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   253篇
  免费   2篇
电工技术   31篇
化学工业   38篇
金属工艺   2篇
机械仪表   5篇
建筑科学   5篇
能源动力   3篇
轻工业   9篇
水利工程   2篇
无线电   34篇
一般工业技术   23篇
冶金工业   83篇
原子能技术   4篇
自动化技术   16篇
  2022年   2篇
  2021年   1篇
  2020年   2篇
  2019年   2篇
  2016年   2篇
  2014年   1篇
  2013年   6篇
  2012年   7篇
  2011年   8篇
  2010年   4篇
  2009年   2篇
  2008年   9篇
  2007年   7篇
  2006年   2篇
  2005年   5篇
  2004年   4篇
  2003年   5篇
  2002年   6篇
  2001年   6篇
  2000年   6篇
  1999年   11篇
  1998年   31篇
  1997年   25篇
  1996年   11篇
  1995年   8篇
  1994年   6篇
  1993年   20篇
  1992年   4篇
  1991年   3篇
  1990年   6篇
  1988年   3篇
  1987年   5篇
  1986年   5篇
  1985年   1篇
  1984年   5篇
  1983年   3篇
  1982年   4篇
  1981年   1篇
  1980年   4篇
  1979年   1篇
  1977年   1篇
  1976年   2篇
  1968年   1篇
  1967年   3篇
  1966年   2篇
  1965年   2篇
排序方式: 共有255条查询结果,搜索用时 15 毫秒
11.
An electrochemical dissolved hydrogen feeder equipped with a multi-cathode system and a high-rate recirculation pump was developed in order to examine its feasibility for bioremediation. Results showed that the feeding efficiency was remarkably higher than that in former studies. The reason for the enhanced hydrogen dissolution rate was thought to be due to the large cathode area by applying multiple granular activated carbon electrodes resulting in low current density. Two mass balance equations were formulated and applied to analyze the performance of the apparatus theoretically. The hydrogen dissolution rate calculated from the equations was in fairly good agreement with observed results. It was suggested that the electrochemical H2 feeder would be a competitive alternative as a hydrogen feeding method for bioremediation.  相似文献   
12.
A novel 1.3?m InGaAsP/lnP distributed-feedback buried-heterostructure laser diode on p-type InP substrate has been developed utilising a dopant diffusion technique. The laser has achieved a threshold current as low as 20 mA and high output power of 32 mW under CW and SLM operation.  相似文献   
13.
The hyperbranched polymers (HBP-SA-Acs) with both a sulfonic acid group as a functional group and an acryloyl group as a cross-linker at terminals in different ratios of sulfonic acid group/acryloyl group (SO3H/Ac) were successfully synthesized as a new thermally stable proton-conducting electrolyte. The cross-linked hyperbranched polymer electrolyte membranes (CL-HBP-SAs) were prepared by thermal polymerizations of the HBP-SA-Acs using benzoyl peroxide, and their ionic conductivities under dry condition and thermal properties were investigated. The ionic conductivities of the CL-HBP-SAs were found to be in the range of 2.2 × 10−4 to 3.3 × 10−6 S/cm, depending upon the SO3H unit contents, at 150 °C under dry condition, and showed the Vogel-Tamman-Fulcher (VTF) type temperature dependence, indicating that proton transfer is cooperated by local polymer chain motion. All CL-HBP-SAs were thermally stable up to 260 °C, and they had suitable thermal stability as electrolyte membranes for the high-temperature fuel cells under dry condition. Fuel cell measurement using a single membrane electrode assembly cell with a cross-linked electrolyte membrane was successfully performed under non-humidified condition. It was demonstrated that applying the concept of dry polymer system to proton conduction is one possible approach toward high-temperature fuel cells.  相似文献   
14.
15.
Subjective sleep feelings and motor activity were measured in seven healthy elderly subjects for 6 days. The subjects were exposed to bright light (6000 lux) for 30 min in the morning or instructed to sit in front of a desktop lighting device without light. The average level of motor activity during the night was significantly decreased in the bright light condition, compared with the controlled condition. However, daytime motor activity did not show significant differences between the two conditions. From these findings, even a short duration of morning bright light is effective in maintaining sleep without changing daytime activity.  相似文献   
16.
17.
BACKGROUND: Late potentials (LPs) after myocardial infarction identify the risk of arrhythmic events and sudden death, and the absence of anterograde flow in the infarct-causing occluded coronary artery frequently is associated with LPs on signal-averaged electrocardiography. The present study was designed to clarify the influence of revascularization of the infarct artery on the LPs in the late course after myocardial infarction. METHODS: We studied 21 patients after myocardial infarction with positive LPs who had at least one occluded infarct coronary artery. We investigated the LPs on signal-averaged electrocardiograms on the day of elective coronary artery bypass grafting (CABG) and 1 week after CABG. RESULTS: There were 25 infarct arteries in the study patients, 13 of which were grafted. The positive LPs disappeared soon after CABG in 13 patients, 10 of whom had grafts to all of the infarct arteries. The LPs persisted in 8, who received no graft to the infarct artery. One week after CABG, the LPs were still present in 4, all of whom had no graft to the infarct right coronary artery. CONCLUSIONS: In patients with positive LPs late after myocardial infarction, grafting to the infarct artery eliminated the LPs soon after CABG.  相似文献   
18.
The availability of acoustic emission technique for detecting and monitoring defects of piping components in fast breeder reactors has been studied in the FAET Committee of the Japan Welding Engineering Society sponsored by,the Power Reactor & Nuclear Fuel Development Corporation. The researches which extended over four years have covered a wide range of experiments and evaluations in order to ensure the usefulness of the acoustic emission technique as a monitoring tool of plant operation.  相似文献   
19.
A 71-year-old man was admitted to our hospital with massive GI bleeding and followed by acute myocardial infarction. Severe three vessel coronary artery disease with poor left ventricular performance (EF: 40%) was demonstrated by coronary angiography. He was referred for CABG. He had also cholecystitis, which needed surgical treatment simultaneously. Combined CABG and cholecystectomy were performed without using gastroepiploic artery as a bypass graft, and through separate median sternotomy and through right upper transrectal laparotomy. Postoperative course was uneventful. This combined procedure is beneficial for the patients with acute cholecystitis and unstable angina.  相似文献   
20.
To better understand genetic alterations in atypical adenomatous hyperplasia (AAH) of the prostate, we examined the prevalence of allelic imbalance at 5 microsatellite polymorphic markers on chromosomes 7q31-35, 8p12-21, 8p22, 8q22.2, and 18q12.2 from 15 patients with AAH. DNA samples were obtained from formalin-fixed paraffin-embedded sections using tissue microdissection. We found allelic imbalance in 7 of 15 (47%) cases of AAH. Genetic changes that commonly occur in early prostatic carcinogenesis and prostate carcinoma are found in AAH. Current data provide evidence of a genetic link between some cases of AAH and carcinoma.  相似文献   
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