全文获取类型
收费全文 | 328088篇 |
免费 | 24165篇 |
国内免费 | 12308篇 |
专业分类
电工技术 | 17643篇 |
技术理论 | 56篇 |
综合类 | 19631篇 |
化学工业 | 55073篇 |
金属工艺 | 18357篇 |
机械仪表 | 21138篇 |
建筑科学 | 25423篇 |
矿业工程 | 10801篇 |
能源动力 | 9746篇 |
轻工业 | 18563篇 |
水利工程 | 5180篇 |
石油天然气 | 22686篇 |
武器工业 | 2600篇 |
无线电 | 36273篇 |
一般工业技术 | 39334篇 |
冶金工业 | 17844篇 |
原子能技术 | 3193篇 |
自动化技术 | 41020篇 |
出版年
2024年 | 810篇 |
2023年 | 4917篇 |
2022年 | 7310篇 |
2021年 | 11872篇 |
2020年 | 9537篇 |
2019年 | 7729篇 |
2018年 | 8983篇 |
2017年 | 10194篇 |
2016年 | 9131篇 |
2015年 | 12132篇 |
2014年 | 15785篇 |
2013年 | 19092篇 |
2012年 | 20167篇 |
2011年 | 22434篇 |
2010年 | 19194篇 |
2009年 | 18326篇 |
2008年 | 17974篇 |
2007年 | 17393篇 |
2006年 | 18276篇 |
2005年 | 16131篇 |
2004年 | 10345篇 |
2003年 | 9124篇 |
2002年 | 8133篇 |
2001年 | 7472篇 |
2000年 | 8005篇 |
1999年 | 9615篇 |
1998年 | 8112篇 |
1997年 | 6710篇 |
1996年 | 6305篇 |
1995年 | 5290篇 |
1994年 | 4319篇 |
1993年 | 3053篇 |
1992年 | 2463篇 |
1991年 | 1937篇 |
1990年 | 1480篇 |
1989年 | 1212篇 |
1988年 | 989篇 |
1987年 | 634篇 |
1986年 | 507篇 |
1985年 | 323篇 |
1984年 | 225篇 |
1983年 | 190篇 |
1982年 | 191篇 |
1981年 | 122篇 |
1980年 | 125篇 |
1979年 | 67篇 |
1978年 | 33篇 |
1977年 | 38篇 |
1976年 | 55篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
951.
储运罐区计算机监测系统的开发与应用 总被引:3,自引:1,他引:2
储运罐区计算机监测系统是石化企业自动控制的薄弱环节。中国石油集团公司抚顺石油一厂使用ZYG-101型电子智能液位仪,以及使用FIX组态软件完成该系统的数据库组态、工艺流程显示、实时和历史趋势显示、报警和报表等处理过程,通过二次表的串行口与计算机进行通信,由计算机实时监测每个罐的各种重要参数。运行证明:该系统测量误差小,数据实时性好.易于存储及远程传送,较理想地达到储运罐区的自动检测功能。 相似文献
952.
In this paper, we study a three-dimensional axisymmetric boundary-value problem of a slender cylinder composed of a nonlinearly elastic material subjected to an axial force. Starting from the field equations, after a transformation and proper scalings, we identify a small variable and two small parameters, which characterize the present problem. Then, by an approach involving compound series-asymptotic expansions, a nonlinear ODE is derived, which governs the axial strain (the first-term in the series expansion). By imposing the zero radial displacement conditions at two ends, we manage to get the analytical solution of the axial strain, from which all other physical quantities can be deduced and thus the three-dimensional displacement field can be determined. Graphical results are presented, which show that there are two boundary layers near the two ends while the middle part is in a state of almost uniform extension. The asymptotic structure of the analytical solution is derived, which offers clear explanations to the structure of the deformed configuration and shows that the thickness of both boundary layers is of the order of the radius. We also point out the relevance of the present results to the St. Venant’s problem. In particular, we obtain the explicit uniformly-valid exponentially small error term, when the obtained deformed configuration is compared to the configuration of a uniform extension. 相似文献
953.
胜利炼油厂重油加氢 (VRDS)装置的常压分馏塔为填料塔 ,2 0 0 1年检修开工后该系统出现异常 ,经过查找分析 ,确定轻烃 /产品减压渣油换热器和柴油汽提塔重沸器内漏是装置异常的主要原因 相似文献
954.
955.
956.
957.
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
958.
960.