全文获取类型
收费全文 | 16688篇 |
免费 | 1778篇 |
国内免费 | 926篇 |
专业分类
电工技术 | 1594篇 |
综合类 | 1817篇 |
化学工业 | 1734篇 |
金属工艺 | 1073篇 |
机械仪表 | 2324篇 |
建筑科学 | 1151篇 |
矿业工程 | 1119篇 |
能源动力 | 774篇 |
轻工业 | 558篇 |
水利工程 | 513篇 |
石油天然气 | 774篇 |
武器工业 | 486篇 |
无线电 | 1894篇 |
一般工业技术 | 1553篇 |
冶金工业 | 505篇 |
原子能技术 | 149篇 |
自动化技术 | 1374篇 |
出版年
2024年 | 96篇 |
2023年 | 220篇 |
2022年 | 422篇 |
2021年 | 502篇 |
2020年 | 579篇 |
2019年 | 462篇 |
2018年 | 502篇 |
2017年 | 665篇 |
2016年 | 694篇 |
2015年 | 702篇 |
2014年 | 1127篇 |
2013年 | 1095篇 |
2012年 | 1280篇 |
2011年 | 1270篇 |
2010年 | 980篇 |
2009年 | 1006篇 |
2008年 | 864篇 |
2007年 | 1063篇 |
2006年 | 950篇 |
2005年 | 746篇 |
2004年 | 612篇 |
2003年 | 560篇 |
2002年 | 458篇 |
2001年 | 464篇 |
2000年 | 349篇 |
1999年 | 300篇 |
1998年 | 247篇 |
1997年 | 254篇 |
1996年 | 187篇 |
1995年 | 164篇 |
1994年 | 127篇 |
1993年 | 100篇 |
1992年 | 78篇 |
1991年 | 62篇 |
1990年 | 44篇 |
1989年 | 39篇 |
1988年 | 35篇 |
1987年 | 24篇 |
1986年 | 15篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1962年 | 1篇 |
1959年 | 2篇 |
1958年 | 2篇 |
1957年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
济钢燃气厂针对济钢转炉煤气储存加压系统的设备现状,组织了一次设备大修,大修后煤气柜升降速度提高到了1.0m/min,并解决了加压机前负压等问题。 相似文献
4.
W. Shang B. Robrahn F. Golding M. H. J. Koch 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2004,530(3):513-520
A data acquisition system for time resolved X-ray scattering experiments using linear, quadrant or area gas proportional detectors with delay line readout based on commercially available hardware (National Instruments) is described. The system can easily be configured for recording data from point detectors (e.g. photomultipliers and photodiodes) and/or ancillary data only. Applications involving measurements with two different types of time to digital converters illustrate the features and performances of the system. 相似文献
5.
D. M. Suckling R. W. Peck L. M. Manning L. D. Stringer J. Cappadonna A. M. El-Sayed 《Journal of chemical ecology》2008,34(12):1602-1609
Disruption of Argentine ant trail following and reduced ability to forage (measured by bait location success) was achieved
after presentation of an oversupply of trail pheromone, (Z)-9-hexadecenal. Experiments tested single pheromone point sources and dispersion of a formulation in small field plots. Ant
walking behavior was recorded and digitized by using video tracking, before and after presentation of trail pheromone. Ants
showed changes in three parameters within seconds of treatment: (1) Ants on trails normally showed a unimodal frequency distribution
of walking track angles, but this pattern disappeared after presentation of the trail pheromone; (2) ants showed initial high
trail integrity on a range of untreated substrates from painted walls to wooden or concrete floors, but this was significantly
reduced following presentation of a point source of pheromone; (3) the number of ants in the pheromone-treated area increased
over time, as recruitment apparently exceeded departures. To test trail disruption in small outdoor plots, the trail pheromone
was formulated with carnuba wax-coated quartz laboratory sand (1 g quartz sand/0.2 g wax/1 mg pheromone). The pheromone formulation,
with a half-life of 30 h, was applied by rotary spreader at four rates (0, 2.5, 7.5, and 25 mg pheromone/m2) to 1- and 4-m2 plots in Volcanoes National Park, Hawaii. Ant counts at bait cards in treated plots were significantly reduced compared to
controls on the day of treatment, and there was a significant reduction in ant foraging for 2 days. These results show that
trail pheromone disruption of Argentine ants is possible, but a much more durable formulation is needed before nest-level
impacts can be expected.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
本文介绍了磁电机点火系统的点火提前角测量原理。对点火系统的点火信号和触发信号进行采集、调理,再用单片机进行处理,最后用LabVIEW进行点火提前角数据存储和显示。 相似文献
7.
CAO Wei-feng WANG Wen-boBeijing University of Posts Telecommunications Beijing P.R. China 《中国邮电高校学报(英文版)》2005,12(4)
1IntroductionCurrently,smart antenna technology can greatly en-hance system performance and i mprove the system ca-pacity so that it has been considered as a keytechnologyinthe third generation wireless communicationsystems .The researches on channel model , beamforming algo-rithms and receive algorithms have been widely carriedout and a great many of proposition have beensubmittedtothe 3th Generation Project Partner (3GPP) . Fromthe viewpoint of link-level and system-level research,many asp… 相似文献
8.
This study investigates the relationship between the critical surface tension of wetting of celestite and agglomeration recovery as well as the zeta potential in dependence of pH and amount of collector (Na‐Oleate). For this purpose, effects of pH and collector amount on the agglomeration recovery are investigated and zeta potential measurements and Fourier Transform Infrared Spectrophotometer (FTIR) analyses are carried out to determine the adsorption type of Na‐Oleate on celestite surface. The sessile drop technique is used for the measurement of contact angle and determination of the critical surface tension of wetting (YC) of celestite. The maximum agglomeration recovery is obtained at pH 7. The critical surface tension of wetting of celestite is very close to the surface tension of kerosene, which is 25.95 mN/m. Furthermore, at the optimum Na‐Oleate amount of 10 kg/ton, the critical surface tension of wetting of celestite is approximately equal to the surface tension of kerosene. 相似文献
9.
Titanium Dioxide, TiO2, is a photocatalyst with a unique characteristic. A surface coated with TiO2 exhibits an extremely high affinity for water when exposed to UV light and the contact angle decreases nearly to zero. Inversely, the contact angle increases when the surface is shielded from UV. This superhydrophilic nature gives a self-cleaning effect to the coated surface and has already been applied to some construction materials, car coatings and so on. We applied this property to the enhancement of boiling heat transfer. An experiment involving the pool boiling of pure water has been performed to make clear the effect of high wettability on heat transfer characteristics. The heat transfer surface is a vertical copper cylinder of 17 mm in diameter and the measurement has been done at saturated temperature and in a steady state. Both TiO2-coated and non-coated surfaces were used for comparison. In the case of the TiO2-coated surface, it is exposed to UV light for a few hours before experiment and it is found that the maximum heat flux (CHF) is about two times larger than that of the uncoated surface. The temperature at minimum heat flux (MHF) for the superhydrophilic surface is higher by 100 K than that for the normal one. The superhydrophilic surface can be an ideal heat transfer surface. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
10.
井巷掘进爆破工程中,工作面按设计要求,布置各种斜形炮孔,利用量角器和垂直尺控制钎杆与工作面夹角,使炮孔钻孔精度与设计炮孔角度基本上符合,在生产中取得了良好的爆破效果. 相似文献