全文获取类型
收费全文 | 12099篇 |
免费 | 264篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 124篇 |
综合类 | 35篇 |
化学工业 | 1925篇 |
金属工艺 | 138篇 |
机械仪表 | 119篇 |
建筑科学 | 489篇 |
矿业工程 | 29篇 |
能源动力 | 140篇 |
轻工业 | 5615篇 |
水利工程 | 41篇 |
石油天然气 | 2篇 |
无线电 | 456篇 |
一般工业技术 | 1420篇 |
冶金工业 | 839篇 |
原子能技术 | 53篇 |
自动化技术 | 959篇 |
出版年
2017年 | 125篇 |
2016年 | 176篇 |
2015年 | 128篇 |
2014年 | 196篇 |
2013年 | 294篇 |
2012年 | 283篇 |
2011年 | 401篇 |
2010年 | 294篇 |
2009年 | 320篇 |
2008年 | 348篇 |
2007年 | 392篇 |
2006年 | 289篇 |
2005年 | 256篇 |
2004年 | 230篇 |
2003年 | 175篇 |
2002年 | 161篇 |
2001年 | 123篇 |
2000年 | 122篇 |
1999年 | 139篇 |
1998年 | 207篇 |
1997年 | 146篇 |
1996年 | 156篇 |
1995年 | 132篇 |
1994年 | 110篇 |
1993年 | 143篇 |
1992年 | 111篇 |
1990年 | 125篇 |
1989年 | 137篇 |
1988年 | 127篇 |
1987年 | 136篇 |
1986年 | 104篇 |
1985年 | 122篇 |
1984年 | 128篇 |
1982年 | 104篇 |
1981年 | 111篇 |
1977年 | 118篇 |
1976年 | 135篇 |
1973年 | 129篇 |
1916年 | 108篇 |
1915年 | 106篇 |
1913年 | 105篇 |
1912年 | 134篇 |
1911年 | 115篇 |
1910年 | 123篇 |
1909年 | 136篇 |
1908年 | 131篇 |
1907年 | 129篇 |
1906年 | 130篇 |
1905年 | 131篇 |
1904年 | 120篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
阿维斯塔波莱瑞特厂正在进行一个现代化改造项目,以提高炉卷轧机的生产能力,达到年产100万吨。但是,由于在阿维斯塔波莱瑞特厂炉卷轧机上的现有技术已达到极限,只有通过对轧机及自动化系统进行现代化的改造才有可能提高和增强轧机的利用率和易维护性。 相似文献
42.
To clarify whether motion information per se has a separable influence on action control, the authors investigated whether irrelevant direction of motion of stimuli whose overall position was constant over time would affect manual left-right responses (i.e., reveal a motion-based Simon effect). In Experiments 1 and 2, significant Simon effects were obtained for sine-wave gratings moving in a stationary Gaussian window. In Experiment 3, a direction-based Simon effect with random-dot patterns was replicated, except that the perceived direction of motion was based on the displacement of single elements. Experiments 4 and 5 studied motion-based Simon effects to point-light figures that walked in place--displays requiring high-level analysis of global shape and local motion. Motion-based Simon effects occurred when the displays could be interpreted as an upright human walker, showing that a high-level representation of motion direction mediated the effects. Thus, the present study establishes links between high-level motion perception and action. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
Lüps und Petrak 《Zeitschrift für Jagdwissenschaft》2003,49(2):159-160
Ohne Zusammenfassung 相似文献
44.
45.
During the BOF process for the production of crude steel, the specific amount of dust emitted is of the order of 2 % of the steel weight at turn down. The process gas conveys the dust through the boiler system into the primary and secondary dust catchers. The transportation of dust particles is influenced by blowing parameters; physical properties of process gas and of dust phases; and, type and layout of the converter and the filter system. In this work, a numerical simulation model is developed that simulates the pneumatic conveyance and sedimentation of primarily coarse dust particles in the BOF gas cleaning system. Comparison is then made of predicted coarse dust characteristics with values for dust sampled from an existing plant in order to verify the plausibility of the developed model. 相似文献
46.
Part 1 of this contribution reported on the effects of system properties on heat transfer between heating or cooling surfaces and bubbling fluidized beds. This investigation produced four correlations which define the respective maximum heat transfer. Part 2 of this study suggests that the heat transfer between exchanger surfaces and bubbling fluidized beds depends on superficial gas velocity, expressed as dimensionless excess gas velocity. The present paper shows that heat transfer coefficients in circulating fluidized beds can be predicted by evaluation of a state diagram, which combines three dimensionless groups: Nusselt number, Archimedes number and a dimensionless pressure gradient. A comparison of coal combustion experiments with own cold model measurements indicates that the radiative component of heat transfer coefficients is only evident at very low dimensionless pressure gradients. 相似文献
47.
48.
Ernst L.J. Hinman W.L. Quam D.H. Thorp J.S. 《Power Delivery, IEEE Transactions on》1992,7(4):1834-1852
The authors describe the relaying concepts of charge comparison. Charge comparison is a new transmission line protection system. It is a form of current differential relaying. Charge comparison largely resolves the traditional problems of current differential relaying of transmission lines, which are that protection is lost if a channel fails, a large channel capacity is required, and precise channel delay compensation is required. This technique is suitable for the protection of two- or three-terminal AC transmission lines, of all lengths and voltage levels, with or without series of shunt compensation, with three-hole or single-pole tripping 相似文献
49.
Giuseppe G. G. Manzardo Sandra Kürsteiner-Laube und Daniel Perrin 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1996,203(6):501-506
In diethyl ether extracts from celeriac (Apium graveolens L. var.rapaceum) all four stereoisomers of (3a–7a)-cis-3-butylhexahydrophthalide were found to be present. The analyses were carried out by means of GC, enantioselective GC and GC-MS. The assignment of the relative configuration of the diastereomers3 and4 was accomplished by NOE difference spectroscopy. 相似文献
50.