全文获取类型
收费全文 | 10477篇 |
免费 | 998篇 |
国内免费 | 390篇 |
专业分类
电工技术 | 2047篇 |
技术理论 | 9篇 |
综合类 | 1058篇 |
化学工业 | 739篇 |
金属工艺 | 184篇 |
机械仪表 | 401篇 |
建筑科学 | 1375篇 |
矿业工程 | 368篇 |
能源动力 | 531篇 |
轻工业 | 678篇 |
水利工程 | 1454篇 |
石油天然气 | 167篇 |
武器工业 | 38篇 |
无线电 | 530篇 |
一般工业技术 | 453篇 |
冶金工业 | 704篇 |
原子能技术 | 63篇 |
自动化技术 | 1066篇 |
出版年
2024年 | 43篇 |
2023年 | 243篇 |
2022年 | 326篇 |
2021年 | 522篇 |
2020年 | 373篇 |
2019年 | 304篇 |
2018年 | 282篇 |
2017年 | 336篇 |
2016年 | 338篇 |
2015年 | 375篇 |
2014年 | 663篇 |
2013年 | 554篇 |
2012年 | 666篇 |
2011年 | 763篇 |
2010年 | 596篇 |
2009年 | 614篇 |
2008年 | 567篇 |
2007年 | 705篇 |
2006年 | 600篇 |
2005年 | 517篇 |
2004年 | 467篇 |
2003年 | 384篇 |
2002年 | 288篇 |
2001年 | 282篇 |
2000年 | 189篇 |
1999年 | 167篇 |
1998年 | 110篇 |
1997年 | 107篇 |
1996年 | 75篇 |
1995年 | 81篇 |
1994年 | 78篇 |
1993年 | 44篇 |
1992年 | 36篇 |
1991年 | 28篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1966年 | 6篇 |
1965年 | 3篇 |
1958年 | 3篇 |
1956年 | 3篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
随着开关磁阻电机的调速控制系统日臻完善,因其优越性能使得在各行业得到迅速推广,但在煤矿井下的特定环境中使用该调速系统仍存在着诸多问题有待分析研究。 相似文献
23.
应用水量调度决策支持系统 ,研究了小浪底水库考虑多个兴利目标的非汛期优化运用方案 ,对运用方案分析提出了水库优化运用区间 ,采用数理统计方法探讨了水库非汛期的线性调度函数 ,取得了初步成果可供水量调度部门参考使用 相似文献
24.
文章通过分析多相流模拟井的实际工作要求 ,提出了简单实用的流量自动控制模型。应用成型的计算机数据采集和控制模块及稳定可靠的流量控制部件 ,实现了各相流量的自动控制过程。该流量自动控制系统调节精度高、速度快、整体造价低 ,在实际应用中取得了良好的效果。 相似文献
25.
26.
The Florida Department of Transportation (FDOT) is in the process of implementing Pontis, a Bridge Management System, to provide decision support to engineers in the headquarters and district offices as they make routine policy, programming, and budgeting decisions regarding the preservation and improvement of the state’s bridges. As part of this effort, an ongoing research program is underway to adapt the system to FDOT needs as well as to advance the state of the art in several areas important to the Department. Most of the research results are organized around a new project-level decision support framework that complements and builds on Pontis’ existing network-level analysis. Specific new models include accident risk and user cost due to roadway width and alignment deficiencies; user cost of load capacity and vertical clearance restrictions, and moveable bridge openings; project-level prediction models for bridge element condition and costs; and prediction of economics of scale and scoping possibilities. The new models are built into a highly graphical spreadsheet model for decision support use. 相似文献
27.
Shi Wei Zhao Xuefeng Ma Conghui Management of the National Development Reform Commission 《中国通信》2008,(3)
After the new round of restructuring of Chinese telecom sector,it's pressing to formulate and implement asymmetric regulation policies so as to shape an effectively competitive market structure in a relatively short term.This paper reviewed the asymmetric regulation policies and practices carried out in foreign telecom market,and then according to the specific situations of Chinese telecom market,proposed the principles and corresponding policies for establishing an asymmetric regulation system fit for Chin... 相似文献
28.
With the increasing interest in yardstick regulation, there is a need to understand the most appropriate method for realigning tariffs at the outset. Benchmarking is the tool used for such realignment and is therefore a necessary first-step in the implementation of yardstick competition. A number of concerns have been raised about the application of benchmarking, making some practitioners reluctant to move towards yardstick based regimes. We assess five of the key concerns often discussed and find that, in general, these are not as great as perceived. The assessment is based on economic principles and experiences with applying benchmarking to regulated sectors, e.g. in the electricity and water industries in the UK, The Netherlands, Austria and Germany in recent years. The aim is to demonstrate that clarity on the role of benchmarking reduces the concern about its application in different regulatory regimes. We find that benchmarking can be used in regulatory settlements, although the range of possible benchmarking approaches that are appropriate will be small for any individual regulatory question. Benchmarking is feasible as total cost measures and environmental factors are better defined in practice than is commonly appreciated and collusion is unlikely to occur in environments with more than 2 or 3 firms (where shareholders have a role in monitoring and rewarding performance). Furthermore, any concern about companies under-recovering costs is a matter to be determined through the regulatory settlement and does not affect the case for using benchmarking as part of that settlement. 相似文献
29.
30.