全文获取类型
收费全文 | 7865篇 |
免费 | 90篇 |
专业分类
电工技术 | 75篇 |
综合类 | 2篇 |
化学工业 | 672篇 |
金属工艺 | 83篇 |
机械仪表 | 91篇 |
建筑科学 | 169篇 |
矿业工程 | 17篇 |
能源动力 | 83篇 |
轻工业 | 475篇 |
水利工程 | 53篇 |
石油天然气 | 17篇 |
无线电 | 606篇 |
一般工业技术 | 749篇 |
冶金工业 | 4161篇 |
原子能技术 | 39篇 |
自动化技术 | 663篇 |
出版年
2021年 | 43篇 |
2020年 | 30篇 |
2019年 | 65篇 |
2018年 | 69篇 |
2017年 | 52篇 |
2016年 | 51篇 |
2015年 | 41篇 |
2014年 | 69篇 |
2013年 | 212篇 |
2012年 | 121篇 |
2011年 | 175篇 |
2010年 | 128篇 |
2009年 | 124篇 |
2008年 | 179篇 |
2007年 | 178篇 |
2006年 | 162篇 |
2005年 | 142篇 |
2004年 | 122篇 |
2003年 | 110篇 |
2002年 | 113篇 |
2001年 | 118篇 |
2000年 | 98篇 |
1999年 | 189篇 |
1998年 | 1180篇 |
1997年 | 736篇 |
1996年 | 482篇 |
1995年 | 300篇 |
1994年 | 289篇 |
1993年 | 313篇 |
1992年 | 113篇 |
1991年 | 96篇 |
1990年 | 117篇 |
1989年 | 118篇 |
1988年 | 102篇 |
1987年 | 95篇 |
1986年 | 89篇 |
1985年 | 108篇 |
1984年 | 75篇 |
1983年 | 67篇 |
1982年 | 62篇 |
1981年 | 63篇 |
1980年 | 71篇 |
1979年 | 61篇 |
1978年 | 64篇 |
1977年 | 113篇 |
1976年 | 262篇 |
1975年 | 55篇 |
1974年 | 37篇 |
1973年 | 37篇 |
1972年 | 36篇 |
排序方式: 共有7955条查询结果,搜索用时 8 毫秒
51.
52.
53.
Fast restoration of ATM networks 总被引:3,自引:0,他引:3
Anderson J. Doshi B.T. Dravida S. Harshavardhana P. 《Selected Areas in Communications, IEEE Journal on》1994,12(1):128-138
Asynchronous transfer mode (ATM) is now well recognized as the fundamental switching and multiplexing technique for future broadband ISDN. As these networks will be increasingly relied upon for providing a multitude of integrated voice, data, and video services, network reliability is a key concern. There are several intrinsic features of ATM networks that could potentially be exploited to provide improved restoration techniques, beyond those established for synchronous transfer mode (STM) networks, such as digital cross-connect restoration or self-healing rings. These features include ATM cell level error detection, inherent rate adaptation and nonhierarchical multiplexing. The authors explore the use of these features in developing fast restoration strategies for ATM networks. In particular, they address: (1) ATM error detection capabilities for enhanced failure detection, (2) network rerouting strategies, (3) spare capacity allocation, and (4) network control architecture and related implementation aspects. Their findings suggest that fast network span failure detection and bandwidth-efficient rerouting capabilities can be combined to develop restoration strategies for ATM networks with significantly greater performance-cost ratios when compared to existing STM network restoration strategies 相似文献
54.
55.
Shiun Ling Ph.D. Michael P. Anderson D.Eng.Sc. 《JOM Journal of the Minerals, Metals and Materials Society》1992,44(9):30-36
The prediction and control of metal grain structures during processing have been major objectives of materials science. However, methodologies that are accurate and can be easily generalized to a variety of processing conditions have been difficult to formulate due to the complexity of the grain interactions. A novel Monte Carlo-based approach that explicitly incorporates these interactions has been developed to simulate the microstructural evolution driven by the minimization of grain boundary energy and lattice defect density. The applicability of this procedure has been demonstrated by the good correspondence between simulation results and experimental observations. This article reviews recent advances in the application of this technique to the investigation of a variety of phenomena, including normal and abnormal grain growth as well as static and dynamic recrystallization. 相似文献
56.
Evan E. Anderson 《Information Systems》1988,13(4):327-333
Many organizations, best illustrated by libraries, have access to hundreds of databases possessing varying degrees of complimentary and overlapping records. While users may receive positive marginal benefits from data duplications, all databases and their services cannot be supported because of resource limitations. This paper attempts to conceptualize the problem of database collection in an environment of multiple databases, with differential content and performance characteristics, diverse users, and limited resources. It defines the database collection problem as a constrained zero-one integer programming problem and solves for the optimal combination or union of databases. Several extensions are shown, where special conditions are imposed on the relationships between databases and/or their availability. 相似文献
57.
58.
59.
60.
Recently, Timmermann and Nowak developed algorithms for estimating the means of independent Poisson random variables. The algorithms are based on a multiscale model where certain random variables are assumed to obey a beta-mixture density function. Timmermann and Nowak simplify the density estimation problem by assuming the beta parameters are known and only one mixture parameter is unknown. They use the observed data and the method of moments to estimate the unknown mixture parameter. Taking a different approach, we generate training data from the observed data and compute maximum likelihood estimates of all of the beta-mixture parameters. To assess the improved performance obtained by the proposed modification, we consider a denoising application using Poisson data. 相似文献