全文获取类型
收费全文 | 23308篇 |
免费 | 2333篇 |
国内免费 | 1091篇 |
专业分类
电工技术 | 847篇 |
技术理论 | 1篇 |
综合类 | 1763篇 |
化学工业 | 1705篇 |
金属工艺 | 562篇 |
机械仪表 | 1025篇 |
建筑科学 | 8630篇 |
矿业工程 | 395篇 |
能源动力 | 188篇 |
轻工业 | 448篇 |
水利工程 | 238篇 |
石油天然气 | 420篇 |
武器工业 | 235篇 |
无线电 | 2389篇 |
一般工业技术 | 923篇 |
冶金工业 | 369篇 |
原子能技术 | 73篇 |
自动化技术 | 6521篇 |
出版年
2024年 | 212篇 |
2023年 | 507篇 |
2022年 | 837篇 |
2021年 | 942篇 |
2020年 | 956篇 |
2019年 | 658篇 |
2018年 | 462篇 |
2017年 | 499篇 |
2016年 | 481篇 |
2015年 | 652篇 |
2014年 | 1649篇 |
2013年 | 1272篇 |
2012年 | 1668篇 |
2011年 | 1767篇 |
2010年 | 1425篇 |
2009年 | 1561篇 |
2008年 | 1539篇 |
2007年 | 1686篇 |
2006年 | 1451篇 |
2005年 | 1287篇 |
2004年 | 1056篇 |
2003年 | 892篇 |
2002年 | 656篇 |
2001年 | 548篇 |
2000年 | 481篇 |
1999年 | 382篇 |
1998年 | 227篇 |
1997年 | 164篇 |
1996年 | 119篇 |
1995年 | 124篇 |
1994年 | 80篇 |
1993年 | 67篇 |
1992年 | 81篇 |
1991年 | 59篇 |
1990年 | 44篇 |
1989年 | 52篇 |
1988年 | 45篇 |
1987年 | 27篇 |
1986年 | 18篇 |
1985年 | 40篇 |
1984年 | 27篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1957年 | 1篇 |
1955年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
43.
In this paper, we propose an efficient design method for area optimization in a digital filter. The conventional methods to reduce the number of adders in a filter have the problem of a long critical path delay caused by the deep logic depth of the filter due to adder sharing. Furthermore, there is such a disadvantage that they use the transposed direct form (TDF) filter which needs more registers than those of the direct form (DF) filter. In this paper, we present a hybrid structure of a TDF and DF based on the flattened coefficients method so that it can reduce the number of flip‐flops and full‐adders without additional critical path delay. We also propose a resource sharing method and sharing‐pattern searching algorithm to reduce the number of adders without deepening the logic depth. Simulation results show that the proposed structure can save the number of adders and registers by 22 and 26%, respectively, compared to the best one used in the past. 相似文献
44.
Michael V. Antony 《Minds and Machines》1991,1(3):321-341
Fodor and Pylyshyn (1988) have argued that the cognitive architecture is not Connectionist. Their argument takes the following form: (1) the cognitive architecture is Classical; (2) Classicalism and Connectionism are incompatible; (3) therefore the cognitive architecture is not Connectionist. In this essay I argue that Fodor and Pylyshyn's defenses of (1) and (2) are inadequate. Their argument for (1), based on their claim that Classicalism best explains the systematicity of cognitive capacities, is an invalid instance of inference to the best explanation. And their argument for (2) turns out to be question-begging. The upshot is that, while Fodor and Pylyshyn have presented Connectionists with the important empirical challenge of explaining systematicity, they have failed to provide sufficient reason for inferring that the cognitive architecture is Classical and not Connectionist. 相似文献
45.
46.
加快电信管制改革 实现电信健康发展 总被引:1,自引:0,他引:1
通过对我国电信业市场结构、市场行为及市场绩效进行分析,阐明了在我国进行电信管制的必要性。通过管制,以实现电信企业的有效竞争,使我国电信业得到健康发展。 相似文献
47.
48.
Research on the Handover of a Novel Cellular Architecture in Wireless Personal Communication Systems
ZHANG Zu-fan~ 《中国邮电高校学报(英文版)》2003,10(4)
1 IntroductionHandoverbetweencellsisplayinganimportantroleincellularcommunicationsystems[1~ 1 2 ] .Thehandoverprocedureanditseffectivenessareseriouslylimitedbythecellulararchitectureasaresultofmar ketplanning .Basedonthehexagonalcellulararchi tecture,manyhandoverprocedureshavebeendis cussedandevaluated ,andmostoftheimprovementproposedonthemleadstotheintroductionofsector ingcellularorlayeredcellularmodel.Otherwise ,abetterhandoverprocedureisessentialinmaintainingacallinprogressbutitreflectshi… 相似文献
49.
Intelligent methods for automatic protection and restoration are critical in optical transport mesh networks. This paper discusses the problem of quality-of-service (QoS)-based protection in terms of the protection-switching time and availability for end-to-end lightpaths in a WDM mesh network. We analyze the backup lightpath-sharing problem in such networks and study the correlation of the working lightpaths and the impact of the correlation on the sharing of the backup lightpaths. We present a multi-protocol-label-switching (MPLS) control-based fully distributed algorithm to solve the protection problem. The proposed algorithm includes intelligent and automatic procedures to set up, take down, activate, restore, and manage backup lightpaths. It greatly reduces the required resources for protection by allowing the sharing of network resources by multiple backup lightpaths. At the same time, it guarantees, if possible, to satisfy the availability requirement even with resource sharing by taking the correlation of working lightpaths into consideration. A simple analysis of the proposed algorithm in terms of computation time and message complexity indicates that the implementation of the algorithm is practical. The illustrative studies that compare the performance of 1:1, unlimited sharing, and QoS-based backup sharing algorithms indicate that QoS-based sharing achieves comparable performance as unlimited sharing, which is much better than the 1:1 backup scheme in terms of connection blocking probability, average number of connections in the network for a given offered load, and network resource utilization. 相似文献
50.
根据石河子的地理位置、自然环境和居住建筑发展的历史,为当地设计了功能较全,布局合理,实用性强的住宅楼。通过设计实践对住宅设计提出了一些看法。 相似文献