全文获取类型
收费全文 | 36690篇 |
免费 | 3197篇 |
国内免费 | 1424篇 |
专业分类
电工技术 | 4059篇 |
综合类 | 3125篇 |
化学工业 | 3658篇 |
金属工艺 | 1461篇 |
机械仪表 | 3146篇 |
建筑科学 | 5785篇 |
矿业工程 | 1527篇 |
能源动力 | 2861篇 |
轻工业 | 1538篇 |
水利工程 | 612篇 |
石油天然气 | 987篇 |
武器工业 | 728篇 |
无线电 | 2579篇 |
一般工业技术 | 4302篇 |
冶金工业 | 1887篇 |
原子能技术 | 466篇 |
自动化技术 | 2590篇 |
出版年
2024年 | 136篇 |
2023年 | 394篇 |
2022年 | 750篇 |
2021年 | 1053篇 |
2020年 | 1108篇 |
2019年 | 763篇 |
2018年 | 739篇 |
2017年 | 1079篇 |
2016年 | 1100篇 |
2015年 | 1194篇 |
2014年 | 2307篇 |
2013年 | 2232篇 |
2012年 | 2724篇 |
2011年 | 2940篇 |
2010年 | 2116篇 |
2009年 | 2174篇 |
2008年 | 1912篇 |
2007年 | 2603篇 |
2006年 | 2416篇 |
2005年 | 2040篇 |
2004年 | 1757篇 |
2003年 | 1567篇 |
2002年 | 1359篇 |
2001年 | 976篇 |
2000年 | 833篇 |
1999年 | 630篇 |
1998年 | 498篇 |
1997年 | 403篇 |
1996年 | 308篇 |
1995年 | 266篇 |
1994年 | 210篇 |
1993年 | 135篇 |
1992年 | 130篇 |
1991年 | 98篇 |
1990年 | 66篇 |
1989年 | 61篇 |
1988年 | 43篇 |
1987年 | 23篇 |
1986年 | 21篇 |
1985年 | 16篇 |
1984年 | 23篇 |
1983年 | 21篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 5篇 |
1976年 | 4篇 |
1963年 | 4篇 |
1959年 | 10篇 |
1956年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
171.
172.
A test chamber has been developed in order to provide a small and simple emission testing facility capable of testing construction products in a climate where the important climatic parameters such as temperature, ventilation rate and air velocity can be varied independently around typical indoor values. The test chamber CLIMPAQ is made of panes of window glass. Other main surface materials are stainless steel and eloxated aluminium. The chamber has a volume of 50.9 litres and is designed to meet the requirements for quantifying air pollution. In this investigation human subjects acted as air pollution judges, and chemical characterization of the air pollution was carried out. Carpet, linoleum, wall paint and seal- ant were tested simultaneously in the CLIMPAQ and in four other chambers ranging from a full-scale chamber of 28 m3 to a field and laboratory emission cell of 3.5· 10?5m3. Product ranking is the same in all chambers for the sensory measurements. Emission rates based on sensory measurements differ for all products less than 100 % except for tests in a 3-litre chamber where emission rates were higher. Chemical measurements differ up to approximately 10 times for the same product in different chambers. Deviations appear to be the result of different environmental parameters in the various chambers. Low air concentrations or high specific ventilation rates seem to increase emissions, while differences in air velocities and sink properties may also be the cause of differences in emission rates. 相似文献
173.
用发生炉煤气进行快速热风烤窑的应用王善波,王志军(山东荣成市玻搪工程有限公司264309)ProducerGasUsedforFastHeatingupTankFurnace¥WangShanbo;WangZhijun(ShandongRongche... 相似文献
174.
Akira Ishizaki Kazuhiko Takasaki Shoji Shimomura Kouichi Masaki Kanji Kitazawa 《Electrical Engineering in Japan》1996,116(5):128-137
Although brushless resolvers have been used widely as angular position transducers, they are expensive due to their intricate construction, involving a rotary transformer to supply the exciting coils wound on the rotor poles with the current. It is shown theoretically in this paper that the resolver without rotary transformer or brushes can be realized by simple construction, which consists of the stator core with both 4-poles exciting windings and 2-poles output ones and the rotor core carrying no windings. In this resolver the rotor core has minimum gap at one side and a maximum gap at another side of the diameter. It is characterized by an outer surface form that makes the fluctuation part of gap permeance very in proportion to cos θ, where θ represents the angular position of a point in the air gap with respect to the origin on the rotor, the point of minimum air gap. The method determining the rotor form to embody the aforementioned gap permeance variation is also shown. It has been confirmed not only by simulation but also experiment that the 2-phase output voltages of a model designed based on the theory have sinusoidal waveforms with very small harmonic contents. Moreover, the rotor position detected by processing the output voltages through the conventional resolver/digital converter was within acceptable engineering accuracy. 相似文献
175.
大泵站超驼峰水位运行压缩空气断流系统的设计方法 总被引:5,自引:0,他引:5
阐述了压缩空气断流的原理,提出了压缩空气断流装置的一般构成和设计方法,首次应用气体喷射器作为压缩空气减压增量变换器,不但及时地增加了补气量,防止断流后流道压力的下降,而且大大减小了储气罐容积,使该项技术得以满足工程实际的要求,为同类泵站的技术改造 相似文献
176.
对武钢引进的两台3×104m3/h空分设备,为改变其自动变负荷生产调节范围小、时间长的问题,采用了人工手动变负荷的操作方法。实践表明:扩大了增减产范围,缩短了调节时间,有十分明显的综合经济效益,可供大型空分变负荷生产借鉴参考。 相似文献
177.
178.
对新冶钢动力厂制氧机组配套的原料空气压缩机故障现象进行了原因分析,并有针对性地提出了处理措施,经运行检验,故障基本消除。 相似文献
179.
180.
采用气囊作内模进行浇筑桥面板混凝土 ,加快了预制桥面板施工进度 ,确保工程施工质量 ,并降低了工程施工成本 相似文献