of improper thermomechanical processing. Effect of cooling rate after solution heat treatment on the corrosion behaviour of a model AlMgSi(Cu) alloy of nominal composition (wt%) 0.6 Mg, 0.6 Si, 0.2 Fe, 0.2 Mn and 0.1 Cu was investigated. Slow cooling rates were simulated by isothermal treatment for predetermined times in lower temperature baths immediately after solution heat treatment. Treatment for 10-100 s at temperatures below 400 °C introduced susceptibility to IGC. Longer heat treatment at the same temperatures introduced susceptibility to pitting. A corrosion resistant time zone was found between the zones of IGC and pitting at temperatures lower than 350 °C. Quenching in water after solution heat treatment prevented IGC. IGC was related to microgalvanic coupling between the noble Q-phase (Al4Mg8Si7Cu2) grain boundary precipitates and the adjacent depleted zone. Pitting was attributed to coarse particles in the matrix. Possible mechanisms causing the corrosion resistant intermediate zone are discussed. The results indicate possible methods for obtaining increased corrosion resistance of similar alloys by proper thermal processing. 相似文献