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   924篇
  免费   3篇
  国内免费   1篇
电工技术   9篇
化学工业   94篇
金属工艺   4篇
机械仪表   44篇
建筑科学   44篇
矿业工程   6篇
能源动力   1篇
轻工业   307篇
水利工程   8篇
石油天然气   10篇
武器工业   1篇
无线电   42篇
一般工业技术   310篇
冶金工业   8篇
原子能技术   1篇
自动化技术   39篇
  2019年   1篇
  2018年   1篇
  2012年   99篇
  2011年   120篇
  2010年   33篇
  2009年   7篇
  2008年   90篇
  2007年   85篇
  2006年   65篇
  2005年   55篇
  2004年   51篇
  2003年   46篇
  2002年   50篇
  2001年   42篇
  2000年   24篇
  1999年   25篇
  1998年   21篇
  1997年   9篇
  1996年   11篇
  1995年   13篇
  1994年   9篇
  1993年   5篇
  1992年   8篇
  1991年   8篇
  1990年   13篇
  1989年   8篇
  1988年   2篇
  1987年   1篇
  1986年   3篇
  1985年   5篇
  1984年   3篇
  1983年   5篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1978年   3篇
  1968年   1篇
排序方式: 共有928条查询结果,搜索用时 15 毫秒
1.
Murp.TM  杨帆 《国外钢铁》1994,19(1):62-64
轧机不需要延长停机时间,在三个月内,就安装了厚板轧机新的过程控制计算机系统,并运行完全可靠。  相似文献   
2.
3.
The authors focus on the multidimensional inverse scattering of objects buried in an inhomogeneous elastic background structure. The medium is probed by an ultrasonic force and the scattered field is observed along a receiver array. The goal is to retrieve both the geometry (imaging problem) and the constitutive parameters (inverse problem) of the object through an appropriate multiparameter direct linear inversion. The problem is cast in terms of a vector integral equation elastic scattering framework. The multidimensional inverse scattering problem, being nonlinear and ill-posed, is linearized within the Born approximation for inhomogeneous background, and a minimum-norm least-square solution to the discretized version of the vector integral formulation is sought. The solution is based on a singular value decomposition of the forward operator matrix. The method is illustrated on a 2-D problem where constrained least-square inversion of the object is performed from synthetic data. A Tikhonov regularization scheme is examined and compared to the minimum-norm least-square estimate.  相似文献   
4.
5.
A single two-dimensional image is an ambiguous representation of the three-dimensional world?many different scenes could have produced the same image?yet the human visual system is ex-tremely successful at recovering a qualitatively correct depth model from this type of representation. Workers in the field of computational vision have devised a number of distinct schemes that attempt to emulate this human capability; these schemes are collectively known as ``shape from...' methods (e.g., shape from shading, shape from texture, or shape from contour). In this paper we contend that the distinct assumptions made in each of these schemes is tantamount to providing a second (virtual) image of the original scene, and that each of these approaches can be translated into a conventional stereo formalism. In particular, we show that it is frequently possible to structure the problem as one of recovering depth from a stereo pair consisting of the supplied perspective image (the original image) and an hypothesized orthographic image (the virtual image). We present a new algorithm of the form required to accomplish this type of stereo reconstruction task.  相似文献   
6.
The response of Atta sexdens rubropilosa Forel workers to essential oils, epicuticular wax and hexane, dichloromethane, ethyl acetate, and methanol extracts of Eucalyptus maculata was evaluated. Hexane extracts of E. maculata interfered with the recognition mechanism among workers. The main active compounds identified from this plant were the sesquiterpenes elemol and beta-eudesmol. These compounds may be responsible for the resistance of this species to ant attack.  相似文献   
7.
8.
The growth of ferroelectric BaMgF(4) thin films on Si(100), sapphire, and other substrates under ultrahigh vacuum (UHV) conditions is reported. Microstructural characterization of the films using transmission electron microscopy (TEM) revealed that they were oriented crystalline films, although not epitaxial. Ferroelectric hysteresis measurements yielded spontaneous polarization and coercivity values of almost 1.0 muC/cm(2) and 160 kV/cm, respectively. The discrepancy with the bulk ferroelectric values were attributed to the electrical contacts, impurities in the film, and lack of polar axis orientation. Preliminary capacitance-voltage (C-V) hysteresis measurements on a 480-nm-thick BaMgF(4) film yielded a 10.8-V threshold shift (memory window) in response to a +/-10-V programming voltage for a MIS gate structure similar to that of the ferroelectric memory field-effect transistor (FEMFET).  相似文献   
9.
10.
In the past several years, various ontologies and terminologies such as the Gene Ontology have been developed to enable interoperability across multiple diverse medical information systems. They provide a standard way of representing terms and concepts thereby supporting easy transmission and interpretation of data for various applications. However, with their growing utilization, not only has the number of available ontologies increased considerably, but they are also becoming larger and more complex to manage. Toward this end, a growing body of work is emerging in the area of modular ontologies where the emphasis is on either extracting and managing "modules" of an ontology relevant to a particular application scenario (ontology decomposition) or developing them independently and integrating into a larger ontology (ontology composition). In this paper, we investigate state-of-the-art approaches in modular ontologies focusing on techniques that are based on rigorous logical formalisms as well as well-studied graph theories. We analyze and compare how such approaches can be leveraged in developing tools and applications in the biomedical domain. We conclude by highlighting some of the limitations of the modular ontology formalisms and put forward additional requirements to steer their future development.  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