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21.
Understanding the complex phenomena in the BF hearth is essential to increasing furnace productivity and to extending furnace campaign. Numerical modeling provides a cost‐effective tool to obtain such knowledge. We have developed several continuum‐based mathematical/numerical models to simulate the flow, heat transfer and mass transfer in the lower part of BF and in the hearth. These models have generated an improved insight into the mechanisms for liquid drainage efficiency, lining erosion and wall protection in BF hearth under operational conditions. The current paper provides an overview of these studies, as well as dealing with three specific aspects: (a) Gas flow and pressure on the liquid surface, and its effect on the drainage characteristics; (b) Flow and temperature distributions of liquid iron in the hearth, and the temperature distribution in the refractories; and (c), Titania injection to form Ti(C,N)‐rich scaffolds on the hearth refractory surface, to protect the hearth from erosion. 相似文献
22.
To plan testing activities, testers face the challenge of determining a strategy, including a test coverage criterion that offers an acceptable compromise between the available resources and test goals. Known theoretical properties of coverage criteria do not always help and, thus, empirical data are needed. The results of an experimental evaluation of several coverage criteria for finite state machines (FSMs) are presented, namely, state and transition coverage; initialisation fault and transition fault coverage. The first two criteria focus on FSM structure, whereas the other two on potential faults in FSM implementations. The authors elaborate a comparison approach that includes random generation of FSM, construction of an adequate test suite and test minimisation for each criterion to ensure that tests are obtained in a uniform way. The last step uses an improved greedy algorithm. 相似文献
23.
Different varieties of bean (Phaseolus vulgaris), corn (Zea mayz), lentil (Lens sp), soya (Glycine max) and wheat (Tricticum sp) were analyzed in order to obtaining data of chemical composition and content of minerals to contribute to the International Food Data System INFOODS in the elaboration of Regional Food Composition Tables and to evaluate the quality of grains. The selected varieties were the ones produced in the northwestern region of Argentina. The beans were divided in five groups, according to their statistical similarity. The pallares variety is the one that presents bigger content of Cu (2.42 mg/100 g), Fe (76.03 mg/100 g) and Zn (6.08 mg/100 g). The samples of corn were divided in three groups, according to their statistical similarity. The leales yellow corn has bigger content of Zn (3.16 mg/100 g) that the other varieties of the region. The 8 rayas white corn is the one that presents bigger content of Fe (11.48 mg/100 g), while the pisingallo yellow corn is that of bigger content of Cu (1.21 mg/100 g). 相似文献
24.
M. de la L. Olvera A. Maldonado R. Asomoza M. Mele´ndez-Lira 《Journal of Materials Science: Materials in Electronics》2000,11(1):1-5
We present the results of a chemical etching stability study carried out on ZnO thin films doped with several elements deposited by spray pyrolysis. Prior to the etching, a structural study was done by X-ray diffraction and the texture of the samples was obtained by scanning electron microscopy. The samples were etched employing a solution of dilute hydrochloric acid. The etching rates obtained for the different samples depend on the dopant element and our results confirm that films doped with Cr present the highest stability against chemical etching. 相似文献
25.
L. E. Murr E. Ferreyra J. G. Maldonado E. A. Trillo S. Pappu C. Kennedy J. De Alba M. Posada D. P. Russell J. L. White 《Journal of Materials Science》1999,34(5):967-979
Steel-drum fabrication, especially the sinking of the drum head (also referred to as the pan) by hand with a hammer, has been examined in detail utilizing light metallography (LM) and transmission electron microscopy (TEM) to characterize residual microstructures corresponding to reductions in thickness of up to 50 % at the bottom of the drum head. Dislocation densities in the low-carbon (0.01–0.05 wt % C), ferritic steels can exceed 1010 cm-2. Simulations of simple, ideal, free circular notes utilizing 316 stainless-steel plates (0.05 wt % C), cold rolled to reductions up to 40%, revealed that deformation (per cent cold reduction) has an important effect on the acoustic spectrum, especially harmonic spectra. Harmonic-node splitting was observed for thin circular plates (0.076 cm thick); the frequency difference was 60 Hz at 20% cold reduction and 160 Hz at 40% cold reduction. These dispersion effects, due to deformation-induced microstructures, as well as irregularities in the note geometries and thicknesses, point to the complex and non-linear acoustic features that contribute to the unique sounds of the Caribbean steel drum. 相似文献
26.
