全文获取类型
收费全文 | 5523篇 |
免费 | 418篇 |
国内免费 | 193篇 |
专业分类
电工技术 | 570篇 |
综合类 | 577篇 |
化学工业 | 577篇 |
金属工艺 | 88篇 |
机械仪表 | 243篇 |
建筑科学 | 802篇 |
矿业工程 | 197篇 |
能源动力 | 184篇 |
轻工业 | 490篇 |
水利工程 | 263篇 |
石油天然气 | 296篇 |
武器工业 | 17篇 |
无线电 | 310篇 |
一般工业技术 | 414篇 |
冶金工业 | 333篇 |
原子能技术 | 42篇 |
自动化技术 | 731篇 |
出版年
2024年 | 17篇 |
2023年 | 45篇 |
2022年 | 89篇 |
2021年 | 135篇 |
2020年 | 165篇 |
2019年 | 116篇 |
2018年 | 110篇 |
2017年 | 142篇 |
2016年 | 178篇 |
2015年 | 181篇 |
2014年 | 366篇 |
2013年 | 284篇 |
2012年 | 455篇 |
2011年 | 455篇 |
2010年 | 370篇 |
2009年 | 354篇 |
2008年 | 292篇 |
2007年 | 410篇 |
2006年 | 348篇 |
2005年 | 286篇 |
2004年 | 272篇 |
2003年 | 211篇 |
2002年 | 173篇 |
2001年 | 134篇 |
2000年 | 113篇 |
1999年 | 92篇 |
1998年 | 68篇 |
1997年 | 50篇 |
1996年 | 50篇 |
1995年 | 26篇 |
1994年 | 24篇 |
1993年 | 20篇 |
1992年 | 17篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 13篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1977年 | 2篇 |
1974年 | 2篇 |
1967年 | 2篇 |
1963年 | 2篇 |
1961年 | 3篇 |
1955年 | 1篇 |
排序方式: 共有6134条查询结果,搜索用时 15 毫秒
991.
The electrostatic charge distribution in a lab‐scale 2‐D fluidized bed of 900 µm glass beads was determined using arrays of induction probes, and the influence of relative humidity and superficial gas velocity was examined. The bubble presence, relative humidity, and superficial gas velocity were found to influence charge separation. Bipolar charging was observed; the net charge build‐up was found to be negligible. Moreover, the system was monitored by applying the attractor comparison method to the electrostatic charge signals from an induction probe. It was concluded that this approach can indeed be used to monitor changes in the electrostatic behaviour. 相似文献
992.
The paper discusses some misconceptions that have contributed to the continued use of thermal desalination processes and promotion of the hybrid desalination process for new plants being built or considered at Middle East locations. The misconceptions are examined both on the basis of fundamental thermodynamic principles and in terms of practical engineering parameters. The analysis shows that there is no economic or performance advantage in the installation of greenfield hybrid power/thermal desalination/ seawater reverse osmosis (SWRO) plants in preference to power/SWRO plants, because the latter would produce water more cheaply under all conditions and at all fuel costs, and would provide more operational flexibility than the former. The paper identifies situations where the hybrid desalination process can be fully justified: in existing power/desalination plants, where aging boilers and multistage flash (MSF) units need to be repaired or replaced, through retrofitting and repowering. In such situations, abandonment of the MSF process would result in a reduction in the power output of the plant. The paper refers to previous work which showed that the repowering of a typical existing power/desalination station with refurbishment/replacement of the MSF units, together with the addition of SWRO units, would result in a several-fold increase in the water and power output and a dramatic improvement in the fuel efficiency, without any additions to the existing seawater intake system. The paper emphasizes the importance of test stations/demonstration plants at existing power/desalination stations in the Middle East in order to obtain data and make improvements in the technology of higher temperature SWRO, with the feed obtained from the cooling water returning from the power plant condenser and the thermal desalination plant. The paper shows that the potential benefits would easily justify the investment in research and development required to validate this concept. 相似文献
993.
Environmental impact assessment will soon become a compulsory phase in future potable water production projects, especially when alternative treatment processes such as desalination are considered. An impact assessment tool is therefore developed for the environmental evaluation of potable water production. The evaluation method used is the life cycle assessment (LCA) method. The quick and easy assessment of energetic and environmental performances contributes to determine the weak points of potable water production processes or the best suited treatment in a specific context. Studies of some potable water supply scenarios (groundwater treatment, ultrafiltration, nanofiltration, seawater reverse osmosis and thermal distillation associated to water transfer) are presented in order to illustrate the environmental information drawn from this tool. The main source of impacts is shown to be electricity production for plant operation. Improvement levers are presented for impact reduction and for the objective comparison between alternative and conventional water treatment processes. 相似文献
994.
介绍了标准JGJ99—98,GB50011—2001,CECS160:2004,EC8,ANSI/AISC341—02和日本极限状态设计指南中关于钢结构"强节点弱构件"的抗震设计方法,包括梁柱刚性连接、支撑与框架连接和连接部分设计抗力的计算方法。通过归一化后的Φ值比较,评价了各标准的设计方法。分析表明,按JGJ99—98,GB50011—2001设计的节点最弱,按CECS160:2004设计的最强,按ANSI/AISC341—02设计的略弱于CECS160:2004。考虑到大震下要求节点不坏,GB50011—2001和JGJ99—98中有关节点部分的设计有待进一步研究。 相似文献
995.
996.
聚氨酯筛板是一种以聚氨酯为主要原料生产的网状制品,是众多弹性体中的一种。介绍了常压法浇注聚氨酯筛板的工业生产工艺,具体说明了预聚体的合成、常压下的浇注工艺——手工及机械浇注的方法,列表比较了聚氨酯筛板与钢制筛板的性能、各种聚氨酯筛板之间的性能比较及影响因素。 相似文献
997.
998.
煤制合成天然气项目工艺方案与技术经济比较 总被引:1,自引:1,他引:0
介绍了煤制天然气(SNG)典型工艺流程;论述了KBR工艺(流化床)、BGL工艺(固定床)、Shell上行水激冷工艺(气流床粉煤气化)的技术方案、工艺装置和公用工程配置;对比了3种不同类型煤气化工艺的主要原料、公用工程消耗和技术经济测算。结果表明,煤气化技术的选择,不仅要考虑煤质特点、原料煤来源和价格以及产品的经济性,而且要从技术的成熟可靠、环境影响和社会效益等多方面因素进行综合评价和对比。 相似文献
999.
在有机废气污染治理中,蓄热式直接燃烧法和蓄热式催化燃烧法两种技术被广泛采用,针对ABS废气治理,对这两种工艺技术进行了比较分析。 相似文献
1000.
对河南神马氯碱发展有限责任公司10万t/a和20万t/a烧碱配套HCl合成及盐酸装置的工艺、自动控制方案和运行情况进行比较,结果表明:10万t/a烧碱配套HCl合成及盐酸装置的手动操作占优势,20万t/a烧碱配套HCl合成及盐酸装置的占地面积、人员配置、自动控制方面占优势。 相似文献