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排序方式: 共有185条查询结果,搜索用时 15 毫秒
1.
Sonia Hirt 《Journal of the American Planning Association. American Planning Association》2013,79(4):436-450
Problem: Traditional American zoning separates land uses, yet many urbanists and contemporary planners argue that bringing mixed use back to the American city is the key to restoring its vibrancy. Purpose: This article compares the American and the German approaches to regulating land use. Methods: I derive my conclusions from a review of German federal and local regulatory documents, and interviews I conducted in the German city of Stuttgart. Results and conclusions: The U.S. zoning approach assumes that each land use district is suitable for only a single type of human activity, such as residential, commercial, or industrial use; whereas in Germany the prevailing principle is that each land use district is suitable for multiple types of activity, and most districts end up in mixed uses. Thus, despite some nominal similarities in the land use categories employed in both countries, the zoning methods are in fact starkly different. Takeaway for practice: The German zoning system, which commonly mixes the land uses, challenges deeply engrained assumptions that underlie standard U.S. zoning, and it may offer useful alternatives for zoning reform. 相似文献
2.
Twin roll strip casting can be an effective alternative to produce high manganese TWIP steel, which provides extraordinary mechanical properties. In the work presented, 1.5–3 mm thin hot strips with up to 30 wt% manganese were produced directly from the melt and further processed to cold strip. An adapted thermo-mechanical treatment, consisting of cold rolling with or without subsequent annealing, enables to adjust different material states, such as recrystallised or strengthened state, and thus to tailor the mechanical properties. As an example for the superior crash behaviour of high manganese TWIP steels, dynamic crash tests were carried out using cold rolled Fe–29Mn–0.3C steel in different material states. 相似文献
3.
Particularly in fast rolling mills, conventional actuators reach their dynamic limits, when longitudinal thickness variations of the incoming strip shall be reduced with high accuracy by model-predictive roll gap control. Accordingly, the applicability of highly dynamic piezoelectric actuators in combination with electromechanical spindles and a high frequency precision measurement of the thickness in front of the roll gap was examined. Rolling tests in a cold rolling mill for narrow slit strips show that this novel concept is suitable to provide the required dynamic actuation especially at high rolling speed. 相似文献
4.
Few cities in Europe have a history as dramatic and tumultuous as that of the Serbian capital of Belgrade. The gracious “White City,” which rises spectacularly along the banks of the Danube and the Sava River, has been the site of wars, conquests and rapidly changing fortunes for much of its thousands-years long history. Belgrade suffered heavy destruction under both World Wars, and it has the unfortunate distinction of being the only European capital to be bombed at the end of the 20th century. Its modern history is marked by abrupt shifts in political status: from a capital of a relatively small nation-state, to a center of a larger and prosperous multi-national federation, to a capital of a nation-state once again. These shifts parallel the changing geopolitical position of Serbia/Yugoslavia in Europe. In this City Profile, I present the evolution of the built environment of Belgrade in five historic stages: ancient/medieval/Ottoman, early modern, communist, transitional, and contemporary. I show how each period left a distinct spatial imprint on Belgrade’s fabric. Finally, I discuss some contemporary challenges and opportunities in planning Belgrade’s future. 相似文献
5.
In order to produce new high Mn‐high C austenitic steels (Rm>700 MPa), different tests and methods were used to determine a suitable window of process parameters. In‐situ melting hot tensile tests and hot compression tests were carried out to investigate the hot ductility, fracture characteristics and flow behaviour during continuous casting and hot deformation of 3 steels with Mn and C contents between 9‐23% and 0.6‐0.9%, respectively. The results show that these steels are susceptible to interdendritic fracture at high temperatures. Decreasing Mn content improves the reduction of area at high temperatures to 60% or more. Hot deformation loads for processing the investigated steels are not higher in comparison to the stainless steel 1.4301. 相似文献
6.
