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21.
Assessment of cleaning effectiveness for new ecological systems on ancient tempera icon by complementary microscopy techniques 下载免费PDF全文
Silvea Pruteanu Viorica Vasilache Irina Crina Anca Sandu Ana‐Maria Budu Ion Sandu 《Microscopy research and technique》2014,77(12):1060-1070
The study presents an old icon painted in egg tempera on lime wood, with a poor conservation condition and clogged dirt deposits. The icon is attributed to an anonymous painter of XIXth century and to the neo‐classical style of painting. The painting layer was done with only a hand full of pigments, earth colors that were often used in painting the icons from XVIIth to XIXth century in Eastern Europe, that have Byzantine influences. Taking into consideration the nature and the structure of the materials from the upper layers of the painting, affected by deposits of dirt over time, a series of cleaning recipes were studied, using the so called cleaning tests with compatible mixtures of different juices and infusion from indigenes plants, that were freshly done and odorless. A low alkaline 95% ethyl alcohol solution, combined with a few drops of ammoniac 25%, was used as a reference system, due to its compatibility with the greasy deposits found on the polychrome layer and on the wood. The cleaning capacity of the new systems used, in comparison with the standard solution, was analyzed through modern analytical methods of evaluating the degree of cleaning, more exactly by means of visible and UV reflectography, CIE L*a*b* colorimetry by reflection assisted by SEM‐EDX and IR spectroscopy. Microsc. Res. Tech. 77:1060–1070, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
22.
Multicompartment hydrodynamic model for slurry bubble columns 总被引:1,自引:0,他引:1
A core-annulus multicompartment two-dimensional two-bubble class model accounting for slurry recirculation and coupled with catalyst transport was developed as a part and parcel of the analysis of the behavior of slurry bubble column reactors at high gas throughputs corresponding to the churn turbulent flow regime. The model analyzed the contributions of bubble-induced turbulence closures, bubble coalescence and breakup phenomena, and catalyst axial distribution as the resultant of sedimentation, advection via liquid-solid slip, per-compartment axial dispersion and core-annulus lateral exchange of catalyst by bubble-induced turbulence. The model was also used to analyze the effects of catalyst loading, gas density and superficial velocity, and column diameter and vessel aspect ratio on the hydrodynamics of slurry bubble column reactors, namely, the per-compartment phase holdups and interstitial velocities, pressure gradient, bubble coalescence and break-up rates, and loci of velocity inversion for the gas and slurry profiles. 相似文献
23.
24.
Ion V. Nicolaescu Gabriel Tardos Richard E. Riman 《Journal of the American Ceramic Society》1994,77(9):2265-2272
A thermogravimetric method for the measurement of carbon, nitrogen, and oxygen in aluminum nitride is described. Since carbon oxidation occurs at lower temperatures than the oxidation of the aluminum compounds, thermogravimetric analyses in the respective temperature regimes can yield measurement of the oxygen, nitrogen, and carbon content. Thermogravimetric analyses were performed on mixtures of aluminum nitride and carbon with various concentrations in order to evaluate the accuracy of this method. The results were compared with those obtained by the hot gas extraction method. Errors produced by overlapping of the temperature ranges of the reactions were evaluated and experimental conditions were optimized to minimize error. This method can produce reliable results at elemental concentrations higher than a few percent. The absolute errors of the C/AI, N/Al, and O/Al atomic ratios were less then 0.02. The detection limit was evaluated to 0.2 wt% of each element. The applicability of the method to the study of the kinetics of the nitridation reaction was demonstrated. 相似文献
25.
Eugeniu Ivanov Ion Vata Stefan Teodorian Nitisor Stefan 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(2):347-349
Positronium in the triplet spin state (S = 1) decays by 3γ annihilation having a life time of about 140 ns in vacuum. Positronium annihilation is affected by magnetic fields which mix the M = 0 state of ortho-positronium with the M = 0 state of para-positronium. The mixing fraction depends on the magnetic field intensity and causes quantum beats in the time distribution of γ annihilation decay. This effect was predicted by Barishevsky et al. [V.G. Barishevsky, O.N. Metelitsa, V.V. Tikhomirov, J. Phys. B Atom. Mol. Opt. Phys. 22 (1989) 2835]. The time differential perturbed angular correlation method (TDPAC), combined with long-lived positron life time spectroscopy (PLTS), has been used to observe these quantum beats. It is found that the characteristics of the annihilation time distribution are not influenced by the presence of diamagnetic species such as Ar, N2 and H2 but are affected by the presence of the paramagnetic O2 molecule. Our results are encouraging in developing a new method for investigating magnetic fields on an atomic scale. 相似文献
26.
