全文获取类型
收费全文 | 4233篇 |
免费 | 340篇 |
国内免费 | 160篇 |
专业分类
电工技术 | 102篇 |
综合类 | 265篇 |
化学工业 | 266篇 |
金属工艺 | 414篇 |
机械仪表 | 172篇 |
建筑科学 | 1082篇 |
矿业工程 | 245篇 |
能源动力 | 168篇 |
轻工业 | 91篇 |
水利工程 | 274篇 |
石油天然气 | 57篇 |
武器工业 | 39篇 |
无线电 | 149篇 |
一般工业技术 | 182篇 |
冶金工业 | 153篇 |
原子能技术 | 18篇 |
自动化技术 | 1056篇 |
出版年
2024年 | 9篇 |
2023年 | 46篇 |
2022年 | 81篇 |
2021年 | 100篇 |
2020年 | 107篇 |
2019年 | 78篇 |
2018年 | 85篇 |
2017年 | 99篇 |
2016年 | 162篇 |
2015年 | 184篇 |
2014年 | 253篇 |
2013年 | 276篇 |
2012年 | 283篇 |
2011年 | 369篇 |
2010年 | 287篇 |
2009年 | 329篇 |
2008年 | 275篇 |
2007年 | 303篇 |
2006年 | 267篇 |
2005年 | 216篇 |
2004年 | 188篇 |
2003年 | 149篇 |
2002年 | 108篇 |
2001年 | 97篇 |
2000年 | 63篇 |
1999年 | 62篇 |
1998年 | 48篇 |
1997年 | 33篇 |
1996年 | 38篇 |
1995年 | 27篇 |
1994年 | 19篇 |
1993年 | 19篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 16篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1980年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有4733条查询结果,搜索用时 15 毫秒
1.
2.
The proposed work involves the multiobjective PSO based adaption of optimal neural network topology for the classification of multispectral satellite images. It is per pixel supervised classification using spectral bands (original feature space). This paper also presents a thorough experimental analysis to investigate the behavior of neural network classifier for given problem. Based on 1050 number of experiments, we conclude that following two critical issues needs to be addressed: (1) selection of most discriminative spectral bands and (2) determination of optimal number of nodes in hidden layer. We propose new methodology based on multiobjective particle swarm optimization (MOPSO) technique to determine discriminative spectral bands and the number of hidden layer node simultaneously. The accuracy with neural network structure thus obtained is compared with that of traditional classifiers like MLC and Euclidean classifier. The performance of proposed classifier is evaluated quantitatively using Xie-Beni and β indexes. The result shows the superiority of the proposed method to the conventional one. 相似文献
3.
4.
通过对土地处理系统的介绍,结合油气站场污水的特点,分析了不同土地处理技术在实际中的设置情况和方式,给出一般的面积计算方法和结果,总结了土地处理的技术特点和应用前景。 相似文献
5.
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
6.
In Malaysia, no long-term daylight data are measured. It was only recently that the need to measure the availability of daylight became urgent when the importance of daylighting in buildings was rediscovered. The hourly daylight availability has been simulated for the Malaysian sky using daylight modelling techniques based on empirical and measured solar irradiation and cloud cover data. This paper presents the techniques involved in producing exterior illuminance data. These data were then compared with measured illuminance at Shah Alam and Bangi, Malaysia. The global illuminance levels are generally high, with values exceeding 80,000 lux at noon during the months when solar irradiation is highest. Even during the months when the ground receives less solar irradiation, the peak illuminance can reach 60,000 lux. Applications and uses of such data are in daylighting design, both for visual and thermal comfort, task illuminance and energy-conscious design of buildings. Recommendations are made at the end of the paper on the various climatic data that are required to be measured for overall daylighting design applications. 相似文献
7.
1 IntroductionThestickingpointofassociationrulealgorithmsdependsoneffectivelyfindingallcorrelationpatternsthatsatisfyvaluerequirementinthemagnanimityofdata.Butthealgorithmsalsobringanegativeef fect:thenumberofassociationrulesisverylarge.Alsoinformation… 相似文献
8.
9.
Neil Kirkpatrick 《Packaging Technology and Science》1993,6(3):159-172
Solid-waste management, and in particular the disposal of used packaging, is currently the subject of much topical debate. This is driven by both consumer and legislative pressures. Consumers see used packaging as a highly visible element of municipal solid waste, complaining of excessive packaging and low levels of recycling. Legislators, perhaps in pandering to the views expressed by consumer bodies, have been active within the CEC and individual Member States by introducing (or proposing) legislation or similar regulatory tools and targets to facilitate a greater diversion of used packaging from disposal by landfill to alternative solid-waste management practices, in particular recycling, which are widely accepted to have a lower impact on the environment. In this paper the relative environmental profiles of pursuing alternative solid-waste management practices to disposal by landfill are explored, focusing not just on solid waste per se but also on associated considerations of energy consumption and emissions, which are invariably overlooked as factors contributing to the environmental impact of solid-waste management practices. 相似文献
10.
借鉴英国经验完善中国土地产权流转 总被引:1,自引:0,他引:1
本文在简要介绍中、英两国土地产权制度和土地产权流转的基础上,分析了我国土地产权流转过程中出现的问题,如征地过程中的赔偿过低且不完善、国有土地拆迁补偿不公以及补偿的分配方式不公平等问题。由于英国在土地制度方面与中国的相似性,文章借鉴英国土地补偿中的补偿金与改善金相结合原则、土地使用权的租赁行为以及开发收益回馈社会的方法,为完善和健全我国的土地产权流转机制提出措施和建议。 相似文献