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   746篇
  免费   14篇
  国内免费   4篇
电工技术   34篇
化学工业   119篇
金属工艺   31篇
机械仪表   13篇
建筑科学   14篇
能源动力   44篇
轻工业   94篇
水利工程   3篇
无线电   52篇
一般工业技术   107篇
冶金工业   201篇
原子能技术   14篇
自动化技术   38篇
  2023年   2篇
  2022年   4篇
  2021年   6篇
  2020年   7篇
  2019年   8篇
  2018年   14篇
  2017年   14篇
  2016年   11篇
  2015年   13篇
  2014年   5篇
  2013年   27篇
  2012年   27篇
  2011年   30篇
  2010年   30篇
  2009年   26篇
  2008年   21篇
  2007年   36篇
  2006年   21篇
  2005年   21篇
  2004年   13篇
  2003年   18篇
  2002年   27篇
  2001年   26篇
  2000年   22篇
  1999年   22篇
  1998年   82篇
  1997年   55篇
  1996年   41篇
  1995年   20篇
  1994年   14篇
  1993年   15篇
  1992年   5篇
  1991年   6篇
  1990年   4篇
  1989年   3篇
  1988年   2篇
  1987年   3篇
  1986年   2篇
  1985年   5篇
  1984年   5篇
  1983年   5篇
  1982年   6篇
  1981年   7篇
  1980年   3篇
  1979年   3篇
  1978年   5篇
  1976年   8篇
  1975年   2篇
  1974年   5篇
  1972年   2篇
排序方式: 共有764条查询结果,搜索用时 31 毫秒
761.
To investigate important factors affecting the reliability of the analytical results, proficiency tests were attempted for the histochemical method (GUS method) and the qualitative PCR method (PCR method) to detect genetically modified papaya (55-1) in the Japanease official method. The test samples were distributed to twenty-three laboratories that participated in the study and were examined according to the protocol. All the data collected from participating laboratories were statistically analyzed. In the PCR method, one negative sample was detected as positive using detection primers in one laboratory, though the sample was negative when checked using confirmation primers. Contamination might have occurred in the step of the preparation of the PCR sample solution using detection primers. In the GUS method, all the test samples were identified as expected. Thus, all the laboratories reported correct results overall.  相似文献   
762.
An assessment is made of hydrogen technology development; in particular, economy as an energy carrier, applicability for end-uses and the potential of the market in the future. Specifically, rough static cost comparisons are made on several modes of electricity transmission and hydrogen transport, and on several ways of off-peak electricity saving; including energy storage in the form of hydrogen. Then, the quantity of oil that could be saved for some representative end-use sectors if hydrogen fuel were to be introduced is discussed. Finally, a potential market is assessed, by projecting overall future energy supply/demand dynamics in Japan.  相似文献   
763.
Phase equilibria have been established in the binary system Gd2O3MoO3 including Gd2(MoO4)3 with ferroelectricity and ferroelasticity below 159°C, by means of differential thermal analysis and X-ray powder diffraction techniques. It is shown that Gd2(MoO4)3 has no solubility of other compounds in this system and melts congruently on its stoichiometric composition. Three distinct intermediate compounds were found. Gd2O3.6MoO3 and Gd2O3.4MoO3 are formed by a peritectic reaction at 730°C and 825°C, respectively. The remaining compound Gd2O3.MoO3 with the structure closely related to Eu2O3.MoO3 does not decompose below 1400°C.  相似文献   
764.
Hydrogen dissolved in metals as a result of internal and external hydrogen can affect the mechanical properties of the metals, principally through the interactions between hydrogen and material defects. Multiple phenomena such as hydrogen dissolution, hydrogen diffusion, hydrogen redistribution and hydrogen interactions with vacancies, dislocations, grain boundaries and other phase interfaces are involved in this process. Consequently, several hydrogen embrittlement(HE) mechanisms have been successively proposed to explain the HE phenomena, with the hydrogen-enhanced decohesion mechanism, hydrogenenhanced localized plasticity mechanism and hydrogen-enhanced strain-induced vacancies being some of the most important. Additionally, to reduce the risk of HE for engineering structural materials in service, surface treatments and microstructural optimization of the alloys have been suggested. In this review, we report on the progress of the studies on HE in metals, with a particular focus on steels. It focuses on four aspects:(1) hydrogen diffusion behavior;(2) hydrogen characterization methods;(3) HE mechanisms; and(4) the prevention of HE. The strengths and weaknesses of the current HE mechanisms and HE prevention methods are discussed, and specific research directions for further investigation of fundamental HE mechanisms and methods for preventing HE failure are identified.  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