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   824篇
  免费   16篇
  国内免费   3篇
电工技术   80篇
化学工业   173篇
金属工艺   30篇
机械仪表   18篇
建筑科学   11篇
能源动力   32篇
轻工业   47篇
水利工程   2篇
石油天然气   4篇
无线电   86篇
一般工业技术   107篇
冶金工业   198篇
原子能技术   26篇
自动化技术   29篇
  2022年   2篇
  2021年   7篇
  2020年   4篇
  2018年   6篇
  2017年   9篇
  2016年   13篇
  2015年   13篇
  2014年   11篇
  2013年   19篇
  2012年   14篇
  2011年   33篇
  2010年   24篇
  2009年   28篇
  2008年   36篇
  2007年   27篇
  2006年   33篇
  2005年   21篇
  2004年   22篇
  2003年   35篇
  2002年   20篇
  2001年   17篇
  2000年   14篇
  1999年   17篇
  1998年   89篇
  1997年   44篇
  1996年   46篇
  1995年   20篇
  1994年   21篇
  1993年   22篇
  1992年   9篇
  1991年   10篇
  1990年   8篇
  1989年   6篇
  1988年   8篇
  1987年   11篇
  1986年   17篇
  1985年   8篇
  1984年   11篇
  1983年   7篇
  1982年   7篇
  1981年   9篇
  1980年   5篇
  1979年   7篇
  1978年   7篇
  1977年   14篇
  1976年   14篇
  1975年   3篇
  1974年   3篇
  1973年   5篇
  1972年   2篇
排序方式: 共有843条查询结果,搜索用时 15 毫秒
51.
52.
53.
This paper is intended to describe the expert system RHINOS for diagnosing patients whose chief complaints are headache and facial pain. RHINOS assists physicians in diagnosing the above-mentioned disease. For this purpose the authors surveyed diagnosing processes used by physicians to determine what advice physicians want. As a result, the author reached the conclusion that knowledge for diagnosing the above-mentioned disease should be categorized according to four types of rules: exclusive rules (if the patient has disease D, he must have symptoms S1, S2,....,Sn), inclusive rules (if the patient has symptoms S1, S2,...,Sn, he has disease D with a probability X (0 less than X less than 1)), associate rules (if the patient has symptoms S1, S2,...,Sn the probability that he has the disease D increases) and disease image (if the patient has disease D, he may have symptoms S1, S2,...,Sn). Through harmonious use of these four types of rules, RHINOS gives the advise that physicians want. RHINOS is widely available because it is implemented by Prolog-KABA which is operative on personal computers such as NEC PC9801 and IBM-PC.  相似文献   
54.
A simple mechanistic model for brown coal liquefaction has been developed and used in conjunction with data from PDU operation to examine the factors which contribute to hydrogen consumption. It is found that after allowing for hydrogen generation requirements, the maximum achievable refined product yield from Morwell brown coal ((ssuming a naphtha/middle distillate ratio of 5:6 together with refined product H/C ratios of 1.8 for naphtha and 1.5 for middle distillate) is 46 - 48%, corresponding to a hydrogen consumption of 6.6 - 7.6%. Alternatively, if consideration of hydrogen generation is excluded (as in pilot plant operation), the maximum yield would be around 54%, corresponding to 6.6% net hydrogen consumption. These results suggest that an aim of maximizing product yield by decreasing Cl-C4 gas formation may not be as desirable as at first thought.  相似文献   
55.
Disposable Australian iron-slurry (AL) and NiO-MoO3-Al2O3 (NiMo) catalysts were used in hydrocracking experiments to convert Marlim vacuum residue (ML-VR) in a slurry-bed continuous flow reactor at temperatures of 440-460 °C, under a hydrogen pressure of 14.7 MPa and an LHSV of 0.5. The degree of conversion ranged from 54 to 83%, depending on the reaction temperature and catalyst used, with AL giving more complete conversion than NiMo. AL also proved more active in the removal of nickel. Hydrogen consumption was linearly correlated with conversion regardless of the catalyst used.  相似文献   
56.
57.
The epitaxial and homogeneous irradiation induced re-crystallization of amorphous MgAl2O4 was studied by means of continuous Frenkel pair accumulation in the molecular dynamics framework. Present results point out that the re-crystallization induced by Frenkel pair accumulation appears in both cases to be thermally enhanced but non diffusive. It is governed by a local rearrangement of each point defect in the homogeneous case, while spontaneous Frenkel pair recombination process in the crystalline part or at the interface drives the re-crystallization in the epitaxial case.  相似文献   
58.
59.
A new effective catalysts combination of iron — nickel for alcohol CVD technique was found. This catalyst catalyzed well as well as the typical catalyst of iron — cobalt catalysts, but gave a different diameter distribution. Calculating their electrical density of states under the assumption of their solid lattice structures, the result was fairly consistent with experimental results. The number of electrical states near Fermi level that is considered to be important for catalytic reaction is enough and the DOS of iron – nickel catalyst was quite similar to that of cobalt unlike manganese – copper catalyst. Consequently, a blend of catalysts that has a similar DOS to cobalt and has enough states near the Fermi level can be a good catalyst for alcohol CVD.  相似文献   
60.
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