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排序方式: 共有205条查询结果,搜索用时 15 毫秒
1.
Tomi Gominek Andrej Lubej Ciril Pohar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(8):939-947
Precipitation of calcium sulfate dihydrate, gypsum, from (i) a pure sulfuric acid/lime suspension and (ii) a waste sulfuric acid/lime suspension in a continuous pilot plant in the temperature range from 40 °C to 80 °C was studied. It was observed that in the case of waste sulfuric acid with a high content of Mg2+ and Fe2+ ions, several hours after the beginning of the precipitation, partial dissolution of the product and modification of the crystals from needle‐ and plate‐like to agglomerated structures occurred. It is suggested that the secondary changes occur due to the increased concentration of Mg2+ and Fe2+ ions in the reactor. Below 60 °C, and above 70 °C plate‐like and needle‐like single crystals respectively were formed. The mean size (d50) of the crystals was found to increase with increasing temperature and decrease with the initial concentration of lime. Gypsum produced between 70 °C and 80 °C is suitable for further processing for construction plaster. In a precipitation process with pure sulfuric acid only single perfect needle‐like crystals occurred. Copyright © 2005 Society of Chemical Industry 相似文献
2.
Enactive interfaces must incorporate intuitive activity that characterizes naturalistic perception. However, the manner in which information is presented is not more important than the contents: what information is presented. In this contribution, we address the contents of perception. We argue that people perceive affordances, that is, the possible actions that are available in any given situation. We further argue that enactive interfaces should be designed to optimize presentation of information about the possible actions that are available to a person using the enactive interface. The design of enactive interfaces might be guided by an extension of the theory of ecological interface design (Vicente in Hum Factors 44:62–78, 2002) to include multimodal information that is accessed through fast, intuitive exploratory movement. We review two empirical studies that illustrate our arguments. Careful analysis of affordances, together with our increasing understanding of the enactive perception of affordances, should influence the design of enactive interfaces. 相似文献
3.
Nalavany Blace A.; Ryan Scott D.; Gomory Tomi; Lacasse Jeffrey R. 《Canadian Metallurgical Quarterly》2005,14(1):27
In this pilot study, concept mapping, a methodological approach combining qualitative and quantitative analytic strategies, was used to identify the therapist qualities, competencies, and skills necessary for effective play therapy outcomes as perceived by a sub-sample of 28 experienced play therapists who are members of the Association for Play Therapy (APT). The clusters associated with the therapeutic relationship and facilitative skills (e.g., empathy, warmth, and genuineness) were rated as the most essential skills to possess and also as the most difficult to develop. In contrast, the clusters associated with play therapy interventions and theories were rated as the least important skills to possess but as the easiest to acquire. The findings are discussed, with implications for therapeutic practice, research, and policy. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Résumé Cet article présente un modèle permettant de calculer le fluage de poutres fléchies de différentes sections soumises à des
environnements variables en ce qui concerne l'humidité relative. Ce modèle est utilisé ici pour interpréter de nouveaux essais
à long terme sur des poutres en bois massif et lamellé-collé qui ont été chargées pendant plus de 800 jours en conditions
extérieures sous abri à Paris
Summary Long term bending experiments on full size timber and glulam beams have been carried out under external and sheltered climatic conditions in Paris, and more than two years of test results on the creep behaviour of 75 beams are available. A model for predicting the long term mechanical behaviour of timber under variable humidity and load conditions, previously developed by the author, is described. The model is based on transient moisture transfer analysis linked with deformation analysis using a step-by-step computation scheme, and has been compared previously with experiments carried out under laboratory conditions of controlled variable climates by the author as well as with test results obtained from several other institutions. In general, the model has agreed satisfactorily with the experimental results. In the present paper the model is compared with experiments on full size beams carried out under the changeable conditions of a natural climate. The results show that, for low stress levels and corresponding loads, the model provides a reasonable prediction of the end creep levels after two years of loading.相似文献
5.
