全文获取类型
收费全文 | 6715篇 |
免费 | 1534篇 |
国内免费 | 641篇 |
专业分类
电工技术 | 1406篇 |
综合类 | 1086篇 |
化学工业 | 286篇 |
金属工艺 | 111篇 |
机械仪表 | 560篇 |
建筑科学 | 629篇 |
矿业工程 | 407篇 |
能源动力 | 316篇 |
轻工业 | 176篇 |
水利工程 | 444篇 |
石油天然气 | 140篇 |
武器工业 | 219篇 |
无线电 | 662篇 |
一般工业技术 | 582篇 |
冶金工业 | 100篇 |
原子能技术 | 32篇 |
自动化技术 | 1734篇 |
出版年
2024年 | 123篇 |
2023年 | 240篇 |
2022年 | 401篇 |
2021年 | 371篇 |
2020年 | 393篇 |
2019年 | 308篇 |
2018年 | 287篇 |
2017年 | 345篇 |
2016年 | 361篇 |
2015年 | 388篇 |
2014年 | 606篇 |
2013年 | 494篇 |
2012年 | 648篇 |
2011年 | 662篇 |
2010年 | 482篇 |
2009年 | 463篇 |
2008年 | 407篇 |
2007年 | 435篇 |
2006年 | 391篇 |
2005年 | 276篇 |
2004年 | 196篇 |
2003年 | 153篇 |
2002年 | 95篇 |
2001年 | 94篇 |
2000年 | 73篇 |
1999年 | 41篇 |
1998年 | 32篇 |
1997年 | 27篇 |
1996年 | 10篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 3篇 |
1991年 | 14篇 |
1990年 | 5篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1964年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有8890条查询结果,搜索用时 15 毫秒
11.
本研究在确保磁性能不降低的前提下,通过添加少量的添加元素或化合物,如难熔金属,稀土金属,稀土氧化物、钙化合物等,明显改善了定向结晶AlNiCo52(简称五类定向)磁钢的外观,有效地避免了铸造缺陷,从而大幅度地降低了生产成本,提高了生产效益。 相似文献
12.
用层次分析法(AHP)确定煤和瓦斯突出中的有关参数 总被引:1,自引:0,他引:1
介绍了井下瓦斯突出的原因 ,详细阐述了瓦斯突出的有关参数的确定方法。 相似文献
13.
本文介绍了钢铁厂材料核算系统的决策支持系统,描述了系统结构,模型自动生成方法,并用层次分析法说明钢铁厂材料采购的决策过程。 相似文献
14.
15.
16.
17.
“To understand and protect our home planet, to explore the universe and search for life, and to inspire the next generation of explorers” is NASA's mission. The Systems Management Office at Johnson Space Center (JSC) is searching for methods to effectively manage the Center's resources to meet NASA's mission. D-Side is a group multi-criteria decision support system (GMDSS) developed to support facility decisions at JSC. D-Side uses a series of sequential and structured processes to plot facilities in a three-dimensional (3-D) graph on the basis of each facility's alignment with NASA's mission and goals, the extent to which other facilities are dependent on the facility, and the dollar value of capital investments that have been postponed at the facility relative to the facility's replacement value. A similarity factor rank orders facilities based on their Euclidean distance from Ideal and Nadir points. These similarity factors are then used to allocate capital improvement resources across facilities. We also present a parallel model that can be used to support decisions concerning allocation of human resources investments across workforce units. Finally, we present results from a pilot study where 12 experienced facility managers from NASA used D-Side and the organization's current approach to rank order and allocate funds for capital improvement across 20 facilities. Users evaluated D-Side favorably in terms of ease of use, the quality of the decision-making process, decision quality, and overall value-added. Their evaluations of D-Side were significantly more favorable than their evaluations of the current approach. 相似文献
18.
Using the analytic network process (ANP) in a SWOT analysis - A case study for a textile firm 总被引:5,自引:0,他引:5
?hsan Yüksel 《Information Sciences》2007,177(16):3364-3382
Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis does not provide an analytical means to determine the importance of the identified factors or the ability to assess decision alternatives according to these factors. Although the analysis successfully pinpoints the factors, individual factors are usually described briefly and very generally. For this reason, SWOT analysis possesses deficiencies in the measurement and evaluation steps. Although the analytic hierarchy process (AHP) technique removes these deficiencies, it does not allow for measurement of the possible dependencies among the factors. The AHP method assumes that the factors presented in the hierarchical structure are independent; however, this assumption may be inappropriate in light of certain internal and external environmental effects. Therefore, it is necessary to employ a form of SWOT analysis that measures and takes into account the possible dependency among the factors. This paper demonstrates a process for quantitative SWOT analysis that can be performed even when there is dependence among strategic factors. The proposed algorithm uses the analytic network process (ANP), which allows measurement of the dependency among the strategic factors, as well as AHP, which is based on the independence between the factors. Dependency among the SWOT factors is observed to effect the strategic and sub-factor weights, as well as to change the strategy priorities. 相似文献
19.
Pressure to compress the development life cycle and reduce the duration and resources committed to testing lead to experimentation in testing at the NASA Goddard Space Flight Centerís Software Engineering Laboratory. This study investigates the trend to reduce developer testing and increasingly rely upon inspection techniques and independent functional testing to shorten the development life cycle, improve testing productivity, and improve software quality.An approach is developed to conduct this comparison. In particular, the problem faced by software researchers, having a comprehensive characterization of software projects so similar types may be identified for comparative studies, is addressed using expert opinion. 相似文献
20.
一种新型多功能建筑胶 总被引:2,自引:0,他引:2
该胶研制了一种由脲醛改性聚乙烯醇水性胶组成、具有成本低、性能好、用途广等特点,可广泛用于建筑及装饰行业的建筑胶。 相似文献