全文获取类型
收费全文 | 2935篇 |
免费 | 157篇 |
国内免费 | 147篇 |
专业分类
电工技术 | 65篇 |
综合类 | 116篇 |
化学工业 | 297篇 |
金属工艺 | 699篇 |
机械仪表 | 229篇 |
建筑科学 | 69篇 |
矿业工程 | 34篇 |
能源动力 | 185篇 |
轻工业 | 36篇 |
水利工程 | 14篇 |
石油天然气 | 103篇 |
武器工业 | 12篇 |
无线电 | 370篇 |
一般工业技术 | 233篇 |
冶金工业 | 33篇 |
原子能技术 | 40篇 |
自动化技术 | 704篇 |
出版年
2024年 | 1篇 |
2023年 | 19篇 |
2022年 | 30篇 |
2021年 | 40篇 |
2020年 | 27篇 |
2019年 | 47篇 |
2018年 | 43篇 |
2017年 | 55篇 |
2016年 | 69篇 |
2015年 | 62篇 |
2014年 | 158篇 |
2013年 | 155篇 |
2012年 | 128篇 |
2011年 | 288篇 |
2010年 | 252篇 |
2009年 | 227篇 |
2008年 | 205篇 |
2007年 | 215篇 |
2006年 | 186篇 |
2005年 | 148篇 |
2004年 | 135篇 |
2003年 | 106篇 |
2002年 | 101篇 |
2001年 | 48篇 |
2000年 | 63篇 |
1999年 | 59篇 |
1998年 | 69篇 |
1997年 | 82篇 |
1996年 | 41篇 |
1995年 | 41篇 |
1994年 | 35篇 |
1993年 | 21篇 |
1992年 | 14篇 |
1991年 | 20篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有3239条查询结果,搜索用时 15 毫秒
91.
92.
93.
Marcos Sandim Douglas Cedrim Luis Gustavo Nonato Paulo Pagliosa Afonso Paiva 《Computer Graphics Forum》2016,35(2):215-224
This paper presents a novel method to detect free‐surfaces on particle‐based volume representation. In contrast to most particle‐based free‐surface detection methods, which perform the surface identification based on physical and geometrical properties derived from the underlying fluid flow simulation, the proposed approach only demands the spatial location of the particles to properly recognize surface particles, avoiding even the use of kernels. Boundary particles are identified through a Hidden Point Removal (HPR) operator used for visibility test. Our method is very simple, fast, easy to implement and robust to changes in the distribution of particles, even when facing large deformation of the free‐surface. A set of comparisons against state‐of‐the‐art boundary detection methods show the effectiveness of our approach. The good performance of our method is also attested in the context of fluid flow simulation involving free‐surface, mainly when using level‐sets for rendering purposes. 相似文献
94.
Tensors model a wide range of physical phenomena. While symmetric tensors are sufficient for some applications (such as diffusion), asymmetric tensors are required, for example, to describe differential properties of fluid flow. Glyphs permit inspecting individual tensor values, but existing tensor glyphs are fully defined only for symmetric tensors. We propose a glyph to visualize asymmetric second‐order two‐dimensional tensors. The glyph includes visual encoding for physically significant attributes of the tensor, including rotation, anisotropic stretching, and isotropic dilation. Our glyph design conserves the symmetry and continuity properties of the underlying tensor, in that transformations of a tensor (such as rotation or negation) correspond to analogous transformations of the glyph. We show results with synthetic data from computational fluid dynamics. 相似文献
95.
In this paper, we consider Centroidal Voronoi Tessellations (CVTs) and study their regularity. CVTs are geometric structures that enable regular tessellations of geometric objects and are widely used in shape modelling and analysis. While several efficient iterative schemes, with defined local convergence properties, have been proposed to compute CVTs, little attention has been paid to the evaluation of the resulting cell decompositions. In this paper, we propose a regularity criterion that allows us to evaluate and compare CVTs independently of their sizes and of their cell numbers. This criterion allows us to compare CVTs on a common basis. It builds on earlier theoretical work showing that second moments of cells converge to a lower bound when optimizing CVTs. In addition to proposing a regularity criterion, this paper also considers computational strategies to determine regular CVTs. We introduce a hierarchical framework that propagates regularity over decomposition levels and hence provides CVTs with provably better regularities than existing methods. We illustrate these principles with a wide range of experiments on synthetic and real models. 相似文献
96.
