全文获取类型
收费全文 | 6157篇 |
免费 | 133篇 |
国内免费 | 49篇 |
专业分类
电工技术 | 179篇 |
综合类 | 150篇 |
化学工业 | 652篇 |
金属工艺 | 170篇 |
机械仪表 | 417篇 |
建筑科学 | 849篇 |
矿业工程 | 159篇 |
能源动力 | 640篇 |
轻工业 | 280篇 |
水利工程 | 31篇 |
石油天然气 | 137篇 |
武器工业 | 91篇 |
无线电 | 450篇 |
一般工业技术 | 1373篇 |
冶金工业 | 268篇 |
原子能技术 | 67篇 |
自动化技术 | 426篇 |
出版年
2024年 | 6篇 |
2023年 | 43篇 |
2022年 | 74篇 |
2021年 | 89篇 |
2020年 | 94篇 |
2019年 | 72篇 |
2018年 | 75篇 |
2017年 | 113篇 |
2016年 | 121篇 |
2015年 | 117篇 |
2014年 | 304篇 |
2013年 | 354篇 |
2012年 | 350篇 |
2011年 | 520篇 |
2010年 | 405篇 |
2009年 | 410篇 |
2008年 | 321篇 |
2007年 | 437篇 |
2006年 | 406篇 |
2005年 | 328篇 |
2004年 | 260篇 |
2003年 | 279篇 |
2002年 | 247篇 |
2001年 | 163篇 |
2000年 | 127篇 |
1999年 | 133篇 |
1998年 | 93篇 |
1997年 | 62篇 |
1996年 | 63篇 |
1995年 | 48篇 |
1994年 | 44篇 |
1993年 | 24篇 |
1992年 | 26篇 |
1991年 | 24篇 |
1990年 | 13篇 |
1989年 | 23篇 |
1988年 | 14篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1958年 | 6篇 |
1956年 | 2篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有6339条查询结果,搜索用时 0 毫秒
31.
分析 6 0 0 0m3 /h空分设备原氮水预冷系统存在的问题及原因 ,将水循环由原制氧站大循环改为氮水预冷系统内部的自循环 ,只增加水换热器和蓄水器 ,效果明显。 相似文献
32.
33.
Current designs of sanitary collection systems normally only consider the transport of wastewater without attention on the air movement in the sewer airspaces. Under anaerobic conditions, hydrogen sulfide (H2S) can be generated in the liquid phase in sewer systems. H2S is corrosive to concrete and steel structures and odorous or even toxic to human, which can cause corrosion and sewer odor issues. To develop a feasible sewer corrosion and odor control strategy, it is necessary to understand the mechanisms of air flow in sewer systems for developing practical tools to predict and control the air flow. This paper comprehensively reviewed previous efforts on modeling the air flow in sewer systems and provided recommendations on predicting the air flow for engineering applications. The air flow in a single pipe was firstly reviewed followed by the air flow in sewer structures as well as air flow models in sewer networks. Some other considerations such as temperature driven flow, transient water flow, and wind effect were also reviewed. The knowledge gaps were then identified, and recommendations on the further studies were provided. 相似文献
34.
白红利 《网络安全技术与应用》2012,(7):53-55
目前国内空中交通管制系统人机界面的操作越来越趋于人性化,从可用、能用到好用的人机界面发展过程中,软件提供快捷的功能和方便的操作流程起到了很重要的作用,因此研究软件开发对键盘快捷键的支持就显得尤其重要。本文对可以实现的方法进行比较,分析实现方法的优劣,提出了一种实现键盘快捷功能的方法。 相似文献
35.
John A. Hughes Dave Randall Dan Shapiro 《Computer Supported Cooperative Work (CSCW)》1992,1(3):123-141
This paper explores the issues involved in moving from ethnographic explorations of work in context to a practical contribution to system design. It does so using the example of an interdisciplinary research project involving sociologists and computer scientists in the domain of air traffic control systems. It forms a pair with another paper (Sommerville et al., 1992) exploring these questions from the perspective of our computer science partners. We characterise ethnography as a research method, and consider the differences between undertaking it for strictly sociological or anthropological purposes by contrast with interdisciplinary and design purposes. We summarise some of our results in ethnographic explications of the work of air traffic controllers, and the sociality which it manifests. We describe the dialogues involved in rendering these observations informative for systems design, and the mutual translations implied in attempting to reconcile sociological with software engineering questions about supporting the work. We conclude by specifying some features of cooperative work which an engineering approach is in danger of overlooking; the ways, and limits, in which ethnographers can form a bridge between users and designers; and some of the conflicts of interest entrained in generating technical change.The research is funded by the UK MRC/SERC/ESRC Cognitive Science/HCI Initiative with the title Social Analysis of Control Systems for HCI Design, grant number SPG 8931598. The computer science partners are Professor Ian Sommerville, Dr Tom Rodden, Dr Pete Sawyer and Mr Richard Bentley. Thanks are due to Val King, Kjeldt Schmidt, Ian Sommerville and Tom Rodden for very helpful comments on earlier drafts of this paper. 相似文献
36.
纯电动汽车车载动力电池是其唯一的动力源且很有限,辅助设备消耗的电能减少了纯电动汽车的续驶里程,尤其是空调,所以开发高效的纯电动汽车空调系统是纯电动汽车能够被市场接受的关键。将纯电动汽车顶盖布满太阳电池,可以使空调系统的制冷能力增强,同时还能增加纯电动汽车的行驶距离。对小型纯电动汽车的太阳能辅助空调系统进行研究,设计出适合该空调的自动控制系统,可为纯电动汽车创造出一个更加舒适的驾驶和乘座环境。 相似文献
38.
真空压铸的发展 总被引:2,自引:3,他引:2
陈金城 《特种铸造及有色合金》1996,(5):32-33
真空系统是压铸过程中排除气体的最有效的方法之一。然而,真空压铸的发展几经起伏,现在则发展到一个新的阶段。从模具中抽出气体是几种抽气方法中较为简便的一种。真空气道的设计与常规气道则有所不同 相似文献
39.
Local equilibrium model described in Part I is used to stimulate both, the steady state operation conditions and transient regime after the start of PSA equipment. The effect of axial dispersion, adsorption isotherm nonlinearity and high pressure level is simulated. On the basis of numerical analysis, the operation of a classical two-bed oxygen generator is compared with two configurations having pressure equalizing step. The optimization strategy of the given PSA equipment has been proposed and the procedure is demonstrated on an example. The scaling-up condition for PSA equipments which can be described by local equilibrium model has been proposed on the basis of the theoretical analysis. 相似文献
40.
氧和氮在炭分子筛上的吸附与扩散 总被引:1,自引:0,他引:1
用重量法研究了氧、氮在两种空分用炭分子筛上的吸附与扩散。结果表明,氧和氮在炭分子筛中的扩散是活化扩散,该过程可用双孔模型进行描述。求得了氧、氮的扩散系数。 相似文献