全文获取类型
收费全文 | 1711篇 |
免费 | 154篇 |
国内免费 | 103篇 |
专业分类
电工技术 | 54篇 |
综合类 | 77篇 |
化学工业 | 80篇 |
金属工艺 | 45篇 |
机械仪表 | 168篇 |
建筑科学 | 86篇 |
矿业工程 | 37篇 |
能源动力 | 27篇 |
轻工业 | 47篇 |
水利工程 | 35篇 |
石油天然气 | 17篇 |
武器工业 | 8篇 |
无线电 | 217篇 |
一般工业技术 | 164篇 |
冶金工业 | 50篇 |
原子能技术 | 85篇 |
自动化技术 | 771篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 17篇 |
2021年 | 31篇 |
2020年 | 27篇 |
2019年 | 25篇 |
2018年 | 31篇 |
2017年 | 34篇 |
2016年 | 50篇 |
2015年 | 58篇 |
2014年 | 102篇 |
2013年 | 116篇 |
2012年 | 105篇 |
2011年 | 171篇 |
2010年 | 128篇 |
2009年 | 114篇 |
2008年 | 128篇 |
2007年 | 108篇 |
2006年 | 112篇 |
2005年 | 109篇 |
2004年 | 76篇 |
2003年 | 87篇 |
2002年 | 55篇 |
2001年 | 35篇 |
2000年 | 40篇 |
1999年 | 44篇 |
1998年 | 32篇 |
1997年 | 14篇 |
1996年 | 25篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1978年 | 1篇 |
1975年 | 3篇 |
1971年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1968条查询结果,搜索用时 0 毫秒
31.
Active contours with selective local or global segmentation: A new formulation and level set method 总被引:4,自引:0,他引:4
A novel region-based active contour model (ACM) is proposed in this paper. It is implemented with a special processing named Selective Binary and Gaussian Filtering RegularizedLevel Set(SBGFRLS) method, which first selectively penalizes the level set function to be binary, and then uses a Gaussian smoothing kernel to regularize it. The advantages of our method are as follows. First, a new region-based signed pressure force (SPF) function is proposed, which can efficiently stop the contours at weak or blurred edges. Second, the exterior and interior boundaries can be automatically detected with the initial contour being anywhere in the image. Third, the proposed ACM with SBGFRLS has the property of selective local or global segmentation. It can segment not only the desired object but also the other objects. Fourth, the level set function can be easily initialized with a binary function, which is more efficient to construct than the widely used signed distance function (SDF). The computational cost for traditional re-initialization can also be reduced. Finally, the proposed algorithm can be efficiently implemented by the simple finite difference scheme. Experiments on synthetic and real images demonstrate the advantages of the proposed method over geodesic active contours (GAC) and Chan–Vese (C–V) active contours in terms of both efficiency and accuracy. 相似文献
32.
Yunjie ChenAuthor Vitae Jianwei ZhangAuthor VitaeArabinda MishraAuthor Vitae Jianwei YangAuthor Vitae 《Neurocomputing》2011,74(17):3520-3530
Intensity inhomogeneity causes considerable difficulty in the quantitative analysis of magnetic resonance (MR) images. Thus bias field estimation is a necessary pre-processing step before quantitative analysis of MR data. This paper presents a variational level set approach for bias correction and segmentation for images with intensity inhomogeneities. Our method is based on the observation that local intensity variations in relatively smaller regions are separable, despite the inseparability of the whole image. In the beginning we define a function for clustering the image pixels in a smaller neighborhood. The cluster centers in this objective function have a multiplicative factor that estimates the bias within the neighborhood. Generally the local intensity variations are described by the Gaussian distributions with different means and variances. In this work the objective functions are integrated over the entire domain with local Gaussian distribution of fitting energy, ultimately analyzing the data with a level set framework. Our method is able to capture bias of quite general profiles. Moreover, our model can also distinguish regions with similar intensity distribution with different variances. The proposed method has been rigorously validated with images acquired on variety of imaging modalities with promising results. 相似文献
33.
34.
35.
针对云计算技术中的资源调度时间长、开销大、不考虑调度安全的问题,本文在对常见的云环境下工作流任务的资源调度问题进行建模的基础上,提出了一种强安全约束机制下的云计算任务调度方案。该方案按照所用方法的安全强度,再加上相关软件的安全程度,赋予虚拟机不同的安全等级;另一方面,其按照用户的需求等诸多方面,能够赋予操作不同的安全需求等级;最后使用变近邻粒子群算法对该问题进行了求解。在CloudSim仿真平台上的实验结果证明,本文提出的算法与用最大-最小蚁群算法、遗传算法与该算法相比,该算法具有很好的可用性和寻优能力。 相似文献
36.
This paper considers a multiobjective linear programming problem involving fuzzy random variable coefficients. A new fuzzy random programming model is proposed by extending the ideas of level set-based optimality and a stochastic programming model. The original problem involving fuzzy random variables is transformed into a deterministic equivalent problem through the proposed model. An interactive algorithm is provided to obtain a satisficing solution for a decision maker from among a set of newly defined Pareto optimal solutions. It is shown that an optimal solution of the problem to be solved iteratively in the interactive algorithm is analytically obtained by a combination of the bisection method and the simplex method. 相似文献
37.
A shape prior constraint for implicit active contours 总被引:2,自引:0,他引:2
We present a shape prior constraint to guide the evolution of implicit active contours. Our method includes three core techniques. Firstly, a rigid registration is introduced, using a line search method within a level set framework. The method automatically finds the time step for the iterative optimization processes. The order for finding the optimal translation, rotation and scale is derived experimentally. Secondly, a single reconstructed shape is created from a shape distribution of a previously acquired learning set. The reconstructed shape is applied to guide the active contour evolution. Thirdly, our method balances the impact of the shape prior versus the image guidance of the active contour. A mixed stopping condition is defined based on the stationarity of the evolving curve and the shape prior constraint. Our method is completely non-parametric and avoids taking linear combinations of non-linear signed distance functions, which would cause problems because distance functions are not closed under linear operations. Experimental results show that our method is able to extract the desired objects in several circumstances, namely when noise is present in the image, when the objects are in slightly different poses and when parts of the object are invisible in the image. 相似文献
38.
This paper proposes an improved variational model, multiple piecewise constant with geodesic active contour (MPC-GAC) model, which generalizes the region-based active contour model by Chan and Vese, 2001 [11] and merges the edge-based active contour by Caselles et al., 1997 [7] to inherit the advantages of region-based and edge-based image segmentation models. We show that the new MPC-GAC energy functional can be iteratively minimized by graph cut algorithms with high computational efficiency compared with the level set framework. This iterative algorithm alternates between the piecewise constant functional learning and the foreground and background updating so that the energy value gradually decreases to the minimum of the energy functional. The k-means method is used to compute the piecewise constant values of the foreground and background of image. We use a graph cut method to detect and update the foreground and background. Numerical experiments show that the proposed interactive segmentation method based on the MPC-GAC model by graph cut optimization can effectively segment images with inhomogeneous objects and background. 相似文献
39.
用户级实时线程的设计与实现 总被引:1,自引:0,他引:1
连续媒质的应用程序要求有实时线程高效灵活的支持,包括对线程属性的动态管理和多线程模式的支持。本文介绍在RT-Mach微内核上用户实时线程的设计和实现。 相似文献
40.