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排序方式: 共有766条查询结果,搜索用时 15 毫秒
671.
The loss of lithium during solution heat treatment of alloy 2090 clad with approximately 100 μm of 7072 was investigated.
Lithium concentration profiles in the alloy were measured using a nuclear reaction analysis technique after samples had been
subjected to various solution heat treatments. The results showed that the cladding-base metal interface provided no impediment
to lithium diffusion and that the rate of lithium diffusion in the cladding was similar to its rate of diffusion in the base
metal. A lithium-rich oxide was formed on the external surface, but the concentration profiles showed that the effective lithium
concentration at the surface was near zero. Thus, lithium in the bulk experienced a maximum concentration gradient and diffused
to the surface as rapidly as possible. Despite the absence of any lithium diffusion barrier in the cladding, the initial rate
of lithium loss is much less than in bare material. The cladding provides effective protection from lithium loss, and the
rate of loss in clad materials only approaches that of bare materials after approximately 4 hours. 相似文献
672.
Influence of Microstructure on Crack Propagation During fatigue crack propagation under service loads, pronounced load sequence effects can be observed. Only little knowledge exists, how far these sequence effects are influenced by the microstructure of the material and the resulting microstructural fatigue crack propagation mechanisms. Test series are discussed, where with different aluminium alloys and heart treatments varitions of the fatigue crack propagation mechanisms were performed. Additional attention was given to the influence of the environment on the fatigue crack propagation behaviour. Tests were performed in vacuum and, as examples of more aggressive environments, in laboratory air and in a 3.5% NaCl-solution. An attempt is made to explain the observed behaviour on the basis of continuum mechanics considerations and the microstructural properties of the aluminium alloys. 相似文献
673.
W. Feldheim E. Schulte und H. Elbertshagen 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1979,169(5):361-362
Ohne Zusammenfassung 相似文献
674.
675.
Many organizations turn to project management offices (PMOs) in order to increase project efficiency, cut costs, and improve success rates in project delivery. However, many PMOs face the challenge of a lack of recognition of their contribution, leading to the need to repeatedly justify their existence. This article provides new insights into the success and failure of PMOs and also provides the rationale and structure for a holistic approach to establishing and sustaining a PMO. 相似文献
676.
Bas Dado Timothy R. Kol Pablo Bauszat Jean‐Marc Thiery Elmar Eisemann 《Computer Graphics Forum》2016,35(2):397-407
Voxel‐based approaches are today's standard to encode volume data. Recently, directed acyclic graphs (DAGs) were successfully used for compressing sparse voxel scenes as well, but they are restricted to a single bit of (geometry) information per voxel. We present a method to compress arbitrary data, such as colors, normals, or reflectance information. By decoupling geometry and voxel data via a novel mapping scheme, we are able to apply the DAG principle to encode the topology, while using a palette‐based compression for the voxel attributes, leading to a drastic memory reduction. Our method outperforms existing state‐of‐the‐art techniques and is well‐suited for GPU architectures. We achieve real‐time performance on commodity hardware for colored scenes with up to 17 hierarchical levels (a 128K3voxel resolution), which are stored fully in core. 相似文献
677.
Matthias Hollander Tobias Ritschel Elmar Eisemann Tamy Boubekeur 《Computer Graphics Forum》2011,30(4):1233-1240
Level‐of‐Detail structures are a key component for scalable rendering. Built from raw 3D data, these structures are often defined as Bounding Volume Hierarchies, providing coarse‐to‐fine adaptive approximations that are well‐adapted for many‐view rasterization. Here, the total number of pixels in each view is usually low, while the cost of choosing the appropriate LoD for each view is high. This task represents a challenge for existing GPU algorithms. We propose ManyLoDs, a new GPU algorithm to efficiently compute many LoDs from a Bounding Volume Hierarchy in parallel by balancing the workload within and among LoDs. Our approach is not specific to a particular rendering technique, can be used on lazy representations such as polygon soups, and can handle dynamic scenes. We apply our method to various many‐view rasterization applications, including Instant Radiosity, Point‐Based Global Illumination, and reflection/refraction mapping. For each of these, we achieve real‐time performance in complex scenes at high resolutions. 相似文献
678.
Dawid Paja̧k Robert Herzog Elmar Eisemann Karol Myszkowski Hans‐Peter Seidel 《Computer Graphics Forum》2011,30(2):415-424
In this paper, we focus on efficient compression and streaming of frames rendered from a dynamic 3D model. Remote rendering and on‐the‐fly streaming become increasingly attractive for interactive applications. Data is kept confidential and only images are sent to the client. Even if the client's hardware resources are modest, the user can interact with state‐of‐the‐art rendering applications executed on the server. Our solution focuses on augmented video information, e.g., by depth, which is key to increase robustness with respect to data loss, image reconstruction, and is an important feature for stereo vision and other client‐side applications. Two major challenges arise in such a setup. First, the server workload has to be controlled to support many clients, second the data transfer needs to be efficient. Consequently, our contributions are twofold. First, we reduce the server‐based computations by making use of sparse sampling and temporal consistency to avoid expensive pixel evaluations. Second, our data‐transfer solution takes limited bandwidths into account, is robust to information loss, and compression and decompression are efficient enough to support real‐time interaction. Our key insight is to tailor our method explicitly for rendered 3D content and shift some computations on client GPUs, to better balance the server/client workload. Our framework is progressive, scalable, and allows us to stream augmented high‐resolution (e.g., HD‐ready) frames with small bandwidth on standard hardware. 相似文献
679.
680.
Krieger E Nielsen JE Spronk CA Vriend G 《Journal of molecular graphics & modelling》2006,25(4):481-486
pK(a) calculations for macromolecules are normally performed by solving the Poisson-Boltzmann equation, accounting for the different dielectric constants of solvent and solute, as well as the ionic strength. Despite the large number of successful applications, there are some situations where the current algorithms are not suitable: (1) large scale, high-throughput analysis which requires calculations to be completed within a fraction of a second, e.g. when permanently monitoring pK(a) shifts during a molecular dynamics simulation; (2) prediction of pK(a)s in periodic boundaries, e.g. when reconstructing entire protein crystal unit cells from PDB files, including the correct protonation patterns at experimental pH. Such in silico crystals are needed by 'self-parameterizing' molecular dynamics force fields like YASARA YAMBER, that optimize their parameters while energy-minimizing high-resolution protein crystals. To address both problems, we define an empirical equation that expresses the pK(a) as a function of electrostatic potential, hydrogen bonds and accessible surface area. The electrostatic potential is evaluated by Ewald summation, which captures periodic crystal environments and the uncertainty in atom positions using Gaussian charge densities. The empirical proportionality constants are derived from 217 experimentally determined pK(a)s, and despite its simplicity, this pK(a) calculation method reaches a high overall jack-knifed accuracy, and is fast enough to be used during a molecular dynamics simulation. A reliable null-model to judge pK(a) prediction accuracies is also presented. 相似文献