全文获取类型
收费全文 | 33802篇 |
免费 | 4960篇 |
国内免费 | 4267篇 |
专业分类
电工技术 | 4012篇 |
技术理论 | 1篇 |
综合类 | 6109篇 |
化学工业 | 672篇 |
金属工艺 | 582篇 |
机械仪表 | 3030篇 |
建筑科学 | 1365篇 |
矿业工程 | 1108篇 |
能源动力 | 758篇 |
轻工业 | 752篇 |
水利工程 | 1021篇 |
石油天然气 | 601篇 |
武器工业 | 564篇 |
无线电 | 2716篇 |
一般工业技术 | 1867篇 |
冶金工业 | 481篇 |
原子能技术 | 74篇 |
自动化技术 | 17316篇 |
出版年
2024年 | 181篇 |
2023年 | 625篇 |
2022年 | 991篇 |
2021年 | 1017篇 |
2020年 | 1035篇 |
2019年 | 926篇 |
2018年 | 909篇 |
2017年 | 1049篇 |
2016年 | 1242篇 |
2015年 | 1406篇 |
2014年 | 1984篇 |
2013年 | 2175篇 |
2012年 | 2555篇 |
2011年 | 2837篇 |
2010年 | 2141篇 |
2009年 | 2328篇 |
2008年 | 2454篇 |
2007年 | 2822篇 |
2006年 | 2543篇 |
2005年 | 2105篇 |
2004年 | 1655篇 |
2003年 | 1459篇 |
2002年 | 1164篇 |
2001年 | 1022篇 |
2000年 | 897篇 |
1999年 | 729篇 |
1998年 | 576篇 |
1997年 | 440篇 |
1996年 | 348篇 |
1995年 | 308篇 |
1994年 | 234篇 |
1993年 | 171篇 |
1992年 | 146篇 |
1991年 | 107篇 |
1990年 | 85篇 |
1989年 | 95篇 |
1988年 | 66篇 |
1987年 | 27篇 |
1986年 | 19篇 |
1985年 | 17篇 |
1984年 | 24篇 |
1983年 | 19篇 |
1982年 | 17篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1973年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
针对现有作战决策算法存在的不足,提出了一种新的基于直觉模糊集的作战决策算法.用直觉模糊值表示可行方案指标的不确定信息,综合考虑了方案满足指标的可能性、不满足的可能性和未知的可能性3个方面的因素,给出了直觉模糊决策矩阵的建立方法和可行方案优劣度排序方法.实例及实际应用证明了算法的有效性与可行性. 相似文献
63.
In this article, linear programming and fuzzy optimization models are developed for planning and management of available land-water-crop system of Mahanadi-Kathajodi delta in eastern India. The models are used to optimize the economic return, production and labour utilization, and to search the related cropping patterns and intensities with specified land, water, fertilizer and labour availability, and water use pattern constraints. Due to extreme backwardness of the study area, it has been decided to keep all the three objectives of the linear programming models at the same priority level to obtain the compromised solution in a fuzzy environment that incorporates the imprecision in fuzzy goals and fuzzy constraints. These non-structural models facilitate the conjunctive use of available surface water and groundwater resources. A comparative evaluation along with the benefit-cost ratios of the existing and proposed farming systems is also presented. 相似文献
64.
65.
本文提出二种算法分别标号和计数线性八元树表示的三维客体群的连通分量.这些操作典型地需要检查线性八元树中诸八分体在三个主方向上的面邻接对.根据这些邻接对,可以建造在计算机中用关联矩阵表示的邻接图.连通分量标号和计数是在关联矩阵上分别执行相应的操作而完成的.连通分量标号的执行时间是O(n+m·logm),而连通分量计数需要O(n)时间,其中m和n分别是线性八元树中八分体和邻接对的数目. 相似文献
66.
This study was motivated by some difficulties encountered by the authors when trying to express temporal knowledge using Sowa's conceptual graph (CG) approach. An overview of Sowa's approach is given and the difficulties encountered when trying to model temporal knowledge are outlined: the disparity of notations allowed by CG theory for expressing temporal information; the ambiguity and incompleteness of tense sspecification; the difficulty of harmonizing tenses and intergraph temporal relations. Various approaches suggested for representing time both in artificial intelligence and linguistics are presented, and an extension to Sowa's approach is proposed in which temporal and nontemporal knowledge are differentiated. In this model points in time are represented as well as time intervals. A semantic interpretation of verbs is provided based on an extension of Reichenbach's model of temporal markers. The authors show how their approach enables the representation of tenses as well as the aspectual properties of natural language sentences. 相似文献
67.
Waveband switching (WBS) is a promising technique to reduce the switching and transmission costs in the optical domain of a wavelength-division multiplexing (WDM) network. This paper considers the problem of provisioning dynamic traffic using WBS in a WDM mesh network. The network of interest is a homogeneous WBS network, where each node has the functionality of WBS. The problem is called the dynamic WBS problem, which involves searching waveband-routes or wavelength-routes for the dynamically arriving traffic requests. The objective is to minimize the total switching and transmission costs in the optical domain. To solve the dynamic WBS problem, an auxiliary graph model capturing the network state is proposed. Based on the auxiliary graph, two heuristic on-line WBS algorithms with different waveband grouping policies are proposed, namely the wavelength-first WBS algorithm based on the auxiliary graph (WFAUG) and the waveband-first WBS algorithm based on the auxiliary graph (BFAUG). Simulation results indicate that WBS is an attractive technique which reduces the overall switching and transmission costs by up to 30% in the network. The results also show that the WFAUG algorithm outperforms the BFAUG algorithm in terms of port savings and cost savings. 相似文献
68.
69.
本文利用模糊集理论,提出一种非确定环境的描述方法,并且针对机器人在该类环境中的避障轨迹规划,建立了相应的决策函数和规划策略,最后,给出在PC-386计算机上的仿真试验结果。 相似文献
70.
In this paper, a sensor system, called a fuzzy pulse discriminator, is developed to classify various discharge pulses in electrical discharge machining (EDM). The fuzzy rules of the pulse discriminator are obtained based on the features of the gap voltage and gap current between the tool workpiece. The membership functions of the fuzzy pulse discriminator are automatically synthesized by using genetic algorithms. The effectiveness of this approach is verified under different cutting parameters. 相似文献