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   28798篇
  免费   1520篇
  国内免费   127篇
电工技术   467篇
综合类   231篇
化学工业   4806篇
金属工艺   790篇
机械仪表   659篇
建筑科学   785篇
矿业工程   147篇
能源动力   500篇
轻工业   3974篇
水利工程   208篇
石油天然气   135篇
武器工业   10篇
无线电   1517篇
一般工业技术   5291篇
冶金工业   7304篇
原子能技术   164篇
自动化技术   3457篇
  2023年   300篇
  2022年   259篇
  2021年   597篇
  2020年   502篇
  2019年   426篇
  2018年   904篇
  2017年   814篇
  2016年   898篇
  2015年   777篇
  2014年   907篇
  2013年   1731篇
  2012年   1336篇
  2011年   1342篇
  2010年   1139篇
  2009年   1087篇
  2008年   1221篇
  2007年   1168篇
  2006年   828篇
  2005年   664篇
  2004年   487篇
  2003年   451篇
  2002年   418篇
  2001年   331篇
  2000年   322篇
  1999年   448篇
  1998年   2282篇
  1997年   1373篇
  1996年   958篇
  1995年   580篇
  1994年   471篇
  1993年   426篇
  1992年   171篇
  1991年   179篇
  1990年   153篇
  1989年   158篇
  1988年   150篇
  1987年   159篇
  1986年   137篇
  1985年   217篇
  1984年   180篇
  1983年   165篇
  1982年   130篇
  1981年   175篇
  1980年   172篇
  1979年   121篇
  1978年   105篇
  1977年   222篇
  1976年   480篇
  1975年   85篇
  1973年   111篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
Physically based simulation of human hair is a well studied and well known problem. But the “pure” physically based representation of hair (and other animation elements) is not the only concern of the animators, who want to “control” the creation and animation phases of the content. This paper describes a sketch-based tool, with which a user can both create hair models with different styling parameters and produce animations of these created hair models using physically and key frame-based techniques. The model creation and animation production tasks are all performed with direct manipulation techniques in real-time.  相似文献   
73.
74.
观测值序列的粗差探测方法   总被引:5,自引:3,他引:2  
基于小波分析和未确知滤波理论,研究了对观测序列中粗差进行探测和剔除的方法,并结合实例进行了分析和比较,表明这2种方法得到的探测结果基本一致,均具备较好的应用价值。此外,进一步分析了2种方法的优点和局限性,为实际应用提供了有用的参考。根据2种处理方法的特点,提出了粗差探测的综合探测方法。  相似文献   
75.
(上接2004年第3期) 3环境保护的组织 在环境保护的领域中,已经达到了完成给定的一个很复杂的任务的水平,只有通过综合的技术和复杂手段来取得进一步的成功.Rio and约翰内斯堡会议的觉醒,特别是可持续发展的要求,及组织的工具的快速发展.环境保护领域中的技术可以通过以下手段日益完善:  相似文献   
76.
77.
Thomas Fincke (January 6th, 1561–April 24th, 1656), born in Flensburg (Germany), was one of the very most important and significant scientists in Denmark during the seventeenth century, a mathematician and astrologer and physician in the beginning of modern science, a representative of humanism and an influentual academic organizer. He studied in Strasbourg (since 1577) and Padua (since 1583) and received his M.D. in Basel (1587), he practised as a physician throughout his life (since 1587 or 1590) and became a professor at Copenhagen (1591). But he was best known because of his Geometriae rotundi libri XIIII (1583), a famous book on plane and spherical trigonometry, based not on Euclid but on Petrus Ramus. In this influentual work, in which Fincke introduced the terms tangent and secant and probable first noticed the Law of Tangents and the so-called Newton-Oppel-Mauduit-Simpson-Mollweide-Gauss-formula, he showed himself to be „abreast of the mathematics of his time“.   相似文献   
78.
79.
Modeling mechatronic multibody systems requires the same type of methodology as for designing and prototyping mechatronic devices: a unified and integrated engineering approach. Various formulations are currently proposed to deal with multiphysics modeling, e.g., graph theories, equational approaches, co-simulation techniques. Recent works have pointed out their relative advantages and drawbacks, depending on the application to deal with: model size, model complexity, degree of coupling, frequency range, etc. This paper is the result of a close collaboration between three laboratories, and aims at showing that for “non-academic” mechatronic applications (i.e., issuing from real industrial issues), multibody dynamics formulations can be generalized to mechatronic systems, for the model generation as well as for the numerical analysis phases. Model portability being also an important aspect of the work, they must be easily interfaced with control design and optimization programs. A global “demonstrator”, based on an industrial case, is discussed: multiphysics modeling and mathematical optimization are carried out to illustrate the consistency and the efficiency of the proposed approaches.  相似文献   
80.
OBJECTIVE: To investigate the efficacy of the rectus abdominis muscle flap (RAMF) technique for the closure and augmentation of small, non-compliant bladder exstrophies. PATIENTS AND METHODS: The RAMF technique was used in two girls and two boys (mean age at operation, 31.7 months, range 3-72) with bladder exstrophy. The clinical outcome and urodynamics were assessed during a follow-up of 29 months to 6 years (mean 49.2 months) and included imaging, cystoscopy, biochemical and microbiological studies. RESULTS: There were no urinary tract infections, metabolic problems or electrolyte disturbances and kidney function remained normal in all patients. Radiography confirmed intact function and anatomy of the urinary tract and cystoscopy showed complete coverage of the inner peritoneal layer of RAMF with uroepithelium. No stone formation or mucus production were detected. Currently, three patients void using clean intermittent catheterization through the native urethra and the fourth through an appendiceal Mitrofanoff valve. However, the bladder volume was insufficient at the late follow-up and three patients required bladder augmentation. CONCLUSIONS: The RAMF technique is a good alternative for closing bladder exstrophies and achieves an increase in bladder capacity; however, although there is a mild improvement in bladder capacity and compliance. RAMF should not be used as a bladder augmentation procedure. The technique is indicated in the closure of large bladder defects, bladder exstrophies with small, inelastic, non-compliant bladder remnants and failed primary closures.  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