海洋表面矿物油膜、生物油膜等在SAR图像上都呈现为暗色特征,使得单极化SAR图像对矿物油膜和生物油膜的区分存在困难。分析了矿物油膜和生物油膜后向散射系数的极化比,提出一种基于交叉极化比的多极化SAR图像矿物油膜和生物油膜的区分方法,并用SIR\|C多极化数据验证了该方法的有效性。 相似文献
97.
戴价 《电脑与微电子技术》2013,(24):54-56
多台投影机的无缝拼接校正过程主要是投影机的几何校正和颜色校正。多台投影机的颜色校正要求是求出每台投影机的颜色曲线,并对其颜色的相同输出做对应的输入使之达到全局的颜色统一。采用基于相机HDR的方法,先求出相机的亮度响应曲线,再以相机的亮度响应曲线为基础,使相机的输入为投影机的输出,间接求得投影机的亮度响应曲线。实验结果表明,基于HDR的亮度曲线测量,与直接使用照度计比较,结果相差在10%以内。 相似文献
98.
This paper presents a novel multi-directional blending method for heterogeneous object design. Contrary to earlier studies, this paper introduces material blending through multiple features with different heterogeneous material composition. Feature-based method is used to represent and design heterogeneous objects with multi-directional material composition. The Voronoi diagram of multiple curves is constructed to generate bisector of the geometric domain. Then, metamorphosis from the bounding curve to multiple internal curves is performed using dynamic programming based optimization approach in two steps. First, optimum curve matching between internal curves and enclosing Voronoi cells is obtained. Then, an optimum ruling line alignment and insertion technique between the Voronoi diagram and the bounding curve is developed. Metamorphosis through complex concavities is also achieved. Finally, multi-directional material composition is mapped based on a set of relations. 相似文献
99.
We present a method for analytically calculating an anti‐aliased rasterization of arbitrary polygons or fonts bounded by Bézier curves in 2D as well as oriented triangle meshes in 3D. Our algorithm rasterizes multiple resolutions simultaneously using a hierarchical wavelet representation and is robust to degenerate inputs. We show that using the simplest wavelet, the Haar basis, is equivalent to performing a box‐filter to the rasterized image. Because we evaluate wavelet coefficients through line integrals in 2D, we are able to derive analytic solutions for polygons that have Bézier curve boundaries of any order, and we provide solutions for quadratic and cubic curves. In 3D, we compute the wavelet coefficients through analytic surface integrals over triangle meshes and show how to do so in a computationally efficient manner. 相似文献
100.
We introduce a fully automatic algorithm which optimizes the high‐level structure of a given quadrilateral mesh to achieve a coarser quadrangular base complex. Such a topological optimization is highly desirable, since state‐of‐the‐art quadrangulation techniques lead to meshes which have an appropriate singularity distribution and an anisotropic element alignment, but usually they are still far away from the high‐level structure which is typical for carefully designed meshes manually created by specialists and used e.g. in animation or simulation. In this paper we show that the quality of the high‐level structure is negatively affected by helical configurations within the quadrilateral mesh. Consequently we present an algorithm which detects helices and is able to remove most of them by applying a novel grid preserving simplification operator (GP‐operator) which is guaranteed to maintain an all‐quadrilateral mesh. Additionally it preserves the given singularity distribution and in particular does not introduce new singularities. For each helix we construct a directed graph in which cycles through the start vertex encode operations to remove the corresponding helix. Therefore a simple graph search algorithm can be performed iteratively to remove as many helices as possible and thus improve the high‐level structure in a greedy fashion. We demonstrate the usefulness of our automatic structure optimization technique by showing several examples with varying complexity. 相似文献