A Mu?oz E Bureo JJ Ortega C Richard T Olivé MS Maldonado L Madero MA Díaz 《Canadian Metallurgical Quarterly》1998,83(11):981-984
BACKGROUND AND OBJECTIVE: To compare the estimated survival and disease-free survival between children with Ph1-positive chronic myeloid leukemia treated with allogeneic bone marrow transplantation or conventional chemotherapy. DESIGN AND METHODS: In this retrospective study we compared the results obtained in a group of 14 children who received allogeneic bone marrow transplantation (BMT) between 1983 and 1993, and another group of 27 children treated with busulfan, hydroxyurea or alpha-interferon during the same time period. Patients were transplanted at a median of 7 months from diagnosis and all except one were in their first chronic phase. Conditioning consisted in total body irradiation and cyclophosphamide in 12 cases, and busulfan was added in two. RESULTS: Of the 14 patients treated with BMT, two died of transplant-related complications and two relapsed 18 and 48 months after the BMT. Ten children remain alive and disease free at a median follow up of 60 months. The probability of DFS at 5 years is 70%. Of the 27 patients treated with chemotherapy, 22 have died at a median of 36 months from diagnosis. The probability of survival at 5 years is 5% versus 83% for the BMT group (p = 0.001). INTERPRETATION AND CONCLUSIONS: Allogeneic BMT is a safe and very effective treatment for Ph-positive CML in children. Patients who have an HLA-identical sibling donor must receive a transplant as soon as possible after being diagnosed. 相似文献
27.
Optimization of the material flow in a manufacturing plant by use of artificial bee colony algorithm
Alejandro Alvarado-Iniesta Jorge L. Garcia-Alcaraz Manuel Ivan Rodriguez-Borbon Aide Maldonado 《Expert systems with applications》2013,40(12):4785-4790
To survive in today’s competitive global market, companies must perform strategic changes in order to increase productivity, eliminating wasted materials, time, and effort. This study will examine how to optimize the time and effort required to supply raw material to different production lines in a manufacturing plant in Juarez, Mexico by minimizing the distance an operator must travel to distribute material from a warehouse to a set of different production lines with corresponding demand. The core focus of this study is similar to that of the Vehicle Routing Problem in that it is treated as a combinatorial optimization problem. The artificial bee colony algorithm is applied in order to find the optimal distribution of material with the aim of establishing a standard time for this duty by examining how this is applied in a local manufacturing plant. Results show that using this approach may be convenient to set standard times in the selected company. 相似文献
28.
Michael Beetz Freek Stulp Piotr Esden-Tempski Andreas Fedrizzi Ulrich Klank Ingo Kresse Alexis Maldonado Federico Ruiz 《Autonomous Robots》2010,28(1):21-44
This article investigates methods for achieving more general manipulation capabilities for mobile manipulation platforms,
which produce legible behavior in human living environments. To achieve generality and legibility, we combine two control
mechanisms. First of all, experience- and observation-based learning of skills is applied to routine tasks, so that the repetitive and stereotypical character of everyday activity is exploited. Second, we use planning, reasoning,
and search for novel tasks which have no stereotypical solution. We apply these ideas to the learning and use of action-related places, to the model-based
visual recognition and localization of objects, and the learning and application of reaching strategies and motions from humans.
We demonstrate the integration of these mechanisms into a single low-level control system for autonomous manipulation platforms. 相似文献
29.
Nicolas Vogel Mathieu Jung Noelia L. Bocchio Markus Retsch Maximilian Kreiter Ingo Köper 《Small (Weinheim an der Bergstrasse, Germany)》2010,6(1):104-109
Nanoparticle arrays created by nanosphere lithography are widely used in sensing applications since their localized surface plasmon resonances are extremely sensitive to changes in the local dielectric environment. A major drawback for any biologically oriented sensing application of conventionally produced particle arrays is the lack of stability of the nanoparticles in aqueous media and buffer solutions. Here, a robust and reusable nanoscale sensing platform based on localized surface plasmon resonances of gold nanoparticles embedded in a silicon dioxide matrix is presented. The architecture exhibits extremely high stability in aqueous environments and can be regenerated several times by simple mechanical cleaning of the surface. The platforms surface is ultraflat by design, thus making it an ideal substrate for any bio‐oriented sensing application. 相似文献
30.
J López-Jiménez J Pérez-Oteyza A Munoz C Parra L Villalón P Ramos M Maldonado J García-Lara?a E Otheo E Roldán A García-Avello J Odriozola 《Canadian Metallurgical Quarterly》1997,19(5):429-434
Medorinone 5-methyl-1,6-napthyridin-2(1H)-one and some of its analogs having varying degrees of cardiotonic potency have been studied by molecular orbital and electric field mapping methods. Ground state geometries of the molecules were optimized using the MNDO molecular orbital method. Hybridization displacement charges (HDC) combined with L?wdin charges as well as Mulliken charges were used for electric field mapping around the molecules. Electric fields near the O2 site of medorinone and its analogs correlate well with their observed cardiotonic potencies. This result is in agreement with certain pharmacological models for cardiotonics. 相似文献