全文获取类型
收费全文 | 451篇 |
免费 | 33篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 10篇 |
综合类 | 58篇 |
化学工业 | 49篇 |
金属工艺 | 4篇 |
机械仪表 | 9篇 |
建筑科学 | 26篇 |
矿业工程 | 4篇 |
能源动力 | 10篇 |
轻工业 | 24篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
武器工业 | 1篇 |
无线电 | 31篇 |
一般工业技术 | 45篇 |
冶金工业 | 54篇 |
自动化技术 | 175篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 23篇 |
2013年 | 13篇 |
2012年 | 26篇 |
2011年 | 34篇 |
2010年 | 26篇 |
2009年 | 26篇 |
2008年 | 45篇 |
2007年 | 38篇 |
2006年 | 28篇 |
2005年 | 38篇 |
2004年 | 20篇 |
2003年 | 23篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1963年 | 2篇 |
1962年 | 2篇 |
1961年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有508条查询结果,搜索用时 15 毫秒
1.
Anmar W. Sabri Zainab H. Ali Serwan F. Shawkat Lamia A. Thejar Thaer I. Kassim Khalid A. Rasheed 《河流研究与利用》1993,8(3):237-250
The influences of the Samarra impoundment on the ecology of the downstream sector of the river Tigris are investigated. Zooplankton were collected monthly from July 1987 to July 1988. It was found that zooplankton were most abundant during high river discharges in March. During the month of low river discharge, September, the zooplankton population was greatly reduced immediately below the barrage and remained so to the last downstream station. Several factors seem to explain such differences. The high discharge from the impoundment was found to be the dominating factor and may flush the small backwaters in which zooplankton were abundant, thus increasing the population in the river. Zooplankton species vary in their ability to sustain populations in the river, variations which are due mainly to species-specific characteristics. 相似文献
2.
EuLisp has an integrated object system with reflective capabilities. We discuss some example applications which use these facilities to experiment with some advanced and powerful concepts, namely, finalization, virtual shared memory and persistence. A secondary goal is to attempt to illustrate the additional possibilities of metaobject programming over non-metalevel techniques. 相似文献
3.
These studies investigated self-regulation and subjective experience of time from the perspective of the regulatory resource model. Studies 1-2 showed that participants who were instructed to regulate their emotions while viewing a film clip perceived that the film lasted longer than participants who did not regulate their emotions. In Study 3, participants provided time estimates during a resource-depleting or nondepleting task. Subsequent task persistence was measured. Time perceptions mediated the effect of initial self-regulation on subsequent self-regulated performance. In Study 4, participants performed either a resource-depleting or a nondepleting thought-listing task and then performed a different regulatory task. Compared with nondepleted participants, depleted participants persisted less on the 2nd task but estimated that they had persisted longer. Subjective time estimates statistically accounted for reduced persistence after depletion. Together, results indicate people believe that self-regulatory endeavors last overly long, a belief that may result in abandonment of further self-control. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Persistence has been identified as a crucial quality of learning. However, it is hard to attain in online game-based environments as the drive to progress in the game may influence the ability to achieve the learning goals. This study aimed to examine the associations between micro-persistence, that is, the tendency to complete an individual task successfully, and task difficulty while acquiring computational thinking (CT). We further explored whether contextual or personal attributes better explain micro-persistence. We analysed data of 111 school students who used the CodeMonkey platform. We took a learning analytics approach for analysing the platform's log files. We found that micro-persistence is associated with task difficulty and that students who demonstrated an aptitude to learn new material are motivated to achieve the best solution. We also found that contextual variables better-explained micro-persistence than personal attributes. Encouraging micro-persistence can improve CT acquisition and the learning processes involved. 相似文献
5.
随着分布式仿真规模的日益扩大,高性能计算的不断发展,高性能仿真技术逐渐成为仿真领域新的研究热点,其中持久性框架及其实现机制是高性能仿真引擎中至关重要的一层支撑技术,它不但用于系统的负载平衡而且用于检查点及恢复操作。该文针对高性能仿真持久性问题,先提出了持久框架的结构,重点研究了两种持久库对持久框架性能的影响,通过实验数据对其性能差异进行分析,得出基于 C ++模板的持久框架更具优越性的结论。 相似文献
6.
基于可能性测度的计算树逻辑 总被引:1,自引:1,他引:0
首先,提出了可能的Kripke结构的定义,建立了可能的Kripke结构的可能性测度空间,并分析了可能的Kripke结构的一系列性质,即任一路径转移的可能性可由其初始状态的可能性分布与各转移的可能性取下确界而得到;依据可能的Kripke结构所定义的可能性测度具有其合理性等等。其次,给出了可能性计算树逻辑(PoCTL)的概念,讨论了两个PoCTL状态公式以及PoCTL与经典计算树逻辑(CTL)公式的等价性。最后,证明了PoCTL公式有与CTL*公式中"一致性"相对应的公式。 相似文献
7.
校园网业务系统数据整合目的在于使得业务系统数据的利用率达到最佳,消除由于异构数据源引起的信息孤岛。它对基于Java语言的Hibernate框架进行业务系统的数据整合技术进行了分析和研究,并与现有的结构进行了对比。通过对现有的整合平台和整合技术的对比,从而结合Java语言自身的优势和特点提出基于Hibernate框架结构的整合技术,并实现了数据整合的目的。 相似文献
8.
9.
10.
分析目前广泛使用的对象关系映射(ORM)组件——NHibernate,针对NHibernate的不足提出改进的ORM模型,根据该模型设计并实现基于.NET平台的轻量级ORM组件——MYPL,利用该组件无须编写任何映射文件即可实现对象关系映射等数据持久化操作,并能降低业务层和数据层之间的耦合,提高系统的扩展性、可维护性和应用系统的开发效率。 相似文献