首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   222篇
  免费   9篇
  国内免费   1篇
电工技术   13篇
化学工业   81篇
金属工艺   19篇
建筑科学   4篇
能源动力   6篇
轻工业   6篇
无线电   11篇
一般工业技术   53篇
冶金工业   26篇
原子能技术   4篇
自动化技术   9篇
  2023年   1篇
  2022年   3篇
  2021年   5篇
  2020年   6篇
  2019年   3篇
  2018年   4篇
  2017年   6篇
  2016年   8篇
  2015年   6篇
  2014年   8篇
  2013年   11篇
  2012年   7篇
  2011年   22篇
  2010年   13篇
  2009年   9篇
  2008年   11篇
  2007年   17篇
  2006年   4篇
  2005年   6篇
  2004年   8篇
  2003年   11篇
  2002年   5篇
  2001年   3篇
  2000年   3篇
  1999年   7篇
  1998年   16篇
  1997年   8篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   3篇
  1992年   2篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1985年   1篇
  1984年   1篇
  1976年   3篇
排序方式: 共有232条查询结果,搜索用时 310 毫秒
21.
22.
Mg–Al layered double hydroxides (Mg–Al LDHs) intercalated with benzenesulfonate (BS) and benzenedisulfonate (BDS2–) ions were prepared by coprecipitation and characterized by X-ray diffraction, FT-IR spectroscopy, and chemical analyses. The intercalated BS and BDS2– maintained their intrinsic molecular structures within the Mg–Al LDH interlayers. At low intercalation levels, the benzene ring of BS in BS · Mg–Al LDH was inclined at 30° relative to the plane of the brucite-like layers of Mg–Al LDH. With increasing BS content, the benzene ring adopted an additional configuration perpendicular to the Mg–Al LDH layers. In BDS-intercalated Mg–Al LDH, the benzene ring of BDS2– was tilted at 26° relative to the plane of the Mg–Al LDH layers. Intercalation levels of BDS2– were smaller than those of BS despite the greater charge density of BDS2–, which was likely attributable to a greater degree of electrostatic repulsion between intercalated anions.  相似文献   
23.
Cyclohexane isomerization to methylcyclopentane over sulfated zirconia is markedly enhanced in the presence of isopentane which acts as a hydride transfer agent to facilitate the slow step of hydride transfer from cyclohexane to isopropyl cation. This was revealed by deuterium tracer studies. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
24.
To test the effects of eicosapentaenoic acid (EPA) infusion on pulmonary edema induced by coronary ligation and reperfusion, extravascular lung water (EVLW) was measured in situ by the thermal-dye double indicator dilution method in dogs. In the control group of five dogs, 30 mL of a 10% soybean oil emulsion was infused through a leg vein. One hour after infusion, the left anterior descending coronary artery below the first diagonal branch was ligated for 15 min and then reperfused for 30 min. In the EPA group, six dogs were similarly treated with an emulsion of a 10% trieicosapentaenoyl-glycerol (90% pure). EVLW, pulmonary capillary wedge pressure, mean pulmonary artery pressure, mean blood pressure, and cardiac index were measured before and 15 min after coronary ligation, and 15 min and 30 min after coronary reperfusion. There were no significant differences in the hemodynamic indices between the two groups. EVLW significantly increased up to two times of baseline during coronary ligation in the control group (P< 0.05) and more during reperfusion (P<0.01), whereas EVLW did not increase in the EPA group. In conclusion, EPA inhibited EVLW accumulation and may be useful for ameliorating one of the ischemia-reperfusion-induced complications, pulmonary edema.  相似文献   
25.
The purpose of the present research was to clarify the effect of docosahexaenoic acid (DHA) intake on behavior and plasma catecholamines (CA). In Study 1, 42 students took either DHA-rich oil capsules containing 1.5–1.8 g DHA/d or control oil capsules containing 97% soybean oil plus 3% of another fish oil for 3 mon in a double-blind fashion. They took a psychological test (PF Study) at the start and end of the study. This study started at the end of summer vacation and ended just before the final exams. In the control group, external aggression (aggression against others) in PF Study was significantly increased at the end of the study as compared with that measured at the start (+8.9%), whereas it was not significantly changed in the DHA group (?1.0%). In a similar double-blind study (Study 2), we measured external aggression under nonstressful conditions. External aggression slightly decreased in the control group, whereas there were no significant changes in the DHA group. In Study 3 with 14 students, plasma CA were measured at the start and end of capsule administration period of 2 mon. Subjects were under continuous stress of the final exams that lasted throughout the whole study period. The ratio of plasma epinephrine to norepinephrine concentrations was significantly increased in the DHA group (78%), whereas it stayed at the same level in the control group. In Study 4, mice were fed either DHA-deficient diet or -sufficient diet for 4 wk, and their rearing frequency (an anxiety index) was measured. In the DHA-sufficient group, the rearing frequency was significantly less than in the other group. These effects of DHA intake may be applied to people in an attempt to ameliorate stress-related diseases.  相似文献   
26.
Nine electric power companies in Japan have been collecting lightning data with lightning location systems. Five years of the lightning data (2009–2013) are summarized and analyzed in this paper. The recent annual number of lightning flashes of which the current is more than 10 kA in Japan is around 1 million. The variations of lightning occurrence characteristics by areas, seasons, and so on, are clarified. Meteorological conditions that may affect lightning occurrence are also discussed. Furthermore, we show that there is a clear correlation between the number of lightning strikes and the outage rate of transmission lines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   
27.
28.
A novel modularity of heat circulation for distillation process, which reduces the energy consumption, is proposed. By incorporating compressors and heat exchangers, the heat of the distillate is recuperated and exchanged with the heat of the feed streams. The proposed technology achieves the reduction in the required energy more than 75% as compared with a benchmark process which uses external heat source for heating. This shows the proposed modularity of heat circulation for distillation process is very promising technology to drastically reduce energy demand for distillation.  相似文献   
29.
From the point of view of waste recycling, hydroxyapatite (HAp) can be synthesized using the waste sludge from semiconductor process. The possibility of using HAp as an anticorrosive pigment was investigated. The water absorption of coating pigmented with anticorrosive pigment, HAp, red lead (RL) and zinc potassium chromate (ZPC), and the corrosion at interface between coating and substrate were monitored using AC impedance technique. The amount of absorbed water decreased in the order of ZPC- > HAp- > RL-pigmented > unpigmented film. However, the water absorbed into HAp- or ZPC-pigmented film seems to be beneficial to anticorrosive function. The anticorrosive performance of HAp is superior or at least comparable to those of ZPC and RL, which have been known as representative anticorrosive pigments. It seems that the anticorrosive properties of HAp is mainly achieved by passivating the substrate, namely the soluble component of HAp reacts with Fe to form iron phosphate in the presence of water.  相似文献   
30.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号