全文获取类型
收费全文 | 34509篇 |
免费 | 3501篇 |
国内免费 | 2235篇 |
专业分类
电工技术 | 2345篇 |
技术理论 | 9篇 |
综合类 | 3995篇 |
化学工业 | 780篇 |
金属工艺 | 276篇 |
机械仪表 | 1202篇 |
建筑科学 | 15562篇 |
矿业工程 | 1688篇 |
能源动力 | 626篇 |
轻工业 | 387篇 |
水利工程 | 1104篇 |
石油天然气 | 607篇 |
武器工业 | 246篇 |
无线电 | 2623篇 |
一般工业技术 | 1826篇 |
冶金工业 | 636篇 |
原子能技术 | 194篇 |
自动化技术 | 6139篇 |
出版年
2024年 | 126篇 |
2023年 | 368篇 |
2022年 | 770篇 |
2021年 | 903篇 |
2020年 | 966篇 |
2019年 | 761篇 |
2018年 | 793篇 |
2017年 | 864篇 |
2016年 | 1171篇 |
2015年 | 1343篇 |
2014年 | 2532篇 |
2013年 | 2056篇 |
2012年 | 2761篇 |
2011年 | 2925篇 |
2010年 | 2511篇 |
2009年 | 2507篇 |
2008年 | 2323篇 |
2007年 | 2588篇 |
2006年 | 2285篇 |
2005年 | 1810篇 |
2004年 | 1468篇 |
2003年 | 1190篇 |
2002年 | 984篇 |
2001年 | 841篇 |
2000年 | 764篇 |
1999年 | 568篇 |
1998年 | 420篇 |
1997年 | 294篇 |
1996年 | 243篇 |
1995年 | 220篇 |
1994年 | 177篇 |
1993年 | 130篇 |
1992年 | 135篇 |
1991年 | 80篇 |
1990年 | 62篇 |
1989年 | 61篇 |
1988年 | 48篇 |
1987年 | 28篇 |
1986年 | 33篇 |
1985年 | 21篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1959年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Yvon Maday Frédéric Magoulès 《Computer Methods in Applied Mechanics and Engineering》2007,196(8):1541-1553
In this paper an original variant of the Schwarz domain decomposition method is introduced for heterogeneous media. This method uses new optimized interface conditions specially designed to take into account the heterogeneity between the sub-domains on each sides of the interfaces. Numerical experiments illustrate the dependency of the proposed method with respect to several parameters, and confirm the robustness and efficiency of this method based on such optimized interface conditions. Several mesh partitions taking into account multiple cross points are considered in these experiments. 相似文献
92.
93.
Markovian and semi-Markovian random processes are used to analyze the problem of optimal search for signals in a multichannel
communication system with arbitrarily distributed random outputs. The search efficiency factor is found in explicit form based
on state space merging, and a mathematical programming problem is set up to find a numerical suboptimal solution.
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 144–150, May–June 2007. 相似文献
94.
Ambedkar Dukkipati 《Information Sciences》2007,177(24):5707-5714
The measure-theoretic definition of Kullback-Leibler relative-entropy (or simply KL-entropy) plays a basic role in defining various classical information measures on general spaces. Entropy, mutual information and conditional forms of entropy can be expressed in terms of KL-entropy and hence properties of their measure-theoretic analogs will follow from those of measure-theoretic KL-entropy. These measure-theoretic definitions are key to extending the ergodic theorems of information theory to non-discrete cases. A fundamental theorem in this respect is the Gelfand-Yaglom-Perez (GYP) Theorem [M.S. Pinsker, Information and Information Stability of Random Variables and Process, 1960, Holden-Day, San Francisco, CA (English ed., 1964, translated and edited by Amiel Feinstein), Theorem. 2.4.2] which states that measure-theoretic relative-entropy equals the supremum of relative-entropies over all measurable partitions. This paper states and proves the GYP-theorem for Rényi relative-entropy of order greater than one. Consequently, the result can be easily extended to Tsallis relative-entropy. 相似文献
95.
CIE TC8‐01 has adopted a new color appearance model: CIECAM021 replaces the CIECAM97s.2 The new model consists of a number of refinements and simplifications of the CIECAM97s color appearance model. This article describes further tests to the robustness of the forward and reverse modes. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 99–106, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20087 相似文献
96.
介绍了法西斯大厦的基本情况,通过对朱赛普·特拉尼的代表作法西斯大厦的空间结构、承重结构、围护结构、立面结构的分析,以使人们更深刻地理解特拉尼的建筑思想,探索其积极的现实意义。 相似文献
97.
An Efficient Code-Based Voxel-Traversing Algorithm 总被引:3,自引:1,他引:2
The paper considers an efficient approach to traversing a uniformly-subdivided space pierced by a line segment. A voxel, as the basic constituent element of the uniformly subdivided space, is restricted to having the form of a cube. The algorithm works in two steps. In the first step, the so-called Bresenham voxels are identified and, by comparing their position codes, their type of connectivity is determined. To achieve the required connectivity between neighbouring voxels, the second step of the algorithm is applied to find the missing voxels. In this way, the algorithm efficiently switches between face-, edge- and vertex-connectivity. Although the algorithm works with oating-point precision, it is extremely computationally efficient, and tests of speed compared with the Müller, Cleary & Wyvill, Amanatides & Woo, and Zemčik algorithms are described. 相似文献
98.
浅述城市规划管理信息系统 总被引:3,自引:0,他引:3
阐述了城市规划管理信息系统的内容及其建立的方法和步骤,以及其与管理人员构成和该系统的经济效益,并指出城市规划管理信息系统利用计算机技术,科学地现代化地优化了城市规划设计与城市规划管理,为了城市建设的科学发展应加大投入,跟上时代步伐,进入城市建设的计算机时代。 相似文献
99.
阮芙英 《纺织高校基础科学学报》1995,8(1):91-95
现代光学和通讯理论由于引入了傅里叶变换的方法,使计算光学系统和通讯系统的物像的对应关系简洁、清晰。该文用傅氏变换计算长为2a、照度为A的均匀缝光源在观察面上的光强分布为I(x)=│E(x)│^2=AA^2a^2(sin2πfa/2πfa)此方法也可运用于矩形孔、圆孔等。 相似文献
100.
Comparisons of Urban Travel Forecasts Prepared with the Sequential Procedure and a Combined Model 总被引:4,自引:1,他引:3
Justin D. Siegel Joaquín De Cea José Enrique Fernández Renán E. Rodriguez David Boyce 《Networks and Spatial Economics》2006,6(2):135-148
Detailed analyses and comparisons of urban travel forecasts prepared by applying the state-of-practice sequential procedure
and the solution of a combined network equilibrium model are presented. The sequential procedure for solving the trip distribution,
mode choice and assignment problems with feedback is the current practice in most transportation planning agencies, although
its important limitations are well known. The solution of a combined model, in contrast, results from a single mathematical
formulation, which ensures a well-converged and consistent result. Using a real network, several methods for solving the sequential
procedure with feedback are compared to the solution of the combined model ESTRAUS. The results of these methods are shown
to have various levels of instability. The paper concludes with a call for a new paradigm of travel forecasting practice based
on an internally consistent model formulation that can be solved to a level of precision suitable for comparing alternative
scenarios. 相似文献