全文获取类型
收费全文 | 734693篇 |
免费 | 31312篇 |
国内免费 | 13643篇 |
专业分类
电工技术 | 25440篇 |
技术理论 | 56篇 |
综合类 | 20011篇 |
化学工业 | 117381篇 |
金属工艺 | 31958篇 |
机械仪表 | 32744篇 |
建筑科学 | 37199篇 |
矿业工程 | 11818篇 |
能源动力 | 20560篇 |
轻工业 | 61958篇 |
水利工程 | 8514篇 |
石油天然气 | 24707篇 |
武器工业 | 2612篇 |
无线电 | 90472篇 |
一般工业技术 | 113645篇 |
冶金工业 | 92235篇 |
原子能技术 | 8678篇 |
自动化技术 | 79660篇 |
出版年
2023年 | 5880篇 |
2022年 | 10247篇 |
2021年 | 15005篇 |
2020年 | 11490篇 |
2019年 | 10255篇 |
2018年 | 12827篇 |
2017年 | 14066篇 |
2016年 | 13186篇 |
2015年 | 15456篇 |
2014年 | 21326篇 |
2013年 | 37866篇 |
2012年 | 29936篇 |
2011年 | 36535篇 |
2010年 | 30056篇 |
2009年 | 30748篇 |
2008年 | 31391篇 |
2007年 | 31132篇 |
2006年 | 30641篇 |
2005年 | 27709篇 |
2004年 | 21571篇 |
2003年 | 20105篇 |
2002年 | 18822篇 |
2001年 | 18353篇 |
2000年 | 18060篇 |
1999年 | 20179篇 |
1998年 | 31741篇 |
1997年 | 24066篇 |
1996年 | 19967篇 |
1995年 | 16111篇 |
1994年 | 13969篇 |
1993年 | 12280篇 |
1992年 | 9511篇 |
1991年 | 8666篇 |
1990年 | 7808篇 |
1989年 | 7269篇 |
1988年 | 6821篇 |
1987年 | 5540篇 |
1986年 | 5341篇 |
1985年 | 6298篇 |
1984年 | 5822篇 |
1983年 | 5023篇 |
1982年 | 4676篇 |
1981年 | 4567篇 |
1980年 | 4325篇 |
1979年 | 4134篇 |
1978年 | 3798篇 |
1977年 | 4577篇 |
1976年 | 6139篇 |
1975年 | 3132篇 |
1974年 | 3020篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Different hierarchical models in pattern analysis and recognition are proposed, based on occurrence probability of patterns. As an important application of recognizing handprinted characters, three typical kinds of hierarchical models such asM
89-89,M
89-36 andM
36-36 have been presented, accompanied by the computer algorithms for computing recognition rates of pattern parts. Moreover, a comparative study of their recognition rates has been conducted theoretically; and numerical experiments have been carried out to verify the analytical conclusions made. Various hierarchical models deliberated in this paper can provide users more or better choices of pattern models in practical application, and lead to a uniform computational scheme (or code). The recognition rates of parts can be improved remarkably by a suitable hierarchical model. For the modelM
89-36 in which case some of the Canadian standard handprinted characters have multiple occurrence probabilities, the total mean recognition rates of the given sample may reach 120% of that by the model proposed by Li et al., and 156% of that obtained from the subjective experiments reported by Suen. 相似文献
992.
Weijia Shang O'Keefe M.T. Fortes J.A.B. 《Parallel and Distributed Systems, IEEE Transactions on》1994,5(2):193-204
This paper describes several loop transformation techniques for extracting parallelism from nested loop structures. Nested loops can then be scheduled to run in parallel so that execution time is minimized. One technique is called selective cycle shrinking, and the other is called true dependence cycle shrinking. It is shown how selective shrinking is related to linear scheduling of nested loops and how true dependence shrinking is related to conflict-free mappings of higher dimensional algorithms into lower dimensional processor arrays. Methods are proposed in this paper to find the selective and true dependence shrinkings with minimum total execution time by applying the techniques of finding optimal linear schedules and optimal and conflict-free mappings proposed by W. Shang and A.B. Fortes 相似文献
993.