Miodrag Čolić Sergej Tomić Rebeka Rudolf Evgenija Marković Ivana Šćepan 《Journal of materials science. Materials in medicine》2016,27(8):128
Superelastic (SE) and thermo-activated (TA) nickel–titanium (NiTi) archwires are used in everyday orthodontic practice, based on their acceptable biocompatibility and well-defined shape memory properties. However, the differences in their surface microstructure and cytotoxicity have not been clearly defined, and the standard cytotoxicity tests are too robust to detect small differences in the cytotoxicity of these alloys, all of which can lead to unexpected adverse reactions in some patients. Therefore, we tested the hypothesis that the differences in manufacture and microstructure of commercially available SE and TA archwires may influence their biocompatibility. The archwires were studied as-received and after conditioning for 24 h or 35 days in a cell culture medium under static conditions. All of the tested archwires, including their conditioned medium (CM), were non-cytotoxic for L929 cells, but Rematitan SE (both as received and conditioned) induced the apoptosis of rat thymocytes in a direct contact. In contrast, TruFlex SE and Equire TA increased the proliferation of thymocytes. The cytotoxic effect of Rematitan SE correlated with the higher release of Ni ions in CM, higher concentration of surface Ni and an increased oxygen layer thickness after the conditioning. In conclusion, the apoptosis assay on rat thymocytes, in contrast to the less sensitive standard assay on L929 cells, revealed that Rematitan SE was less cytocompatible compared to other archwires and the effect was most probably associated with a higher exposition of the cells to Ni on the surface of the archwire, due to the formation of unstable oxide layer. 相似文献
6.
Tomi A. Pasanen 《Theoretical computer science》2010,411(43):3867-3872
We consider random binary search trees when the input consists of a multiset, i.e. a set with multiple occurrences of equal elements, and prove that the randomized insertion and deletion algorithms given by Martínez and Roura (1998) [4] produce random search trees regardless of multiplicities; even if all the elements are equal during the tree updates, a search tree will maintain its randomness. Thus, equal elements do not degenerate a random search tree and they need not to be handled in any special way. We consider also stability of a search tree with respect to its inorder traversal and prove that the algorithms used produce stable trees. This implies an implicit indexing of equal elements giving another proof that multiplicities do not pose problems when maintaining random binary search trees. 相似文献
7.
Vesa Halava Tero Harju Tomi Kärki Patrice Séébold 《Theoretical computer science》2009,410(8-10):943-948
We prove that there exist infinitely many infinite overlap-free binary partial words containing at least one hole. Moreover, we show that these words cannot contain more than one hole and the only hole must occur either in the first or in the second position. We define that a partial word is -overlap-free if it does not contain a factor of the form where the length of is at least . We prove that there exist infinitely many 2-overlap-free binary partial words containing an infinite number of holes. 相似文献
8.
In this article, the role of the restoring stiffness, as one of the basic parameters in ship hydroelastic analysis, is brought
out. It is formulated using the variational principle and the method of virtual displacements. It is shown that asymmetry
of the restoring stiffness is a physical reality. Moreover, it is confirmed that modal variation, still disputed in the relevant
literature, has to be taken into account to satisfy the ship’s stability. Consistent stiffness is formulated here by regarding
stiffness definition as relation between forces and displacements. Hybrid stiffness known from the literature is wrong since
some terms are specified as relation between forces and displacement gradient. Influence of the consistent and symmetrized
stiffness matrix, and the hybrid one, on dynamic response is illustrated for a prismatic pontoon and a large container ship.
It is found that the latter two matrices do not assure convergence of transfer functions of sectional forces to zero value
as the wave frequency approaches zero. The rigid body and elastic responses are compared, and pertinent conclusions are drawn.
It is also shown that it is not necessary to use the unified geometric and restoring stiffness for ordinary hydroelastic analysis
of ship structures. The consistent formulation of the restoring stiffness matrix will be useful for extending linear potential
theory hydrodynamic codes for rigid body analysis to deformable bodies. 相似文献
9.
To date, there is little evidence that modular reasoning about fault-tolerant systems can simplify the verification process in practice. This question is studied using a prominent example from the fault tolerance literature: the problem of reliable broadcast in point-to-point networks subject to crash failures of processes. The experiences from this case study show how modular specification techniques and rigorous proof re-use can indeed help in such undertakings. 相似文献
10.
Gamal Lazouzi Marija M. Vuksanović Nataša Z. Tomić Miodrag Mitrić Miloš Petrović Vesna Radojević Radmila Jančić Heinemann 《Ceramics International》2018,44(7):7442-7449
Alumina based particles were prepared from aluminium chloride hydroxide as starting material by sol-gel technique. One series of particles was doped with ferrous oxide. Both series of particles were calcinated at three different temperatures: 700?°C, 800?°C and 900?°C. Poly(methyl methacrylate), PMMA, was used as a matrix and two different types of alumina based particles were added into the matrix to form the composites. All composites consisted of 3?wt% of alumina based particles. The aim of this study was to examine whether and how the temperature of particle calcination affects the microhardness and mechanical properties of the composite. The particles were characterized by the X-ray diffraction (XRD) and physical absorption methods. The morphology of the composites was examined using a field emission scanning electron microscope (FESEM). The microhardness of composites was measured using a traditional Vickers hardness (HV) method. The mechanical characteristics of obtained composites were determined using tensile test and impact testing. 相似文献