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   3183篇
  免费   152篇
  国内免费   4篇
电工技术   35篇
综合类   3篇
化学工业   838篇
金属工艺   58篇
机械仪表   79篇
建筑科学   95篇
矿业工程   35篇
能源动力   151篇
轻工业   390篇
水利工程   29篇
石油天然气   8篇
无线电   258篇
一般工业技术   434篇
冶金工业   353篇
原子能技术   31篇
自动化技术   542篇
  2024年   10篇
  2023年   42篇
  2022年   104篇
  2021年   150篇
  2020年   98篇
  2019年   81篇
  2018年   102篇
  2017年   90篇
  2016年   108篇
  2015年   79篇
  2014年   148篇
  2013年   212篇
  2012年   207篇
  2011年   212篇
  2010年   168篇
  2009年   129篇
  2008年   162篇
  2007年   130篇
  2006年   92篇
  2005年   84篇
  2004年   63篇
  2003年   46篇
  2002年   52篇
  2001年   45篇
  2000年   41篇
  1999年   37篇
  1998年   61篇
  1997年   44篇
  1996年   45篇
  1995年   44篇
  1994年   29篇
  1993年   39篇
  1992年   20篇
  1991年   26篇
  1990年   14篇
  1989年   14篇
  1988年   15篇
  1987年   15篇
  1986年   13篇
  1985年   18篇
  1984年   16篇
  1983年   13篇
  1982年   21篇
  1981年   14篇
  1980年   11篇
  1979年   11篇
  1977年   15篇
  1972年   11篇
  1944年   10篇
  1943年   21篇
排序方式: 共有3339条查询结果,搜索用时 15 毫秒
11.
Rapid development of underwater technology during the last two decades yielded more affordable sensors and underwater vehicles, and, as a result, expanded their use from exclusively offshore industry towards smaller interdisciplinary research groups. Regardless of application, knowing the location of the vehicle operating underwater is crucial. Relatively inexpensive solution is sensor fusion based on a dynamic model of the vehicle aided by a Doppler Velocity Log and a Ultra-Short Base Line position system. Raw data from the sensors are highly asynchronous and susceptible to outliers, especially in shallow water environment. This paper presents detailed sensor analysis based on experimental data gathered in shallow waters, identifies outliers, presents an intuitive and simple sensor fusion algorithm and finally, discusses outlier rejection. The approach has been experimentally verified on medium size remotely operated vehicle.  相似文献   
12.
Ermittlung des Einflusses von Silicium, Germanium, Zinn und Kupfer auf Morphologie und Kinetik der feindispersen diskontinuierlichen Ausscheidung in α-Eisen-Zink-Legierungen mit licht- und elektronenmikroskopischen sowie Röntgenbeugungsverfahren. Berechnung der Aktivierungsenergie aus der Temperaturabhängigkeit der Wachstumsgeschwindigkeit und Grenzflächendiffusionskoeffizienten aus der Wachstumsgeschwindigkeit, dem Lamellenabstand und der Grenzschichtdicke.  相似文献   
13.
Crohn’s disease (CD) is a complex, disabling, idiopathic, progressive, and destructive disorder with an unknown etiology. The pathogenesis of CD is multifactorial and involves the interplay between host genetics, and environmental factors, resulting in an aberrant immune response leading to intestinal inflammation. Due to the high morbidity and long-term management of CD, the development of non-pharmacological approaches to mitigate the severity of CD has recently attracted great attention. The gut microbiota has been recognized as an important player in the development of CD, and general alterations in the gut microbiome have been established in these patients. Thus, the gut microbiome has emerged as a pre-eminent target for potential new treatments in CD. Epidemiological and interventional studies have demonstrated that diet could impact the gut microbiome in terms of composition and functionality. However, how specific dietary strategies could modulate the gut microbiota composition and how this would impact host–microbe interactions in CD are still unclear. In this review, we discuss the most recent knowledge on host–microbe interactions and their involvement in CD pathogenesis and severity, and we highlight the most up-to-date information on gut microbiota modulation through nutritional strategies, focusing on the role of the microbiota in gut inflammation and immunity.  相似文献   
14.
In recent years, an increase in the prevalence hypermucoviscous carbapenem-resistant Klebsiella pneumoniae with sequence type 25 (ST25) was detected in hospitals of Tucuman (Northwest Argentina). In this work, the virulence and the innate immune response to two K. pneumoniae ST25 strains (LABACER 01 and LABACER 27) were evaluated in a murine model after a respiratory challenge. In addition, comparative genomics was performed with K. pneumoniae LABACER01 and LABACER27 to analyze genes associated with virulence. Both LABACER01 and LABACER27 were detected in the lungs of infected mice two days after the nasal challenge, with LABACER01 counts significantly higher than those of LABACER27. Only LABACER01 was detected in hemocultures. Lactate dehydrogenase (LDH) and albumin levels in bronchoalveolar lavage (BAL) samples were significantly higher in mice challenged with LABACER01 than in LABACER27-infected animals, indicating greater lung tissue damage. Both strains increased the levels of neutrophils, macrophages, TNF-α, IL-1β, IL-6, KC, MCP-1, IFN-γ, and IL-17 in the respiratory tract and blood, with the effect of LABACER01 more marked than that of LABACER27. In contrast, LABACER27 induced higher levels of IL-10 in the respiratory tract than LABACER01. Genomic analysis revealed that K. pneumoniae LABACER01 and LABACER27 possess virulence factors found in other strains that have been shown to be hypervirulent, including genes required for enterobactin (entABCDEF) and salmochelin (iroDE) biosynthesis. In both strains, the genes of toxin–antitoxin systems, as well as regulators of the expression of virulence factors and adhesion genes were also detected. Studies on the genetic potential of multiresistant K. pneumoniae strains as well as their cellular and molecular interactions with the host are of fundamental importance to assess the association of certain virulence factors with the intensity of the inflammatory response. In this sense, this work explored the virulence profile based on genomic and in vivo studies of hypermucoviscous carbapenem-resistant K. pneumoniae ST25 strains, expanding the knowledge of the biology of the emerging ST25 clone in Argentina.  相似文献   
15.
16.
17.
18.
19.
20.
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