全文获取类型
收费全文 | 80365篇 |
免费 | 4762篇 |
国内免费 | 3248篇 |
专业分类
电工技术 | 6080篇 |
技术理论 | 24篇 |
综合类 | 9220篇 |
化学工业 | 3137篇 |
金属工艺 | 910篇 |
机械仪表 | 3133篇 |
建筑科学 | 13964篇 |
矿业工程 | 5053篇 |
能源动力 | 2463篇 |
轻工业 | 2089篇 |
水利工程 | 7500篇 |
石油天然气 | 2086篇 |
武器工业 | 328篇 |
无线电 | 6031篇 |
一般工业技术 | 3698篇 |
冶金工业 | 5620篇 |
原子能技术 | 477篇 |
自动化技术 | 16562篇 |
出版年
2024年 | 120篇 |
2023年 | 541篇 |
2022年 | 1135篇 |
2021年 | 1618篇 |
2020年 | 1731篇 |
2019年 | 1177篇 |
2018年 | 1162篇 |
2017年 | 1550篇 |
2016年 | 1961篇 |
2015年 | 2257篇 |
2014年 | 6446篇 |
2013年 | 5104篇 |
2012年 | 5760篇 |
2011年 | 6301篇 |
2010年 | 4905篇 |
2009年 | 5164篇 |
2008年 | 5154篇 |
2007年 | 6394篇 |
2006年 | 5668篇 |
2005年 | 4755篇 |
2004年 | 4042篇 |
2003年 | 3636篇 |
2002年 | 2860篇 |
2001年 | 2096篇 |
2000年 | 1657篇 |
1999年 | 1210篇 |
1998年 | 834篇 |
1997年 | 613篇 |
1996年 | 499篇 |
1995年 | 417篇 |
1994年 | 310篇 |
1993年 | 224篇 |
1992年 | 155篇 |
1991年 | 126篇 |
1990年 | 80篇 |
1989年 | 104篇 |
1988年 | 80篇 |
1987年 | 40篇 |
1986年 | 74篇 |
1985年 | 79篇 |
1984年 | 78篇 |
1983年 | 83篇 |
1982年 | 27篇 |
1981年 | 21篇 |
1980年 | 16篇 |
1979年 | 16篇 |
1977年 | 20篇 |
1975年 | 6篇 |
1961年 | 7篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
41.
42.
基于宏观经济结构合理化的宁夏水资源合理配置 总被引:10,自引:1,他引:9
本文分析了宁夏目前经济结构下水资源利用效率及产出效益,研究在一定经济发展水平下,当资源配置最优时,最优的经济均衡增长途径。区域最优经济结构是由国民经济各部门相互依存的关联关系技术矩阵所决定的,其均衡增长率和均衡增长产出结构分别等于非负矩阵的弗罗比尼斯特征根和相对应的弗罗比尼斯向量。本文根据联合国经济发展统计数据,分析出宁夏未来调整第一产业与第二产业结构的比例,认为应适当减少宁夏高耗水水稻种植面积,逐渐把农业用水量向工业用水量转移。转变经济增长方式,从水资源的高效利用及配置出发走内涵式、节水型的社会发展道路,以解决宁夏水资源严重不足的问题。 相似文献
43.
大同市节水型社会建设的探讨 总被引:1,自引:0,他引:1
大同市是全国108个比较严重缺水城市之一,人均水资源量不足全国的1/10(全国人均水资源量2231m^3),稍超过全省的1/2(全省人均水资源量388m^3),市中心城区工农业及城市生活用水近20年来靠超采地下水来支撑。文中就大同市水资源供需不平衡的现状,提出大同市节水型社会建设的必要性,及今后水资源开源和节流的措施。 相似文献
44.
45.
梁斌 《冶金标准化与质量》2006,44(6):41-43
质量管理永远是企业生命的源泉,质量管理体系是一个复杂的系统工程,企业只有不断完善质量体系,进行质量管理创新,保持质量管理体系的长期有效的进行,才能在市场竞争中保持领先。 相似文献
46.
