全文获取类型
收费全文 | 10411篇 |
免费 | 818篇 |
国内免费 | 233篇 |
专业分类
电工技术 | 1646篇 |
综合类 | 666篇 |
化学工业 | 498篇 |
金属工艺 | 226篇 |
机械仪表 | 1046篇 |
建筑科学 | 1665篇 |
矿业工程 | 400篇 |
能源动力 | 279篇 |
轻工业 | 210篇 |
水利工程 | 289篇 |
石油天然气 | 247篇 |
武器工业 | 263篇 |
无线电 | 851篇 |
一般工业技术 | 745篇 |
冶金工业 | 549篇 |
原子能技术 | 65篇 |
自动化技术 | 1817篇 |
出版年
2025年 | 3篇 |
2024年 | 124篇 |
2023年 | 106篇 |
2022年 | 243篇 |
2021年 | 339篇 |
2020年 | 325篇 |
2019年 | 202篇 |
2018年 | 180篇 |
2017年 | 280篇 |
2016年 | 356篇 |
2015年 | 314篇 |
2014年 | 945篇 |
2013年 | 732篇 |
2012年 | 968篇 |
2011年 | 963篇 |
2010年 | 639篇 |
2009年 | 691篇 |
2008年 | 517篇 |
2007年 | 609篇 |
2006年 | 560篇 |
2005年 | 449篇 |
2004年 | 378篇 |
2003年 | 380篇 |
2002年 | 306篇 |
2001年 | 219篇 |
2000年 | 133篇 |
1999年 | 111篇 |
1998年 | 59篇 |
1997年 | 78篇 |
1996年 | 54篇 |
1995年 | 43篇 |
1994年 | 27篇 |
1993年 | 30篇 |
1992年 | 27篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1979年 | 5篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1965年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The study revealed that Fixed Price, Cost Plus and Purchased Labour contracts are the top three maintenance contracts adopted whilst Unit Price, Cost Plus A Percentage Fee contracts are alternatives used in the Kingdom. Some other types of maintenance contract were thought to be inappropriate by ministry departments. 相似文献
2.
Lee Kiang Quah 《Building Research & Information》1992,20(4):229-232
The widening of interest and scope of property management and maintenance has attracted a greater diversity of professional disciplines into facilities management. Dr Quah, coordinator of CIB W70 on Management, Maintenance and Modernization of Building facilities, expresses her personal views on the current fascination with the subject. 相似文献
3.
Michael Vermut William R. Widner Jonathan D. Dinman Reed B. Wickner 《Yeast (Chichester, England)》1994,10(11):1477-1479
MKT1 is required for m aintenance of K2 above 30°C in strains with the L-A-HN variant of the L-A double-stranded RNA virus of Saccharomyces cerevisiae. We report that MKT1 encodes a 92 979 Da protein with serine-rich regions and the retroviral protease signature, DTG, but with no substantial homology to proteins presently in the databases. This sequence is available from GenBank under Accession Number U09129. 相似文献
4.
分析实现永州电力通信交换网集中操作和维护的必要性,介绍了实现程控交换机远程操作和维护的两种方式,总结在实践过程中所得到的经验和教训。 相似文献
5.
Modern database systems desperate for the ability to support highly scalable transactions and efficient queries simultaneously for real-time applications. One solution is to utilize query optimization techniques on the on-line transaction processing (OLTP) systems. The materialized view is considered as a panacea to decrease query latency. However, it also involves the significant cost of maintenance which trades away transaction performance. In this paper, we examine the design space and conclude several design features for the implementation of a view on a distributed log-structured merge-tree (LSMtree), which is a well-known structure for improving data write performance. As a result, we develop two incremental view maintenance (IVM) approaches on LSM-tree. One avoids join computation in view maintenance transactions. Another with two optimizations is proposed to decouple the view maintenance with the transaction process. Under the asynchronous update, we also provide consistency queries for views. Experiments on TPC-H benchmark show our methods achieve better performance than straightforward methods on different workloads. 相似文献
6.
对学院使用的大型精密机械设备——五轴加工中心和数控铣床等设备的安装条件、验收指标、技术管理和日常维护进行了阐述,确保设备到位后及时安装和有效使用。 相似文献
7.
8.
朱德葛 《数字社区&智能家居》2009,(32)
高校的计算机房所用的操作系统大多数是Windows,常用教学软件的安装和维护,需要有非常丰富的计算机知识和动手能力很强的计算机老师来担当,学校的教学机房的维护管理好坏,直接影响到计算机的正常教学工作,该作者从事过一段机房软件安装、维护、管理工作,在此把他的管理经验和技巧归纳了一下。 相似文献
9.
刘澜 《自动化与仪器仪表》2009,(5):86-88
以我国某大型钢铁企业全厂仪表维修设施的设计方案为例,简要说明了仪修设施的设计原则、全厂仪表维修的一般解决方案,较详细地介绍了仪修设施专业划分、实验室及维修车间的设置和主要设备构成,为该类项目的设计和工程建设提供一定参考。 相似文献
10.
In this paper, we consider randomly failing equipment leased several times during their life cycle with a given warranty period. A mathematical model is developed to determine the optimal efficiency levels of preventive maintenance (PM) to be performed on the equipment between successive lease periods, maximising the expected total profit of the lessor over the equipment life cycle. The model considers the expected leasing revenue as well as the equipment acquisition cost and the average PM and repair costs. PM actions allow reducing the age of the equipment to a certain extent with a corresponding cost depending on the PM level adopted. The efficiency of the PM is determinant of the expected revenue during the next lease period. Given a set of K possible PM levels and the number of lease periods n over the equipment life cycle, Kn?1 PM strategies are possible. A genetic algorithm is proposed in order to obtain nearly optimal policies in situations where the number of possibilities Kn?1 is very high. Obtained numerical results are discussed. Small- and big-size instances of the problem are considered in the case of a service company in the oil and gas industry specialised in leasing specific equipment such as separators, to oil companies for production activities with a limited duration of several months like well testing or short production tests. 相似文献