Zinc phthalocyanine dyes, which had been symmetrically and asymmetrically substituted with sulfonate groups were investigated using absorption, fluorescence and photoacoustic spectroscopic methods, supported by light-induced optoacoustic spectroscopy and photoelectric measurements; unsubstituted zinc phthalocyanine was employed as reference. Fluorescence quantum yields were determined on the basis of absorption and fluorescence spectra, whereas thermal parameters as well as the yield of triplet state population and the kinetics of thermal relaxation at microsecond intervals were determined using with photoacoustic methods. The effect of the sulfonate groups on photocurrent generation was discussed in terms of the dye's molecular structure and resonance (mesomeric, inductive, steric) effects. Sulfonation of zinc phthalocyanine changed markedly its absorption and fluorescence properties owing to redistribution of the electron density within the molecule as a result of both mesomeric and inductive effects, although other effects cannot be excluded. The enhanced light-generated photocurrent observed for phthalocyanine with two sulfonate groups is explained in terms of mesomeric effects, whereas in phthalocyanine with three and four sulfonate groups, inductive effects are essential and lead to photocurrent decline. 相似文献
27.
Marek Karpinski Ion I. Mandoiu Alexander Olshevsky Alexander Zelikovsky 《Algorithmica》2005,42(2):109-120
The Quality of Service Multicast Tree Problem is a generalization of
the Steiner tree problem which appears in the context of multimedia
multicast and network design. In this generalization, each node
possesses a rate and the cost of an edge with length l in a
Steiner tree T connecting the source to non-zero rate nodes is l
· re, where re is the maximum node rate in the component of
T-{e} that does not contain the source. The best previously
known approximation ratios for this problem (based on the best known
approximation factor of 1.549 for the Steiner tree problem in
networks) are 2.066 for the case of two non-zero rates and 4.212 for
the case of an unbounded number of rates. In this paper we give
improved approximation algorithms with ratios of 1.960 and 3.802,
respectively. When the minimum spanning tree heuristic is used for
finding approximate Steiner trees, then the previously best known
approximation ratios of 2.667 for two non-zero rates and 5.542 for an
unbounded number of rates are reduced to 2.414 and 4.311,
respectively. 相似文献
28.
29.
Walter Binder Ion Constantinescu Boi Faltings Klaus Haller Can Türker 《Autonomous Agents and Multi-Agent Systems》2006,12(2):219-237
This article presents an architecture to automatically create ad-hoc processes for complex value-added services and to execute
them in a reliable way. The uniqueness of ad-hoc processes is to support users not only in standardized situations like traditional
workflows do, but also in unique non-recurring situations. Based on user requirements, a service composition engine generates
such ad-hoc processes, which integrate individual services in order to provide the desired functionality. Our infrastructure
executes ad-hoc processes by transactional agents in a peer-to-peer style. The process execution is thereby performed under
transactional guarantees. Moreover, the service composition engine is used to re-plan in the case of execution failures.
The work presented in this article was supported by the Swiss National Science Foundation as part of the project MAGIC (FNRS-68155),
as well as by the Swiss National Funding Agency OFES as part of the European projects KnowledgeWeb (FP6-507482) and DIP (FP6-507483).
Authors in alphabetic order 相似文献
30.
Pavlopoulos John Kougia Vasiliki Androutsopoulos Ion Papamichail Dimitris 《Knowledge and Information Systems》2022,64(7):1691-1722
Knowledge and Information Systems - Diagnostic captioning (DC) concerns the automatic generation of a diagnostic text from a set of medical images of a patient collected during an examination. DC... 相似文献