全文获取类型
收费全文 | 5214篇 |
免费 | 106篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 56篇 |
综合类 | 1篇 |
化学工业 | 1073篇 |
金属工艺 | 59篇 |
机械仪表 | 87篇 |
建筑科学 | 268篇 |
矿业工程 | 21篇 |
能源动力 | 93篇 |
轻工业 | 456篇 |
水利工程 | 38篇 |
石油天然气 | 21篇 |
无线电 | 266篇 |
一般工业技术 | 934篇 |
冶金工业 | 1294篇 |
原子能技术 | 43篇 |
自动化技术 | 614篇 |
出版年
2022年 | 34篇 |
2021年 | 46篇 |
2020年 | 46篇 |
2019年 | 48篇 |
2018年 | 62篇 |
2017年 | 44篇 |
2016年 | 78篇 |
2015年 | 71篇 |
2014年 | 132篇 |
2013年 | 301篇 |
2012年 | 198篇 |
2011年 | 263篇 |
2010年 | 176篇 |
2009年 | 195篇 |
2008年 | 251篇 |
2007年 | 217篇 |
2006年 | 230篇 |
2005年 | 201篇 |
2004年 | 164篇 |
2003年 | 150篇 |
2002年 | 136篇 |
2001年 | 95篇 |
2000年 | 106篇 |
1999年 | 92篇 |
1998年 | 130篇 |
1997年 | 127篇 |
1996年 | 123篇 |
1995年 | 85篇 |
1994年 | 98篇 |
1993年 | 97篇 |
1992年 | 88篇 |
1991年 | 64篇 |
1990年 | 85篇 |
1989年 | 81篇 |
1988年 | 63篇 |
1987年 | 81篇 |
1986年 | 75篇 |
1985年 | 85篇 |
1984年 | 79篇 |
1983年 | 57篇 |
1982年 | 62篇 |
1981年 | 63篇 |
1980年 | 40篇 |
1979年 | 56篇 |
1978年 | 52篇 |
1977年 | 41篇 |
1976年 | 45篇 |
1975年 | 36篇 |
1974年 | 33篇 |
1973年 | 31篇 |
排序方式: 共有5324条查询结果,搜索用时 11 毫秒
51.
亚洲公司首次占据了以前属于欧洲公司的位置,主导了显示器展厅,而有些欧洲公司缺席了今年的展览。 相似文献
52.
在便携式的应用中,电源的效率决定着工作时间。举个例子,当你在飞越海洋的客机上使用便携式DVD播放器时,电池的使用时间将会变得十分的重要。电源的效率是由硬件的设计,器件的选择,以及基于软件的功率管理技术来共同决定的。 相似文献
53.
Gary Grandbois 《中国电子商情》2008,(5):33
消费者已感受到经济增长放缓的压力,全球半导体与电子设备供应商也是如此。据iSuppli公司,这些厂商在2008年面临需求增长放慢的局面。
在全球电子设备市场中,六大领域中的五个预计2008年增长率将低于2007年,这五个领域是:电脑、工业设备、汽车设备、有线通讯和无线通讯。 相似文献
54.
Sushmita Biswas David J. Gosztola Gary P. Wiederrecht Michael A. Stroscio Mitra Dutta 《Journal of Electronic Materials》2012,41(3):524-529
The effects of thermal annealing on the morphological and photoconductive properties of cadmium selenide quantum dots coated
with zinc sulfide are studied. The results of transmission electron microscopy with in situ annealing show a number of events taking place simultaneously, including aggregation of dots, changes in the size and shape
distribution, and reduction in interdot separation. Transient absorption results indicate that there is a small redshift of
the spectrum. There is a shortening of the absorption decay lifetimes due to annealing. Higher photocurrents are measured
in the annealed compared with unannealed dots at room temperature. 相似文献
55.
