全文获取类型
收费全文 | 71416篇 |
免费 | 13296篇 |
国内免费 | 9524篇 |
专业分类
电工技术 | 8320篇 |
技术理论 | 2篇 |
综合类 | 8701篇 |
化学工业 | 1454篇 |
金属工艺 | 1841篇 |
机械仪表 | 6507篇 |
建筑科学 | 1316篇 |
矿业工程 | 993篇 |
能源动力 | 1459篇 |
轻工业 | 961篇 |
水利工程 | 1110篇 |
石油天然气 | 793篇 |
武器工业 | 1196篇 |
无线电 | 12591篇 |
一般工业技术 | 4351篇 |
冶金工业 | 532篇 |
原子能技术 | 267篇 |
自动化技术 | 41842篇 |
出版年
2024年 | 552篇 |
2023年 | 1408篇 |
2022年 | 2590篇 |
2021年 | 2789篇 |
2020年 | 3028篇 |
2019年 | 2491篇 |
2018年 | 2473篇 |
2017年 | 2872篇 |
2016年 | 3311篇 |
2015年 | 3953篇 |
2014年 | 5114篇 |
2013年 | 4901篇 |
2012年 | 6155篇 |
2011年 | 6484篇 |
2010年 | 5199篇 |
2009年 | 5336篇 |
2008年 | 5582篇 |
2007年 | 6084篇 |
2006年 | 4840篇 |
2005年 | 3943篇 |
2004年 | 3186篇 |
2003年 | 2535篇 |
2002年 | 1914篇 |
2001年 | 1475篇 |
2000年 | 1263篇 |
1999年 | 998篇 |
1998年 | 809篇 |
1997年 | 653篇 |
1996年 | 505篇 |
1995年 | 359篇 |
1994年 | 300篇 |
1993年 | 231篇 |
1992年 | 215篇 |
1991年 | 108篇 |
1990年 | 137篇 |
1989年 | 96篇 |
1988年 | 67篇 |
1987年 | 24篇 |
1986年 | 34篇 |
1985年 | 34篇 |
1984年 | 26篇 |
1983年 | 26篇 |
1982年 | 28篇 |
1981年 | 17篇 |
1980年 | 20篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1975年 | 9篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Based on the theory of light energy transfer between two differential diffuse surface areas, a generalized radiosity approach is presented. Unlike the conventional radiosity method, curved surfaces are subdivided into triangular surface patches, radiosity is assummed to be vary across each triangular surface patch. By adopting linear interpolation scheme over each triangular surface patch, we have established a complete set of approximated radiosity equations. Their unknowns are radiosities of differential surface areas located at all vertices of surface patches. The generalized radiosity equation has also been extended to non-diffuse environments. Theoretical analysis and experimental results demonstrate the great potential of this method, 相似文献
82.
83.
一种遗传-梯度混合算法 总被引:3,自引:0,他引:3
本文提出一种函数全局优化的遗传-梯度混合算法。该算法由选择、交叉和诱导变异算子组成。通过对自适应滤波和前向神经网络权值训练两个典型问题的数字仿真,表明该算法是一种快速有效的全局优化算法。 相似文献
84.
Jiang Taihui 《电子科学学刊(英文版)》1996,13(4):325-332
In this paper, an adaptive line spectral pair filter is derived from an adaptive lattice filter. A least-mean-square(LMS) type adaptive algorithm used to calculate directly the line spectral pair(LSP) coefficients on a stage-by-stage basis is presented. Experimental results show that the algorithm has higher convergence rate and lower misadjustment as compared with the other algorithms. The LSP coefficients calculated by the algorithm have been used to carry out speech linear predictive synthesis, resulting in better results than PARCOR coefficients. 相似文献
85.
We study the application of the geographic nearest neighbor approach to two problems. The first problem is the construction of an approximately minimum length rectilinear Steiner tree for a set ofn points in the plane. For this problem, we introduce a variation of a subgraph of sizeO(n) used by YaO [31] for constructing minimum spanning trees. Using this subgraph, we improve the running times of the heuristics discussed by Bern [6] fromO(n
2
log
n) toO(n log2
n). The second problem is the construction of a rectilinear minimum spanning tree for a set ofn noncrossing line segments in the plane. We present an optimalO(n logn) algorithm for this problem. The rectilinear minimum spanning tree for a set of points can thus be computed optimally without using the Voronoi diagram. This algorithm can also be extended to obtain a rectilinear minimum spanning tree for a set of nonintersecting simple polygons.The results in this paper are a part of Y. C. Yee's Ph.D. thesis done at SUNY at Albany. He was supported in part by NSF Grants IRI-8703430 and CCR-8805782. S. S. Ravi was supported in part by NSF Grants DCI-86-03318 and CCR-89-05296. 相似文献
86.
Thomas L. Landers Melinda K. Beavers Malik Sadiq Don E. Stuart 《Computers & Industrial Engineering》1994,27(1-4):245-248
This paper describes an approach, conceptual framework, and software architecture for dynamic reconfiguration of the order picking system. The research and development project was sponsored by the Material Handling Research Center (MHRC), a National Science Foundation sponsored Cooperative Industry/University Research Center. The storage configuration is assumed to be an in-the-aisle order picking system in which stockkeeping units (SKUs) can occupy variable capacity storage locations and stock-splitting is allowed among zones (clusters). The product mix may include multiple product families with different life cycles, correlated demand within families and commonality of demand across families. 相似文献
87.
88.
H. Safiri M. Ahmadi G.A. Jullien W.C. Miller 《The Journal of VLSI Signal Processing》2002,31(2):91-100
A new algorithm based on Genetic Programming (GP) for the problem of optimization of Multiple constant Multiplication (MCM) by Common Subexpression Elimination(CSE) is developed. This method is used for hardware optimization for DSP systems. A solution based on Genetic Programming is shown in this paper. The performance of the technique is demonstrated in one- and multi-dimensional digital filters with constant coefficients. 相似文献
89.
90.
测井岩性识别是石油勘探中十分重要的基础工作,准确的岩性识别结果可以为勘探和开发提供可靠的依据。人工神经网络方法可对复杂的高维数据进行非线性映射,在模式识别领域得到越来越广泛的应用。针对传统的BP神经网络算法存在收敛速度慢、隐层数以及隐层节点数难以确定等缺点,研究了一种构造性神经网络学习算法---级联算法(Cascade Correlation Algorithm,简称CC算法)及其在石油工程中的应用。采用该算法对甘肃镇原-泾川地区进行岩性识别研究,通过与BP神经网络的识别结果进行比较,体现出构造性神经网络的优越性。 相似文献