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   5127篇
  免费   765篇
  国内免费   555篇
电工技术   183篇
综合类   518篇
化学工业   895篇
金属工艺   215篇
机械仪表   149篇
建筑科学   154篇
矿业工程   61篇
能源动力   159篇
轻工业   321篇
水利工程   73篇
石油天然气   202篇
武器工业   34篇
无线电   760篇
一般工业技术   691篇
冶金工业   136篇
原子能技术   35篇
自动化技术   1861篇
  2024年   16篇
  2023年   56篇
  2022年   107篇
  2021年   137篇
  2020年   190篇
  2019年   196篇
  2018年   148篇
  2017年   198篇
  2016年   235篇
  2015年   241篇
  2014年   330篇
  2013年   386篇
  2012年   406篇
  2011年   391篇
  2010年   298篇
  2009年   348篇
  2008年   325篇
  2007年   316篇
  2006年   285篇
  2005年   250篇
  2004年   174篇
  2003年   162篇
  2002年   164篇
  2001年   144篇
  2000年   113篇
  1999年   109篇
  1998年   110篇
  1997年   105篇
  1996年   94篇
  1995年   59篇
  1994年   50篇
  1993年   43篇
  1992年   49篇
  1991年   26篇
  1990年   30篇
  1989年   33篇
  1988年   19篇
  1987年   12篇
  1986年   11篇
  1985年   12篇
  1984年   15篇
  1983年   14篇
  1982年   8篇
  1981年   4篇
  1980年   5篇
  1979年   6篇
  1977年   3篇
  1975年   2篇
  1973年   4篇
  1951年   2篇
排序方式: 共有6447条查询结果,搜索用时 0 毫秒
1.
Variation exists in all processes. Significant work has been done to identify and remove sources of variation in manufacturing processes resulting in large returns for companies. However, business process optimization is an area that has a large potential return for a company. Business processes can be difficult to optimize due to the nature of the output variables associated with them. Business processes tend to have output variables that are binary, nominal or ordinal. Examples of these types of output include whether a particular event occurred, a customer's color preference for a new product and survey questions that assess the extent of the survey respondent's agreement with a particular statement. Output variables that are binary, nominal or ordinal cannot be modeled using ordinary least‐squares regression. Logistic regression is a method used to model data where the output is binary, nominal or ordinal. This article provides a review of logistic regression and demonstrates its use in modeling data from a business process involving customer feedback. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
2.
Studies on odor mixture perception suggest that although odor components can often be identified in mixtures, mixtures can also give rise to novel perceptual qualities that are not present in the components. Using an olfactory habituation task, the authors evaluated how the perceptual similarity between components in a mixture affects the perceptual quality of the mixture itself. Rats perceived binary mixtures composed of similar components as different from their 2 components, whereas binary mixtures composed of dissimilar components were perceived as very similar to their components. Results show that for both types of mixtures, pretraining to Component A reduces subsequent learning about Component B in rats trained in the presence of A. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
With a view to evaluate the effects of hydraulic retention time and volatile solids loading rate on methane production using water hyacinth, experiments were conducted in a 160 dm3 capacity, well-mixed continuous digestion unit at ambient temperature. The optimal design of biogas plant using water hyacinth was elucidated, to provide a unit giving a maximum methane yield of 0.16 nm3 kg?1 volatile solids added, which was 60% greater than the conventional plant using cowdung. The calculations of optimal design factors were based on reactor size, hydraulic retention time and volatile solids loading rate; considerations were made of capital cost, running costs and operational revenue.  相似文献   
4.
数字调幅制式是当前国际上较先进的调制技术,DX系列全固态数字调幅中波发射机的电声指标和工业效率都是很先进的,过去的DX大功率机采用风冷方式,本文介绍了最新水冷DX-600发射机的设备情况和技术特点。  相似文献   
5.
The general relationship between binary phase diagrams and the thermodynamic properties was system-atically derived without any assumption.A procedure was presented to estimate the thermodynamic proper-ties from the binary phase diagrams.  相似文献   
6.
This report highlights developments in the fields of microporous and mesoporous materials that were published mostly during the year 2002. Selected examples are provided to illustrate new zeolite structures, porous coordination materials, mesoporous solids with new compositions, controlled morphologies, and increased hydrothermal and thermal stabilities, as well as porous solids with tunable pore openings or other structural features that can be dynamically modified. A number of applications are discussed, including stabilization of reactive guests, separations, electronic materials, and sensors.  相似文献   
7.
Grinding, pH adjustment, heat treatment and centrifugation were studied to recover solids from ground cod frames and to apply ultrafiltration (UF) to the resulting aqueous phase. Early heat treatment (90°C/20 min) dissolved collagen into aqueous phase resulting in a very low UF flux. A pH adjustment to 4.5 after grinding (~0.32 cm die), with no heat resulted in efficient separation after centrifuging. UF of the aqueous phase showed an increase in initial flux (23 L/hr m2). However, when the same aqueous material was heated and then centrifuged (1–2% solids removed), UF flux was further increased to 46 L/hr m2and this process gave highest solids recovery (90%).  相似文献   
8.
Tao Li 《Machine Learning》2006,62(3):199-215
Clustering is the problem of identifying the distribution of patterns and intrinsic correlations in large data sets by partitioning the data points into similarity classes. This paper studies the problem of clustering binary data. Binary data have been occupying a special place in the domain of data analysis. A unified view of binary data clustering is presented by examining the connections among various clustering criteria. Experimental studies are conducted to empirically verify the relationships.  相似文献   
9.
An 8-valued commutative ring is developed to process colored images. Algebraic operators are defined to perform a number of operations such as the extraction of the primary colors and contours of different colors.  相似文献   
10.
形态学边缘检测的新算法及其应用   总被引:3,自引:0,他引:3  
提出了一种基于数学形态学的边缘检测的所算法,该算法具有简便和灵活可编程控制等优点,比原来主算法更国完善,在实际应用中有着很好的前景,并给出了实验结果。  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