Lake Chivero: A management case study 总被引:1,自引:0,他引:1
C. H. D. Magadza 《Lakes & Reservoirs: Research and Management》2003,8(2):69-81
Lake Chivero in Zimbabwe was shown to be hypereutrophic. Historical data showed that the eutrophication process had been arrested in the late 1970s. However, a combination of poor planning, multiplicity of jurisdiction, mismatch between rate of urbanization and waste management investment, recent changes in the local climate and a permissive, immature political system that called for no public accountability resulted in environmental management breakdown leading to hypereutrophication of the lake. The case of Lake Chivero is presented as an example of a wider global issue regarding the status of environmental management in competition with other priorities in emerging democracies. 相似文献
47.
Kurjenniemi Janne Hämäläinen Seppo Ristaniemi Tapani 《Wireless Personal Communications》2003,27(4):337-351
In this article we consider the performance of the 3.84 Mcpstime-division duplex (TDD) mode of UTRA (Universal TerrestrialRadio Access) network. We emphasize two of the radio resourcemanagement algorithms, handover and uplink power control, whoserole in the overall system performance is studied extensively.First, a handover algorithm used in WCDMA (Wideband Code DivisionMultiple Access) standard is considered in a TDD-mode operation.This gives rise to a careful setting of different handoverparameters, and the evaluation of the effects to the systemperformance. Secondly, the specified uplink power controlalgorithm is considered. Since it is based on several user-mademeasurements which may involve both random and systematic errors acareful study about the suitability of the power control scheme iscarried out. 相似文献
48.
49.
以典型行为为导向的培训课程体系研究课题组 《石油化工管理干部学院学报》2006,(1):1-6
提高对人才能力建设的培训水平,是国有企业培训机构在人才培训工作与人力资源开发过程中需要深入研究、探索的重要课题。针对中国石油化工集团公司推进改革发展、实现企业战略目标对高级管理人才的需求,以企业高级管理人才任职前培训为目标,在培训需求研究、课程设计与内容开发、教学手段和方法、培训过程管理与质量保证机制、培训效果评估等方面进行研究。 相似文献
50.
With the proliferation of mobile computing technologies, location based services have been identified as one of the most promising
target application. We classify mobile information service domains based on feature characteristics of the information sources
and different patterns of mobile information access. By carefully examining the service requirements, we identify the dynamic
data management problem that must be addressed for effective location based services in mobile environments. We then devise
a general architecture and cost model for servicing both location independent and location dependent data. Based on the architecture
and cost model, we propose a set of dynamic data management strategies that employs judicious caching, proactive server pushing
and neighborhood replication to reduce service cost and improve response time under changing user mobility and access patterns.
Detail behavior analysis helps us in precisely capturing when and how to apply these strategies. Simulation results suggest
that different strategies are effective for different types of data in response to different patterns of movement and information
access.
Shiow-yang Wu is an associate professor of the Department of Computer Science and Information Engineering at National Dong Hwa University,
Hualien, Taiwan, R.O.C. He received the BS and MS degrees in computer engineering from National Chiao Tung University, Hsinchu,
Taiwan, ROC, and the PhD degree in computer science from the University of Texas at Austin in 1984, 1986, and 1995, respectively.
His research interests include data/knowledge bases, mobile computing, distributed processing, intelligence information systems,
and electronic commerce.
Kun-Ta Wu was born in Taipei, Taiwan, R.O.C., in 1976. He received the B.S. degree in computer science from Soochow University, Taipei,
Taiwan, R.O.C., in 1999 and the M.S. degree in computer science and information engineering from National Dong Hwa University,
Hualien, Taiwan, R.O.C., in 2001.
Currently, he is an Assistant Researcher in the Domestic Division at Science and Technology Information Center, National Science
Council, R.O.C., as a member of Information Gathering and Analysis Group of National Information and Communication Security
Taskforce. His research interests include mobile computing, wireless network and information security. 相似文献