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   1923篇
  免费   21篇
  国内免费   3篇
电工技术   8篇
化学工业   179篇
金属工艺   8篇
机械仪表   13篇
建筑科学   38篇
矿业工程   2篇
能源动力   11篇
轻工业   84篇
水利工程   4篇
石油天然气   1篇
无线电   54篇
一般工业技术   135篇
冶金工业   1303篇
原子能技术   9篇
自动化技术   98篇
  2023年   6篇
  2022年   8篇
  2021年   15篇
  2020年   5篇
  2019年   7篇
  2018年   10篇
  2017年   9篇
  2016年   13篇
  2015年   13篇
  2014年   20篇
  2013年   49篇
  2012年   21篇
  2011年   30篇
  2010年   27篇
  2009年   31篇
  2008年   31篇
  2007年   38篇
  2006年   26篇
  2005年   27篇
  2004年   17篇
  2003年   14篇
  2002年   21篇
  2001年   15篇
  2000年   11篇
  1999年   49篇
  1998年   418篇
  1997年   237篇
  1996年   144篇
  1995年   91篇
  1994年   67篇
  1993年   88篇
  1992年   36篇
  1991年   33篇
  1990年   17篇
  1989年   24篇
  1988年   14篇
  1987年   25篇
  1986年   19篇
  1985年   21篇
  1984年   6篇
  1983年   5篇
  1982年   11篇
  1981年   11篇
  1980年   5篇
  1979年   5篇
  1978年   9篇
  1977年   36篇
  1976年   66篇
  1975年   8篇
  1969年   8篇
排序方式: 共有1947条查询结果,搜索用时 15 毫秒
41.
The arrangement of 18-S rRNA and 28-S rRNA within their 40-S common precursor molecule (pre-rRNA) of Xenopus laevis was investigated by electron microscopic analysis of secondary structure of nascent pre-rRNA chains of oocytes, and by 5'-end analysis of 18-S rRNA and 28-S rRNA hybridized to the EcoRI fragment of rDNA cloned as plasmid pCD42. Secondary structure mapping of phenol-extracted RNA from nucleolar cores revealed complete pre-rRNA chains or molecules at various stages of processing and pre-rRNA molecules apparently lacking one end. In this latter group, which was regarded as representing nascent chains, more than 90% of the molecules had no 28-S rRNA REGION. This shows that the 28-S rRNA sequence is transcribed after the 18-S rRNA region and hence must be located nearer to the 3' end of the pre-rRNA molecule. For 5' end-group determination [3H]uridine-labelled 18-S rRNA and 28-S rRNA were hybridized, as fragments of about 200 nucleotides, to the plasmid pCD42 containing coding sequences for four-fifths of the 18-S rRNA sequence, the external transcribed spacer, the non-transcribed spacer and a tenth of the 28-S rRNA sequence. The RNA was recovered from the hybrids and analyzed for uridine 3',5'-bisphosphate (pUp) after alkaline hydrolysis. The pUp content of the hybridized 18-S rRNA fragments was 20-fold higher than in those of 28-S rRNA, THUS DEMONSTRATING THAT THE 5' END OF THE 18-S rRNA is located next to the external spacer region. From these results it is concluded that the 18-S rRNA is located close to the 5' end of the 40-S pre-rRNA molecule.  相似文献   
42.
43.
44.
45.
46.
47.
48.
Summary A method is presented that allows the efficient implementation of conditional critical regions combined with scheduling of the waiting processes. It is based on the knowledge of static and invariant relations that exist among the conditional critical regions of a process system. Mathematical methods are applied in order to show the nature of these relations, and to determine them for practical applications.By collecting the conditional critical regions in a program module, a monitor is obtained. Its rather abstract user level allows clear and well structured programming style. It also shows some advantages in comparison to other monitor proposals on the implementation level.Work done mainly at the Fakultät für Informatik, Universität Karlsruhe, Karlsruhe, and also at the Department of Computer Science, University of Toronto, Toronto.  相似文献   
49.
In intermediate risk hormone receptor (HR) positive, HER2 negative breast cancer (BC), the decision regarding adjuvant chemotherapy might be facilitated by multigene expression tests. In all, 142 intermediate risk BCs were investigated using the PAM50-based multigene expression test Prosigna® in a prospective multicentric study. In 119/142 cases, Prosigna® molecular subtyping was compared with local and two central (C1 and C6) molecular-like subtypes relying on both immunohistochemistry (IHC; HRs, HER2, Ki-67) and IHC + tumor grade (IHC+G) subtyping. According to local IHC, 35.4% were Luminal A-like and 64.6% Luminal B-like subtypes (local IHC+G subtype: 31.9% Luminal A-like; 68.1% Luminal B-like). In contrast to local and C1 subtyping, C6 classified >2/3 of cases as Luminal A-like. Pairwise agreement between Prosigna® subtyping and molecular-like subtypes was fair to moderate depending on molecular-like subtyping method and center. The best agreement was observed between Prosigna® (53.8% Luminal A; 44.5% Luminal B) and C1 surrogate subtyping (Cohen’s kappa = 0.455). Adjuvant chemotherapy was suggested to 44.2% and 88.6% of Prosigna® Luminal A and Luminal B cases, respectively. Out of all Luminal A-like cases (locally IHC/IHC+G subtyping), adjuvant chemotherapy was recommended if Prosigna® testing classified as Prosigna® Luminal A at high / intermediate risk or upgraded to Prosigna® Luminal B.  相似文献   
50.
We present The Chinese Room , a visualization interface that allows users to explore and interact with a multitude of linguistic resources in order to decode and correct poor machine translations. The target users of The Chinese Room are not bilingual and are not familiar with machine translation technologies. We investigate the ability of our system to assist such users in decoding and correcting faulty machine translations. We found that by collaborating with our application, end-users can overcome many difficult translation errors and disambiguate translated passages that were otherwise baffling. We also examine the utility of our system to machine translation researchers. Anecdotal evidence suggests that The Chinese Room can help such researchers develop better machine translation systems.  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