We develop a characterization for m-fault-tolerant extensions, and for optimal m-fault-tolerant extensions, of a complete multipartite graph. Our formulation shows that this problem is equivalent to an interesting combinatorial problem on the partitioning of integers. This characterization leads to a new procedure for constructing an optimal m-fault-tolerant extension of any complete multipartite graph, for any m⩾0. The proposed procedure is mainly useful when the size of the graph is relatively small, because the search time required is exponential. This exponential search, however, is not always necessary. We prove several necessary conditions that help us, in several cases, to identify some optimal m-fault-tolerant extensions without performing any search 相似文献
994.
Bezier曲线树 总被引:2,自引:0,他引:2
王晓东 《计算机辅助设计与图形学学报》1994,6(4):266-270
本文提出Bezier样条曲线树结构用以高效地实现对曲边几何体的各种几何运算。对任意一条Bezier样条曲线,用deCasteljau算法进行分割后,将分割结果用一平衡二叉树来存储。此后,对于该曲线所作的各种几何运算可以一种逼近等级的方式来进行。先以粗糙的逼近来进行计算,必要时增加精密度,从而提高各种运算的效率。 相似文献
995.
本文研究程序代码可视化技术,即从现存的程序生成某种可视化表示,增强程序的易读性、易理解性和易维护性。首先介绍ProVS的设计思想和实现技术,然后给出输出例子。 相似文献
996.
997.
利用TM资料测量毛乌素沙地面积的方法和结果 总被引:1,自引:0,他引:1
利用1:25万陆地卫星TM资料和地形图,在GIS支持下,建立毛乌素沙地图形数据库,对毛乌素沙地目前流沙分布的范围进行了调查研究。重.资、介绍了利用陆地卫星TM资料对毛乌素沙地的面积进行测童计算的技术和方法,给出了最新测贡得到的毛乌素沙地全区总面积和分布于各旗县的沙地面积数据。 相似文献
998.
本文分析并推导了应力波在弹性体中传播时,质点的运动速度、压力、位移及应力载波的聚流的形成与表达式.利用得到的公式描述了冲击能传感器的工作机理.给出了某风动工具的测试结果. 相似文献
999.
字结构不同的计算机互连,以往用软件转换字结构,增加了软件开销,导致传输效率降低。现介绍一种用硬件逻辑转换的方案,在数据传送过程中,使一台计算机的数据结构适应另一台计算机的要求。简捷、可靠、快速,大大地提高了异种机互连的传输率。 相似文献
1000.
Neural network control of communications systems 总被引:1,自引:0,他引:1
Neural networks appear well suited to applications in the control of communications systems for two reasons: adaptivity and high speed. This paper describes application of neural networks to two problems, admission control and switch control, which exploit the adaptivity and speed property, respectively. The admission control problem is the selective admission of a set of calls from a number of inhomogeneous call classes, which may have widely differing characteristics as to their rate and variability of traffic, onto a network. It is usually unknown in advance which combinations of calls can be simultaneously accepted so as to ensure satisfactory performance. The approach adopted is that key network performance parameters are observed while carrying various combinations of calls, and their relationship is learned by a neural network structure. The network model chosen has the ability to interpolate or extrapolate from the past results and the ability to adapt to new and changing conditions. The switch control problem is the service policy used by a switch controller in transmitting packets. In a crossbar switch with input queueing, significant loss of throughput can occur when head-of-line service order is employed. A solution can be based on an algorithm which maximizes throughput. However since this solution is typically required in less than one microsecond, software implementation policy is infeasible. We will carry out an analysis of the benefits of such a policy, describe some existing proposed schemes for its implementation, and propose a further scheme that provides this submicrosecond optimization. 相似文献