全文获取类型
收费全文 | 12387篇 |
免费 | 571篇 |
国内免费 | 215篇 |
专业分类
电工技术 | 1029篇 |
综合类 | 738篇 |
化学工业 | 1778篇 |
金属工艺 | 609篇 |
机械仪表 | 901篇 |
建筑科学 | 1317篇 |
矿业工程 | 954篇 |
能源动力 | 547篇 |
轻工业 | 707篇 |
水利工程 | 448篇 |
石油天然气 | 642篇 |
武器工业 | 54篇 |
无线电 | 413篇 |
一般工业技术 | 732篇 |
冶金工业 | 1350篇 |
原子能技术 | 89篇 |
自动化技术 | 865篇 |
出版年
2024年 | 31篇 |
2023年 | 88篇 |
2022年 | 179篇 |
2021年 | 257篇 |
2020年 | 273篇 |
2019年 | 167篇 |
2018年 | 171篇 |
2017年 | 175篇 |
2016年 | 273篇 |
2015年 | 299篇 |
2014年 | 812篇 |
2013年 | 601篇 |
2012年 | 962篇 |
2011年 | 1000篇 |
2010年 | 730篇 |
2009年 | 665篇 |
2008年 | 555篇 |
2007年 | 819篇 |
2006年 | 731篇 |
2005年 | 697篇 |
2004年 | 645篇 |
2003年 | 611篇 |
2002年 | 482篇 |
2001年 | 401篇 |
2000年 | 365篇 |
1999年 | 276篇 |
1998年 | 216篇 |
1997年 | 183篇 |
1996年 | 157篇 |
1995年 | 94篇 |
1994年 | 65篇 |
1993年 | 43篇 |
1992年 | 45篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1979年 | 3篇 |
1973年 | 1篇 |
1967年 | 1篇 |
1965年 | 1篇 |
1964年 | 2篇 |
1958年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
11.
12.
基于类比的软件成本估算方法利用相似的历史项目信息来预测目标项目的属性值,具有不需要校准、能够在没有统计关系可以利用的情况下发挥作用等优点。本文在类比估算四个基本步骤的框架下,详细说明了类比估算所必须进行的相关操作,并参照案例推理系统把类比估算过程描述为一个从数据收集、属性选取开始,到估算报告输出、结果重用的循环结构。根据估算实践,提出了针对大数据集的计算优化方法,不仅有效降低了估算过程中的计算量,而且在一定程度上避免了次要因素的影响,提高了估算的可信度。 相似文献
13.
14.
用定量分析的方法改进性能是信息化武器系统开发和运用中必须解决的重要问题,借助仿真和博弈分析的混合方法,在对传统混合策略纳什均衡原理应用的基础上,构建基于二人非零和(TPNZS)非合作博弈模型来改进信息化武器系统的性能,对典型信息化武器系统-舰载导弹防空系统的初步研究表明:用识别正确、错误目标能力以及导弹命中目标能力描述的舰载导弹防空系统的最优改进性能策略为△*=(0,△2*,1-△2*)=(0.0000,0.7118,0.2882). 相似文献
15.
Most of the published literature on robust design is basically concerned with a single response. However, the reality is that common industrial problems usually involve several quality characteristics, which are often correlated. Traditional approaches to multidimensional quality do not offer much information on how much better or worse a process is when finding optimal settings. Köksoy and Fan [Engineering Optimization 44 (8): 935–945] pointed out that the upside-down normal loss function provides a more reasonable risk assessment to the losses of being off-target in product engineering research. However, they only consider the single-response case. This article generalizes their idea to more than one response under possible correlations and co-movement effects of responses on the process loss. The response surface methodology has been adapted, estimating the expected multivariate upside-down normal loss function of a multidimensional system to find the optimal control factor settings of a given problem. The procedure and its merits are illustrated through an example. 相似文献
16.
对我公司硝铵装置降膜蒸发工序存在的问题进行分析 ,并通过技术改进 ,使干燥洗涤液全部返回系统 ,造粒塔粘塔问题得到缓解 ,取得可观的经济效益和环保效益 相似文献
17.
The purpose of this study was to investigate cortical interaction between brain regions in people with and without severe motor disability during brain-computer interface (BCI) operation through coherence analysis. Eighteen subjects, including six patients with cerebral palsy (CP) and three patients with amyotrophic lateral sclerosis (ALS), participated. The results showed (1) the existence of BCI performance difference caused by severe motor disability; (2) different coherence patterns between participants with and without severe motor disability during BCI operation and (3) effects of motor disability on cortical connections varying in the brain regions for the different frequency bands, indicating reduced cortical differentiation and specialisation. Participants with severe neuromuscular impairments, as compared with the able-bodied group, recruited more cortical regions to compensate for the difficulties caused by their motor disability, reflecting a less efficient operating strategy for the BCI task. This study demonstrated that coherence analysis can be applied to examine the ways cortical networks cooperate with each other during BCI tasks. PRACTITIONER SUMMARY: Few studies have investigated the electrophysiological underpinnings of differences in BCI performance. This study contributes by assessing neuronal synchrony among brain regions. Our findings revealed that severe motor disability causes more cortical areas to be recruited to perform the BCI task, indicating reduced cortical differentiation and specialisation. 相似文献
18.
19.
分析了济钢10万m3低压湿式储气罐防腐失效的原因,从防腐涂料的选择、施工过程等环节提出了改进的措施,实施后效果良好。 相似文献
20.
Michael B. C. Khoo 《Quality Engineering》2005,17(3):453-458
A semicircle control chart can be used in detecting both increases and decreases in the mean and/or variance. In this paper, we propose two modified semicircle charts for detecting a reduction in the process variance, a.k.a. process improvement. Each of these modified semicircle charts, namely, SC1 and SC2 has two limits, defined by the inner and outer semicircles. A process improvement is detected by the SC1 scheme if a point is plotted inside the smallest semicircle, or if two successive points are plotted between the inner and outer semicircles and by the SC2 scheme if a point plots inside the smallest semicircle or if two of three successive points plot between the inner and outer semicircles. It will be shown that the two modified semicircle charts have superior average run length (ARL) performances to the basic semicircle chart in the detection of process improvement. The ARL study is conducted by means of a simulation. 相似文献