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   703篇
  免费   28篇
  国内免费   1篇
电工技术   20篇
化学工业   139篇
金属工艺   4篇
机械仪表   4篇
建筑科学   18篇
矿业工程   4篇
能源动力   3篇
轻工业   239篇
水利工程   12篇
石油天然气   1篇
无线电   37篇
一般工业技术   64篇
冶金工业   143篇
原子能技术   1篇
自动化技术   43篇
  2023年   8篇
  2022年   18篇
  2021年   16篇
  2020年   8篇
  2019年   19篇
  2018年   16篇
  2017年   15篇
  2016年   12篇
  2015年   11篇
  2014年   20篇
  2013年   26篇
  2012年   20篇
  2011年   24篇
  2010年   17篇
  2009年   16篇
  2008年   18篇
  2007年   16篇
  2006年   15篇
  2005年   19篇
  2004年   11篇
  2003年   13篇
  2002年   12篇
  2001年   13篇
  2000年   6篇
  1999年   13篇
  1998年   47篇
  1997年   37篇
  1996年   20篇
  1995年   11篇
  1994年   9篇
  1993年   9篇
  1992年   11篇
  1991年   8篇
  1990年   14篇
  1989年   7篇
  1988年   11篇
  1987年   7篇
  1986年   18篇
  1985年   17篇
  1984年   10篇
  1982年   9篇
  1981年   7篇
  1980年   5篇
  1978年   6篇
  1977年   6篇
  1976年   15篇
  1975年   9篇
  1974年   10篇
  1973年   10篇
  1972年   8篇
排序方式: 共有732条查询结果,搜索用时 15 毫秒
1.
2.
42 different plywoods consisting of a maximum number of 9 beechveneers were investigated. This report describes the relations between the composition of the panels and the impact bending behavior. Recommandations are given for the manufacture of plywood with a high shock resistance.  相似文献   
3.
4.
A novel method for the computation of the steady state of nonlinear oscillators including distributed elements is presented which exploits advantages of both time-domain and frequency-domain simulation. The oscillator network is divided into a linear subnetwork described by a hybrid matrix in the frequency domain and a nonlinear differential equation solved in the time domain. The periodic steady state of the oscillator is shown to be equivalent to the solution of a boundary value problem, where the boundary conditions are given at a set of points along the time axis. For the solution of the boundary value problem the multiple shooting algorithm is applied. It is shown that the bandwidth in the nonlinear subnetwork can be chosen arbitrarily high regardless of the number of harmonics at the ports connecting the subnetworks. In order to demonstrate the feasibility of the method and to discuss the error mechanisms it is applied to two examples: a Clapp oscillator including a piecewise-linear characteristic and an integrated GaAs MESFET oscillator at 10.7 GHz  相似文献   
5.
Potential for large-scale physical transport processes to affect recruitment of Lake Michigan yellow perch (Perca flavescens) was studied by examining the variation in larval distribution, growth rate, and settlement during June–August 1998–2003 using a 3D particle transport model linked with an individual-based bioenergetics growth model. In all years, virtual larvae were released nearshore in southwestern Lake Michigan, a known and important spawning region for yellow perch. For any given year, the same circulation pattern and water temperature either promoted or reduced yellow perch settlement depending on the consumption rates and settlement size chosen in the growth model. Increased consumption increased the number of settled larvae and expanded the total area where larvae settled, whereas increased settlement size reduced the number of settled larvae and reduced the overall settlement area. Interannual variability in circulation patterns and water temperature also resulted in contrasting larval settlement rates, settlement locations, and size of settlement areas between years. Model predictions were most consistent with field observations of age-0 yellow perch from Illinois and Michigan waters when settlement was assumed to occur at 50 mm. Moreover, our model suggests that larvae originating from southwestern Lake Michigan can recruit anywhere within the southern basin and even in the northern basin. Future model improvement will require information on the relative contribution of various sectors to the larval pool, their distribution with reference to the hydrodynamic landscape, the feeding and growth of yellow perch during their pelagic phase, and the size at transition to demersal stage.  相似文献   
6.
Curvilinear reformatting of 3D magnetic resonance imaging data has been recognized by the medical community as a helpful noninvasive tool for displaying the cerebral anatomy. It consists of automatically creating, with respect to a reference surface, a series of equidistant curvilinear slices at progressively deeper cuts. In comparison with planar slices, it allows more precise localization of lesions and identification of subtle structural abnormalities. However, current curvilinear reformatting tools either rely on the time-consuming manual delineation of guiding curves on 2D slices, or require costly automatic brain segmentation procedures. In addition, they extract the skin and skull, impeding a precise topographic correlation between the location of the brain lesion and skin surface. This impairs planning of craniotomy for neurosurgery, and of the appropriate implantation of electrodes for intracranial electroencephalography in presurgical evaluation. In this work, we present a novel approach based on direct manipulation of the visualized volume data. By using a 3D painting metaphor, the reference surface can be defined incrementally, according to the principle that the user interacts with what she/he sees. As a response, an animation of the reformatting process is displayed. The focus of this paper is a new volume tagging algorithm behind user interactions. It works at an interactive frame rate on current graphics hardware.  相似文献   
7.
Deposited layers are often negative phenomena of membrane processes. They reduce flux and elongate the time for concentration or separation. Electron micrographs made by other investigators have shown that the deposit is compact adjacent to the membrane and spongy on top. The compact layer is as homogeneous as the active layer of the membrane; therefore, it may have the same retention behaviour as the membrane.

Our objective has been to investigate the rejection behaviour of deposit layers in reverse osmosis. Membrane fouling was caused by whey proteins and skin milk proteins with or without additional heat treatment. After the forming of the deposited layer the rejection of apple juice flavour was determined and compared with an experiment without a deposited layer. The measurements show that the rejection could be influenced depending on the treatment of the layer.  相似文献   

8.
Microsystem Technologies - We report the synergistic photoluminescent effect observed in heterogeneous colloidal solutions comprising different volumetric concentrations of Si and CdTe quantum dots...  相似文献   
9.
No doubt, words play a major role in language production, hence finding them is of vital importance, be it for writing or for speaking (spontaneous discourse production, simultaneous translation). Words are stored in a dictionary, and the general belief holds, the more entries the better. Yet, to be truly useful the resource should contain not only many entries and a lot of information concerning each one of them, but also adequate navigational means to reveal the stored information. Information access depends crucially on the organization of the data (words) and the access keys (meaning/form), two factors largely overlooked. We will present here some ideas of how an existing electronic dictionary could be enhanced to support a speaker/writer to find the word s/he is looking for. To this end we suggest to add to an existing electronic dictionary an index based on the notion of association, i.e. words co-occurring in a well balanced corpus, the latter being supposed to represent the average citizen’s knowledge of the world. Before describing our approach, we will briefly take a critical look at the work being done by colleagues working on automatic, spontaneous or deliberate language production,—that is, computer-generated language, simulation of the mental lexicon, or WordNet (WN),—to see how adequate they are with regard to our goal.  相似文献   
10.
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