全文获取类型
收费全文 | 26592篇 |
免费 | 3478篇 |
国内免费 | 2376篇 |
专业分类
电工技术 | 911篇 |
技术理论 | 2篇 |
综合类 | 2485篇 |
化学工业 | 802篇 |
金属工艺 | 247篇 |
机械仪表 | 665篇 |
建筑科学 | 3237篇 |
矿业工程 | 9586篇 |
能源动力 | 495篇 |
轻工业 | 286篇 |
水利工程 | 641篇 |
石油天然气 | 332篇 |
武器工业 | 98篇 |
无线电 | 1186篇 |
一般工业技术 | 711篇 |
冶金工业 | 1620篇 |
原子能技术 | 61篇 |
自动化技术 | 9081篇 |
出版年
2024年 | 44篇 |
2023年 | 214篇 |
2022年 | 595篇 |
2021年 | 840篇 |
2020年 | 1038篇 |
2019年 | 659篇 |
2018年 | 665篇 |
2017年 | 732篇 |
2016年 | 870篇 |
2015年 | 951篇 |
2014年 | 1795篇 |
2013年 | 1491篇 |
2012年 | 2258篇 |
2011年 | 2230篇 |
2010年 | 1760篇 |
2009年 | 1926篇 |
2008年 | 1997篇 |
2007年 | 2217篇 |
2006年 | 1974篇 |
2005年 | 1629篇 |
2004年 | 1411篇 |
2003年 | 1302篇 |
2002年 | 912篇 |
2001年 | 658篇 |
2000年 | 572篇 |
1999年 | 423篇 |
1998年 | 260篇 |
1997年 | 202篇 |
1996年 | 187篇 |
1995年 | 153篇 |
1994年 | 130篇 |
1993年 | 93篇 |
1992年 | 77篇 |
1991年 | 65篇 |
1990年 | 30篇 |
1989年 | 19篇 |
1988年 | 23篇 |
1987年 | 22篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Mining process models with non-free-choice constructs 总被引:6,自引:0,他引:6
Lijie Wen Wil M. P. van der Aalst Jianmin Wang Jiaguang Sun 《Data mining and knowledge discovery》2007,15(2):145-180
Process mining aims at extracting information from event logs to capture the business process as it is being executed. Process
mining is particularly useful in situations where events are recorded but there is no system enforcing people to work in a
particular way. Consider for example a hospital where the diagnosis and treatment activities are recorded in the hospital
information system, but where health-care professionals determine the “careflow.” Many process mining approaches have been
proposed in recent years. However, in spite of many researchers’ persistent efforts, there are still several challenging problems
to be solved. In this paper, we focus on mining non-free-choice constructs, i.e., situations where there is a mixture of choice
and synchronization. Although most real-life processes exhibit non-free-choice behavior, existing algorithms are unable to
adequately deal with such constructs. Using a Petri-net-based representation, we will show that there are two kinds of causal
dependencies between tasks, i.e., explicit and implicit ones. We propose an algorithm that is able to deal with both kinds
of dependencies. The algorithm has been implemented in the ProM framework and experimental results shows that the algorithm
indeed significantly improves existing process mining techniques. 相似文献
52.
53.
A Simple Constraint-Based Algorithm for Efficiently Mining Observational Databases for Causal Relationships 总被引:4,自引:0,他引:4
Gregory F. Cooper 《Data mining and knowledge discovery》1997,1(2):203-224
This paper presents a simple, efficient computer-based method for discovering causal relationships from databases that contain observational data. Observational data is passively observed, as contrasted with experimental data. Most of the databases available for data mining are observational. There is great potential for mining such databases to discover causal relationships. We illustrate how observational data can constrain the causal relationships among measured variables, sometimes to the point that we can conclude that one variable is causing another variable. The presentation here is based on a constraint-based approach to causal discovery. A primary purpose of this paper is to present the constraint-based causal discovery method in the simplest possible fashion in order to (1) readily convey the basic ideas that underlie more complex constraint-based causal discovery techniques, and (2) permit interested readers to rapidly program and apply the method to their own databases, as a start toward using more elaborate causal discovery algorithms. 相似文献
54.
简要回顾了我国钨矿业悠久的历史、资源的优势、技术的进步和卓越的贡献 ;20世纪80年代中期以后 ,逐步陷入困境 ,举步维艰的主要表现 ;以及在解决“四矿”(矿业、矿山、矿工、矿城)问题中的艰苦经历。指出应在“四矿”问题讨论中做更多、更深的对策思考 ,并对钨业的“四矿”问题加以重点研究。 相似文献
55.
回顾了体制、制度的改革和科学技术的发展给十局带来的巨大变化,就十局当前改革任务从理顺产权关系、进一步完善内部治理结构、继续深化三项制度改革、实施科教兴局战略等四个方面提出了看法和意见。 相似文献
56.
本文针对金翅岭金矿矿体开采条件极其复杂的情况,在采矿方法试验中,率先在岩金矿山采用了三强作业技术,既保证了安全回采,又取是了较好的技术经济指标。 相似文献
57.
文中提出了在高阶段不分层开采的露天矿场采用“有规则安全小平台开采方法”。开采坡度能够得到控制,有效地控制了采石场经常发生的塌方事故,能提高产量,降低生产成本,安全性好,且技术简单,易于推广。 相似文献
58.
This paper presents an algorithm that permits the search for dependencies among sets of data (univariate or multivariate time-series, or cross-sectional observations). The procedure is modeled after genetic theories and Darwinian concepts, such as natural selection and survival of the fittest. It permits the discovery of equations of the data-generating process in symbolic form. The genetic algorithm that is described here uses parts of equations as building blocks to breed ever better formulas. Apart from furnishing a deeper understanding of the dynamics of a process, the method also permits global predictions and forecasts. The algorithm is successfully tested with artificial and with economic time-series and also with cross-sectional data on the performance and salaries of NBA players during the 94–95 season. 相似文献
59.
锦屏磷矿对其东山采区松软矿体所使用的分段崩落法做了集中快速采准施工、增加分段高度、实行水平或上向扇形深孔连续崩矿等改进,简化了采场结构,矿石损失率由原来的63%下降到改进后的20.34%,贫化率由23.92%下降到15.10%。 相似文献
60.
基于STEP的零件加工工艺计划模型 总被引:1,自引:0,他引:1
为了满足CIMS环境下工艺系统与其它系统集成的需要,建立了标准工艺计划模型具十分重要的意义。本文描述了一个基于STEP的零件加工工艺计划模型,介绍了建立这一模型的关键技术,给出了参照STEP建立工艺计划模型的方法。 相似文献