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   2853篇
  免费   145篇
  国内免费   11篇
电工技术   44篇
综合类   13篇
化学工业   540篇
金属工艺   70篇
机械仪表   67篇
建筑科学   150篇
矿业工程   12篇
能源动力   88篇
轻工业   164篇
水利工程   5篇
石油天然气   10篇
无线电   306篇
一般工业技术   543篇
冶金工业   490篇
原子能技术   26篇
自动化技术   481篇
  2023年   25篇
  2022年   11篇
  2021年   79篇
  2020年   61篇
  2019年   73篇
  2018年   60篇
  2017年   51篇
  2016年   88篇
  2015年   72篇
  2014年   80篇
  2013年   171篇
  2012年   135篇
  2011年   188篇
  2010年   134篇
  2009年   130篇
  2008年   128篇
  2007年   154篇
  2006年   109篇
  2005年   110篇
  2004年   82篇
  2003年   88篇
  2002年   80篇
  2001年   53篇
  2000年   41篇
  1999年   60篇
  1998年   128篇
  1997年   69篇
  1996年   74篇
  1995年   66篇
  1994年   29篇
  1993年   34篇
  1992年   26篇
  1991年   21篇
  1990年   21篇
  1989年   21篇
  1988年   19篇
  1987年   27篇
  1986年   14篇
  1985年   10篇
  1984年   15篇
  1983年   15篇
  1982年   14篇
  1981年   8篇
  1980年   13篇
  1979年   15篇
  1978年   11篇
  1977年   12篇
  1976年   24篇
  1975年   9篇
  1971年   10篇
排序方式: 共有3009条查询结果,搜索用时 15 毫秒
1.
This study investigates the behavior of fruit and vegetable samples during drying. The experimental data are fitted to several different thin-layer drying models. Regression analysis is used to determine model parameters, while statistical indicators serve to evaluate the goodness of fit. The power function model gives the best fit for all examined samples. Based on this model, different drying and heat storage technologies can be combined to ensure that the required residual moisture content of an agricultural product is reached. It is demonstrated on the case of a specific Togolese processing plant that under favorable conditions, fossil fuel consumption can be decreased by 33 %.  相似文献   
2.
We demonstrate in this study that the combination of modern inline monitoring methods [here: inline nuclear magnetic resonance (NMR)] with simulations gains more exact and profound kinetic results than previously used methods like linearization without that combination. The 1H-NMR spectroscopic data (more than 100 data points) are used to construct the copolymerization diagram. The reactivity ratios are obtained applying the van Herks nonlinear least square method. The examination of the radical copolymerization of 2-hydroxyethyl methacrylate (HEMA) with (2-{[2-(ethoxycarbonyl)prop-2-en-1-yl]oxy}ethyl) phosphonic acid (ECPPA) as important adhesive monomer used in dentistry yields reactivity ratios of rHEMA = 1.83; rECPPA = 0.42. The copolymerization diagram reflects nonideal, non-azeotropic copolymerization. The sequence distribution of the obtained by Monte Carlo simulation indicates the generation of statistical copolymers. As an important finding, it is demonstrated that the repeating units responsible for etching and adhesion are arranged over the whole polymer chain, which is necessary to achieve proper functionality. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48256.  相似文献   
3.
4.
The thermal equilibrium decomposition properties of the PdO-Pd system under oxygen partial pressures ranging from 0.1 to 1.0 atm in a total combined pressure of oxygen and nitrogen of 1.0 atm were investigated by means of thermal-gravimetric analyses. The phase diagram of Pd-PdO over the range of oxygen/nitrogen gas concentration was established. The decomposition temperature of PdO to Pd was found to increase with the partial pressure of oxygen.  相似文献   
5.
6.
7.
8.
A total of 438 manufacturing firms reported their business relocation activity, their overall attitude toward the business climate in Michigan, and their assessment of 34 business climate dimensions. Using a lens model paradigm, we explored reasons for a lack of relation between actual relocation decisions and overall business climate attitudes. Location decisions were most highly correlated with distance and labor considerations, whereas overall business climate was most highly correlated with tax considerations, and secondarily correlated with labor problems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
9.
Various image processing applications exploit a model of the human visual system (HVS). One element of HVS-models describes the masking-effect, which is typically parameterized by psycho-visual experiments that employ superimposed sinusoidal stimuli. Those stimuli are oversimplified with respect to real images and can capture only very elementary masking-effects. To overcome these limitations a new psycho-visual test method is proposed. It is based on natural scenery stimuli and operates in the wavelet domain. The collected psycho-visual data is finally used to evaluate the performance of various masking models under conditions as found in real image processing applications like compression.  相似文献   
10.
Due to their small size, mammalian oocytes and embryos pose unique problems during preparation for transmission electron microscopy. This paper outlines a method which combines protein embedding with centrifugation to locate the specimens on the face of a Beem capsule mould. This method facilitates both the processing of oocytes with minimal loss and rapid location of the specimens within the block for simultaneous sectioning, staining and examination.  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