Abdulrahman Alharthi Madini O. Alassafi Robert J. Walters Gary B. Wills 《Telematics and Informatics》2017,34(2):664-678
Saudi universities have at their disposal a huge number of low cost IT resources to aid in teaching, research and learning. By migrating to cloud services, Saudi universities will be moving data and programs from local servers to the internet, thereby providing users with the ability to access and share information at any time from multiple devices. The migration to cloud-based IT resources is not yet widespread in Saudi universities due to several challenges including security, legal policies and implementation. At present, there is lack of research and guidance for Saudi universities on how to overcome these challenges and how contextual factors can influence the successful migration to the educational clouds.This research presents a framework for the successful migration to cloud technology in the Saudi Arabian universities. In this research, a set of key critical success factors (CSFs) were identified by synthesizing components from studies concerned with the migration of cloud for higher education and factors identified from the successful implementation of WBL (Web Based Learning) and ERP (Enterprise Resource Planning) on higher education in Saudi Arabia. Based on this knowledge, the proposed framework was evaluated via expert review and a survey by IT specialists from the Saudi universities. The initial CSFs were updated based on the expert reviews and the results were analysed. Based on the findings at this stage, additional CSFs were added to the framework as suggested by the experts. Subsequently, in order to confirm the reviewed CSFs, additional investigation via a structured online questionnaire was conducted and the outcome was analysed via one-sample t-test with the data integrity analysed via Cronbach’s alpha. The outcome indicated the majority of CSFs to be statistically significant except the Physical Location CSF. Potential future study and contributions are discussed. 相似文献
56.
Christopher J. Norris Gregory J. Meadway Michael J. O'Sullivan Ian P. Bond Richard S. Trask 《Advanced functional materials》2011,21(19):3624-3633
This paper demonstrates the first steps towards self‐healing composites that exploit a design philosophy inspired by the damage tolerance and self‐repair functions of bone. Cracking in either fibre reinforced polymers (FRP) or bone, if left unattended, can grow under subsequent cyclic stresses eventually leading to catastrophic failure of the structure. On detection of cracks, an FRP component must be repaired or completely replaced, whereas bone utilises a series of complex processes to repair such damage. Under normal circumstances, these processes allow the skeleton to continually perform over the lifespan of the organism, a highly desirable aspiration for engineering materials. A simple vasculature design incorporated into a FRP via a “lost wax” process was found to facilitate a self‐healing function which resulted in an outstanding recovery (≥96%) in post‐impact compression strength. The process involved infusion of a healing resin through the vascule channels. Resin egress from the backface damage, ultrasonic C‐scan testing, and microscopic evaluation all provide evidence that sufficient vascule–damage connectivity exists to confer a reliable and efficient self‐healing function. 相似文献
57.
Interconnections between semiconductor devices in integrated circuits continue to present difficult problems in the tradeoffs
between RC time constants, production worthiness, reliability, structural complexity, and compactibility for any single technology.
A process and structure has been demonstrated for integrated circuit interconnections which uses a conformai tungsten layer
deposited by chemical vapor deposition to provide step coverage into via holes of variable height. The film is then patterned
with a via interconnect pattern designed for liftoff processing, layers of chromium copper and chromium are then depositedinsitu on the wafers by way of evaporation. The undesired material is lifted off in a solvent process and the resulting metal pattern
is used as the mask for the reactive ion etching of CVD tungsten. This combination of materials and process allows for high
conductivity reliable interconnections with negligable step coverage problems. Processing and test information will be presented
in the paper. 相似文献
58.
In many developing countries such as Saudi Arabia the adoption of cloud computing is still at an early stage. This research aims to investigate the influencing factors in the decision to adopt cloud computing in the private sector. An integrated model is proposed incorporating critical factors derived from a literature review, along with other factors (such as physical location) that have not been examined in previous studies as main factors in the organisation’s decision to adopt cloud services. Data were collected from 300 IT staff in different organisations in the private sector in Saudi Arabia, in order to test the cloud adoption model and explore factors that were positively or negatively associated with cloud adoption. The most influential determinants of cloud adoption were found to be quality of service and trust. However, security and privacy concerns still prevent cloud adoption in this country. This study also showed that the effect of these variables differed according to organisation size and in adopter and non-adopter companies. Overall, these research findings provide valuable guidelines to cloud providers, managers, and government policy makers on ways of encouraging the spread of cloud computing in Middle Eastern countries and increasing its implementation, particularly in Saudi Arabia. 相似文献
59.
Reza Arghavani Gary Miner Melody Agustin 《集成电路应用》2008,(1):28-32,39
到了45纳米技术节点,高介电常数绝缘材料和金属栅电极将被用于射造逻辑电路器件。而采用高金属功函数和能隙工程电荷陷阱的闪存也能从这些项技术中获益。 相似文献
60.
2008北京奥运会是现代奥运史上首次选用高清设备进行高清转播的奥运会。这也意味着中国电视机顶盒市场的繁荣会随着北京奥运进入倒计时。 相似文献