Very early in an electronic design cycle the physical buildup of a system, such as bonding method, substrate technology, and number of layers, needs to be chosen before any layout is performed. But when developing high density systems, a huge number of technology choices are available, each having impact on various aspects of the system performance. This paper describes virtual prototyping as a method for systematically analyzing and choosing the suitable buildups and selecting one of them in a cost-performance analysis for implementation and layout. Unlike former design advisors, our method analyzes several possibilities in parallel, allowing for a better design space exploration. The framework is implemented in the Java based tool JavaCAD, JavaCAD manages the different buildups and provides a size/layer count estimation for all first level interconnect/packages on various substrate technologies. It calculates the component footprints, analyzes the routing with as few data as available and allows cost estimation of all feasible buildups. The benefits of our approach are illustrated in the design of a 9:4 satellite switch operating at 2.4 GHz 相似文献
7.
Devine Patricia G.; Hirt Edward R.; Gehrke Elizabeth M. 《Canadian Metallurgical Quarterly》1990,58(6):952
The role of diagnostic and confirmation strategies in trait hypothesis testing is examined. The present studies integrate theoretical and empirical work on qualitative differences among traits with the hypothesis-testing literature. Ss tested trait hypotheses from 2 hierarchically restrictive trait dimensions: introversion–extraversion and honesty–dishonesty. In Study 1, Ss generated questions to test trait hypotheses, and diagnosticity was theoretically defined (e.g., questions associated with nonrestrictive ends of trait dimensions). In Study 2, Ss selected questions from an experimenter-provided list in which diagnosticity was empirically defined. In Study 3, Ss chose between 2 equally diagnostic questions. In each of the studies, Ss showed a primary preference for diagnostic information and a secondary preference for confirmatory information. Ss' preference for diagnostic information suggests that they prefer to ask the most informative questions. The explanation for the confirmation bias is less obvious, and possible reasons for this effect are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
9.
ABSTRACT Regardless of the fast-growing popularity of shrinking cities in the literature, certain misconceptions persist. Urban shrinkage is often assumed to be near-synonymous with urban distress, and shrinking cities are assumed to be in need of growth. In this paper, we seek to achieve a greater conceptual clarity for both shrinkage and distress, thereby informing present debates on the topic and inviting more nuanced ones in the future. The paper is organized in three main parts. We first use a historical lens to challenge the conflation of shrinkage and distress. Western history is rife with examples of when growth—shrinkage’s opposite—was associated with distress. Second, we comment on some contradictions in the conceptual currents that underlie the idea of shrinking as distress, particularly in the United States. Third, we highlight how shrinkage may benefit cities and the people who live in them. 相似文献
10.
Luca Hirt Alain Reiser Ralph Spolenak Tomaso Zambelli 《Advanced materials (Deerfield Beach, Fla.)》2017,29(17)
Currently, the focus of additive manufacturing (AM) is shifting from simple prototyping to actual production. One driving factor of this process is the ability of AM to build geometries that are not accessible by subtractive fabrication techniques. While these techniques often call for a geometry that is easiest to manufacture, AM enables the geometry required for best performance to be built by freeing the design process from restrictions imposed by traditional machining. At the micrometer scale, the design limitations of standard fabrication techniques are even more severe. Microscale AM thus holds great potential, as confirmed by the rapid success of commercial micro‐stereolithography tools as an enabling technology for a broad range of scientific applications. For metals, however, there is still no established AM solution at small scales. To tackle the limited resolution of standard metal AM methods (a few tens of micrometers at best), various new techniques aimed at the micrometer scale and below are presently under development. Here, we review these recent efforts. Specifically, we feature the techniques of direct ink writing, electrohydrodynamic printing, laser‐assisted electrophoretic deposition, laser‐induced forward transfer, local electroplating methods, laser‐induced photoreduction and focused electron or ion beam induced deposition. Although these methods have proven to facilitate the AM of metals with feature sizes in the range of 0.1–10 µm, they are still in a prototype stage and their potential is not fully explored yet. For instance, comprehensive studies of material availability and material properties are often lacking, yet compulsory for actual applications. We address these items while critically discussing and comparing the potential of current microscale metal AM techniques. 相似文献